Moon mission, India/ Chandrayaan

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The first images of the Moon as viewed by Chandrayaan-3 in 2023, August

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Till 2023 Jan

Priyanka Deo, January 27, 2023: The Times of India

India has a long and rich history of space exploration, with a focus on low-cost, high-impact missions, specifically to the moon. But isn’t going to the moon “old news?”

After all, American astronaut Neil Armstrong was the first person to walk on the moon in 1969; more than 50 years ago.

Why is going to the moon still relevant? And what will it mean for India? These are the core questions.

Ancient cultures and the moon

Moon exploration is not just old news, but very old news. Humans have been studying the moon for centuries now. In fact, it was ancient cultures that made some insightful observations about it. Ancient Egyptians believed the moon was a divine being, having the power to influence weather, tides and even human behavior. The Mayans linked the moon with fertility and agriculture.

The moon was thought to be made of an incorruptible substance by the ancient Greeks.

They called it "lunar material," and they believed it was what gave the moon its dazzling aspect.

The ancient Chinese, like the Egyptians, also thought the moon was formed of jade and was in charge of regulating water tides.

Moon exploration

Fast forward 10-15 centuries.

USA’s NASA launched Apollo 11 in 1969. It was the first manned lunar mission. Neil Armstrong made the first human steps on the moon, ushering in a new age of lunar research.

The importance of visiting the moon can be attributed to many factors. As the sole naturally occurring satellite of the Earth, the moon is a great place to research the formation of the solar system, the makeup of the moon's interior, and the effects of the moon's gravity on Earth.

The moon is also a potential resource for humankind. It contains minerals and other materials that could be useful for development. The moon’s environment could also be used to foster new technology that could be used in navigation, communication and transportation.

Like our ancestors, the moon still has cultural and religious importance for humans around the world, just as it did for our ancestors.

Hindu god Chandra is a representation of calmness, tranquility, and purity. The lunar phases and cycles of time dictate our activities. The moon is also connected with god Krishna who is depicted holding the crescent moon on his head.

What has India done in moon exploration?

India's first moon mission, Chandrayaan-1, was launched in October 2008 with the goal of studying the lunar surface and looking for evidence of water.

The mission was a major success for the Indian Space Research Organisation (ISRO), as it discovered the presence of water molecules on the moon.

In addition to this, ISRO deployed the Moon Impact Probe, which landed on the moon’s surface and collected data on the composition and density.

Chandrayaan-1's success inspired ISRO to launch a number of other lunar missions, notably Chandrayaan-2, which launched in July 2019.

Since Chandrayaan-2 had a lander, rover, and orbiter, it was a more ambitious mission.

The Pragyan rover was created to investigate the lunar surface and carry out various scientific experiments, while the Vikram lander was planned to settle on the south pole zone of the moon. Unfortunately, the Chandrayaan-2 mission failed when the Vikram lander lost communication with mission control just minutes before its planned landing.

Despite this setback, the mission was still considered a success, as the orbiter was able to gather a wealth of data on the moon's surface and atmosphere.

ISRO space exploration

In addition to its lunar missions, India has also conducted a number of other space missions, including the launch of its first satellite, Aryabhat, in 1975.

Since then, other satellites have been launched by the nation for a range of uses, including communication, navigation, and earth observation.

ISRO is working on Gaganyaan, which will send Indian astronauts into space.

One of India's most notable space achievements was the successful launch of the Mars Orbiter Mission (MOM) in 2014.

The MOM spacecraft, also known as Mangalyaan, was India's first interplanetary mission and was designed to study the surface and atmosphere of Mars.

India became the 4th nation after the United States, the Soviet Union, and the European Space Agency to successfully reach Mars thanks to the mission's great success.

India's space program has come a long way in a short time, and the country is now considered a major player in the global space community. The nation is in an especially unique position to make important global contributions to space exploration in the years to come with an emphasis on low-cost, high-impact missions and a dedication to pursuing cutting-edge research.

Moon missions

An overview, till 2023 July

Amitabh Sinha, August 24, 2023: The Indian Express

The anatomy of the Chandrayaan-3 spacecraft
From: Amitabh Sinha, August 24, 2023: The Indian Express
How Chandrayaan-3 inched closer to the Lunar surface
From: Amitabh Sinha, August 24, 2023: The Indian Express
Timeline of the Chandrayaan-3 mission
From: Amitabh Sinha, August 24, 2023: The Indian Express

Kalam ensured Chandrayaan-1 left imprint on Moon

Chandrayaan-1, India’s first mission to the Moon in 2008, was just an Orbiter. When the spacecraft was being assembled, President A P J Abdul Kalam visited the Indian Space Research Organisation (ISRO) office. According to an account by former ISRO chairman G Madhavan Nair, Kalam asked scientists what evidence Chandrayaan-1 would have to show it had been to the Moon.

When the scientists said it would have pictures of the lunar surface, Kalam apparently shook his head and said that would not be enough. He then suggested that the spacecraft carry an instrument that could be made to fall on the Moon’s surface.

ISRO heeded Kalam’s advice and made design changes to accommodate a new instrument. This Moon Impact Probe hit the lunar surface, and became the first Indian object on the Moon.

Chandrayaan-2 lander was to come from Russia

Russia’s Luna-25 spacecraft crashed on the lunar surface on Saturday. An earlier version of the same lander was supposed to go on India’s Chandrayaan-2 spacecraft, but did not.

The Chandrayaan-2 mission, which had a lander and a rover, was originally supposed to go in the 2011-12 time frame. At that time, India had not developed its own lander and rover. The original Chandrayaan-2 spacecraft was supposed to be a joint mission with Russia. India was supposed to provide the rocket and Orbiter, while the lander and rover would have come from Russia.

The kind of lander and rover that Russia was developing for Chandrayaan-2, however, showed problems on a different mission, forcing Russia’s space agency Roscosmos to make design changes. The new design, however, was larger and could not be accommodated on the Indian rocket.

Russia eventually pulled out of the collaboration, and ISRO went in for indigenous development of the lander and rover. That took time, and Chandrayaan-2 could fly only in 2019.

India’s next Moon mission is not called Chandrayaan

Unlike some countries that have a whole series of lunar missions planned, India has not yet announced follow-up missions to Chandrayaan-3. While there would obviously be a Chandrayaan-4, 5, 6 or more, India will, before those, send another Moon mission in collaboration with Japan. It is called LUPEX. The mission is likely to be launched in the 2024-25 timeframe.

Europe withdrew from Russia’s Luna-25 due to Ukraine war

The European Space Agency was an important partner for Roscosmos, not just on Luna-25 but also on the Luna-26 and Luna-27 missions, planned for later this decade. The ESA was putting a navigation camera and an optical navigation system on Luna-25. More robotic equipment was planned to be integrated into Luna-26 and Luna-27. Similar cooperation was going on for a Russian Mars mission as well.

However, all that was suspended by the European agency in April last year, after Russian forces invaded Ukraine. The science and technology objectives that Europe planned to fulfill through these missions will now be fulfilled through collaboration with NASA.

Japan, Israel landing bids were by private companies

Over the last decade, five countries have attempted to land on the Moon — China, Israel, India, Japan, and Russia. Only China has succeeded so far. The Moon missions from Israel and Japan, Beresheet and Hakuto-R respectively, were sent by private companies. Till date, these remain the only attempts by private space agencies to land on the Moon.

Japan’s space agency JAXA is readying to send its first Moon landing mission. It is called SLIM, or Smart Lander for Investigating Moon.

Why does India/ the world want moon missions?

The rationale

Surendra Singh, July 2, 2019: The Times of India

July 16, the day after India’s Chandrayaan-2 lifts off from Sriharikota, marks the 50th year of the launch of Nasa’s Apollo-11, the mission that took US astronauts Neil Armstrong and Buzz Aldrin to Moon. Half a century later, why Chandrayaan-2? Are we reinventing the wheel?

Similar questions were raised before Chandrayaan-1 mission (which involved only an orbiter) in 2008. But India’s first Moon mission silenced critics when it found evidence of water ice on lunar surface. The mission cost India Rs 386cr — a fraction of what the US and the USSR had spent on similar missions. Chandrayaan-2, involving an orbiter, a lander and a rover this time, will expand the ambit of India’s first lunar probe and perhaps have some surprise finds.

The first object from Earth to kiss Moon was USSR’s Luna-2 craft, on Sept 14, 1959. Under the Luna programme, USSR sent a series of robotic craft missions to Moon between 1959 and 1976, which cost $4.5 billion.

Joining the Moon race, US started the Apollo programme and 10 years later, Armstrong and Aldrin became the first humans to step on Moon, on July 20, 1969. From 1968 to 1972, Nasa launched 11 spaceflights to the Moon and a total of 12 astronauts walked on Moon. The missions cost the $25 billion, considered to be the most expensive lunar programme.

