India's First Moon Mission Cost ₹386 Crore and Carried the NASA Instrument That Found Water on the Lunar Surface

A PSLV-XL rocket lifted off from Sriharikota at 00:52 UT on 22 October 2008, which was 6.22 am in India, carrying Chandrayaan-1, the country’s first mission to the Moon. On 24 September 2009, NASA announced that an instrument on board had detected water and hydroxyl, a molecule of one oxygen atom and one hydrogen atom, on the lunar surface. The paper in the journal Science was led by Carle Pieters of Brown University, with 28 co-authors.

By then the orbiter had been silent for almost a month. ISRO lost contact with it about ten months into a planned two-year mission.

Eleven instruments, five of them Indian

ISRO’s mission page lists eleven scientific instruments, built in India, the United States, the United Kingdom, Germany, Sweden and Bulgaria. Five were Indian: the Terrain Mapping Camera, the Hyper Spectral Imager, the Lunar Laser Ranging Instrument, the High Energy X-ray Spectrometer and the Moon Impact Probe. The other six came from abroad. ESA says Europe supplied three, an X-ray spectrometer (C1XS), a particle analyser (SARA) and a near-infrared spectrometer (SIR-2). NASA supplied the Moon Mineralogy Mapper, known as M3, and a radar called Mini-SAR. Bulgaria supplied RADOM, a radiation dose monitor.

The spacecraft was a cube 1.5 metres on a side, built on the same bus as ISRO’s remote-sensing satellites, and it weighed 1,380 kilograms at lift-off. The idea was first raised at a 1999 meeting of the Indian Academy of Sciences, and the government approved the mission in November 2003, ISRO says. A mission this far out also needed a way to talk to it. ISRO built the Indian Deep Space Network before launch, with a 32-metre and an 18-metre dish at Byalalu near Bengaluru.

The cost was ₹386 crore. That is the figure the Minister of State in the Prime Minister’s Office, Prithviraj Chavan, gave the Rajya Sabha in a written reply on 18 December 2008, and he said it includes the Deep Space Network. ABC News described it in August 2009 as an $80 million spacecraft. How ISRO went on to do Mars and the Moon on small budgets is the subject of our piece on its frugal engineering.

Thirteen days to leave Earth, one probe to hit the pole

After launch, five engine burns over 13 days stretched the spacecraft’s orbit, ESA reports. A final burn on 8 November put it into lunar orbit, and over the next four days it settled into a polar orbit about 100 kilometres above the surface.

On 14 November 2008 the Moon Impact Probe separated from the orbiter. NASA’s mission page says it fired a small deorbit motor, fell freely while sending readings from three instruments, and crashed near Shackleton Crater at the south pole at 15:01 UT. The instruments were a radar altimeter, a video camera and a mass spectrometer called CHASE. The Press Information Bureau’s 2008 reply records the descent as complete at 20:35 Indian time.

ESA writes that the impact “officially marked India as the fourth nation to reach the lunar surface.” Indian scientists reported that CHASE data suggested water in the thin lunar atmosphere. NASA’s page calls that result inconclusive without further verification.

What the Moon Mineralogy Mapper saw

M3 was an infrared imaging spectrometer built at NASA’s Jet Propulsion Laboratory, with Pieters as principal investigator. It split reflected sunlight into wavelengths from 430 to 3,000 nanometres, and JPL describes it as a guest instrument on Chandrayaan-1. Water and hydroxyl absorb light near 3 micrometres, so they leave a dip in the spectrum.

The Science paper reports absorption features between 2.8 and 3.0 micrometres across the Moon. The signal is widespread and strongest at cooler high latitudes and in some fresh craters. NASA says the molecules sit in the top few millimetres of the soil. The authors suggest the hydroxyl and water are still forming and being retained at the surface, and that the soil could be a source of volatiles for human exploration. Crewed lunar exploration is the subject of our piece on NASA’s Artemis flights.

