The HST observation planning was coordinated with Mars Reconnaissance Orbiter characterization of the comet's nucleus, Chandra X-ray Observatory observations of comet coma X-ray emission, and Kepler Space Telescope light curves. The HST investigation teams worked together on the scheduling in order to maximize the science. Twenty-two HST orbits were planned around the encounter. The Space Telescope Science Institute created extensive observing plans for the comet's encounter with Mars. It was determined that the risk to the orbital assets was low however, the spacecraft still adjusted their orbits as a precaution, placing them on the other side of Mars during the period of greatest risk. Using data from prior observations by the Hubble Space Telescope (HST), the Spitzer Space Telescope, the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), Swift and ground-based telescopes, experts modeled the dust ejected from the comet that could pose a risk to our orbiting Mars spacecraft. NASA spacecraft and ground-based observatories joined the Mars missions in studying this once-in-a-lifetime event and observing how the Martian upper atmosphere would respond to the interaction with the comet, helping us learn more about how comets may have seeded our planet with water and the organic material we call the building blocks for life. It has been estimated that this type of close passage of a comet to the planet Mars coming from the Oort cloud occurs about once in eight million years! CSS passed close enough to Mars to blanket it with its cometary material. NASA's Mars missions gave us the first opportunity to image and study the nucleus of a comet from the Oort cloud region. From the furthest reaches of our solar system, known as the Oort cloud, comet Siding Spring has travelled for more than a million years, and for the first time since it was formed, visited the inner solar system and passed within 80,000 miles (130,000 km) from the surface of Mars.

Since the formation of our solar system, comets have been bombarding our inner planets, providing water and organic materials necessary for life.

Comets stars the moon and mars