When a comet makes an extremely close pass by the planet Mars, scientists on Earth will get a good look at it -- courtesy of three orbiters and two rovers awaiting the event at the Red Planet.
Around a dozen assets, including the rovers and orbiters along with a suite of space-based and Earth-based telescopes, will zero in on Comet C/2013, also dubbed comet Siding Spring, when it come within 87,000 miles of Mars on Oct. 19, NASA says.
The Mars orbiters should get a particularly good look at the comet, the space agency says.
"Normally you send spacecraft to comets," says NASA program scientist Kelly Fast. "Here, the comet is coming to our spacecraft."
The European Space Agency and India also have spacecraft orbiting Mars.
Comet Siding Spring, first detected at the beginning of 2013, is estimated to have a nucleus measuring between half a mile and 5 miles in diameter.
It is approaching the sun near the end of a journey of a million miles that began in the Oort cloud, a spherical swarm of icy objects surrounding the most distant reaches of the solar system.
The Oort cloud is thought to be made up of material left over after the formation of our solar system 4.8 billion years ago.
Comet Siding Spring is making good time as it hurtles toward the sun, astronomers say, and when it passes Mars it will be traveling at more than 125 mph.
All of NASA's eyes and ears will be focused on it when it makes its pass, scientists said.
"This is a cosmic science gift that could potentially keep on giving, and the agency's diverse science missions will be in full receive mode," says John Grunsfeld, associate administrator for NASA's Science Mission Directorate in Washington. "This particular comet has never before entered the inner solar system, so it will provide a fresh source of clues to our solar system's earliest days."
In getting ready for the flyby of the comet, controllers are maneuvering three Mars orbiters -- the Mars Odyssey, Mars Reconnaissance Orbiter (MRO), and the Mars Atmosphere and Volatile EvolutioN (MAVEN), to reduce any chance of impact with high-velocity particles of dust being thrown off by the comet.
NASA's rovers Opportunity and Curiosity are set to make observations of the comet, as is the Hubble Space Telescope, several space observatories and a ground-based infrared telescope in Hawaii.
Images will be posted online before and after the comet flyby, NASA says.