A GSLV-MIII carrying Chandrayaan-2 will lift off on July 15, and its lunar-rover module, which will cover a distance of 384,400km to reach the lunar orbit, is expected to land on the south pole of Moon, which remains virtually unexplored.

The pioneers are also getting back to the game. Fifty years after the Moon race during the Cold War era, the US and Russia have revived their Moon programmes. China and Israel, too, have the jumped on the lunar bandwagon.

In May this year, Nasa awarded $253 million to three US firms to develop robotic landers that will carry payloads to Moon as a prelude to its Artemis programme to return astronauts to Moon by 2024. Russia also plans to land cosmonauts on Moon by 2030. In January this year, China’s Chang’e-4 probe made a historic landing on the far (dark) side of Moon that always faces away from Earth and has a rugged terrain with several impact craters. After Chang’e-4 success, China announced plans to follow up with three more missions, laying the groundwork for a lunar base.

In February this year, Israel launched its first lunar mission ‘Beresheet’ with the help of SpaceX launcher Falcon 9. Though the module, a joint venture of startup SpaceIL and state-run space agency, successfully reached the lunar orbit, it crashed on Moon. A determined Israel has now started working on Beresheet 2.0 programme.

Private players, too, are eyeing Earth’s natural satellite. The Elon Musk-led SpaceX has unveiled plans for a spacecraft that would allow the company to build a base on Moon and colonise Mars. Jeff Bezosowned Blue Origin is working on a spacecraft (Blue Moon) that will be used to transport scientific equipment and humans to Moon by 2024. For mankind, the love for Moon or Chandamama never wanes.

The road to the Chandrayaan mission

Chethan Kumar, July 4, 2019: The Times of India

After centuries of romanticising the Moon, mankind has been dreaming of colonising it. As our search for habitable planets still revolves around Mars, however, more space scientists are looking at Earth’s natural satellite as a layover point or a launchpad to farther expeditions.

India, which will launch its second lunar mission (Chandrayaan-2) + on July 15, has been conducting research on various aspects of Moon, including building habitats there. We are interested in sending people to the Moon, Isro chairman K Sivan had said.

Among some serious work by the US, Europe and China is one on using local material to build structures on Moon and building bigger rockets to transport instruments and people. Nasa is leading most of these efforts, with 2028 as the target year, while the European Space Agency is burning the midnight oil on Moon projects.

M Annadurai, the man behind Chandrayaan-1, earlier told TOI: “There’s serious thinking to use Moon as an outpost, just like missions in Antarctica. In the longrun, the space station is likely to be scrapped, and countries including the US are seriously considering building structures more permanent on Moon and working out of there. When it happens, we want India to have contributed.”

Isro has been thinking of building “igloos” on Moon. Earlier this year, Nasa administrator Jim Bridenstine said: “We’ll go to Moon in the next decade. When we go, we will stay. We’ll use what we learn as we move forward to Moon to take the next giant leap – sending astronauts to Mars.”

Senior space scientist P S Goel, however, is not so optimistic about such ventures in the near future. “Colonising Moon is slightly far-fetched as of now. But, using it as a transit point seems more realistic in the next five to ten decades. There are several engineering challengeslike how to generate energy for one—that must be overcome,” he told TOI.

China, which has soft-landed on Moon’s ‘dark side’, has been making significant strides. Scientists agree that humans on future lunar missions will be spending way more time than any of the Apollo missions (US has had 12 of them) did. But a lot of work is yet to be done to accommodate humans there, and this will be done in collaboration with serious space-faring nations combined with big private players like SpaceX.

A senior scientist advising Isro said that in the next few decades, Moon will see a lot of action, but, given the cost, countries cannot do it alone. “It has to be a collaboration, and India can earn a seat at the high table with Chandrayaan-2. You’ll also see big private participation,” he said.

2019, Sept: India and other countries with lunar missions

2019, Sept: India’s position among countries with lunar mission
From: Sep 8, 2019: The Times of India

See graphic :

2019, Sept: India’s position among countries with lunar missions

Research and development

How to land on the moon

U Tejonmayam, July 10, 2019: The Times of India

How Chandrayaan 2 intends to land on the moon
From: U Tejonmayam, July 10, 2019: The Times of India

For India’s second date with the Moon, expected in the first week of September, Isro scientists have swiped left and right through 3,500 images in search of the right place for the rendezvous near the lunar south pole.

Here, they hope to find clues to the origin and early history of not just the Moon, but Earth and some other members of the solar system as well. Also expected is more evidence of water.

Scientists studied data from Nasa’s Lunar Reconnaissance Orbiter and Japan’s Kaguya Lunar Orbiter to stitch together mosaics and study craters, boulders and slopes. Images of the lunar surface captured by instruments aboard Chandrayaan-1 including terrain mapping camera, hyperspectral imager, lunar laser ranging instrument, moon mineralogy mapper and synthetic aperture radar also came in handy.

“Chandrayaan-1 mapped the entire moon when the orbiter went around for nine months,” said Mylsamy Annadurai, who was the project director of Chandrayaan-1. The orbiter high resolution camera (OHRC) onboard Chandrayaan-2 orbiter will again study the landing site to detect hazards like boulders up to 32cm.

In a paper presented at the 49th Lunar and Planetary Science Conference 2018, Isro scientists said two potential sites were identified— a primary site between the two craters Manzinus and Simpelius, located 350km north of the south pole Aitken basin rim and a second site nearby.

China was the first country to land on the far side of the moon, on a crater about 180km from south pole Aitken basin. “As solar energy powers the system, a place with good visibility and area of communication was needed. Also, the place should not have many boulders or craters. The slope for landing should be less than 12 degrees. The south pole has a near-flat surface, with good visibility and sunlight,” said Isro chairman K Sivan.

The lunar south pole is especially interesting because a larger section of its surface stays in the shadow, which means a higher probability of finding water. The region also has craters that are ‘cold traps’ containing fossilised records of the early solar system, Isro said in a web post.

Accuracy is the key. “We are travelling about 3,84,000km from Earth. Even if we have an error of 1km on the landing site, all these factors should hold good,” Annadurai said. A study by Physical Research Laboratory on the topography of the landing ellipse revealed that 23,605 craters are present, including 12,600 craters with a diameter greater than 10m and 11 craters with greater than 500m diameter. The landing ellipse is generally flat with the primary landing site devoid of craters with significant depth.

Vikram has to soft-land without causing much disturbance. Lunar dust can stick to the instruments, affecting deployment of solar panel, sensors and navigational aids. The less the hovering time, the less the disturbance, said PRL scientists.

Chandrayaan 1

See graphic:

Decision making process of Chandrayaan- I

Help in creation of first global map of water in Moon's soil

India's Chandrayaan-1 helps scientists map water on Moon, Sep 14, 2017: The Times of India


The water concentration reaches a maximum average of around 500 to 750 parts per million in the higher latitudes

NASA's Moon Mineralogy Mapper flew aboard India's Chandrayaan-1 spacecraft

Although the bulk of the water mapped in this study could be attributed to solar wind, there were exceptions

NEW YORK: Using newly-calibrated data taken from NASA's Moon Mineralogy Mapper, which flew aboard India's Chandrayaan-1 spacecraft, scientists have created the first global map of water in the Moon's soil.

The study, published in the journal Science Advances, builds on the initial discovery in 2009 of water and a related molecule - hydroxyl, which consists of one atom each of hydrogen and oxygen - in lunar soil.

"The signature of water is present nearly everywhere on the lunar surface, not limited to the polar regions as previously reported," said the study's lead author Shuai Li, who performed the work while a PhD student at Brown University in Providence, Rhode Island, US.

"The amount of water increases toward the poles and does not show significant difference among distinct compositional terrains," Li, now a postdoctoral researcher at University of Hawaii, added.

The water concentration reaches a maximum average of around 500 to 750 parts per million in the higher latitudes. That is not a lot - less than is found in the sands of Earth's driest deserts - but it is also not nothing.

"This is a roadmap to where water exists on the surface of the Moon," study co-author Ralph Milliken, Associate Professor at Brown University said.

"Now that we have these quantitative maps showing where the water is and in what amounts, we can start thinking about whether or not it could be worthwhile to extract, either as drinking water for astronauts or to produce fuel," Milliken said.

The way the water is distributed across the Moon gives clues about its source, the researchers said. The distribution is largely uniform rather than splotchy, with concentrations gradually decreasing toward the equator, the study said. That pattern is consistent with implantation via solar wind - the constant bombardment of protons from the Sun, which can form hydroxyl and molecular water once emplaced.

Although the bulk of the water mapped in this study could be attributed to solar wind, there were exceptions. For example, the researchers found higher-than-average concentrations of water in lunar volcanic deposits near the Moon's equator, where background water in the soil is scarce.

