[X] My Assistant

[Guest_Oersted_*]

It would great to have a new impact crater carved, so we could send the Mars Science Laboratory to that! Let's hope that, if it hits Mars, it will impact somewhere that permits EDL for MSL.

As for Opportunity, a debris cloud in the higher atmosphere will be just one more thing to weather on her epic journey...

[SteveM]

JPL's Near Earth Object Program has a good report on 2007 WD5 with a lot of useful links and figures. It says that

The uncertainty region during the Mars encounter currently extends over a million kilometers (700,000 miles) along a very slender ellipsoid only 1200 km (700 miles) wide, but the ellipsoid does intersect Mars. The zone of potential impact on the surface of Mars is approximately 800 km wide, and sweeps across the Martian equator from southwest to northeast, crossing the equator at roughly 30 deg W longitude. The MER Opportunity rover is close to the southern edge of this possible impact zone but clearly outside it.

Especially interesting is an animation showing the intersection of the asteroid's uncertainty elipsoid with Mars. With future observations the uncertainty elipsoid will get smaller and may move.

Steve M



This post has been edited by SteveM: Dec 22 2007, 02:54 PM

[DDAVIS]

"Squyres added that the rover team, of course, would try to image the sky at the predicted time of impact to see if anything can be seen, “but that’s got to be considered a very improbable long shot.”
[/quote]

This is amazing! I would hope an actual impact could be recorded by one or more of the orbiters if line of sight considerations work out . A series of frames shot in as rapid a sequence as possible for an 'animation' would be useful to document the ejecta plume as it spreads from the impact point.

Some of the very fresh impact craters on Mars are surrounded by ray patterns bearing signs of fine material near the crater being prevented from reaching the ground, then at a certain radius outwards appearing very much like Lunar crater rays in negative. This may be due to the innermost ejecta cone being disrupted by nearby inward rushing winds filling the column of air evacuated by the shock wave, as well as later winds feeding the rising 'mushroom cloud'. What a thing that would be to observe!

If it were possible to observe a fortuitous (but distant!) impact with a rover, especially a future one with a true video capability, so much the better.

Don

[Stu]

Well, we can dream, eh..?

[ngunn]

I like it!

[nprev]

Awesome thought; awesome image, Stu! Thanks!!!

[ugordan]

Well, we can dream, eh..?

I was thinking about something on the lines of this:


*sigh* If only...

[algorimancer]

It had not occurred to me before, but it seems like the MER rovers' inertial navigation system might double as a seismometer. Completely aside from recording this impact, this strikes me as a useful capability.

[djellison]

The resolution and sensitivity of the IMU's is almost certainly several orders of magnitude short of what would be required to detect a distant impact or any seismic activity.

Doug

[algorimancer]

My recollection is that running the IMU burns a lot of energy (relatively speaking), so it is probably not practical to keep it running for any great length of time. On the other hand, both rovers are sitting on bedrock at the moment, so if the sensitivity exists they're in a good position to take advantage of it. Pure speculation - I have no idea what the specs on the accelerometers are, nor whether the computer can access them in isolation from the IMU system.

[nprev]

Are they ring-laser gyro IMUs, or are they mechanical? Makes a big difference in power requirements, also sensitivity. Most modern intertial nav systems can detect accelerations of a few thousandths of a g, which is why they're now integral for autopilots.

This is a great idea, AG; as long as the MERs are stationary at the time of impact (allowing for propagation time) they should be able to detect some sort of shock. (I didn't know that the MERs even HAD IMUs...)

[Juramike]

Could you use a Pancam image of a bright star at night to record shaking due to impact?

Would the image jiggle be enough to tell you how much the rover felt?

-Mike

[Del Palmer]

Are they ring-laser gyro IMUs, or are they mechanical?

The MERs use the popular LN-200 IMU. Full specs here:

http://www.nsd.es.northropgrumman.com/Auto...cts/LN-200.html

[dvandorn]

You know... don't get me wrong, guys, but, um... one in 75 is still pretty big odds against something happening.

I'm seeing people getting real excited over something that is more than likely not going to happen.

Let's not get ourselves all het up over it and then get all upset when it doesn't happen, okay, folks?



-the other Doug

[Stu]

Aw, other Doug, it's all part of the fun! 1/75 is rubbish odds, I know, but it's fun to speculate. Heck, we've spent weeks before speculating on such things as the location and nature of "Beacon" etc. It's Christmas, let's play a little.