Linked Questions

14
votes
2answers
2k views

Tiangong-1 reentry impact place probabilities

Following all the news concerning Tiangong-1, I have seen the following plot made by the Aerospace Corporation where Blue area: null probability of impact Yellow area: high probability of impact ...
4
votes
1answer
654 views

What does “supersonic large amplitude ID maneuver PTI” mean, and what does a tumble motor do?

In this question I linked to a YouTube video of the Ares X-1 launch. You can start listening at 02:00 for the point where these are mentioned: "Supersonic large ...
16
votes
2answers
977 views

Have spacecraft ever dipped below the Karman line and then safely continued spaceflight?

The item in Science Alert's A Harvard Astrophysicist Says Outer Space Is Actually Closer Than We Think (see also Science; Outer space may have just gotten a bit closer) talks about the recent Acta ...
5
votes
1answer
754 views

Why does Earth's atmospheric density have a big “knee” around 100 km? Is there a good analytical approximation?

I've used a quick very rough approximation of the drop of atmospheric density with altitude in this answer and in this answer by using a single exponential and scale height parameter, but that's not ...
4
votes
1answer
887 views

What is the lowest altitude that an ion thruster can be used for station keeping?

What is the lowest altitude that an ion thruster can realistically be used for station keeping before its small amount of thrust is overcome by atmospheric drag? Please state your assumptions such as ...
4
votes
1answer
435 views

Why are deorbited satellites allowed a slow orbit decay instead of burning them up rapidly?

In "What are the conditions for re-entry of an object in a (highly) elliptical orbit?" Eerie asks about orbital mechanics of orbital decay of decommissioned satellite: starting with extremely ...
3
votes
2answers
305 views

North Korean objects 41332 and 41333; how fast are they losing altitude?

I cited objects 41332 and 41333 launched in early 2016 as counterexamples to this answer on my highly down voted and closed but otherwise "perfect" question What regulations, agreements, or other ...
4
votes
1answer
427 views

How do I calculate re-entry velocity when decaying from a circular orbit?

I am trying to find the velocity of an object during re-entry so that I can calculate the peak heat flux but I'm a bit stuck. I know how to find the velocity of the original, circular orbit (300km) ...
4
votes
2answers
273 views

PSLV-C39/IRNSS-1H TLE accuracy

The TLEs accuracy for PSLV-C39/IRNSS-1H seems low when compared to that of the other LEO satellites (ISS, HST, Tiangong, Sfera 2, ...). Look, for example, at the following graph that shows the radius ...
1
vote
2answers
121 views

Why will OGO-1 reenter from an elliptical orbit rather than circularize first?

According to all the sources cited in Why does OGO-1's trajectory and imminent reentry come from sky surveys and NEO tracking rather than normal satellite tracking? OGO-1 is in a highly ...