Mer Sfx Images, A Long Time Ago ... Options

[SigurRosFan]

First, there's a landing site overview (full version 152 KB).

Spirit on Sol 6:

[djellison]

Not far from perfectly circular
Rasied rim
Similar to many other round-raised-rimed-impactey-type-features.

I don't think the thought that it was anything else would have crossed peoples minds.

Doug

[Bob Shaw]

Not far from perfectly circular
Rasied rim
Similar to many other round-raised-rimed-impactey-type-features.

Doug

Doug:

It's a joy when you set a sand-trap and somebody rolls straight in!

OK, you're right. But tiny craters don't have raised rims in the same ways that big chaps do. And I see no particular evidence of any impactey-type-features other than the circumstantial similarity to say, the Hellas Basin.

And as for the sand-trap - well, it looks awfully like a golf course bunker, doesn't it? Round, full of sand, concave, and a raised rim...

It's said that bunkers were originally naturally occuring features on traditional Scottish 'links' golf courses - features caused by wind erosion, with a weakness in the grassy covering over coastal dunes growing into a pit.

So, once more: how do we know Eagle Crater is an impact feature, and not something else?

Bob Shaw

[djellison]

So, once more: how do we know Eagle Crater is an impact feature, and not something else?

Because it looks like one. That's about it. I mean - what do you WANT it to look like to classify it as a crater?

Tiny craters do have raised rims - even Fram had one. A small rise at its rim, but it's a small crater so you'd expect that. Eagle and it's sister a few hundreds meters SW - both appeared as raised rims from a distance.

Tjere are hundreds of thousands of these things around the planet - what makes you think they're NOT craters?
Doug

[Bob Shaw]

Because it looks like one. That's about it. I mean - what do you WANT it to look like to classify it as a crater?

Tiny craters do have raised rims - even Fram had one. A small rise at its rim, but it's a small crater so you'd expect that. Eagle and it's sister a few hundreds meters SW - both appeared as raised rims from a distance.

Tjere are hundreds of thousands of these things around the planet - what makes you think they're NOT craters?
Doug

Doug:

It's not that I think they're *not* impact craters, just that I have an open mind about some of the features which we see!

Obviously, Mars is covered with impact craters. Big and small, no problem.

But, at Meridiani, we have seen other sorts of holes in the ground, ranging from the infamous (and dynamically somewhat improbable) mini-craters right up to Anatolia (and perhaps the Payson depression). Fram looked more like a traditional small Lunar crater, to my mind, than does Eagle.

Eagle was characterised as an impact feature *before* we saw the other holes, so the natural assumption was made that it was due to something which fell from the sky. However, there are few bits of direct evidence to support that belief, just habit: round hole = impact crater.

I'm not being contrary for the sake of it - I simply got thinking about holes in the ground, and began to ask myself whether we'd all jumped the gun.

Bob Shaw