Rather than coming from solar wind, the water in those localised deposits likely comes from deep within the Moon's mantle and erupted to the surface in lunar magma. The study also found that the concentration of water changes over the course of the lunar day at latitudes lower than 60 degrees, going from wetter in the early morning and evening to nearly bone dry around lunar noon.

The fluctuation can be as much as 200 parts per million. As useful as the new maps may be, they still leave plenty of unanswered questions about lunar water. The Moon Mineralogy Mapper, which supplied the data for the research, measures light reflected off of the lunar surface. That means that it can't look for water in places that are permanently shadowed from the sun's rays.

Many scientists think these permanently shadowed regions, such as the floors on impact craters in the Moon's polar regions, could hold large deposits or water ice. "Those ice deposits may indeed be there, but because they are in shadowed areas it's not something we can easily confirm using these data," Milliken said.

Nasa probe finds water distributed across lunar surface

Srinivas Laxman, Water distributed across lunar surface: Nasa probe on Chandrayaan-1, February 26, 2018: The Times of India

An analysis of data from India’s first mission to the moon, Chandrayaan-1, and Nasa’s Lunar Reconnaissance Orbiter (LRO) has found evidence that the moon’s water is distributed across the lunar surface and not confined to a particular region or type of terrain as stated earlier.

The water appears to be present day and night, though it’s not necessarily easily accessible, said Nasa in a statement. The space agency added that they derived the conclusion after obtaining data from a diviner instrument on the LRO. Nasa has stated that the new data was obtained from the diviner instrument on LRO. “The team applied this temperature model to data gathered earlier by the moon mineralogy mapper, a visible and infrared spectrometer that NASA’s Jet Propulsion Laboratory in Pasadena, California, provided for India’s Chandrayaan-1 orbiter,” it has stated.

“The findings could help researchers understand the origin of the moon’s water and how easy it would be to use as a resource. If the moon has enough water, and if it’s reasonably convenient to access, future explorers might be able to use it as drinking water or convert it into hydrogen and oxygen for rocket fuel or oxygen to breathe,” reads the statement.

The results contradict some earlier studies, which had suggested that more water was detected at the moon’s polar latitudes and that the strength of the water signal waxes and wanes according to the lunar day (29.5 Earth days). “We find that it doesn’t matter what time of the day or which latitude we look at, the signal indicating water always seems to be present,” said Joshua Bandfield, a senior research scientist with the Space Science Institute in Boulder, Colorado, and lead author of the new study published in Nature GeoScience.

Chandrayaan-1 device finds ice on moon surface

Chandrayaan-1 device found ice on moon surface: Nasa, August 22, 2018: The Times of India

Scientists have confirmed the presence of frozen water deposits in the darkest and coldest parts of the moon’s polar regions using data from the Chandrayaan-1 spacecraft, which was launched by India 10 years ago, Nasa said on Tuesday.

With enough ice within the top few millimetres of the surface, water would possibly be accessible as a resource for future expeditions to explore and even stay on the moon, and potentially easier to access than water detected beneath the surface. The ice deposits are patchily distributed and could be ancient, according to a study published in the journal PNAS.

The scientists used data from Nasa’s moon mineralogy mapper, an instrument carried on Chandrayaan-1, to identify three specific signatures that definitively prove the presence of ice. Learning more about it will be a key focus for Nasa and its commercial partners.

'Lost' in 2009; NASA finds it orbiting Moon in 2017

Srinivas Laxman, Chandrayaan-1 found by Nasa after 8 years, March 11, 2017: The Times of India

Eight years after it was considered “lost“, India's first lunar spacecraft, Chandrayaan-1, has been “re-discovered“ by Nasa's ground-based radars, the American space agency announced.

Chandrayaan-1, launched on October 22, 2008, was credited with the first discovery of water on the moon on November 14. After that, it suddenly lost communication with Isro ground stations on August 29, 2009 due to a technical problem. Speculation was rife at Isro then that it had crashed on the moon.

But nine years since its launch, a new radar technology pioneered by scientists at Nasa's Jet Propulsion Laboratory (JPL) was put into place to trace Nasa's Lunar Reconnaissance Orbiter and Chandraya an-1. “This technique could assist planners of future moon missions,“ Nasa said.

JPL's orbital calculations indicated that Chandrayaan-1 was still circling 200km above the lunar surface. The father of India's moon mission, Krishnaswamy Kasturirangan, told TOI, “To be declared lost and then found after eight years is a great accomplishment.“ Chandrayaan-1 was our first interplanetary mission, and I am delighted that it has been found,“ Kasturirangan said.

According to Nasa, the main challenge in detecting Chandrayaan-1 was on account of its size; the spacecraft is very small, a cube of about 1.5 metres on each side -about half the size of a smart car. It has not been transmitting signals.

According to Nasa, to find the spacecraft 3.80 lakh km away , the Jet Propulsion Laboratory (JPL) team used its 70-metre antenna at the Goldstone Deep Space Communications Complex in California.

A powerful beam of microwaves was directed towards the moon. The radar echoes then bounced back from the lunar orbit, which were received by the 100-metre Green Bank telescope in West Virginia in the US, Nasa said.

The radar team utilised the fact that Chandrayaan-1 is in polar orbit around the moon. So, it would always cross above the lunar poles on each orbit. On July 2, 2016, the team pointed Goldstone and Green Bank at a location 160km above the moon's north pole and waited to see if Chan drayaan-1 crossed the radar beam. Chandrayaan-1 was predicted to complete one orbit around the moon every two hours and eight minutes. Nasa said that the timing of the detections matched the time it would take for Chandrayaan-1 to complete one orbit and return to the same position above the moon's pole.

Chandrayaan 2


Chethan Kumar, India’s tryst with Moon: 10 years and two missions, October 21, 2018: The Times of India

At 6.22am on October 22, 2008, the PSLV carrying Chandrayaan-1 roared into the sky paving the way for the future of India’s endeavours for planetary exploration. And, on November 8 that year, Chandrayaan-1 reached the polar orbit around the Moon.

M Annadurai, called the Moon-man of India recollects: “On November 14, in the presence of then Indian President APJ Abdul Kalam, we commanded a tiny Moon Impact Probe (MIP) to detach from the mother craft targeting to touch down the moon after 27 minutes of flight into the atmosphere of the moon. While climbing down to the lunar surface one of the science equipment onboard the MIP, namely CHACE— a mass spectrometer—started indicating the presence of water (vapour) in the moon’s atmosphere.”

The signal then got more pronounced when the probe was going nearer to moon’s surface. The presence of water near moon was considered to be sourced from the lunar surface. So remaining instruments on board Chandrayaan-1 mother craft were programmed to look for presence of water on the Lunar surface. Untitled design (96)

The search was for the entire surface of the moon. Accordingly Chandrayaan-1 paved the way for deriving Lunar Map with water resources (see pic). “Discovery of ice on the poles of the moon is also credited to the Chandrayaan-1. When another set of International Scientists used Chandrayaan-1 data for their research again the claim was once again got confirmed,” Annadurai said.

Chandrayaan-1 received three international awards , one each for Discovery of water on the moon, Spacecraft Design and compact accommodation of 11 Science instruments and the very high level of international co-operation that paved the way for new wave in planetary exploration.

2019: The planned path

Chandrayaan 2: The planned path
From: June 13, 2019: The Times of India

See graphic:

Chandrayaan 2: The planned path

2019: The mission

Chethan Kumar, June 11, 2019: The Times of India

7 challengers of the Moon landing
From: Chethan Kumar, June 11, 2019: The Times of India

Isro has entered the last leg of testing of Chandrayaan-2 with integration nearly complete. Final tests are happening at Mahendragiri in Tamil Nadu and Byalalu in Bengaluru. The agency is looking at a July 9 launch. As part of Isro’s present schedule, spacecraft will leave Bengaluru on June 19, and reach the launchpad in Sriharikota on June 20 or 21. From 3D mapping to finding water molecules, and from checking out minerals to landing where nobody has landed, scientists say Isro has prepared to land a “dream on the Moon”.


The Cryogenic Upper Stage

Surendra Singh, July 23, 2019: The Times of India

The ABC of cryogenic upper stage
From: July 23, 2019: The Times of India

See graphic:

The ABC of cryogenic upper stage

How Isro toiled for years to develop cryo engine to power ‘Bahubali'

SRIHARIKOTA: A technical snag in the cryogenic stage of the GSLV-MkIII rocket carrying Chandrayaan-2 module had stalled Isro’s launch of the moon mission on July 15. Though the space agency successfully launched the mission in its second attempt after taking great efforts to fix the snag, the moot question is why it is so difficult to deal with a snag in the cryogenic upper stage of GSLV Mk III, popular as 'Bahubali' + .

