Just as NASA's Mars orbiters took shelter from a debris-spewing comet behind the Red Planet on Sunday, they also took the opportunity to study the flyby's effect on Mars.
Scientists also are hoping to use the orbiters' observations to gain new clues about the origin of our solar system.
"We're glad the spacecraft came through," said Bruce Jakosky, NASA's principal investigator for its Maven spacecraft. "We're excited to complete our observations of how the comet effects Mars, and we're eager to get to our primary science phase."
NASA has been preparing for the flyby of the comet, known as Comet C/2013 A1 Siding Spring, for several months. While scientists worked to position its three orbiters — the Mars Odyssey, the Mars Reconnaissance Orbiter and the Mars Atmosphere and Volatile Evolution orbiter — on the opposite side of the planet during the flyby, they also wanted to take advantage of their front-row seat to the event.
"The spacecraft performed flawlessly throughout the comet flyby," said Mars Reconnaissance Orbiter Project Manager Dan Johnston of NASA's Jet Propulsion Laboratory. "It maneuvered for the planned observations of the comet and emerged unscathed."
Comet Siding Spring hurtled past Mars on Sunday at about 125,000 mph, coming within about 87,000 miles of the planet. That is equivalent to about one-third of the distance between Earth and its moon.
NASA reported Sunday night that the closest approach of the comet's nucleus came at about 2:27 p.m. ET. Dust and debris from the comet was reaching Mars at its peak about 100 minutes later.
While the nucleus of the comet was too far away from Mars to affect the orbiters, the comet was shedding material as it passed by. That debris was expected to hurtle toward the planet at 35 miles per second.
NASA noted that at that velocity, even a particle only one-50th of an inch across could cause enough damage that it would be disastrous for the Mars orbiters.
Without the Martian atmosphere to protect them, the orbiters weren't as safe. That's why NASA maneuvered them to the opposite side of the planet.
The space agency reported that Mars Odyssey was out of communications with Earth, as planned, while conducting observations of the comet with its Thermal Emission Imaging System. The images it captured are expected to be downlinked to NASA and processed this week.
The spacecraft's neutron spectrometer and high-energy neutron detector also are being used to assess the effects the comet's dust and gas are having on Mars' atmosphere.
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