India's lunar exploration program seems to be on hold for the moment. The ambitiousplan to land a rover on the Moon in a joint mission with Russia, followed in the future by a sample-return mission, won't make its original timeline. The problems largely stem from the ongoing problems with India's launch vehicle program, which has suffered from a string of performance failures in recent years.
India has experienced a good record of successful launches with its Polar Satellite Launch Vehicle, a medium-light rocket that launched Chandrayaan-1, India's first mission to the Moon. This orbiter performed fairly well, despite experiencing some technical problems that caused the mission to end prematurely.
India's next planned mission, Chandrayaan-2, was heavier. This was a project to launch a combined orbiter-lander with aRussian landing stage and an Indian rover. Chandrayaan-2 would lift off aboard a version of the Geosynchronous Satellite Launch Vehicle (GSLV), a larger and more complex rocket that carries heavier payloads. GSLV has suffered from development problems, often related to troubles India has experienced in mastering cryogenic rocket engines.
Its launch success rate is unacceptably low. More launches of GSLV are planned for the near future. A couple ofsuccessful missions would be encouraging, but it would takea longer track record of successto restore confidence in this launch vehicle.
Without a reliable heavy-lift vehicle, India really cannot implement its original plans for lunar exploration. But that doesn't mean that India shouldabandon the Moon. It's time for India to consider a revised lunar program that plays to its strengths.
The Polar Satellite Launch Vehicle remains ready to serve as a workhorse for a revised lunar program. India also has the basic framework for a lunar orbiter in its original Chandrayaan mission. There is a bevy of scientific instrumentswaiting for flight opportunities. International partners are still interested in working with ISRO, India's space agency, on joint projects.
It would be technically feasible, and scientifically useful, for India to launch another orbiter mission in the near future. This second orbiter would re-use the Chandrayaan-1 design, with modifications to protect it from the hostile environment of deep space. More attention to thermal control would be necessary, but this would be fairly straightforward to introduce.
The instruments on the second orbiter would be different. Some instruments that scientists wanted to fly on Chandrayaan-1 could not be accommodated on the mission.A second orbiter would give these instruments a chance to fly.
The original mission sent an impactor flying into the surface of the Moon. The second mission could delete the impactor to allow for more instruments for observing the Moon from orbit. Certain instruments seem obvious choices to fly again, such as cameras.
The next orbiter could fly a different orbital profile and observe different areas of the Moon more closely. Global mapping seemed important to the first mission, but the second could be more focused on specific regions of interest.
ISRO should also consider landing a spacecraft on the Moon, but it should also consider revising the lander mission. A small-scale lander could be launched with the Polar Satellite Launch Vehicle. This would be less complex than the originally proposed lander, but it would be feasible.
The lander could use an airbag-style landing system instead of the larger footpad design proposed by the Russians. It would be smaller and less capable than this design. But it would still give India a soft landing on the Moon.
Some of the instruments underdevelopment for the original lander mission could be included on the small-scale lander, but not all.
A large rover seems unrealistic for such a mission, but India may wish to experiment with amicrorover.
These proposed missions would give India an ambitious,interesting and productive lunar program for the near future. While these missions fly, India will hopefully debug and demonstrate the Geosynchronous Satellite Launch Vehicle. When this heavy rocket is ready, it will be time for even more ambitious flights to the Moon.
Dr Morris Jones is an Australian space writer. He is the author of "When Men Walked on the Moon" from Space Frontier Science Press.