The basic rule of thumb that I use is that an atmosphere will stop bodies smaller than about half its condensed thickness - so on Earth we have 10m of atmosphere, if you condense it, which would stop a 5m body (Tunguska, say).
On Mars the Atmosphere is 18 cm thick (when condensed), so it will stop a 10 cm rock.
Impact craters are typically 20 times the diameter of the impactor, so on Mars we don't expect to see craters smaller than 2m diameter.
And yes, everywhere we've landed so far has been relatively young (although still a couple of billion years old).
For the new landings this holiday season expect the following:
Beagle 2 - Isidis - a dusty plain with few rocks. Possible low hills on the skyline. 30 - 300m impact craters will be visible as low ridges. There is a fair chance the lander will come to rest inside the low bowl of a subdued km-scale crater. Some dust drifts near obstacles.
Mer-A (Spirit) - Gusev - a rolling plain with few rocks. small sand/dust dunes and 30m to several km craters visible as low ridges. other low "wrinkle" ridges will also occur, in some places as close as every few hundred metres. Unlikely to see any hills on the horizon.
Mer-B (Opportunity) - Haematite - A scabby eroded plain with occasional sand/dust drifts and small impact craters (30-100m). lots of crusty patches and some exposures of layered bedrock emerging almost parallel to the ground surface. No hills expected. Rocks rare.
Space/Science » in reply to re: Bill Hartmann (Scientist, textbook/fiction Author, & Painter)
Atmosphere as filter, and landing site predictions...
The whole thread (52 posts)
- Bill Hartmann (Scientist, textbook/fiction Author, & Painter)
- More B*** S*** impact "science"
- Sense of humor, too
- re: Bill Hartmann (Scientist, textbook/fiction Author, & Painter)
- re: Bill Hartmann
- Hartmann's Travelers Guide to Mars
- re: Bill Hartmann (Scientist, textbook/fiction Author, & Painter)