ROSAT (short for Röntgensatellit, in German X-rays are called Röntgenstrahlen, in honour of Wilhelm Röntgen) is a defunct German Aerospace Center-led satellite X-ray telescope, with instruments built by Germany, the UK and the US. It was launched on 1 June 1990, on a Delta II rocket from Cape Canaveral,
on what was initially designed as an 18 month mission, with provision
for up to 5 years of operation. ROSAT actually operated for over 8
years, finally shutting down on 12 February 1999.
ROSAT is expected to re-enter
the Earth's atmosphere between October 21 and 23 2011. In February
2011, it was reported that the 2,400 kg satellite was unlikely to burn
up entirely while re-entering the earth atmosphere due to the large
amount of ceramics and glass used in construction. Parts as heavy as
400 kg could impact the surface intact.
These sites do on demand calculations of satellite position based on an observer's location and recent satellite elements (via NORAD).
Guide to viewing ROSAT in Orbit
Before re-entry, as with other satellites, ROSAT will be visible from occasionally depending on your location, satellite position and time of day. A satellite is potentially visible when it is lit by the sun, and is bright enough to be seen against the sky (the darker the sky the better). There is only a small window (near the satellite's orbital sunrise and orbital sunset) when it will be both lit by the sun and visible to an observer with a dark enough sky. Stand-alone and online software can assist in predicting visible passes of a satellite for your location.
The world map based visibility guide (see below) allows you to quickly get an estimate on whether you are near enough to be able to sight a visual pass.
Who does this?
Data and Simulation
These estimates and ranges very.
Current Projection & Prediction UTC (as at 21.8-Oct)
|| 23 OCT 13:24 UTC
|| ± 16h
|| 23 OCT 05:49 UTC
|| ± 24h
| Ted Molczan
|| 23 OCT 11:30 UTC
|| ± 12h
| Harro Zimmer
|| 23 OCT 07:21 UTC
|| ± 6h
| TS Kelso
|| 23 OCT 02:47 UTC
|| ± ?h
|| 23 OCT 11:00 UTC
|| ± 9h*
The atmospheric density and thus the re-entry times are heavily effected by Solar Flux, which has been predicted to rise above nominal levels in the coming week. This will lead to a decay earlier than expected by possibly a day or two.
Count-down clock app (iPhone)
FAA issues NOTAM:
!FDC 1/9172 FDC .. SPECIAL NOTICE .. EFFECTIVE IMMEDIATELY
UNTIL 1110252359 UTC. AIRCRAFT ARE ADVISED THAT A POTENTIAL HAZARD MAY
OCCUR DUE TO REENTRY OF THE SATELLITE ROSAT INTO THE EARTH'S ATMOSPHERE.
THE FEDERAL AVIATION ADMINISTRATION (FAA) IS WORKING WITH THE
DEPARTMENT OF DEFENSE (DOD) AND THE NATIONAL AERONAUTICS AND SPACE
ADMINISTRATION (NASA) TO ENSURE THAT THE MOST CURRENT RE-ENTRY
INFORMATION IS PROVIDED TO OPERATORS AS QUICKLY AS POSSIBLE. FURTHER
NOTAMS WILL BE ISSUED IF SPECIFIC INFORMATION BECOMES AVAILABLE
INDICATING A UNITED STATES (US) AIRSPACE IMPACT. IN THE INTEREST OF
FLIGHT SAFETY, IT IS CRITICAL THAT ALL PILOTS/FLIGHT CREW MEMBERS REPORT
ANY OBSERVED FALLING SPACE DEBRIS TO THE APPROPRIATE ATC FACILITY AND
INCLUDE POSITION, ALTITUDE, TIME, AND DIRECTION OF DEBRIS OBSERVED. THE
DOMESTIC EVENTS NETWORK /DEN/ TELEPHONE 202-493-5107, IS THE FAA
Once the ROSAT reaches the height of 120 km (75 miles) above the Earth's surface it will have only around 30 minutes left before re-entry (less than one third of an orbit). Re-entry is generally accepted as commencing from orbit around at around 80km altitude. At this point the acceleration due to drag becomes appreciable (greater than 0.1G) thus causing further irreversible loss of altitude and increase in drag. At peak deceleration extreme heating, due to friction, and drag forces can destroy the objects integrity and disintegrate part or all of the object. This continues to around 45km altitude when the remaining objects have slowed and deceleration forces decrease. Remaining objects continue a ballistic trajectory, impacting the earths surface.
graph is a simple plot of observed perigee and apogee, plus a few days more of "calculated" perigee and apogees, superimposed with a numerical simulation of an object re-entering a standard atmosphere. The co-efficient of drag is adjusted to allow the graphs to follow closely for previous observed values, and then effectively extrapolated to the eventual re-entry of the object.
map (see above), is a guide to help identify global location that may get a visual on the orbiting satellite.
map shows an indicative path over which the decaying satellite travels as predicted around re-entry time.
At the end of the page is a Google Earth kml file that can be File->Opened to show the orbital tracks. Will try to update these with date/time stamps. This kml file may/will change as more updates are applied.
- The file
rosat.kml is path only (and ground path).
- A simple addition of time stamps on the location has been added for the file
rosat-vis.kml has (shortened) timestamps, yellow path for a Lit satellite (by the sun), cyan path for unlit, and a green stripe for the center path of a visible path (where sky is nautical twilight or darker).
- An quick
rosat-vis+live.kml experiment adding an AGI provided live location and combining with the above file.
- Using @ROSAT_Reentry orbit data directly
- Post analysis re-entry range
- Post analysis 3 hours prior to re-entry range
[Last Updated 2011-10-16 02:45GMT]
- Apogee : Furthest from Earth (within a particular orbit)
- Perigee : Closest approach to Earth (within a particular orbit)