Pieters set the scale herself. “When we say ‘water on the moon,’ we are not talking about lakes, oceans or even puddles,” she said in NASA’s release.

Two other spacecraft reached the same answer

Two more papers appeared in the same issue of Science, each from a different spacecraft. Roger Clark of the US Geological Survey reanalysed data from a 1999 flyby by NASA’s Cassini probe and found absorption near 3 micrometres from adsorbed water, with an estimated 10 to 1,000 parts per million. Jessica Sunshine of the University of Maryland and colleagues used the Deep Impact spacecraft, flying as EPOXI, which observed the Moon in June 2009. They found the surface hydrated during part of the lunar day, with the amount consistent with less than 0.5 per cent water by weight. The hydration rose and fell with temperature within a single lunar day.

NASA’s release says that at the top of Clark’s range, a ton of the uppermost soil layer could yield as much as 32 ounces of water.

Ice in the dark craters

M3 measured sunlit ground. A second Chandrayaan-1 instrument looked into the shadows. NASA announced on 1 March 2010 that Mini-SAR, a lightweight radar, had found more than 40 small craters near the north pole whose radar signature resembled ice. The craters are 2 to 15 kilometres across, and the team estimated at least 600 million metric tons of water ice, depending on how thick it lies in each crater. The result appeared in Geophysical Research Letters. NASA’s Jason Crusan called it “a strong indication of water ice,” and the release itself says the deposits have radar characteristics “similar to ice”, which is an inference and not a sample.

ESA says a fuller analysis of M3 data later found water ice at multiple spots in permanently shadowed regions. The paper behind that, Li and colleagues in the Proceedings of the National Academy of Sciences in 2018, found exposed ice in several thousand M3 pixels, each about 280 metres across, all within 20 degrees of the poles. Only about 3.5 per cent of the cold traps it examined, the permanently shadowed patches cold enough to hold ice, showed any.

Contact lost, 28 August 2009

ISRO raised the orbit to 200 kilometres in May 2009. NASA’s page says abnormally high temperatures began in late November 2008, and a star sensor, which the spacecraft uses to find its orientation, failed after nine months in orbit. Radio contact ended at 20:00 UT on 28 August 2009, which was 1:30 am on 29 August in India. ISRO’s page gives 29 August.

ABC News quoted ISRO spokesman S. Satish as saying the agency was studying telemetry to find the problem. ISRO says the spacecraft had made more than 3,400 orbits of the Moon. NASA’s page says the most likely cause was a power-supply failure from overheating. Both ESA and NASA report that ISRO considered at least 95 per cent of the mission objectives achieved.

A radar finds it again

In July 2016, almost seven years after the last contact, JPL’s Marina Brozovic led a test to find the orbiter with ground radar. On 2 July 2016 NASA’s 70-metre Goldstone dish in California sent microwaves toward a point about 160 kilometres above the Moon’s north pole, and the 100-metre Green Bank Telescope in West Virginia listened for echoes.

Over four hours, an object with a small spacecraft’s radar signature crossed the beam twice, and the gap matched Chandrayaan-1’s expected orbital period of 2 hours and 8 minutes. JPL’s Ryan Park said the old orbit estimate from 2009 had to be moved by about 180 degrees. Seven more echoes over three months matched the corrected orbit, and the Arecibo Observatory helped with follow-up. JPL announced the result on 9 March 2017 and described the orbiter as dormant. Its own calculations had put the craft about 200 kilometres above the surface.

What followed

ISRO’s later Moon missions went for the surface itself. Chandrayaan-3 soft-landed on 23 August 2023 at about 69.37 degrees south, in the southern high latitudes, according to ISRO. Ten days after that landing, on 2 September 2023, a PSLV launched Aditya-L1, a solar observatory whose seven scientific payloads ISRO says were developed by itself and national research laboratories, among them the Indian Institute of Astrophysics in Bengaluru and the Inter University Centre for Astronomy and Astrophysics in Pune.