To know about the cryo stage snag, first an understanding of the art of cryogenics is needed. Among all rocket fuels, hydrogen is known to provide enormous thrust as compared to solid and earth-storable liquid propellants. But hydrogen in its natural gaseous form is difficult to store and handle, and is, therefore, not used in normal engines like that of PSLV. However, hydrogen in liquid form can be stored in a rocket engine but that requires it to be maintained at a very low temperature — minus 253 degrees Celsius. And to burn the liquid fuel, oxygen too needs to be in liquid form — minus 187 degrees Celsius. Creating an atmosphere of such low temperatures in the rocket is quite challenging as it creates problem for other materials.

Over 25-30 years ago, Isro was desperate to develop the cryogenic technology for its GSLV rocket in order to lift heavier payload of over 3-4 tonnnes into the geo orbit at 36,000km altitude, from where it could send its spacecraft to deep space or other planets. This was because Isro’s mainstay rocket PSLV without a cryogenic engine, could deliver payload only up to 1.7 tonne to the lower earth orbit up to an altitude of 600 km. It could go to geo tranfer orbit but at reduced payload. Though PSLV was used for launching India’s first moon mission Chandrayaan-1 in 2008 and Mars Orbiter Mission in 2014, in both the cases the payload was not above 1.4 tonne.

In early 1990s, India had approached the US, Soviet Union, Japan and France for cryo technology. Only Soviet Union came forward. But Moscow too stepped back when the US cited a violation of the international Missile Technology Control Regime (MTCR) to threaten it and imposed sanctions on Isro and Soviet Union's launch service provider Glavkosmos. Though the US threat stalled the transfer of Russian cryo technology, India still managed to import seven such engines from Glavkosmos. The engines were used to launch initial versions of GSLV rockets. But desperate to have an indigenous technology, Isro scientists worked tirelessly for over two decades to develop its own cryo engine. Being a complex system, Isro still faces some hiccups in its cryo stage like the July 15 snag.

The July 15 glitch was due to a leak in helium bottle joint in the cryo upper stage (Helium is used to maintain pressure in the cryogenic chamber). The leak occurred after the propellant tanks were filled with liquid hydrogen, the fuel, and liquid oxygen, the oxidiser. With the pressure not holding in the cryogenic chamber, the mission control centre had no option but to call off the liftoff.

Extra brake thrust may have sent Vikram out of control

Chethan Kumar, Sep 8, 2019: The Times of India

The Vikram lander’s last 5km descent to the Moon
From: Chethan Kumar, Sep 8, 2019: The Times of India

When silence descended upon the Isro mission control and millions of Indian homes minutes before Vikram was to touch down on the Moon at 1.53am on Saturday, many thought the lander had too little thrust to brake to a halt. A day later, Isro scientists are looking at whether Vikram had too much braking thrust, which spun it out of control.

“We thought one of the thrusters may have underperformed,” said an Isro scientist. “But after some preliminary analysis, it looks like a thruster overperfor med.” Descending from its orbit 30km from the Moon, Vikram had achieved perfect roughbraking for 10 minutes, reducing its velocity from 1,680 metres per second to 146 metres per second. Soon after the fine-braking that signalled Vikram’s last 5km descent to the Moon, mission control lost contact with the lander.

Officially, Isro maintained that data was still being analysed. However, a scientist told TOI, “Vikram’s legs were to be horizontal during the roughbraking and had to be rotated by 90 degrees to bring them vertical to the landing surface before fine-braking. At this point, the thrust might have been more than optimal, impacting the lander’s orientation. It’s like a car losing direction due to sudden braking at high speed.”

When Vikram went silent, Isro mission control searched for links from Nasa’s deep space network centre in Madrid and the Indian station in Mauritius, but to no avail. 

Why the July 2019 launch was postponed

Arun Ram, Isro pinpoints GSLV-MkIII leak to 'nipple joint' of cryo engine, July 17, 2019: The Times of India

CHENNAI: Working overnight on the aborted Chandrayaan-2, the Indian Space Research Organisation (Isro) teams have pinpointed the leak in the GSLV-MkIII cryogenic engine to a ‘nipple joint’ of the helium gas bottle that supplies pressure to the fuel and oxidiser. Why it happened remains the crucial question Isro engineers are trying to answer.

Isro had aborted the Chandrayaan-2 launch 56 minutes before its scheduled lift-off at 2.51am on Monday. “The good news is that we can fix the leak without dismantling the rocket, since there is an access door to the gas bottle which is atop the oxygen tank,” a senior scientist told TOI. “The bad news is that unless we ascertain the reason for the leak, there is a probability of the problem recurring.” Not having to dismantle means Chandrayaan-2 may be able to fly before the end of the July launch window, but a final failure analysis will be available only in a day or two.

Sources told TOI that the leak wasn’t serious enough to impair the flight, but Isro decided to apply “abundant caution,” given the importance of the Rs 978-crore project that would make India only the fourth country – after the US, Russia and China – to land a craft on the lunar surface.

The helium gas bottle has a capacity of 34 litres and it was to be pressured up to 350 bars before regulating the output to 50 bars. “The leak was bringing down the pressure by four bars per minute. The rocket could’ve still made it, but we didn’t want to take any chances,” a source said.

A veteran of Isro failure analysis said teams would now look at the proximity of the faulty ‘nipple joint’ to the oxidiser tank that stores liquid oxygen at minus 183 degrees Celsius. “If the joint was close to such a low temperature, the reason could be micro shrinkage of the joint. In that case we need to insulate it or shift the joint away from the coldest point,” the scientist said.

Bigger leaks in the gas bottle can, besides affecting combustion and velocity, send the rocket spinning out of control. For now, Isro is confident of rectifying the fault and flying to moon without much delay.

More than 7,000 people from across the country had gone to the Sriharikota spaceport to witness the Monday launch. President Ram Nath Kovind was with senior Isro scientists at the mission control centre when the launch was called off at 1.55am.

90-95% of mission objectives achieved

June 27, 2020: The Times of India

In its first statement after moon mission suffered a huge setback on Saturday, the Indian Space Research Organisation described India’s Chandrayaan-2 as a highly-complex mission that represented a “significant technological leap”.

The space agency also underscored that 90-95 per cent of the mission objectives had been achieved and would contribute to lunar science despite the loss of communication with the Vikram lander.

It specifically counted the precise launch and the mission management as one success area, one that would enable the Orbiter to stay in place for the next seven years instead of the planned one year.

“This was a unique mission which aimed at studying not just one area of the Moon but all the areas combining the exosphere, the surface as well as the sub-surface of the moon in a single mission,” the statement said.

The Vikram Lander followed the planned descent trajectory from its orbit of 35 km to just below 2 km above the surface. The statement did not spell out what exactly had happened beyond this point.

Making lunar spacecraft think and act

U Tejonmayam, July 23, 2019: The Times of India

Within a week after Chandrayaan-1 was launched in 2008, scientists had to abort a manoeuvre of the spacecraft as all ground stations lost visibility. But that did not hamper the mission, as the spacecraft used its own electronic brain fed with commands in advance to manoeuvre on its own. Six years later, it is with the same ebrain that Mangalyaan found its way to Mars by correcting its altitude and the position of its antenna and solar panels during its 300-day journey. Rocket science calls it autonomy.

With Chandrayaan-2, Isro will once again demonstrate its mastery over autonomy when Vikram will soft land on the south pole on its own sans intervention from ground control. And that is going to keep India in good stead as Isro plans future interplanetary missions.

“It’s like an aircraft on auto-pilot. Vikram will have only one chance. It has to see the landing place correctly, reduce its velocity and land with minimal impact,” said Chandrayaan-1 project director Mylsamy Annadurai.

Rover Pragyan, too, will work on its own. It will have the ability to ‘think’ it is not in the right position and move back to its last step if it does not receive commands from the ground station.

India has planned seven inter-planetary missions in the next 10 years, starting with Xposat to study cosmic radiation in 2020, Aditya L1 to Sun in 2021, Mars Orbiter Mission-2 in 2022, a date with Venus in 2023, Lunar Polar Exploration or Chandrayaan-3 in 2024 and Exoworlds, an exploration outside the solar system, in 2028.

Simultaneously, as it adds more satellites to meet its demands, monitoring and controlling from the ground could become humanly impossible. Injecting smarter satellites into orbit meant it can decide autonomously what, when and how to carry out operational tasks, like capturing images of Earth, analyse and process them before selecting important data for downloading to the earth station. This also allows satellites to communicate with each other and do tasks like identifying a target to be monitored continuously, like a moving vehicle.

“This is an electronics revolution. It simply puts intelligence into a satellite,” said TK Alex, former director of UR Rao Satellite Centre. “On the software side, India is on the top.”

