Credit: fernandozhiminaicela/pixabay

Moon mission pushed to October, so we wait

So, the Indian Space Research Organisation’s (ISRO’s) Chandrayaan 2 mission to the Moon has been pushed to October from April. Delays of this sort are to be expected for missions of this scale, although I’ve also heard that ISRO often does a poor job of setting realistic launch dates for its missions in general.

The actual launch window for Chandrayaan 2 had been April-November, but recent reports in the media quoting ISRO officials had created the impression that people were confident April would be it.

But now, with the announcement of delay, officials’ confidence on display earlier this year that the launch would happen in April is now in serious question. The most recent media report I can find that quotes a senior official saying Chandrayaan 2 will be launched in April is dated February 16, 2018. The primary Google search result still says “April 2018”.

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I also find it curious that the mission’s delay was announced barely 30 or so days before it was slated to launch instead of much earlier. For missions of this size, delays can be anticipated sooner… unless something unexpected has happened. Has it? No clue. Is it because of the probe itself or the launcher, a GSLV Mk II? Again, no clue.

So we do what we always have: wait.

Mission readiness is one thing but setting realistic launch dates, communicating them to the public in a timely manner and keeping all stakeholders – including the people – informed of the reasons for delay are quite another.

Featured image credit: fernandozhiminaicela/pixabay.

Is it so blasphemous to think ISRO ought not to be compared to other space agencies?

ISRO is one of those few public sector organisations in India that actually do well and are (relatively) free of bureaucratic interference. Perhaps it was only a matter of time before we latched on to its success and even started projecting our yearning to be the “world’s best” upon it – whether or not it chose to be in a particular enterprise. I’m not sure if asserting the latter or not affects ISRO (of course not, who am I kidding) but its exposition is a way to understand what ISRO might be thinking, and what might be the best way to interpret and judge its efforts.

So last evening, I wrote and published an article on The Wire titled ‘Apples and Oranges: Why ISRO Rockets Aren’t Comparable to Falcons or Arianes‘. Gist: PSLV/GSLV can’t be compared to the rockets they’re usually compared to (Proton, Falcon 9, Ariane 5) because:

  1. PSLV is low-lift, the three foreign rockets are medium- to -heavy-lift; in fact, each of them can lift at least 1,000 kg more to the GTO than the GSLV Mk-III will be able to
  2. PSLV is cheaper to launch (and probably the Mk-III too) but this is only in terms of the rocket’s cost. The price of launching a kilogram on the rocket is thought to be higher
  3. PSLV and GSLV were both conceived in the 1970s and 1980s to meet India’s demands; they were never built to compete internationally like the Falcon 9 or the Ariane 5
  4. ISRO’s biggest source of income is the Indian government; Arianespace and SpaceX depend on the market and launch contracts from the EU and the US

While spelling out any of these points, never was I thinking that ISRO was inferior to the rest. My goal was to describe a different kind of pride, one that didn’t rest on comparisons but drew its significance from the idea that it was self-fulfilling. This is something I’ve tried to do before as well, for example with one of the ASTROSAT instruments as well as with ASTROSAT itself.

In fact, when discussing #3, it became quite apparent to me (thanks to the books I was quoting from) that comparing PSLV/GSLV with foreign rockets was almost fallacious. The PSLV was born out of a proposal Vikram Sarabhai drew up, before he died in 1970, to launch satellites into polar Sun-synchronous orbits – a need that became acute when ISRO began to develop its first remote-sensing satellites. The GSLV was born when ISRO realised the importance of its multipurpose INSAT satellites and the need to have a homegrown launcher for them.

Twitter, however, disagreed – often vehemently. While there’s no point discussing what the trolls had to say, all of the feedback I received there, as well as on comments on The Wire, seemed intent ISRO would have to be competing with foreign players and that simply was the best. (We moderate comments on The Wire, but in this case, I’m inclined to disapprove even the politely phrased ones because they’re just missing the point.) And this is exactly what I was trying to dispel through my article, so either I haven’t done my job well or there’s no swaying some people as to what ISRO ought to be doing.


We’re not the BPO of the space industry nor is there a higher or lower from where we’re standing. And we don’t get the job done at a lower cost than F9 or A5 because, hey, completely different launch scenarios.


