Sol 91
Endurance Sol 92, 10 pixel 0.5 stren unsharp mask, contrast stretched

Guys... there are so many craters of so many different sizes that I wonder HOW could rovers have survived till now without being hit by a metorite!!! They are TOO MUCH, if you consider strong Martian winds... probably new ones are created every month (week? day?...).

Luca

Every century - perhaps even less frequently.

The winds may be fast on mars - but the atmosphere is so very thing it has little force.

Most of the little dimples around here will probably be secondary craters from larger impacts anyway.

Doug

Cassioli,

Your argument actually works the other way.

SINCE the rovers have not been hit by meteorites

THEN the many craters must have accumulated over a huge time

AND erosion rates on Mars are VERY slow...

These 2 NavCam shots are pretty spectacular, look like the rover may have driven towards the north rim.

http://qt.exploratorium.edu/mars/opportuni...00P1829R0M1.JPG
http://qt.exploratorium.edu/mars/opportuni...00P1829L0M1.JPG

There appears to be a bit of bedrock exposed on the rim that opportunity might be able to reach without doing into the crater itself.

Is it possible to make a comparison between Earth and Mars wind?
I mean: a 200 Km/h wind on Earth would easily take me away... How fast should a Martian wind blow to take me away?

Maybe we (you...) should express in better measure units: I suppose you can use pressure units, or others: "On Earth, a 100 Km/h wind would push a 1 m^2 area with 1 Newton force", or "would put a 1 Kg object a 1 g acceleration", or similar...

Luca

I don't think so. Seems to me Oppy is at the west rim looking to the southeast. There seems to be the heatshield in view.

Tom

I found an interesting page about wind:

wind science

It says the wind kinetic energy is:
E=0.5 * r * A * u^3

r = air density
A = section area
u = velocity

As Mars atmosphere has 1/1000 of Earth's atmosphere density (I think: 1/1000 pressure = 1/1000 density?!?), I think this means that Martian wind has 1/1000 of equivalent Earth wind power. Is it right? If it was true, this would mean that a 180 Km/h Martian wind would be equivalent to 0.18 Km/h Earth wind! I think there is something wrong, can you help?

Luca

Typical earth density = 1000 mbars

Typical Mars Density = 6 - 12 mbars - typically 8

Thus, approx 0.8% the density - or 8 1/1000ths

Doug

... 10 is easier!
So, Mars wind has 1/100 of the power of Earth wind?
So, a 200 Km/h Mars wind has the effect of a 2 Km/h Earth wind?

Luca

Luca, don't think that will work -- velocity term is cubed -- can't play with both terms in a linear manner. At the same velocity, the energy is 1/100 but at high velocity even mars' wind could get rough.

Greg