India’s bid to join the elite group of nations that have successfully bridged the gap to Mars has overcome an early glitch that could have left its Mangalyaan spacecraft orbiting Earth.
The successful 5 November launch of the Mars orbiter mission put the spacecraft in a highly elliptical, 247km by 23,566km Earth orbit – due to be raised by a series of six engine burns to 600km by 215,000km – before a final burn push that would bring it into a Hohmann transfer orbit path to Mars.
However, according to the Indian Space Research Organisation (ISRO), the fourth orbit-raising burn failed owing to a premature shutdown of the main engine. The spacecraft’s back-up logic attempted to correct by thruster firings, with the result that velocity increased by just 35m/s, rather than the 130m/s planned. The orbital high point, or apogee, was left at 78,276km – around 22,000km short of plan.
Fortunately, ISRO reports, an attempt to recover was successful, with a five-minute burn late on 11 November that raised the apogee to 117,000km.
The 299-day trip to Mars should end by placing the small orbiter – carrying a methane sensor, thermal infrared imaging spectrometer, Lyman Alpha Photometer, quadruple mass spectrometer and a tri-colour camera to image the surface – in an elliptical orbit, rather than the circular orbits characteristic of other Mars satellites.
The flightplan is, in part, a product of India’s decision to fly with a variant of its proven Polar Satellite Launch Vehicle, PSLV-XL, instead of the more powerful but so-far less reliable Geosynchronous Satellite Launch Vehicle. Including the Mangalyaan launch, the PSLV family has completed 23 successful flights, one partial success and one failure. The GSLV, however, has failed five times in seven flights. An eighth attempt is scheduled for 15 December.
If India succeeds in placing Mangalyaan into orbit, it will join the USA, Soviet Union and Europe in having made the crossing to Mars, a notoriously hazardous destination for spacecraft. Several early US and Soviet attempts failed before NASA’s Mariner 4 reached the Mars orbit in 1965.
The mixed success rate of subsequent orbiter and lander missions suggests that India should be not be too upset if Mangalyaan is lost in interplanetary space. The two most recent Mars attempts flew in 2011, including NASA’s Curiosity rover mission and Russia’s ambitious Phobos-Grunt sample return mission. While Curiosity has been wildly successful, Phobos-Grunt might be classified as a fiasco; software failure left the spacecraft stranded in Earth orbit and, ultimately, in the Pacific Ocean – along with its passenger, China’s Yinghuo 1 Mars satellite.
Source: FlightGlobal.com