The Orbiter continues looking for water, minerals

Surendra Singh. Sep 8, 2019: The Times of India

All is not lost with Vikram and Pragyan losing contact with Indian Space Research Organisation (Isro) moments before their scheduled landing. Their separated brother, the lunar orbiter, is going around the Moon, collecting valuable information on possibility of finding water and minerals.

Equipped with eight payloads, the orbiter, that has been in place since September 1, has a life span of more than seven years.

Nasa veteran Jerry Linenger, who had flown on space shuttles and spent five months on Russian space station Mir in 1997, said, “With Chandrayaan-2’s orbiter doing three-dimensional mapping of the Moon and looking beneath the lunar surface, we are expecting a lot of information. Anyone looking to set up a base on Moon will be benefited by such infor mation.”

Retired Isro scientist M Annadurai, who was the project director of the 2008 Chandrayaan-1 mission, told TOI that the orbiter does many things that the lander and the rover couldn’t have. “While the rover’s research area would have been 500 metres, the orbiter will map the entire Moon from an altitude of about 100km. Onboard equipment such as IR spectrometer, two cameras and dual-band synthetic aperture radar can do a lot,” Annadurai said.

“The IR spectrometer covers the entire Moon to study what three payloads of Chandrayaan-1 — India’s hyperspectral imager, Germany’s near infrared spectrometer and Nasa’s moon mineralogy mapper — have done,” he added.

The Chandrayaan-2 orbiter’s terrain mapping camera has a spatial resolution of 5m and a swath of 20km, which will help Isro prepare 3D maps of the lunar surface. The high-resolution camera can pick up details as small as 30cm (Chandrayaan-1 camera had 1m resolution). The indigenous synthetic aperture radar used this time has dual band (frequency), whereas the Nasa-imported one used in Chandrayaan-1 had just one band.

Another senior Isro scientist told TOI that the synthetic aperture radar will help Isro make accurate estimates of water in the polar craters. “It can capture images of lunar rocks of up to one foot. This camera will be used in the Cartosat-3 series of surveillance satellites and also the Indo-US joint venture NISAR satellite due for launch in 2022,” he said. 

Not a failed mission

World media, experts

Sep 7, 2019: The Times of India

All is not lost, Chandrayaan-2 not a failed mission: World media, space experts BENGALURU: International space experts and media around the world on Saturday called the communication loss with Vikram lander a "partial loss" and said "all is not lost" as the orbiter with key scientific instruments on board is still circling Moon's orbit. 

Former US astronaut and space analyst Jerry M Linenger said, “India was trying to do something very, very difficult. Everything was going as planned as the lander came down. Unfortunately, it never quite made it to the hover point. That would be at an altitude of about 400 metre if it had made it to that point, and even if it had not succeeded beyond that, it would have been helpful because the radar altimeters and lasers could have been tested. This would obviously be very helpful for follow-on missions. Overall, the mission has been very successful." 

He said, "The orbiter will continue to downlink very valuable information for the next year. And by all indications, all systems are go on the orbiter. I look forward to watching complete success in the future based upon lessons learned from this bold attempt.” 

Writer and managing editor of Nasa Spaceflight Chris G said, "The orbiter is where 95 per cent of the experiments are. The orbiter is safely in lunar orbit and performing its mission. This is not a total failure. Not at all," Chris G tweeted. 

Israel, whose Beresheet lander crashlanded in April this year, too responded positively about the Chandrayaan-2 mission. Israel ambassador Ron Malka tweeted, "Take pride India and have courage. This is a great achievement and it is not the end. Israel is no stranger to the stumbling blocks on the way to a soft landing and we know India will try again and complete the last step. We will see you there. #IndiaOnTheMoon" 

Most of the world newspapers did not call India's mission a total failure. 

"All is not lost for the mission", the online edition of US magazine 'Wired' said on Vikram's "deviation from its expected trajectory". The New York Times lauded India's "engineering prowess and decades of space development have combined with its global ambitions." 

'The Guardian', in its article titled -- India's moon landing suffers last-minute communications loss, quoted Mathieu Weiss, a representative in India for France's space agency CNES, as saying, "India is going where probably the future settlements of humans will be in 20 years, in 50 years, 100 years." 

Amid the increasing hostility with Pakistan, its minister for science and technology Fawad Chaudhry only made a sarcastic remark on Vikram lander. "Please sleep. The toy landed in Mumbai instead of landing on the moon," he tweeted. 

American magazine Wired said the Chandrayaan-2 programme was India's "most ambitious" space mission yet. 

"The loss of the Vikram lander and the Pragyan rover it was carrying to the lunar surface would be a big blow for India's space program...but all is not lost for the mission," it said. 

The Washington Post in its headline "India's first attempt to land on the moon appears to have failed" said the mission had been a source of "immense national pride". 

"Social media erupted in support of the space agency and its scientists despite the setback... The incident could now set back India's growing space ambitions, seen as a reflection of the aspirations of its young population," it said. 

"One of the successes of India's space program has been its cost-effectiveness. Chandrayaan-2 cost $141 million, a small fraction of what the United States spent on its historic Apollo moon mission," the report said. 

American network CNN described it "India's historic landing on moon's polar surface may have failed". 

"India's historic attempt to soft land a rover on the moon may have ended in failure moments... The crowd had celebrated every small step during the controlled descent and the moment the landing was expected to take place, silence descended," it said. 

The BBC wrote the mission had made global headlines because it was "so cheap". 
"The budget for Avengers: Endgame, for instance, was more than double at an estimated $356 million. But this isn't the first time Isro has been hailed for its thrift. Its 2014 Mars mission cost $74 million, a tenth of the budget for the American Maven orbiter," it said. 

French daily Le Monde mentioned the success rate of soft landing on the moon. 

It said, "so far, scientists point out, only 45 per cent of missions aimed at alleviating have been successful". 

It started its article with words "A broken dream" and said that the Indian newspapers "were quick to titrate their websites, after announcing the worse scenario that could expect the Indian Space Research Organisation". 

In the early hours of Saturday, Indian space agency Isro's plan to soft land Chandrayaan-2's Vikram module on the lunar surface did not go as per script. 

The lander lost communication with ground stations during its final descent. Isro officials said, adding that the orbiter of Chandrayaan-2 - second lunar mission - remains healthy and safe. 

Prime Minister Narendra Modi on Saturday asked Isro scientists not to get disheartened by the hurdles in the moon mission Chandrayaan-2 and asserted that there will be a "new dawn and better tomorrow". 

( With agency inputs)

Shanmuga Subramanian locates the lander’s debris

Surendra Singh, Dec 3, 2019 Times of India

The impact site of Chandrayaan2’s lander
From: Surendra Singh, Dec 3, 2019 Times of India

NEW DELHI: After almost three months of frantic search for the Vikram lander by space scientists and space agencies from across the world, it was a techie from Chennai who found the debris of Chandrayaan-2's Vikram lander on Moon's south pole by using US space agency Nasa images.

Shanmuga Subramanian (Shan), a mechanical engineer and a computer programmer who works as a technical architect at engineering company Lennox India Technology Centre in Chennai, has made India's greatest space discovery of the lander, which had made a hard-landing on Moon's surface during a landing attempt on September 7, 2019.

Shanmuga, who hails from Madurai and had earlier worked for Cognizant as a programme analyst, used lunar images from Nasa's Moon's Lunar Reconnaissance Orbiter (LRO) captured on different dates (September 17, October 14, 15 and November 11) and studied them for weeks to locate the debris of the lander.

After making the discovery, Shanmuga wrote to Nasa informing it about his findings for which the US space agency took some time to confirm it. Authenticating his discovery finally, Nasa's deputy project scientist (LRO mission) John Keller wrote to him, "Thank you for your email informing us of your discovery of debris from the Vikram lander. The LROC team confirmed that the location does exhibit changes in images taken before and after the date of the landing. Using the information, the LROC team did additional searches in this area and located the site of the primary impact as well as other debris around the impact location and has announced the sighting on the Nasa and ASU pages where you have been given credit for your observation."

Wishing Shanmuga for his hard work, Keller further wrote, "Congratulations for what I am sure was a lot of time and effort on your part. We apologise for the delay in getting back to you as we needed to be certain of our interpretation as well as making sure that all stakeholders had an opportunity to comment before we could announce the results".

Later, confirming news to the world, Nasa tweeted: "The Chandrayaan-2 Vikram lander has been found by our NasaMoon mission, the Lunar Reconnaissance Orbiter. See the first mosaic of the impact site." An image of Moon with blue and green dots show the impact point of Vikram and an associated debris field.

"Green dots indicate spacecraft debris. Blue dots locate disturbed soil, likely where small bits of the spacecraft churned up the regolith (moon soil). "S" indicates debris identified by Shanmuga Subramanian," the Nasa statement read. The debris, first located by Shanmuga, is about 750 metre northwest of the crash site.

