Tianwen-1 At Mars |
Tianwen-1 At Mars |
Feb 8 2021, 03:04 PM
Post
#1
|
|
Member Group: Members Posts: 219 Joined: 14-November 11 From: Washington, DC Member No.: 6237 |
For those who haven't already seen, there is excellent work independently tracking and predicting the trajectory of Tianwen-1 by radio amateurs (using that word only technically, since they are very much pros).
The latest is predicting orbital insertion at 8 seconds before 1200 UTC on Wednesday 10 February, with a 386 km periapsis - burn starts a few minutes before that if you, like me, are planning your peanut consumption carefully this week. Plenty of details to be found at these links (even a GMAT script and Jupyter notebook, and some doppler data, for the astrodynamically inclined). https://destevez.net/tag/tianwen/ Daniel Estévez recent twitter thread with MOI images Scott Tilley recent twitter thread |
|
|
Jul 2 2022, 09:43 AM
Post
#2
|
|
Senior Member Group: Members Posts: 1044 Joined: 17-February 09 Member No.: 4605 |
To me it looks like erosion of an armored dune, or more like a large ripple; effectively a blowout. As erosion progressed, armoring pebbles rolled down the slope
|
|
|
Jul 2 2022, 01:51 PM
Post
#3
|
|
Member Group: Members Posts: 611 Joined: 23-February 07 From: Occasionally in Columbia, MD Member No.: 1764 |
To me it looks like erosion of an armored dune, or more like a large ripple; effectively a blowout. As erosion progressed, armoring pebbles rolled down the slope Yes, I'm inclined to agree. Very interesting locale! There are aspects that remind me of the yardangs in the Argentine Puna (where there are also gravel ripples) but I dont think I've seen rock tracks like this on a ripple. It doesnt look like there is a lot of slope to drive motion, so presumably the rolling pebbles are wind-driven (or just possibly they roll when wind undercuts the sand from underneath). But if the sand can move, how are the trails preserved ? I dont doubt some modeler could come up with a scenario, but it would take a bit of fine-tuning for sand to be scoured in the lee of a pebble but not elsewhere... It definitely looks like an armored dune overall, maybe an ejecta layer from a nearby impact covered the dune, immobilizing it, and then as you say, once the wind gets in it undercuts and blows out parts Ralph |
|
|
Lo-Fi Version | Time is now: 3rd June 2024 - 01:16 AM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |