My article on missing science from Mangalyaan has gotten a response from two planetary scientists, one of whom used to work at ISRO. The response raises some intriguing points to explain the lack of science from India’s highly regarded Mars mission, pointing to an even deeper problem. However, some points in the article that push the blame away from ISRO need a rebuttal.

The response argues that Mangalyaan’s instruments package was restricted to a mere 15 kilograms not because of the mission’s low development time of just 18 months due to political considerations but rather due to a technical constraint.

The payload was restricted to 15 kg because ISRO’s Polar Satellite Launch Vehicle (PSLV) could carry 1.4 tonnes in all to the geostationary transfer orbit. More powerful rockets – the GSLV Mk II and Mk III – with a proven track record only became available later. If ISRO had waited for these vehicles, the Mars mission would have been delayed by eight years or so.

The GSLV Mk II launch record shows the rocket’s first operational flight was in January 2014, just two months after Managalyaan launched, followed by the second and third flights in 2015 and 2016 respectively. If Mangalyaan targeted the 2016 launch opportunity instead, it could’ve been on Mk II rocket, which has double the capacity of the PSLV.

Besides, it’s not like ISRO hasn’t carried flagship missions on brand new rockets, the best example being Chandrayaan 2, which launched on the GSLV Mk III’s first operational flight in 2019. So the claim that the Mars mission would’ve been delayed by “eight years” if ISRO had waited for these rockets doesn’t stand no matter how you slice their launch history.

Next, coming to the methane sensor which was supposed to globally map methane with a sensitivity of parts per billion, to help decide if the methane on Mars could be a sign of subsurface life. Two years after launch, the instrument was found to have a design flaw and so it can’t detect methane at all. The response piece says,

It did not fail; it is still working. The issue is that MSM is sensitive to both methane and carbon dioxide. And the SAC team has published a paper on a way to extract the methane signal along from the instrument’s data, subtracting the interference of other gases.

The fact that the sensor can’t distinguish between methane and any other gas, not just carbon dioxide, and that ISRO officially repurposed the instrument as an albedo mapper is a failure of the original objective. The published paper being referred to was out in 2018, and a single scientific publication is yet to come in the over two years since.

Another curious case is about an instrument that I didn’t talk about in my original article but the response piece does.

Martian Exospheric Composition Explorer (MENCA) is a mass spectrometer capable of measuring parts per billion or lower concentrations of the substances in Mars’s exosphere. However, MENCA can perform its measurements only within the exosphere itself. And this hasn’t been possible thus far thanks to MOM’s orbit, which takes it to within 400 km of the surface.

Deep-dip experiments or manoeuvres are designed to make measurements closer to the lower end of Mars’s upper atmosphere. MAVEN’s lowest point was at 125 km. But MOM could deep-dive only up to 265 km—while MENCA needs to be within 100 km of the surface or less (to perform its measurements). This may become possible once MOM runs out of fuel and begins to spiral in towards the ground.

This raises the question of the instrument being onboard in the first place. The orbit that Mangalyaan was designed for, and successfully put into, is a highly elliptical one, of 76,000 x 460 kilometers. It hasn’t changed drastically since then, those changes being due to maneuvers required to keep the spacecraft operational. If even during the deep-dip orbits Mangalyaan doesn’t and won’t go lower than 265 kilometers, much higher than the less than 100 kilometers required for MENCA, why was the instrument selected in the first place? Alternatively, why wasn’t the orbit chosen to be in line with what MENCA needs?

The spacecraft orbits are well known before the development of mission hardware begins. If anything, the science team usually dictates parts of these requirements. As such, the orbit chosen for Mangalyaan squarely points to the mission being a tech demonstrator rather than a science one.

Regarding the lack of an appropriate planetary exploration framework to drive ISRO’s space exploration missions, the response piece says,

In ISRO, the choice of what science is to be done is made by the Advisory Committee on Space Sciences (ADCOS), primarily comprising former directors of ISRO academic centres, like the Physical Research Laboratory (PRL) or the National Atmospheric Research Laboratory. ADCOS identifies experts for each proposed area of science (e.g. geology, atmospherics, etc.), with decadal plans.

Upon searching on ISRO’s website to learn about ADCOS, I found no information except for passing mentions of it existing. Then I learnt that ADCOS has been dissolved and is superseded by APEX. Again, there’s no information about APEX on ISRO’s website apart from passing mentions. And those ‘decadal plans’ are nowhere to be seen. The only place I found anything useful about APEX was ISRO’s 2019-2020 annual report, which says,

The APEX Science Board (ASB) was constituted to review and recommend steps for the cutting edge research projects on various fields related to space science. Based on the recommendations of ASB, interested scientists/faculties of various research institutes are encouraged to undertake space instrument/payload developmental activities with ISRO funding support. In addition to ongoing approved programs, feasibility studies of experiments for future space missions are also undertaken at several ISRO/DOS centers. The Apex Science Board of ISRO has selected a few scientific proposals to conduct experiments onboard an orbiter mission around Venus and Mars.

That seems to be the only publicly available information about APEX, a bit too brief for an entire Board that chooses what science will be done on ISRO’s space exploration missions. Like NASA’s Decadal plans, the details of the process followed by APEX, what members constitute its board, and the papers that they produce should be available to the public, us taxpayers, and in an accessible way.

Regarding the criticism in my article about ISRO not collaborating with Indian universities and institutions, the response piece says,

At ISRO’s behest, PRL initiated the Planetary Science and Exploration (PLANEX) program in 2001. The idea was to motivate young researchers and provide planetary research facilities in the country, including for remote-sensing, astro-materials, payload development and laboratory/simulation studies of planetary analogues.

Today, a large number of projects are being run in universities and institutes around India that are supported by PLANEX. So saying ISRO isn’t as open as it can be to collaborations with academic institutions may not be entirely fair.

I, again, found nothing on ISRO’s website or the annual report about PLANEX and its progress. Even PRL’s website is limited to stating a couple of sentences about the program.

PLANEX (Planetary Science and Exploration Programme) : Develop payloads for planetary missions, Establishment of National facilities for research in planetary sciences, encourage research projects related to planetary sciences at universities and institutes in India. A X-Ray Fluorescence Spectrometer, Electron Probe Micro Analyser, Inductively Coupled Plasma Mass Spectrometer and a Noble Gas Mass Spectrometer have been procured and are part of the National Facilities for analysis of astromaterials at PRL.

The response piece ends by trying to lay the case for how the sorry state of Indian academic institutions is responsible for Mangalyaan’s missing science output, not ISRO. It’s unclear how it takes away ISRO’s share of the problem, who is after all the one undertaking Indian planetary science missions anyway, and orchestrating the related programs. The mystery remains as to why ISRO couldn’t have collaborated with foreign space agencies and universities for Mangalyaan science, like it did with Chandrayaan 1, or taken the time to launch later with a better instruments package of its own.

Republished by The Wire Science.

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