India’s first lunar mission, Chandrayaan 1, confirmed the existence of water on the Moon.
It was a groundbreaking achievement for mission director Srinivasa Hegde, who worked at the Indian Space Research Organization (ISRO) for 36 years, from 1978 to 2014. At ISRO’s Satellite Center in Bangalore he was involved in planning, analysis and operations for dozens of space missions.
Supercluster chats with Srinivasa about his role as Mission Director for Chandrayaan 1 and India’s future in space. Responses have been edited for clarity.
As a kid, I was influenced by my grandfather. He was a Sanskrit scholar and an astrologer, with a love for stars in the sky. He used to take me for early morning walks before dawn. During those days of reduced pollution, many constellations were clearly visible. He used to identify and explain all the constellations to me and I was intrigued. Besides, I was generally interested in science and reading up on new discoveries and happenings in the field.
Then one day I came across a job opening at ISRO for which I applied and got selected.
Dr. K. Kasturirangan chaired ISRO from 1994 to 2003. He wanted the organization to play a small role in India’s ambition to become a superpower. This planted the seed for undertaking more ambitious missions. The idea of a Moon orbiter was floated and was received positively by everyone.
At the time, ISRO already had satellites intended for geostationary applications, which had plenty of fuel. So the basic infrastructure was ready and the only delta was adapting it to the Moon. Initial calculations showed that our PSLV rocket was capable of giving an Earth-bound orbit beyond which the fuel on the spacecraft could be used to go to the Moon, and perform orbital capture. In all, Chandrayaan 1 seemed like a logical extension of our capabilities.
I was involved in all aspects of the Mission Design — the design of the various orbits, data management, orbit determination, strategies for mid-course corrections, etc., and also in aspects of operating the spacecraft.
Chandrayaan 1 was the first ISRO project to involve many foreigners who had their scientific instruments onboard. As Mission Director, I was tasked with accommodating their needs. It posed challenges because they had diverse requirements.
For instance, scientists behind the Mini-SAR payload wanted to calibrate the instrument when the spacecraft is en-route to the Moon. They were unhappy with the fact that we couldn’t accommodate that due to certain changes in our launch schedule. However, at a later stage we provided them with geometry in lunar orbit for calibration which they said was even better than what they asked for.
Absolutely. NASA missions to the Moon in the past decade had already hinted at the possibility of water ice being trapped in the permanently shadowed regions of the Moon. So it was crucial to confirm its presence, as it has implications for future human settlements. It also provides insights on the Moon’s origin.
We had our own science payloads on Chandrayaan 1, but given the renewed global interest in the Moon after so many decades, we also wanted to provide the spacecraft as a platform for others. And so ISRO put out an announcement of opportunity to scientists all over the world to pitch payloads for Chandrayaan 1. We got instruments from ESA as well as NASA, including from Universities associated with them. I think the timing of Chandrayaan 1 was good, as NASA’s next Moon mapper, LRO, was still a year away.
As discussed, NASA scientists were really interested in putting their instruments on Chandrayaan 1 and working with us on confirming the presence of water. The discovery ultimately came from two NASA-built instruments - the Miniature Synthetic Aperture Radar (Mini-SAR) and the Moon Mineralogical Mapper (M3).
Mini-SAR found that more than 40 craters on the lunar poles reflected signals in patterns consistent with water ice. However, there was still some uncertainty like previous missions as to if the detections were really of water ice.
It was the M3 instrument that confirmed the presence of water ice in the polar craters, based on how the surface absorbed infrared light. In fact, M3 detected water and hydroxyl molecules almost everywhere on the Moon. Scientists now knew for the first time that the lunar soil does hold trace amounts of water even in the non-polar regions.
Through the India-USA partnership on Chandrayaan 1, NASA also extended access to its iconic Deep Space Network which was used for communication with the spacecraft.
Oh, this is myfavorite part!Chandrayaan 1actually managedto view a solar eclipsefrom the Moon.
We were able to see the Moon’s shadow cast here on Earth. In 2009, a year after launch, both the star sensors onboard the spacecraft had failed. With that, the spacecraft lost its ability to precisely point to a desired attitude in space.
A mission failure was looming.
Instead of losing the craft, we came up with a solution that involved using the Sun sensors to get knowledge of two spatial axes, and get aid from the ground station to know the third. This data was utilized by the onboard gyroscopes to be able to point the spacecraft again with reasonable accuracy.
The mission was back up and running.
As the spacecraft passed between the Moon and Earth in its lunar orbit on July 22, 2009, it imaged the Moon’s shadow cast on our planet. This was a first for any lunar mission and completely executed when the spacecraft was in a non-nominal state.
It’s too early to comment but going by the amount estimated from Chandrayaan 1 Mini-SAR observations, it seems there could be enough. Chandrayaan 2’s orbiter can tell us more details about it.
The Chandrayaan 2 orbiter has upgraded instruments. Its infrared spectrometer will build a global, high-resolution map of water concentrations in the lunar soil and study how the amount changes in response to the lunar environment.
The upgraded radar will map the water ice trapped in the lunar poles and quantify its amount, something no one has adequately done yet.
It is difficult — as both these nations have enormous resources and manpower. But the spectrum of science that can be done on the Moon is vast and our strategy has been to fill crucial gaps in our current understanding, like the discovery of water.
Saturn's moon Enceladus. It is mostly covered with fresh, clean ice, making it one of the most reflective bodies in the Solar System and is known to host water underneath that icy surface. After the Cassini spacecraft’s discovery of organic compounds in Enceladus’ plumes, it is to me by far the most interesting object in the Solar System.
It plays an important role in the eventual settlement of space. Doing such missions means we gain new capabilities and experiences, all of which give us a good starting point for future endeavors. For instance, the most notable thing in Chandrayaan 2 is that all its cutting-edge scientific instruments are designed and built indigenously.
Sending humans to space involves too many challenges, like ruggedization of the spacecraft and launcher, having enough fuel at all stages, complex trajectories, multi-layered redundancy in spacecraft functions, etc. At every stage, there should be a means to get back humans safely and there is little to no tolerance for failure. With all those requirements, Gaganyaan is certainly a very expensive undertaking.
But it has to be done sooner or later for space settlement, so why not now?
The Moon is good from an energy point of view though it has limited areas for potential habitability i.e. lava tubes or polar regions. But Mars has a much more conducive environment, a near 24 hours day, relatively benign temperatures, and is, in general, a more hospitable place.
If huge rockets like SpaceX’s Starship Super Heavy are available in the future, then energy is not really a problem and Mars becomes a better target than the Moon.