[X] My Assistant

[elakdawalla]

EDIT: Moved these posts from the Feb 14 HiRISE Release thread to here to collect all Beagle 2 search related stuff in one place.

I'm downloading them now too -- guess I can't blog about them until I've examined them very carefully!

For a bit of history on the search,
Here's a blog entry I wrote about this spot a while ago
Here's the MOC team's take on that spot
And here's the BBC page with the Beagle 2 team's take on it

EDIT: and here's my updated blog entry with links to the Beagle 2 landing ellipse images split up into 40-MB chunks.

--Emily

[dvandorn]

As I understand it, though, what's now being speculated is that Beagle 2 failed to successfully cross transition boundaries, not that the heat shield failed during the heat pulse. The shape of the entry vehicle is critical to how the vehicle maintains stability through hypersonic to supersonic velocities, and there are a lot of factors, including the actual atmospheric deceleration rate, that affect how the shape and the regime interact.

Huygens continued to decelerate at a faster and faster rate as it dug into Titan's thicker atmosphere. Beagle 2 continued moving faster for longer after it hit its maximum deceleration (which would have been less decel than Huygens saw, since Mars' atmosphere doesn't thicken with depth to the extent that Titan's does). I would be extremely surprised if Huygens and Beagle 2 were traveling at similar airspeed velocities a minute after the end of peak heating.

You would have to plug in speed, deceleration rate and air density throughout the descent profile for each probe to determine the differences in transition boundaries between the two events. I guess what I'm thinking is that Huygens was slowed more quickly and effectively, and thus plowed through the transition boundaries very quickly, with very little time for the vehicle to become unstable (and, as I recall, there *are* some indications that Huygens tumbled briefly at some points during its descent). Because of the thinner air, Beagle 2 slowed more slowly and spent more time passing through transition boundaries than Huygens did, thus increasing the possibility that both its spin rate and any inherent instability in the aerodynamics of the vehicle's shape would cause the craft to tumble while still in a fairly challenging heating regime.

Make sense?

-the other Doug