Tomorrow will be busy for me. We’ve got two slooh.com shows about the close encounter between Comet Siding Spring and Mars.
I host, surrounded by cometary experts. I still have to know the science.
This is an unprecedented event. We’ve never seen a comet get so close to a planet.
That worries NASA.
Actually, let me modify that. Their worry is later.
First, cards on the table. NASA is always interested in ‘visitors’ to our part of the solar system. But there’s a lot more buzz for Comet Siding Spring C/2013 A1. It will come close to Mars and to billions of dollars of hardware circling Mars, plus rovers on-the-ground.
Siding Spring is speeding in from the Oort Cloud, a theorized mass of billions of comets 100,000 times farther from the Sun than we are. It will zip by Mars at a closing speed 35 miles per second–186,000 mph.
The comet misses Mars. We’ve all got that, right?
Later, Mars passes through the debris field left in the comet’s wake. Scientists expect some fragments will be drawn toward the planet where we have satellites and stuff.
NASA’s official “Best Estimate” says the particles miss. Their conservative estimate says 90-100 minutes after the closest approach a stream of small debris will come, then quickly go.
Our satellites all had their orbits disrupted, putting them on the far side of Mars when this happens.
T-0 is officially called the “time of the particle fluence center.”
NASA is praying one or more of the rovers will take a photo or two of the comet brightly shining through the Martian atmosphere. That’s pretty damn cool. It will likely happen and will surely include a part of the rover, lest we forget whodunit.
We’ll also get images from whatever sensors can be turned around on satellites.
I’m not sure how much of this is actually advancing science and how much is showing off. An opportunity and challenge like this shouldn’t be squandered, but this is more photo-op than anything. After all, we’re landing on a comet next month!
Everything is now set. It’s too late for change to matter. Any debris that hits the Red Planet was jettisoned off the comet years ago.
Distance and time are very different in space. You can’t think in minutes and seconds or inches and feet. Our best orbital predictions say C/2013 A1 won’t be back for around a million years.