Again, the same mistake. Don’t compare! At this point, I began to wonder if people were simply taking one look at the headline and going “Yay/Ugh, another comparison”. And I’m also pretty sure that this isn’t a social/political-spectrum thing. Quite a few comments I received were from people I know are liberal, progressive, leftist, etc., and they all said what this person ↑ had to say.


Compete? Grab market? What else? Colonise Mars? Send probes to Jupiter? Provide internet to Africa? Save the world?


Now you’re comparing the engines of two different kinds of rockets. Dear tweeter: the PSLV uses alternating solid and liquid fuel motors; the Falcon 9 uses a semi-cryogenic engine (like the SCE-200 ISRO is trying to develop). Do you remember how many failures we’ve had of the cryogenic engine? It’s a complex device to build and operate, so you need to make concessions for it in its first few years of use.


“If [make comparison] why you want comparison?” After I’ve made point by [said comparison]: “Let ISRO do its thing.” Well done.


This tweet was from a friend – who I knew for a fact was also trying to establish that Indian and foreign launchers are incomparable in that they are not meant to be compared. But I think it’s also an example of how the narrative has become skewed, often expressed only in terms of a hierarchy of engineering capabilities and market share, and not in terms of self-fulfilment. And in many other situations, this might have been a simple fact to state. In the one we’re discussing, however, words have become awfully polarised, twisted. Now, it seems, “different” means “crap”, “good” means nothing and “record” means “good”.


Comments like this, representative of a whole bunch of them I received all of last evening, seem tinged with an inferiority complex, that we once launched sounding rockets carried on bicycles and now we’re doing things you – YOU – ought to be jealous of. And if you aren’t, and if you disagree that C37 was a huge deal, off you go with the rocket the next time!


The Times of India even had a cartoon to celebrate the C37 launch: it mocked the New York Times‘s attempt to mock ISRO when the Mars Orbiter Mission injected itself into an orbit around the red planet on September 27, 2014. The NYT cartoon had, in the first place, been a cheap shot; now, TOI is just saying cheap shots are a legitimate way of expressing something. It never was. Moreover, the cartoons also made a mess of what it means to be elite – and disrupted conversations about whether there ought to be such a designation at all.

As for comments on The Wire:


Obviously this is going to get the cut.


As it happens, this one is going to get the cut, too.

I do think the media shares a large chunk of the blame when it comes to how ISRO is perceived. News portals, newspapers, TV channels, etc., have all fed the ISRO hype over the years: here, after all, was a PSU that was performing well, so let’s give it a leg up. In the process, the room for criticising ISRO shrank and has almost completely disappeared today. The organisation has morphed into a beacon of excellence that can do no wrong, attracting jingo-moths to fawn upon its light.

We spared it the criticisms (offered with civility, that is) that would have shaped the people’s perception of the many aspects of a space programme: political, social, cultural, etc. At the same time, it is also an organisation that hasn’t bothered with public outreach much and this works backwards. Media commentaries seem to bounce off its stony edifice with no effect. In all, it’s an interesting space in which to be engaged, as a researcher or even as an enthusiast, but I will say I did like it better when the trolls were not interested in what ISRO was up to.

Featured image credit: dlr_de/Flickr, CC BY 2.0.

And the GSLV flew!

The Copernican
January 6, 2014

Congratulations, ISRO, for successfully launching the GSLV-D5 (and the GSAT-14 satellite with it) on January 5. Even as I write this, ISRO has put out an update on its website: “First orbit raising operation of GSAT-14 is successfully completed by firing the Apogee Motor for 3,134 seconds on Jan 06, 2014.”

With this launch comes the third success in eight launches of the GSLV program since 2001, and the first success with the indigenously developed cryogenic rocket-engine. As The Hindu reported, use of this technology widens India’s launch capability to include 2-2.5 tonne satellites. This propels India into becoming a cost-effective port for launching heavier satellites, not just lighter ones as before.

The GSLV-D5 (which stands for ‘developmental flight 5′) is a variant of the GSLV Mark II rocket, the successor to the GSLV Mark I. Both these rockets have three stages: solid, liquid and cryogenic. The solid stage possesses the design heritage of the American Nike-Apache engine; the liquid stage, of the French Vulcain engine. The third cryogenic upper stage was developed at the Liquid Propulsion Systems Centre, Tamil Nadu—ISRO’s counterpart of NASA’s JPL.

