On-orbit Satellite Collision |
On-orbit Satellite Collision |
Feb 16 2009, 02:46 AM
Post
#61
|
|
Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Hmm. The speed of the object is fairly slow, which is consistent for a debris re-entry, but it could still be a natural meteor. Either way, if I was in central/eastern Texas right now I'd start lookin' for chunks!
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
|
|
|
Guest_PhilCo126_* |
Feb 16 2009, 07:29 AM
Post
#62
|
Guests |
|
|
|
Feb 17 2009, 03:44 AM
Post
#63
|
||
SewingMachine Group: Members Posts: 316 Joined: 27-September 05 From: Seattle Member No.: 510 |
I've been following this story with astonishment and dismay. Such infinitesimal odds, and so much potential for harm! Just a few weeks ago I was watching WALL-E with my son and explaining why I thought it was funny when they ploughed through the mass of satellites when leaving Earth. Doesn't seem so funny now. I stumbled across this lovely image while working on another project today, and it seems appropriate.
-------------------- ...if you don't like my melody, i'll sing it in a major key, i'll sing it very happily. heavens! everybody's all aboard? let's take it back to that minor chord...
Exploitcorporations on Flickr (in progress) : https://www.flickr.com/photos/135024395@N07/ |
|
|
||
Feb 23 2009, 02:48 PM
Post
#64
|
|
Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
http://www.thespacereview.com/article/1314/1 is a very good summary of this event.
-------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
|
|
|
Feb 23 2009, 04:42 PM
Post
#65
|
|
Senior Member Group: Members Posts: 1592 Joined: 14-October 05 From: Vermont Member No.: 530 |
http://www.thespacereview.com/article/1314/1 is a very good summary of this event. QUOTE In this vein, I think it can be argued that the US military committed a sin of omission in the case of the Iridium-Cosmos collision. The US military maintains the best and most complete satellite catalog in the world and had the data to provide collision warning to Iridium. But as was discussed earlier in this article, the US military only looks at a limited list of satellites for collisions. It also appears that at some point they stopped providing collision warning for the Iridium constellation. Given the complexities of the conjunction assessment process, it is understandable that the US military does not have the resources or capability to screen all of the estimated 900 payloads in Earth orbit. But both the US military and Iridium knew that there were many close approaches with the Iridium constellation and that eventually one could collide. Perhaps both thought that if they stopped looking at the problem it would go away. My bold. Ha. Given that supercomputers and salaries are an order of magnitude cheaper than satellites, perhaps that will change. (Although the Iridium constellation is odd in that is was essentially gotten for free after bankruptcy.) The conclusions in the article are a little more nuanced. Good article! |
|
|
Feb 23 2009, 06:12 PM
Post
#66
|
|
Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
Nice post on the collision by Diandra over at CocktailPArtyPhysics.
She mentions two things that I hadn't come across before - firstly that the predicted closest approach of the two satellites prior to the impact had been around 600m and secondly that the increased atmospheric drag caused by the recent Sunspot minimum is a prime suspect in explaining why the predicted orbits were sufficiently incorrect to turn that 600m into 0. 600m would still seem like far too close for comfort to me but does anyone know what the normal error in such things would have been expected to be? |
|
|
Feb 24 2009, 01:39 PM
Post
#67
|
|
Junior Member Group: Members Posts: 22 Joined: 3-January 07 Member No.: 1551 |
Nice post on the collision by Diandra over at CocktailPArtyPhysics. She mentions two things that I hadn't come across before - firstly that the predicted closest approach of the two satellites prior to the impact had been around 600m and secondly that the increased atmospheric drag caused by the recent Sunspot minimum is a prime suspect in explaining why the predicted orbits were sufficiently incorrect to turn that 600m into 0. 600m would still seem like far too close for comfort to me but does anyone know what the normal error in such things would have been expected to be? http://celestrak.com/SOCRATES/top10maxprob.asp almost always shows at least one expected pass at 0.1km or less, with an estimated probability of collision more than one in a thousand; since we don't see a collision every few years, I suspect their model is not perfect. From a 500km circular orbit, a change in velocity by 1 centimetre per second changes the radius of the orbit by 18 metres, so you have to know the velocity very accurately indeed. |
|
|
Lo-Fi Version | Time is now: 23rd September 2024 - 10:24 PM |
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. |