Celestia Forums

Hi!

Could it be that there is a problem with the ISS Orbit in v1.2.4?

Five Minutes ago, I spotted the ISS in the clear dark Sky over Germany, and at the same time Celestia positioned the Station somewhere West of South America in the Atlantic Ocean.

PS: Before you ask: YES, the object crossing Germany really was the ISS. In order to verify that the ISS has another Position than in Celestia 1.2.4, i recommend a visit of one of the websites with realtime-position of the ISS

It's a known bug. The positions of ISS and other Earth-orbiting satellites are not correct because there's currently no way for Celestia to automatically download new orbital elements for them.

--Chris

As a side topic, how does Celestia position, eg, the moon? If the moon's "up" in Celestia, it'll be "up" in real life. How does Celestia put the moon in the correct part of its orbit?

The answer to that question is that the Orbit of the Moon is (more or less) constant, and has been for the past couple of years at least. The ISS constantly undergoes orbital maneuvers which alter it's altitude, thus altering it's speed. With a complicated orbit like that, we would be talking about downloading a position upgrade AT LEAST every week. More likely every three days or so.

There are several places I know of that send raw data to upgrade programs tracking the ISS and formerly MIR. Most arte for PDA astronomy programs. But the Celestia program is just not conducive to upgrading that tiny four or so lines of text in the solarsys.ssc every week.

I wish it could be a more accurate observational sim, but damn, on the whole, it's a pretty good astronomical sim.

Declan.

Declan Royce wrote:The answer to that question is that the Orbit of the Moon is (more or less) constant, and has been for the past couple of years at least. The ISS constantly undergoes orbital maneuvers which alter it's altitude, thus altering it's speed. With a complicated orbit like that, we would be talking about downloading a position upgrade AT LEAST every week. More likely every three days or so.

There are several places I know of that send raw data to upgrade programs tracking the ISS and formerly MIR. Most arte for PDA astronomy programs. But the Celestia program is just not conducive to upgrading that tiny four or so lines of text in the solarsys.ssc every week.

I wish it could be a more accurate observational sim, but damn, on the whole, it's a pretty good astronomical sim.

Declan.

The well known emphemeris program XEphem, with which I have been involved for many years, has this update feature built in. It's no big deal and the increase in accuracy dramatic as you said.

Bye Fridger

also the ISS has a close to earth orbit so it is affected by friction of the air and other particles close to the earth, even though it is a thin amount