Indian Space Research Organisation (Isro) and Nasa have been looking for the Vikram lander since September 7. In fact, Nasa had used its deep space network antennas in California, Madrid and Canberra to send signals to the Vikram lander with the hope that it would reflect the signals if the lander's systems were working but all the US space agency's efforts went in vain. Finally, it used its orbiter LRO, circling around the Moon, to take images of the south pole region to locate the lander. Isro, too, has been using Chandrayaan-2's functional orbiter, circling Moon at 100km altitude, to scan the landing zone to look for the lander.

Recently, in a written reply to a question in the Lok Sabha, Union minister for department of space Jitendra Singh explained the reason for the Vikram's hardlanding. He said, "During the second phase of descent (of lander), the reduction in velocity was more than the designed value. Due to this deviation, the initial conditions at the start of the fine braking phase were beyond the designed parameters. As a result, Vikram hard-landed within 500 metres of the designated landing site."

Debris spread around impact site

Chethan Kumar, Dec 3, 2019 Times of India

BENGALURU: Shattering theories that Vikram — the lander on Chandrayaan-2 — was intact despite a failed soft-landing on September 7, latest images from Nasa’s Lunar Reconnaissance Orbiter (LRO) camera show a field of debris on the lunar surface indicating that the hard-landing may have broken the lander into multiple pieces.

Analysis of Nasa images shows a debris field of Vikram about 750 metres away from the main landing site (the intended one). Vikram, according to Isro, hard-landed 500m away from the intended site, going by which the debris is about 150m away from where Vikram crashed on September 7.

The US space agency released these images early on December 3 (IST), showing the debris for the first time. “Vikram lander found,” a Nasa statement read. It added that Shanmuga Subramanian — who TOI later found out was a mechanical engineer from Chennai — was the first to identify the debris. An image of the lunar surface with blue and green dots shows the impact point of Vikram and an associated debris field.

“Green dots indicate spacecraft debris (confirmed or likely). Blue dots locate disturbed soil, likely where small bits of the spacecraft churned up the regolith. "S" indicates debris identified by Shanmuga Subramanian,” the Nasa statement read ( see image).

While multiple calls and messages to Isro chairman K Sivan went unanswered, the space agency did provide answers to an email questionnaire on the latest revelations. Isro spokesperson Vivek Singh told TOI: “We have no comments to offer.”

Elated by Nasa’s response, Subramanian, said: “Nasa has credited me for finding Vikram Lander on Moon’s surface.” Subramanian, who works at Lennox India Technology Centre in Chennai, had contacted the LRO project with positive identification of debris.

“...After receiving this tip, the LROC team confirmed the identification by comparing the before and after images,” Nasa said.

While the LRO Camera team released the first mosaic (acquired September 17) of the site on September 26, the impact point was poorly illuminated and not easily identifiable. LRO project then acquired two subsequent image sequences on October 14 and 15, and November 11.

“The LROC team scoured the surrounding area in these new mosaics and found the impact site (70.8810°S, 22.7840°E, 834m elevation) and associated debris field. The November mosaic had the best pixel scale (0.7 meter) and lighting conditions (72° incidence angle),” Nasa added.

The debris first located by Shanmuga is about 750 meters northwest of the main crash site and was a single bright pixel identification in that first mosaic (1.3 meter pixels, 84° incidence angle).

The November mosaic shows best the impact crater, ray and extensive debris field. The three largest pieces of debris are each about 2x2 pixels and cast a one-pixel shadow.

Although Isro had never officially said that Vikram was intact and in a tilted position, reports quoting unnamed scientists from the space agency had made the claim, which now appears to be false.

How Subramanian did it

U Tejonmayam, Dec 4, 2019 Times of India It was not rocket science but a painstaking pixel-by-pixel comparison of nearly 30 images that helped Chennai techie Shanmuga Subramanian spot Vikram lander’s debris after it crashed on the lunar surface on September 7.

The 33-year-old, who hails from Madurai, woke up on Tuesday to an email from Nasa confirming that the American space agency has confirmed Vikram lander’s crash site and giving him credit for the discovery.

“I spotted the debris about 0.75km north of the lander’s intended landing location. All I did was a basic apples-to-apples comparison of two images at a time on the computer screen. No software or complex calculation, just an old school method,” said the mechanical engineer and programmer who friends call Shan. “It didn’t require a lot of science, but a basic understanding of lunar days and nights and the surface of the moon,” he said.

A day after Vikram went missing, Isro said it had located the lander, but did not publish any image. Nasa’s analysis of its Lunar Reconnaissance Orbiter (LRO) images too did not reveal any impact scar on the lunar surface. Shan downloaded a 1.5GB resolution image of the region on the moon published by Nasa on September 17 and compared it with nearly 30 old images captured by the LRO which has been circling the moon for a decade, with a 1.25m resolution per pixel. Some simple calculations with data on the lander’s path and last known velocity available on the public domain, Shan decided to search for the debris on the north side.

“During the landing, a few radio astronomers had tweeted that the lander had crossed the north pole. With that, I figured out that the debris must be within a 2km x 2km area north of the landing spot,” he said. Placing two ‘before’ and ‘after’ images on his screen, Shan zoomed in pixel by pixel and compared. When he noticed a white speck on the new image that was not visible in the old images, he knew it. “There is a definite difference that you can tell between a man-made object and others. For instance, a man-made object would be less illuminated and smaller than a boulder,” he said.

A graduate from Government Engineering College, Tirunelveli, Shan is a weather and space enthusiast. His phone has not stopped ringing since Tuesday morning when he posted Nasa’s email on his social networking site.

ISRO’s statement

Speaking to reporters in Ajmer, Isro chief K Sivan said the space agency had made the announcement about its orbiter finding Vikram earlier. “One can see on our website that our own orbiter has already identified the crashed lander on the moon,” he said.


2008, 2019 and 2023 (planned)

Chandrayaan-3, some basic facts
From: July 13, 2023: The Times of India

See graphic:

Chandrayaan-3, some basic facts

2023 Aug: soft landing; first ever on south pole

Chethan Kumar, August 25, 2023: The Times of India

Vikram and Propulsion module
From: Chethan Kumar, August 25, 2023: The Times of India
Vikram landing on moon, A timeline
From: Chethan Kumar, August 24, 2023: The Times of India

Day after, Vikram ‘full on’, Pragyan does a Moonwalk

Bengaluru : A day after Chandrayaan-3 lander Vikram touched down on Moon’s south polar region, Isro on Thursday switched on the payloads on Vikram and started moving Pragyan, the rover, on the lunar surface.

“All activities are on schedule and all systems are normal. Rover mobility operations have commenced,” Isro said, adding three of the lander payloads, Instrument for Lunar Seismic Activity (ILSA), Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA) and Chandra’s Surface Thermophysical Experiment (ChaSTE), were turned on. Isro had, on Sunday, activated the Spectro-polarimetry of HAbitable Planet Earth (SHAPE) payload on the propulsion module. On why the rover took more than 4 hours to roll out, Isro chairman S Somanath told TOI: “After the landing, we had to check the inclination, terrain condition and tempe ratures, and wait for the lunar dust to settle. The rover came out late last night.”

Nov 2023/ No ‘second innings’

Chethan Kumar, Oct 4, 2023: The Times of India

BENGALURU: As Cricket fever grips India, another headline-hogger, Chandrayaan-3, did not get a ‘second innings’ on the Moon where the Sun has set for the second time since the soft-landing on August 23, making way for another long, cold night.

Although both Vikram (the lander) and Pragyan (the rover) were designed to last one lunar day (14 Earth days), Isro and lakhs of its supporters had hoped that would wake up again, which would have been a bonus.

While the first three days, September 20, 21 and 22 would have been the best window for them to have woken up after they had been put on sleep mode in the first week of September, that did not happen.

Later, Isro chairman S Somanath told TOI that the space agency would wait till the last day for the two to wake up as even a small window would give Isro the opportunity to repeat some experiments using the scientific instruments onboard Vikram and Pragyan.

However, in its day-night affair some 3.8-lakh-km away, India’s third lunar mission did not even get the ‘super over’ — a bonus of waking even for a short time.

M Sankaran, director, UR Rao Satellite Centre, the lead centre for Chandrayaan-3, told TOI: “The lander and rover have not woken up. While the chances of them waking up again after this lunar night ends in the next 14 days are very very slim, we are not closing that option.”

That said, both Vikram and Pragyan had a great outing on a tough pitch that the Moon can be, with a picture-perfect lunar landing, exploring alien terrain, and even a daring lunar hop by the lander.

