Last week, I read about some morons in UK get all bitchy about an official announcement regarding India plan to launch an unmanned orbiter probe to mars during late 2013. While this project has been known to exist since 2010, most people outside ISRO never thought that it would be followed up so vigorously. This belief is understandable since Indian politicians and bureaucrats, who control the purse strings of government projects, are rightly seen as morons who drive out or destroy the career and dreams of competent Indian scientists. However this post is not about the state of politics and governance in India, which almost every Indian has had considerable experience with. My post is about whether such a probe is feasible and deliverable within the set time-frame, with available funding using available technology.
I had originally considered starting this post by going through a quick explanation of the basic design, and components used in, a generic space probe. However I realized that it would be far easier to use previously launched space probes as examples to illustrate what I am talking about. So let us begin by using the first really successful Mars probe Mariner 9 as my initial example.
Mariner 9 (Mariner Mars ’71 / Mariner-I) is a NASA space orbiter that helped in the exploration of Mars and was part of the Mariner program. Mariner 9 was launched toward Mars on May 30, 1971 from Cape Canaveral Air Force Station and reached the planet on November 14 of the same year, becoming the first spacecraft to orbit another planet — only narrowly beating Soviet Mars 2 and Mars 3, which both arrived within a month. After months of dust-storms it managed to send back clear pictures of the surface. Mariner 9 returned 7329 images over the course of its mission, which concluded in October 1972.
For such a small spacecraft and late 1960-era technology, it achieved a lot. For one, it was the first spacecraft to orbit another planet. Over 349 days in orbit, Mariner 9 had transmitted 7,329 images, covering 100% of Mars’ surface. The mission resulted in a global mapping of the surface of Mars, including the first detailed views of the martian volcanoes, Valles Marineris, the polar caps, and the satellites Phobos and Deimos. It also provided information on martian dust storms as well as their effect on shaping the landscape of that planet. Now you have to remember that the probe was launched in 1971, so it used nickel-cadmium battery packs to store solar energy and the resolution of its digital camera was 1 pixel= 100 m to 1 km, depending on its altitude above the martian surface.
Now as some of you know, India did launch a successful unmanned orbiter (Chandrayaan-1) to the moon in late 2008. Its specs, instrumentation and other common parameters of performance were in many cases superior to those of contemporary moon probes from other countries such as Chang’e 1 and SELENE, though it weighed about half as much as either of them. For example, the Terrain Mapping Camera of Chandrayaan-1 had a per pixel resolution of 1-5 m per pixel compared to the 10m per pixel of SELENE (Japanese lunar orbiter) or the 60 m per pixel of Chang’e 1 (Chinese lunar orbiter). Only the later Lunar Reconnaissance Orbiter has imaged the moon at a higher resolution. It is also worth noting that Chandrayaan-1 provided the first unequivocal evidence of trace amounts of water on the moon’s surface, as well as provide an explanation about its mode of creation and dissipation during each lunar day and night. My only quip with the Indian lunar program has been their laziness or stupidity with regards to not providing public access to tons of pretty pictures (over 70,000 high-resolution 2.5 D photos) of the moon. It might be also helpful for readers to read a bit about the capabilities of Indian Remote Sensing (IRS) satellites, telecommunication satellites (INSAT series) and Radar imaging satellites such as RISAT-1 and RISAT-2.
Therefore the ability of India to design, manufacture and assemble high quality unmanned spacecraft is unquestionable. The proposed 2013 mars orbiter is, if anything, far more spartan than the many satellites designed and built by India over the 2 decades. The next question is- Can they launch it with the PSLV-XL which is the most powerful version of the PSLV.
The logical place to start for an answer to this question is to compare the capabilities of the PSLV-XL to other rocket launchers which have previously launched similar payloads into martian orbits. Mariner 9 was launched towards mars by an Atlas-Centaur SLV-3C rocket, which could supposedly put a maximum of 1,800 kg in Geostationary Transfer Orbit (GTO). Moreover the fully fueled Mariner-9 weighted about 998 kg, or just under a ton at launch and about 560 kg by the time it reached mars. Chandrayaan-1, launched by a previous PSLV-XL rocket, weighed just under 1,400 kg at launch and 675 kg by the time it reached the moon.
Many of you might think that it takes much more fuel to get to Mars than the Moon. However that is not true, as far as conventional unmanned space probes are concerned. The single biggest factor which decides fuel consumption of a probe in orbit around the earth on its way to the next astronomical body is the Delta-v budget. It takes very little energy to push a probe already in earth orbit towards another body in the solar system as long as you factor things like gravity and relative motion of the objects. Without going in too much detail right now, everything else being equal and optimal, you can send a 80-85 kg mass to orbit mars with the same launcher and basic probe design which could send a 100 kg mass to orbit the Moon. Since the mass of Chandrayaan-1 was 675 kg when it was inserted into a stable lunar orbit, we assume that the same launcher and basic probe design can put 80% of that mass (540 kg) into orbit around mars. Let us conservatively reduce that number further to 500 kg. So there you have it.. India could put an unmanned probe with an initial mass of 1400 kg and final orbital mass of 500kg into orbit around mars.
The next logical question is- What can you achieve with a mars probe with a mass of 500 kg? The answer is .. plenty!
Consider the Mars Global Surveyor, an older (1997-2006) american unmanned mars probe. It weighed 1,060 kg at launch and 767 kg at the time it first inserted itself into a stable orbit around Mars. and here is an interesting fact about that mission:
The Mars Global Surveyor mission cost about $154 million to develop and build and $65 million to launch. Mission operations and data analysis cost approximately $20 million/year.
For a mission that cost just over 200 million dollars in the late 1990s, it was able to able to transmit tens if not hundreds of thousands of high-resolution views (best resolution 1 pixel = 1.5 meters) of the Martian surface and information about its atmosphere. The data sent back by that probe was useful for the first detailed geo-chemical study of mars, and the images it returned were used to select landing sites for future mars rovers such as Spirit and Opportunity. The Mars Reconnaissance Orbiter is basically the next generation, and much bigger, version of Mars Global Surveyor. Other martian probes launched in the early 2000s such as the 2001 Mars Odyssey and Mars Express have launch and orbital masses similar to those within the capability of the PSLV-XL. Furthermore, ISRO has been able to build space probes of a similar design, ability and overall weight characteristics to those built and flown by NASA and ESA in the late 1990s-early 2000s.
Therefore, the unmanned Indian 2013 Mars Mission is feasible in the given time frame (Nov 2013 launch). The technological capabilities and budgetary outlay is also not unrealistic. The behavior and lack of competence exhibited by senior Indian bureaucrats and politicians remains the single biggest obstacle to the success of this mission, and any other endeavor in India.
What do you think? Comments?