News ROSAT falls from the sky

[MattBaker]

So, after the more or less "safe" reentry of UARS some days ago there is another satellite on his way back to us.

It's german satellite [ame="http://en.wikipedia.org/wiki/ROSAT"]ROSAT[/ame] (RÖntgenSATellit, german for x-ray-satellite)

Because of big glass and ceramics parts it will survive the reentry and parts ~400 kg could reach the surface.

Heavens-above states the orbit with 258x264 km (~160 miles).
Twitter-account ROSAT Rentry says the same and states reentry for 23rd October (+- a few days)

Inclination of ROSAT is 53°, so northern Europe and big parts of Canada and Russia are save.


So, second chance within a month to get hit by a satellite, three weeks to go.

 

[RisingFury]

Here we go again! :lol:

Let the guessing start!

 

[Jarvitä]

I knew I shouldn't have filled in that shelter I dug for UARS.

 

[Urwumpe]

I say it will fall approximately 400 NM south of Japan.

 

[T.Neo]

I predict it will fall directly on a piece of sharp-edged UARS debris and be split in two.

 

[MaverickSawyer]

I say it will land in the drink again...

:hunter:
"SPLASH ONE!"
"SPLASH TWO!"

 

[MattBaker]

Update: Orbit is 253 x 258 km (160 miles)
Reentry is 23-28 October

DLR (German Aerospace Agency) states that up to 30 pieces with an overall mass of 1.6 tons of ROSAT will reach the surface.
Probability that ROSAT hits a person is 1:2000 (UARS was 1:3200, ROSAT seems to have more sharp edges)

 

[Urwumpe]

My last knowledge was just 400 kg of debris parts, which is still a lot of German engineering, if you remember that this is almost as much as predicted for UARS, despite the satellite being 3 times less massive.

1600 kg is almost 2/3 of the gross mass of the satellite - that sounds pretty doubtful to me.

 

[MattBaker]

I have this number out of DLR-FAQ to ROSAT.

Neuesten Untersuchungen zufolge muss damit gerechnet werden, dass etwa 30 einzelne Fragmente mit einer Gesamtmasse von bis zu 1,6 Tonnen die Erdoberfläche erreichen können.

In English: As a result of latest analysis we have to reckon that around 30 single fragments with an overall mass of up to 1.6 tons could reach the surface of earth.

 

[Urwumpe]

In English: As a result of latest analysis we have to reckon that around 30 single fragments with an overall mass of up to 1.6 tons could reach the surface of earth.

I can read it, but I strongly doubt the numbers. Even as worst case number, it is far too high.

That number would mean that just 800 kg of spacecraft would be capable of absorbing enough energy so the remaining parts can survive the reentry. This is maybe true for the optics, but the structural parts of the spacecraft are not that temperature resistant.

 

[orb]

SPACE.com: Falling German Satellite Poses 1-in-2,000 Risk of Striking Someone This Month

 

[T.Neo]

I keep misreading this thread title as "RORSAT falls from the sky", which gets a bit frightening... :shifty:

 

[astrosammy]

:yes: http://www.orbiter-forum.com/showthread.php?t=20904

 

[orb]

Universe Today: German ROSAT Satelite Heading Towards Uncontrolled Re-Entry to Earth

 

[n122vu]

I keep misreading this thread title as "RORSAT falls from the sky", which gets a bit frightening... :shifty:

I keep misreading it as "ROAST' falls from the sky", which would be even scarier. :blink:

 

[T.Neo]

I keep misreading it as "ROAST' falls from the sky", which would be even scarier.

Or perhaps not.

Free Sunday Lunch, anyone?

 

[PennyBlack]

"The largest single fragment will probably be the telescope’s mirror, which is very heat resistant and may weigh up to 1.7 tons."

With upto 30 pieces making it to the surface I think somebody may be at risk. An estimated 1 in 2000 chance of being hit while Germans stand a 1 in 700,000 chance of being hit. Don't figure does it.

Questions...
Are these things insured.?
If they hit property or injure/kill somebody, who pays.?
Why carn't they predict with more acuracy where these things come down when they can lob a nuc within inches of a target around the planet.?

 

[Urwumpe]

Questions...
Are these things insured.?

Not really, since no insurance company likes to calculate the risks - it is nearly impossible.

If they hit property or injure/kill somebody, who pays.?

The German government since they are the responsible country by space law. And the DLR a government agency, if this alone wouldn't be enough.

Why carn't they predict with more acuracy where these things come down when they can lob a nuc within inches of a target around the planet.?

Simple: First, a nuke has the much simpler trajectory. It flies only 25 minutes, and generally tries to aim for a point 90° around Earth from its launch site, so the errors are further minimized.

Next, it has an aerodynamically defined and stable shape with its spinning reentry vessel, while the satellite is complex and tumbling.

This is both also augmented by the fact, that the reentry angle of the satellite is close to zero, while a nuclear warhead reenters at more than 9°, which means the warhead has approximately a straight line during its ballistic reentry from entry interface to impact (Since it never again reaches a place where gravity dominates over aerodynamic forces).

 

[PennyBlack]

I'm getting a passport and coming to Germany. Statistically I stand a better chance of not being hit. :thumbup:

Thankyou.

 

[Urwumpe]

I'm getting a passport and coming to Germany. Statistically I stand a better chance of not being hit. :thumbup:

Thankyou.

LOL, I would maybe ask yourself first, who did this statistic and how he did it.

It is a 1:2000 chance that a single human between 53° North and 53° South is hit by debris. About 5 billion people together bring 1:2,000.

Germany is mostly inside this region, (except the places north of Bremen), which means 65 million people together have a risk of 1:700,000 that a single person of them is hit.