Ten months and 442 million miles outbound from Earth, NASA's MAVEN spacecraft fired its braking rockets Sunday to slip into orbit around the red planet, kicking off a $671 million mission to find out how much of the martian atmosphere leaked away in the distant past in an extreme case of climate change.
The liquid apogee motor (LAM) engine has been idle for about 300 days since the spacecraft left the Earth's orbit on a Martian trajectory on December 1, 2013.
The short-duration test was to ensure that the engine is in good shape for the 24-minute manoeuvre on Wednesday.
"What a night! You get one shot at Mars orbit insertion, and MAVEN nailed it tonight," said NASA project manager David Mitchell. "We've got a really happy crew in the building here, across the country and literally around the world."
MOM executed with precision a set of commands sent from mission control in Bangalore last week and fired the 440N engine for close to four seconds.
This test took the spacecraft away from its trajectory by more than 100km, but a different set of commands have been fed into the system to bring it back to the ideal Martian orbital insertion.
Scientists believe the Martian atmosphere holds clues as to how Earth's neighbor went from being warm and wet billions of years ago to cold and dry. That early moist world may have harbored microbial life, a tantalizing question yet to be answered.
Flight controllers will spend the next six weeks checking out MAVEN's instruments, deploying booms and antennas and fine-tuning its orbit, firing the spacecraft's thrusters five more times to lower the high point to around 3,860 miles and the low point to less than 100 miles.
The spacecraft was launched from Cape Canaveral this past November, making it the 10th U.S. mission sent to orbit the red planet. Three earlier ones failed, and until the official word came of success late Sunday night, the entire team was on edge.
"I don't have any fingernails any more, but we've made it," said Colleen Hartman, deputy director for science at Goddard Space Flight Center in Greenbelt, Maryland. "It's incredible."
"We are obviously relieved," said an Isro scientist (Indian Space Research Organisation.) "Now we know that the engine is fit for Wednesday's exercise." There were apprehensions of the long duration of idling would have affected some valves because of the corrosive fuel used. If the main engine doesn't fire on Wednesday, an alternative plan is to fire the eight thrusters of the spacecraft to capture the Martian orbit.
Maven's chief investigator, Bruce Jakosky of the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder, hopes to learn where all the water on Mars went, along with the carbon dioxide that once comprised an atmosphere thick enough to hold moist clouds.
The gases may have been stripped away by the sun early in Mars' existence, escaping into the upper atmosphere and out into space. Maven's observations should be able to extrapolate back in time, Jakosky said.
If everything goes fine, Isro aims to put the spacecraft in an orbit with a periapsis (closest point to Mars) of 423km and an apoapsis (farthest point) of 80,000km. Of the 51 Mars mission so far by various countries, only 21 have been successful.
All these robotic scouts are paving the way for the human explorers that NASA hopes to send in the 2030s.
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