“Given that this mission is not like a remote sensing or communication satellite, the quantity of data from Vikram and Pragyan payloads won’t be large, but the important thing would be the outcome of what we’ve received when they worked on the first day. The analysis of data is ongoing,” Sankaran said.

He added that sufficient data has been collected from the propulsion module payload — Spectro-polarimetry of HAbitable Planet Earth (SHAPE) — which will specifically study habitable planet-like features of Earth while it goes around the Moon. Isro has already made some announcements about observations made by instruments it put on the Moon, including unambiguous detection of Sulphur and measurements of temperature, while the movement of the rover has provided new insights into the lunar soil properties which may need further studies.

Experts and institutions involved

Chethan Kumar, August 27, 2023: The Times of India

Bengaluru: As Chandrayaan-3’s success party continues with India naming its landing site as ‘Shiv Shakti Point’, PM Narendra Modi on Saturday said he was eager to meet the team behind the mission in person and salute them for their diligence, courage and passion. “From the southern part of India to the southern part of the Moon was not an easy journey,” Modi told the Isro team in Bengaluru.

Given that space is an unforgiving environment without possibilities for in-situ repairs, development of missions demands meticulous planning, design, testing, analysis and review. According to Isro: “It is a true example of ‘rocket science’ that necessitates a multi-disciplinary team of domain experts working hand-in-hand with execution teams, to tailor solutions for each specific mission. ”

Apart from the core team of 30 Isro scientists and engineers, Chandrayaan-3 had just the right mix of such teams. Isro said personnel from 12 of its major labs — UR Rao Satellite Centre, Vikram Sarabhai Space Centre, Liquid Propulsion Systems Centre, Isro Satellite Tracking Centre, Space Applications Centre, Laboratory for Electro-Optics Systems, Inertial Systems Unit, Isro Propulsion Complex, Satish Dhawan Space Centre, National Remote Sensing Centre, Physical Research Laboratory and Space Physics Laboratory —and nearly 20 non-Isro institutions helped the mission.

“Throughout Chandrayaan-3’s realisation across different stages, expert committees from academia and Isro meticulously reviewed test results, observations and noncompliances, and offered nec- essary guidelines to proceed as-is, repair, or replace components. Former chairpersons K Radhakrishnan, A S Kiran Kumar and K Sivan reviewed overall configuration as members of the apex committee,” Isro said.

Besides, a committee of experts headed by V Koteswara Rao oversaw special tests on the lander. “The directors or eminent senior scientists from several institutions contributed,” the agency added. These institutions include National Aerospace Laboratory, Aeronautical Development Agency, National Institute of Advanced Studies, Inter-University Centre for Astronomy and Astrophysics and Indian Institute of Astrophysics.

Academics from IISc, University of Hyderabad, IITKharagpur, IIT-Madras, IITBombay, IISER-Kolkata, Ashoka University and IIT-BHU also contributed, said Isro.

Touchdown in 2024

Chethan Kumar, April 5, 2024: The Times of India

India’s Chandrayaan-3 mission made history on Aug 23, 2023 with an incredibly gentle landing. Despite the powerful engines required for descent, the lander kicked up minimal lunar dust, a new paper presented by Isro scientists at last month’s Lunar and Planetary Science Conference in Texas reveals. 

The study was carried out by Amitabh, K Suresh, Kannan V Iyer, Ajay K Prashar, Shweta Verma and Abdullah Suhail from Isro’s Space Applications Centre.

That Chandrayaan-3, which made so much noise on Earth, barely kicked up any dust on Moon has significant implications for future lunar exploration missions.

Art Of Soft Landings

Landing on Moon’s surface is no easy task. Spacecraft must fire powerful engines to slow down and descend in a controlled manner. However, this engine exhaust can interact with the lunar surface, kicking up plumes of dust and debris, and spreading it around the landing site. 
Previous lunar landing missions, such as the famous Apollo missions and China’s Chang’e-3, raised dust plumes of up to 60m (nearly 200 feet) height. Such massive dust clouds can potentially damage sensitive equipment, obscure the view of the landing site, and even contaminate scientific samples collected by rovers or astronauts.

Minimal Dust Disturbance

Vikram, the Chandrayaan-3 lander, however raised a dust plume of only 8.7-12m (28-39 feet), images captured by cameras on the lander, orbiter (from Chandrayaan-2), and rover Pragyan reveal. Furthermore, the area affected by the dust spread was relatively small, covering only about 145 sq-m (around 1,560 sq feet), with a spread of roughly 17m (56 feet) in one direction and 14m (46 feet) in another.

The soft touchdown suggests the lander’s design and engine configuration were optimised for minimal interaction between the engine plume and the lunar surface. Chandrayaan-3’s feat is likely due to a combination of factors, such as the lander’s light-weight design, precise control of the engine thrust during descent, and the specific properties of the lunar soil at the landing site.

30km Of Controlled Descent

Vikram landed on the lunar southern hemisphere between craters “Manzinus-U” and “Boguslawsky-M” at a point later named “Shiv Shakti” by Prime Minister Narendra Modi. Its lander imager (LI) captured and transmitted a total of 835 images to Earth in nearreal-time mode, providing crucial in- sights into the landing process and the lunar surface environment.

While landing, all four engines of Chandrayaan-3 started firing at an altitude of nearly 30km for deceleration and worked until the lander’s first hovering at an altitude of 800m. After that, only two diagonal engines were kept on until touchdown.

When the four sensors in the lander’s footpad indicated touchdown, in combination with an accelerometer reading of zero, the engines were shut down within 30 milliseconds, ensuring a gentle and controlled landing on the lunar surface.

Key To Design Improvement

The minimal disturbance of lunar dust has significant implications for future lunar exploration missions. It demonstrates the possibility of landing spacecraft on Moon with minimal environmental impact, preserving the pristine nature of the lunar surface for scientific study and reducing the risk of damage to sensitive equipment.

Additionally, understanding the mechanisms behind this low dust disturbance could help engineers design even more efficient and environmentally-conscious landers and rovers for future missions.


Chandrayaan 1 and 2, vis-à-vis the world

The cost of key USSR, US, Japanese, European, Chinese lunar missions and a comparison of the costs with Chandrayaan 1 and 2
From: July 2, 2019: The Times of India

See graphic:

The cost of key USSR, US, Japanese, European, Chinese lunar missions and a comparison of the costs with Chandrayaan 1 and 2

Findings/ discoveries

H2O on lunar surface/ 2021

Surendra Singh, August 12, 2021: The Times of India

NEW DELHI: Though Chandrayaan-2 mission lander hard-landed on the lunar surface in 2019, its orbiter is doing wonders as one of the eight key scientific instruments on board it has detected the “unambiguous presence of hydroxyl and water molecules” on the lunar surface. The findings will certainly give a heads-up to Isro as it is scheduled to launch its next lander-specific lunar mission Chandrayaan-3 in 2022.

Indian researchers used the data obtained by the orbiter's imaging infrared spectrometer (IIRS), meant to collect information from the Moon's electromagnetic spectrum, to understand the lunar mineral composition. Three strips on the Moon’s surface were analysed by an IIRS sensor for hydration presence.

“The initial data analysis from IIRS clearly demonstrates the presence of widespread lunar hydration and unambiguous detection of OH and H2O signatures on the Moon between 29 degrees north and 62 degrees north latitude,” said the findings of Indian researchers that were recently published in Current Science journal. Plagioclase-rich rocks have been found to have higher OH or possibly H2O molecules when compared to mare regions, which were found to have more dominance of OH at higher surface temperature, it said.

The study, authored by scientists, including former Isro chairman A S Kiran Kumar, from Indian Institute of Remote Sensing (IIRS), Dehradun, Ahmedabad-based Space Applications Centre, Bengaluru-based U R Rao Satellite Centre and the Isro headquarters, says the discovery is “significant for future planetary exploration for resource utilisation”, as several international missions, both manned and unmanned, to the Moon are lined up in the next few years.

India’s first moon mission Chandrayaan-1, launched in 2008, had first confirmed the presence of water when an instrument on board it — Moon Mineralogy Mapper or M3— belonging to Nasa’s JPL, first detected widely distributed hydration signatures across the Moon using 3 µm spectral response. However, due to limited spectral coverage of M3 (only up to 3 µm), the exact nature of the hydration signatures could not be ascertained. This made discrimination between OH and H2O detection difficult, said the report. But IIRS on-board Chandrayaan-2, which was launched on 22 July 2019, is not only indigenous but has also been designed to measure lunar reflected and emitted solar radiation in 0.8–5.0 µm spectral range. Its high spatial resolution (~80 m) and extended spectral range is most suitable to completely characterise lunar hydration (2.8–3.5 µm region) attributed to the presence of OH and H2O.

