NASA is preparing its spacecraft floating around Mars for an impending close encounter with a comet heading towards the Red Planet this autumn.

According to the Los Angeles Times, engineers are worried because of the tiny particles that will hurtle through space, posing a potential risk to various spacecraft. The bits of dust and ice will be traveling approximately 35 miles per second, essentially a wave of destructive shrapnel.

There are three Mars-orbiting spacecraft likely to be vulnerable, all valued at a total of $1.5 billion from building and launching. The flying bits of dust and ice is known as the Comet Siding Spring and the close encounter is expected Oct. 19.

"They are essentially little cannonballs and bullets flying around, and they could do real damage," Richard Zurek, chief scientist for the Mars Program Office at NASA's Jet Propulsion Laboratory (JPL), told the Times. "The typical area of a spacecraft is five square meters, so it doesn't sound like much risk."

The Siding Spring was first noticed Jan. 3, 2013 past even Jupiter's orbit at an observatory in Australia. After running trajectory models, observing scientists believe the Spring originated in the remote Oort Cloud outside the solar system.

One spacecraft in danger will be arriving in Mars' orbit in poor timing. The Mars Atmosphere and Volatile Evolution (MAVEN) probe left NASA's Air Force Station in Cape Canaveral Nov. 18, 2013. It is set to arrive Sept. 21, at which time it will enter the Red Planet's orbit.

"Everything is working well on the spacecraft, and we're not working any issues," Bruce Jakosky, MAVEN's principal mission investigator, told the Boulder Daily Camera. "We've turned the instruments off and are doing very little on the spacecraft right now - we want it quiet for the remaining 1.5 months until orbit insertion, so that we can focus on getting ready for that event."

In all, spacecraft orbiting Mars are projected to be subject to the Spring's bits of dust and ice for a total of 30 minutes, Zurek told the Times. Though a collision is on the better side of unlikely, many NASA engineers will be holding their collective breath.

"There's a small probability of an impact, but it's not zero," Zurek said. "And it only takes one to do you in."