When the moon samples came to India
Forty-five years ago, India played an important role in deciphering the secrets of extra-terrestrial rocks
A top the steampunk USSR lander called Luna 20 rested a sphere. In 1972, after a robotic drill captured lunar soil from the Apollonius Highlands (a mountainous area on the moon), the sample was deposited in a tube inside it. The sphere took off from the moon on a jet pack and parachuted down in what is today Kazakhstan.
Later, a few hundred milligrams of the lunar soil were packed in glass vials, then in aluminium containers and finally in a rectangular steel box that Narendra Bhandari carried from Moscow.
The moon samples were in his hand luggage. “Things were not so strict," he laughs, adding that he doesn’t think it would be allowed through airport security check today, “particularly when you don’t allow them to open and see inside."
Bhandari, then a scientist at the Tata Institute of Fundamental Research (TIFR) in Mumbai, had worked on the Apollo 11 samples as well in 1970. Those came to TIFR through the diplomatic pouch, routed through the American consulate general. The samples eventually would go to the Physical Research Laboratory in Ahmedabad.
India had, in this way, benefitted from both the USSR and the Americans, rivals in the Moon Race. Samples from Apollo 11 through 17 (the abortive Apollo 13 mission did not return samples), and the successful Luna 16, 20 and 24 missions came to India. These corresponded to locations on the moon, all of which were around its equatorial regions. “All the nine locations were studied in India," says Bhandari.
Before his death in December 1971 at the age of 52, India’s space ambitions were led by the charismatic Vikram Sarabhai, who adhered to a “leapfrog" philosophy. Although technology for development, such as remote sensing, was an area where the Indian Space Research Organization (Isro) followed his vision to generate extensive capabilities, Sarabhai’s ambitions encompassed exploratory science. There are letters from Sarabhai lobbying to have Indian instruments carried on the Luna missions, says Asif Siddiqi, a science historian at Fordham University, New York.
After the Apollo 11 astronauts returned to earth, the samples—rocks as well as moon dust—would undoubtedly have been taken to Nasa’s underground laboratory in Houston, Texas. In the late 1960s, Bhandari had worked with James Arnold at the University of California, San Diego, who played a crucial role in the establishment of the Texas facility.
Over the course of the Apollo missions, the laboratory became a hoard, storing several hundred kilograms of the material. The USSR samples, in contrast, were measured in grams, although the feat of unmanned sample return has yet to be repeated more than 40 years after the last of the Luna landers, Luna 24 in 1976.
One of the early findings that emerged from the moon landings was that Apollo 11 rocks were dated to be around 3.2 billion years old. During the Apollo 15 mission, even older samples, such as the “Genesis" rock, dated to over four billion years old, had been found.
Lacking erosion due to wind and water, volcanism and a magnetic field, the moon appeared to have been preserved in pristine condition. “It is like keeping the moon in a refrigerator," says Bhandari.
The initial proposal put forward by the Indian scientists was to study what are called nuclear tracks in the moon samples. When a low energy heavy nuclei hits silicate grains in the material, it produces damage trails along its path, which can be enlarged and studied under a microscope.
Having been exposed to space radiation for millions of years, even a grain measuring less than a millimetre has tremendous collecting power, as J.N. Goswami and S.V.S. Murthy point out in a 2010 article, published in Current Trends In Science to celebrate 75 years of the Indian Academy of Sciences. Because the moon does not have an atmosphere, which typically deflects solar flares, the flares can leave tracks on its surface layer. This factor revealed information about the behaviour of the ancient sun on a million-year scale.
A chemical processing technique was developed which would allow tracks across a centimetre of the rock to be seen. The amount of rock surface you can see through a microscope depends on the magnification. If there is high magnification, you see a very small area that is not statistically significant. “That is not good because you can’t do much work," says Bhandari, “you can see one track or something." With the technique, you could use a lower powered microscope and see the tracks, covering a larger, statistically significant area.
The window for moon samples closed after the 1970s. Nasa pulled back on its Apollo programme and Russia too shifted priorities. There was a clampdown by Nasa on sharing samples as well, says Siddiqi.
But there is a new sample return mission on the horizon. In 2019, China plans to launch its Chang’e 5 mission, a robotic mission of the kind which has not been attempted since the Luna landers. India, too, plans to launch its Chandrayaan-2 mission early next year. While that mission will not return samples, the hope is that it will pave the way for such missions later.
The Chandrayaan-2 will drop a buggy on a crater rim near the lunar south pole. That it lands on the rim of the crater, where there is sunlight for its solar battery, and not inside the crater, is essential. This makes it a very complex mission, says Bhandari.
There are extremes of temperature on the lunar surface, between 230 degrees Celsius below zero in the shadowed dark regions of the poles and 120 degrees above zero during the lunar day. Water easily boils near the equator, explains Bhandari, “so we must go near the poles".
Beginning with hints in Nasa’s Clementine probe in the 1990s, signals of water on the moon were confirmed by the end of the millennium. For Bhandari, these harkened back to Arnold, who in a 1979 paper in the Journal of Geophysical Research, wrote about potential sources of water on the moon, at a time when it was considered to be “bone-dry."
This may in part have been because of where the samples came from. “All these samples that Apollo brought were from near the lunar equator," says Bhandari, “The polar samples were not brought back."
Ten years ago, on 14 November 2008, the Moon Impact Probe separated from the Chandrayaan-1 spacecraft from a height of 100km above the moon’s surface. Snapping over 3,000 photos, it fell towards the South Pole and picked signals of water in its mass spectrometer. Other instruments like the Moon Mineralogy Mapper’s infrared sensor picked up signals as well, showing absorption bands at 2.8 microns corresponding to OH and H20.
Bhandari still recalls the formal ceremony in 1972 when he was in Moscow to collect the Luna samples: He met the president of the USSR academy of sciences and there was an open exhibition. “At that time I didn’t realize India would have a mission so soon and in my lifetime," he says.