The report from the data also observed that the brighter sunlit highland regions at higher latitudes of the Moon were found to have higher hydroxyl or possibly water molecules, that is enhanced hydration, compared to the large basaltic plain regions where hydroxyl appeared to be dominant, especially at higher surface temperature.

The thermal stability of these hydration features depends upon how they interact with one another, with the surface and their environment at particular temperature range and therefore provides important clues about their origin and evolution, the research paper said.

International comparisons

Vis-à-vis US, USSR missions

Surendra Singh, August 9, 2019: The Times of India

Chandrayaan 2’s path vis-à-vis Saturn V’s path
From: Surendra Singh, August 9, 2019: The Times of India

Have you wondered why Chandrayaan-2 will take 48 days to reach Moon whereas missions launched by USSR and US over five decades ago reached the lunar surface in under a few days? USSR’s Luna-2 craft took just 34 hours to reach Moon in 1959. Ten years later on July 20, 1969, Nasa’s Apollo-11 mission carrying humans landed on Moon in just four days, 6 hours and 45 minutes. Besides being the world’s first manned Moon mission, Apollo-11 was also the fastest trip of astronauts to the Moon.

So why is Chandrayaan-2 taking more than a month? The answer lies in the build of the rocket, the amount of fuel it’s carrying and the speed of the lunarcraft.

In space, covering long distances requires high speeds and straight trajectories. For Apollo-11, Nasa had used Saturn V, a super heavy-lift launcher, to travel at more than 39,000km per hour. The powerful rocket had a lifting capability of 43 tonnes, including the lunar module, service module and command module housing the crew capsule. Saturn V’s third stage put the modules (command with crew capsule, service and lunar modules) into the trans-lunar trajectory soon after orbiting Earth for the second time (see graphic below). The launcher and the lunar craft used powerful engines to reach Moon covering 3.8 lakh km in just four days. However, Nasa had to pump in $185 million ($1.2 billion in 2016 value) for each Apollo mission between 1969 & 1971. Of the $185 million, it spent $110m ($690m in 2016 value) on every Saturn V.

India does not have a rocket powerful enough to hurl Chandrayaan-2 on a straight path to Moon. It’s the reason Isro chose a circuitous route to take advantage of Earth’s gravity, which will help slingshot the craft towards the Moon. The role of GSLV-MkIII, with only 4-tonne lifting capability, was limited to putting Chandrayaan-2 (3.8 tonnes) in the geosynchronous transfer orbit. Currently, the lunarcraft’s propulsion system is raising its orbit. Once the craft reaches its apogee (farthest point from Earth), and with added acceleration, the final orbit will become so stretched out that the farthest part will be very close to Moon’s orbit.

Isro chairman K Sivan told TOI, “The spacecraft requires a minimum velocity of 11km/ second to go to Moon. Of that, 10.3km/second is provided by the vehicle and 700m/second is being provided by the craft’s propulsion system. Being a small engine, we are burning the engine not continously but in short bursts to manoeuvre the craft. If we had a powerful engine like Saturn V, we could have reached Moon in a single shot.” He added, “We are using Moon’s gravitational pull to take craft to the lunar orbit. Though we are taking 29 days to reach the lunar orbit, this is the most cost-effective way to travel to Moon.”

Isro invested Rs 978cr in the Chandrayaan-2 mission. Rs 375cr ($142m) of the total was spent on building GSLVMkIII, a fraction compared to what Nasa had spent on Saturn V.


The three-stage rocket is Isro’s heaviest lifter with the capacity to carry up to 4 tonnes. Though it’s called Isro’s ‘Bahubali’, the rocket is no match for Nasa’s Saturn V. GSLV-MkIII is 43.4m in height (as tall as a 14-storey building) and weighs 641 tonnes. It carried the module to the geosynchronous transfer orbit.


Nasa’s heavy-lift vehicle was a three-stage liquid-propellant rocket. As of 2019, Saturn V is the tallest (111 metre or a 36-storey building), heaviest (2,950 tonnes) and most powerful rocket built. It had the largest payload capacity of 140 tonnes, which included third stage and unburnt propellant to send a command and service module and lunar module to the Moon. Saturn V carried a 43-tonne payload

Vikram Lander

2023: success

Sep 10, 2023: The Times of India

When Vikram, the lander in Isro’s Chandrayaan-3 mission, safely touched down on the Moon at 6.03pm on August 23, a 500-strong team of scientists looked back upon four years of work with pride. 
They we re years when the team “breathed Chandrayaan-3,” says Isro’s associate project director K Kalpana. And she means it. Hundreds of tests were done, thousands of simulations run. In the words of project director P Veeramuthuvel, “Failure was not an option.”

TOI spoke to some scientists in Chandrayaan-3’s 34-member core team to find out how they ensured everything worked this time.
Isro Chairman S Somanath, and M Sankaran, director of UR Rao Satellite Centre – the lead centre for Chandrayaan-3 – give all the credit to the relentless toil and unwavering commitment of their scientists and engineers. Chandrayaan-3 succeeded because nothing was left to chance, says Veeramuthuvel. “The lander was meticulously crafted to adapt to any descent path it encountered. No room for compromise was left.”

For this, the team developed multiple mission plans and designed tests to fix the shortcomings identified in Chandrayaan-2.

Putting Things To The Test

It was crucial to anticipate every possible fault, and build systems capable of overcoming them. That’s why, after hundreds of lab and field tests, the team was fully confident of success on landing day.

They had done more than 80 integrated cold tests (no engines), integrated hot tests (with engines) and drop tests. The cold tests alone had involved 25 hours of flight time and 23 sorties in an IAF helicopter. As issues arose, they were addressed to guarantee reliability.

The preparation differed from Chandrayaan-2 in one crucial way, says Veeramuthuvel: “In Chandrayaan-2, we used an aeroplane so we couldn’t hover or bring it to low altitudes, like 10 metres.” As the equipment was tested on a flat bed at a 6km altitude, system-level sensors could not be evaluated thoroughly for Chandrayaan-2. 
However, the use of a helicopter for Chandrayaan-3’s testing allowed Isro to test sensors “at different levels of the power descent phase for five months. We even did tests while it hovered at 800m and 150m, just as Vikram did while landing on the Moon,” adds Veeramuthuvel.

While the cold testing focused on sensors and navigation, the hot testing at Sriharikota in Andhra Pradesh checked for engine firing. It included dry runs, static tests, closed-loop evaluations, and truncated de-boost tests under conditions similar to those on the Moon.

Sure-Footed Vikram

They also had to ensure that Vikram landed on its feet, so they built seven models of the lander, three of which were scaled-down pieces, and did extensive lander leg drop tests at Chitradurga in Karnataka where craters and boulders served as a test bed for helicopter experiments. These tests improved the team’s know-how of powered descent and landing. 
“We closely assessed integrated sensors and navigation performance, ensuring every system was in sync,” says Veeramuthuvel. The lander leg tests were done for conditions ranging from steep slopes to flat surfaces, hard and soft terrain, and various combinations of horizontal and vertical velocity.

Practice In Virtual World

Chandrayaan-3 had something Chandrayaan-2 did not – a dedicated simulation group. The 2019 mission’s simulations were done by its control system teams and were less elaborate. Aditya Rallapalli, project manager (simulations), says, “We have 25TB simulation data from more than one lakh tests.”

Bharath Kumar GV, deputy project director for navigation, guidance and control (NGC) simulations, says, “Testing for nominal conditions wasn’t enough. We predicted various parameters that could go wrong and built models. Then corrections were carried out at each level.”

Four different simulation test beds – six degrees of freedom (6-DOF), onboard in-loop simulation (OILS), software in-loop simulation (SILS), and hardware simulation – were used with one clear goal: making Vikram soft-land on the Moon. A team led by Prashant Kulshreshtha built and exhaustively tested the onboard software, a key component of the redesigned lander.

Guiding It Home

And finally, someone had to ensure that the systems behaved exactly like the simulations showed they would. Madhavraj, project manager (trajectory), Kuldeep Negi and their team were on the job. “Our role was to see that all the planning on the ground worked. It involved a lot of mathematics,” says Negi.

The five Earth-bound manoeuvres, the trans-lunar injection, lunar orbit insertion, five lunar-bound manoeuvres, and the two de-boosts to get into the pre-landing orbit had to happen exactly as planned. “We had a Plan B for each of them, but our Plan A worked every single time,” says Madhavraj. “If I’ve to sum everything up, I’d say, guidance couldn’t fail,” says Rijesh MP, also a deputy project director with NGC controls and dynamics. One of their key challenges was to ensure the guidance systems were in sync with the engines. If the engines were slow to respond to a command, the guidance system shouldn’t have read it as an error. It didn’t.

See also

Indian Space Research Organisation (ISRO)

The ISRO Spy case: 1994

Moon mission, India/ Chandrayaan

Satellites: India

Space technology: India

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