There is a significant difference of capability based on which engines are used. ISRO’s other more successful launch vehicle, the Polar Satellite Launch Vehicle (PSLV), uses four stages: alternating solid and liquid ones. Its payload capacity to the geostationary transfer orbit (GTO), from which the Mars Orbiter Mission was launched, is 1,410 kg. With the cryogenic engine, the GSLV’s capacity to the same orbit is 2,500 kg. By being able to lift more equipment, the GSLV hypothetically foretells our ability to launch more sophisticated instruments in the future.

The better engine

The cryogenic engine’s complexity resides in its ability to enhance the fuel’s flow through the engine.

An engine’s thrust—its propulsive force—is higher if the fuel flows faster through it. Solid fuels don’t flow, but they let off more energy when burnt than liquid fuels. Gaseous fuels barely flow and have to be stored in heavy, pressurised containers.

Liquid fuels flow, have higher energy density than gases, and they can be stored in light tanks that don’t weigh the rocket down as much. The volume they occupy can be further reduced by pressurising them. Recall that the previous launch attempt of the GSLV-D5, in August 2013, was called off 74 minutes before take-off because fuel had leaked from the liquid stage during the pre-pressurisation phase.

Even so, there seems no reason to use gaseous fuels. However, when hydrogen burns in the presence of oxygen, both gases at normal pressure and temperature, the energy released provides an effective exhaust velocity of 4.4 km/s—one of the highest (p. 23, ‘Cosmic Perspectives in Space Physics’, S. Biswas, 2000). It was to use them more effectively that cryogenic engines were developed.

In a cryogenic engine, the gases are cooled to very low temperatures, at which point they become liquids—acquiring the benefits of liquid fuels also. However, not all gases are considered for use. Consider this excerpt from a NASA report written in the 1960s:

A gas is considered to be cryogen if it can be changed to a liquid by the removal of heat and by subsequent temperature reduction to a very low value. The temperature range that is of interest in cryogenics is not defined precisely; however, most researchers consider a gas to be cryogenic if it can be liquefied at or below -240 degrees fahrenheit [-151.11 degrees celsius]. The most common cryogenic fluids are air, argon, helium, hydrogen, methane, neon, nitrogen and oxygen.

The difficulties arose from accommodating tanks of super-cold liquid propellants—which includes both the fuel and the oxidiser—inside a rocket engine. The liquefaction temperature for hydrogen is 20 kelvin, just above absolute zero; for oxygen, 89 kelvin.

Chain of problems

For starters, cryopumps are used to trap the gases and cool them. Then, special pumps called turbopumps are required to move the propellants into the combustion chamber at higher flow-rates and pressures. Next, relatively expensive igniters are required to set off combustion, which also has to be controlled with computers to prevent them from burning off too soon. And so forth.

Because using cryogenic technology drove advancements in one area of a propulsion system, other areas also required commensurate upgrades. Space engineers learnt many lessons from the American Saturn launch vehicles, whose advanced engines (for the time) were born of using cryogenic technology. They flew between 1961 and 1975.

In the book ‘Rocket Propulsion Elements’ (2010) by George Sutton and Oscar Biblarz, some other disadvantages of using cryogenic propellants are described (p. 697):

Cryogenic propellants cannot be used for long periods except when tanks are well insulated and escaping vapours are recondensed. Propellant loading occurs at the launch stand or test facility and requires cryogenic propellant storage facilities.

With cryogenic liquid propellants there is a start delay caused by the time needed to cool the system flow passage hardware to cryogenic temperatures. Cryogenically cooled fluids also continuously vaporise. Moreover, any moisture in the same tank could condense as ice, adulterating the fluid.

It was in simultaneously overcoming all these issues, with no help from other space-faring agencies, that ISRO took time. Now that the Mark II has been successfully launched, the organisation can set its eyes on loftier goals—such as successfully launching the next, mostly different variant of the GSLV: the Mark III, which is projected to have a payload capacity of 4,500-5,000 kg to GTO.

While we are some way off from considering the GSLV for manned missions, which requires mastery of reentry technology and spaceflight survival, the GSLV Mark III, if successful, could make India an invaluable hub for launching heavier satellites at costs lesser than ESA’s Ariane program, which India used in lieu of the GSLV.

Good luck, ISRO!