Comet / Mars (2014) Impact (video)
Posted 27 March 2013 - 06:16 PM
nothing else will.
Posted 27 March 2013 - 07:51 PM
perhaps that could stop Opportunity
nothing else will.
Bite your tongue. sir or madam. We do not want to see Opportunity stopped.
Do you? Why?
Posted 28 March 2013 - 01:27 AM
Posted 28 March 2013 - 05:46 AM
Agree with rdandrea. Wouldn't want any comets / asteroids hitting planets so close to us.
Why not? that is one less comet that can hit Earth.
Posted 28 March 2013 - 08:33 AM
Posted 28 March 2013 - 08:35 AM
Posted 28 March 2013 - 08:55 AM
We do not want to see Opportunity stopped.
Of course not. But the science opportunities of seeing a major comet hit a major planet would dwarf anything that Opportunity might discover.
Posted 29 March 2013 - 01:18 AM
If the comet strieks Mars, a lot of debris will be thrown into space, and if the spacecraft orbiting the planet fly into it, they will be destroyed. I expect the dust in the coma to be a serious threat to their solar arrays and optics, if not all of their electronics. Impacting dust graines can create strong electrical charges that could burn out electronics. An impact also would throw ejecta very far through the near vacuum of Mars' atmosphere, which may jepordize one of the rovers. I am inclined to agree with Yeomans, namely this will be a very close flyby, the closest yet ever seen between a comet and a planet. Lexells comet missed us by three million miles back in the 1700's, this one will break that record handily.
You got that exactly right. At a relative velocity of 57 miles per second, even a small dust grain would hit with the kinetic energy of an explosive charge. Molecule-sized particles will cause severe electro-static discharge problems as you say. If the comet misses Mars (estimates of miss distance are on the order of 100,000 miles), Mars could still pass through the dusty coma. There are many unknowns in trying to estimate how much dust there will be but it would pose a serious risk to the orbiters. They all have large solar arrays, and while the spacecraft can be maneuvered to present minimum surface area to the incoming particles, not a whole lot else can be done to protect them. The Cassini Saturn orbiter has made a number of passes through the ring plane, and they have evolved methods for analyzing risk and protecting the spacecraft. That playbook will certainly get dusted off! (sorry about the pun...)
If C/2013 A1 impacts Mars (2000 to one odds it will miss) it could create up to a 500 km wide impact basin. Material will be ejected into interplanetary space. Some of that will eventually make its way to earth. A number of Martian meteorites have been found on Earth. This is the process by which they got here. It has happened before, it will happen again over the span of astronomical time.
Much of the ejecta will be sub-orbital and will make numerous secondary craters. Huge clouds of dust will envelop Mars. The thin atmosphere of Mars will do little to slow rock-sized ejecta, so even pebbles will hit hard. If a lander is within several hundred kilometers of the impact zone, it would likely be destroyed. Curiosity would fare better than Opportunity, as it would be less affected by dust that could obscure Opportunity's solar panels.
A significant amount of material will be blown up to orbital altitudes. The orbiters are all in polar orbits with approximately 2 hour periods and 800 km altitudes. Over a period of several hours, they will unavoidably pass through the debris cloud. I have not heard of any analyses yet, but it is not hard to imagine that there is serious ejecta risk to the orbiters.
So an impact has a serious potential to destroy our entire fleet of Martian spacecraft.
And since I am having so much fun with doom-and-goom, consider this. The 35 million Megaton impact energy could create enormous temperatures (I read 100,000C somewhere, no idea if that is accurate). Imagine looking at that in your telescope. Even if it only covers several arc seconds, it will be vastly brighter per unit solid angle than staring at the sun with its 5000C surface temperature (radiant energy goes as the fourth power of temperature). We would all have a second blind spot in our retinas!
Now for the positive side of things. NASA spent hundreds of millions of dollars to send the Deep Impact spacecraft to comet Temple 1. Now all we have to do is sit back and wait and Mother Nature will send a comet right in front of a fleet of spacecraft just waiting at Mars. All gratis. The Mars Reconaisance Orbiter HiRise camera system may be able to get sub-meter resolution images of the comet nucleus. There are a host of other instruments that can take invaluable measurements of the comet and its coma and tail as it zooms by.
The Mars program office has not yet kicked into gear to evaluate risks and how best to manage an observing program for the comet. More information is needed on trajectory, composition and evolution of the comet as it gets closer to the sun and starts to warm. We have until late 2014 to get ready. One way or the other it should be an awesome show!