Either on the evening of April 1st* or the afternoon of April 2nd, the defunct Tiangong-1 space station will fall out of the fringes of the atmosphere and "burn up." Because the descent has been uncontrolled, we have no idea exactly where the schoolbus-sized craft will fall; it's a vast swathe "42.8 North and 42.8 South latitude", meaning it could as easily sprinkle flaming crap on Shanghai, San Diego, all of Brazil. (Source: Marco Langbroek, SatTrackCam Leiden.)
What to do? Watch the skies at night if you live south enough; the "ship" is in a flat spin, spiraling. It might look like a meteorite falling. If the zillion-to-one shot happens and you are lucky enough to be near some flaming remains, especially containers, just call your fire department and they will send out people in hazmat suits to put out the fire and pick up the thing(s).
*Predictions have still not ruled out late March 31st. I wrote "sprinkle" instead of "rain" because the Tiangong-1 is only 8.5 metric tons. The Chinese space program planned for two years of usefulness out of "Celestial Palace-1". It launched late, it is returning late.
Re: Space Junk (Tiangong-1 and others) thread
Posted: Sat Mar 31, 2018 9:15 pm
by ericbarbour
Most of the remains of a deorbited ship are harmless once on the ground, with two major exceptions.
*Explosive bolts used to separate stages, hatches etc.
*Tanks full of hypergolic fuel. Quite often the tanks reach the ground intact, and the usual fuels are extremely toxic and corrosive (hydrazine, peroxide etc.)
ericbarbour wrote:Most of the remains of a deorbited ship are harmless once on the ground, with two major exceptions.
*Explosive bolts used to separate stages, hatches etc.
*Tanks full of hypergolic fuel. Quite often the tanks reach the ground intact, and the usual fuels are extremely toxic and corrosive (hydrazine, peroxide etc.)
Certainly, but in this case it was also a science lab, and who knows what they were dicking around with - probably simple experiments with plants or simple organisms in microgravity; taikonaut crews were never in there for really long stretches....but you never know*. Also I did write "zillion-to-one"; I think any debris will hit the ocean or fall on uninhabited territory.
1 April 20:30 UT ± 7h is SatTrackCam Leiden's latest prediction; the last US prediction on Friday was 1 April 21:29 UT ± 10 h.
* I'm not saying "plague bacillus" or "radioactive material" - Some of the short-term Soviet Salyut space stations were actually combination manned reconnaissance cameras/armed anti-satellite gun platforms/testbeds for the "orbital freighter" concept used during the Mir program and for the International Space Station. Salyuts 2, 3, and 5 were actually Almaz ("Diamond") craft run by the military and armed with a standard 23mm Rikhter cannon like those mounted on Ilyushin bombers and military transports - it was test-fired in orbit. Much like with the fictional Soviet "Doomsday Machine" in Dr. Strangelove these satellites were only designed this way because they feared that America would do it first....which we were, but then Apollo and the goal of making it to the Moon pretty much killed the US program. We blinked; the Soviets didn't.
Re: Space Junk (Tiangong-1 and others) thread
Posted: Sun Apr 01, 2018 10:26 pm
by Strelnikov
New predicted time from Leiden: 2 April 00:56 ± 130 min. Link.
Re: Space Junk (Tiangong-1 and others) thread
Posted: Mon Apr 02, 2018 2:37 am
by Kumioko
Well I hear it crashed into the South Pacific ocean tonight! So it fell in a relatively safe area.
Re: Space Junk (Tiangong-1 and others) thread
Posted: Mon Apr 02, 2018 3:38 am
by Strelnikov
Kumioko wrote:Well I hear it crashed into the South Pacific ocean tonight! So it fell in a relatively safe area.
All predictions were in Universal Time....shiiiiit, nobody got to see flaming crap fall into the ocean!
....Of particular note is part of an Indian Polar Satellite Launch Vehicle (PSLV) rocket that delivered a remote sensing satellite into space in April 2012, said McDowell, who tracks the launches, orbits and deaths of spacecraft and details this information in the email-distributed newsletter Jonathan's Space Report.
The PSLV rocket body weighs about 1 ton (907 kilograms) — far less than the 9.4-ton (8.5 metric tons) Tiangong-1 — and is expected to enter Earth's atmosphere tomorrow (April 3), give or take a day, according to The Aerospace Corporation, a California-based company that tracks re-entries.
The Space.com article continued:
.....Not all space junk is orbiting in a circular path, though. Almost on the same day as the PSLV is expected to re-enter, part of a half-ton (440 kg) European rocket, an Ariane 5, will be heading for Earth, according to Aerospace. The Ariane 5 launched in May 2007, and it traveled in an elliptical orbit, dipping close to Earth and then swinging around into a high altitude several times to deploy the Astra 1L and Galaxy 17 communications satellites into geosynchronous orbit, some 26,000 miles (42,000 km) above Earth.
After the rocket finished its job, some of its components — including its payload dispenser, called a SYLDA (for "Systeme de Lancement Double Ariane") — continued along the elliptical path, losing energy each time it dipped close to Earth. As of April 2, it was reaching 295 miles (475 km) in altitude at its high point and 96 miles (155 km) at closest approach — treacherous territory for a satellite. The relatively thick atmosphere down so low saps the craft's kinetic energy, and eventually, it won't have enough to rise again.
But the SYLDA spends little time at the lower altitude — 22 minutes out of a total 90-minute orbit, as of April 2, said McDowell. It's traveling at 17,900 mph (28,807 km/h) at its closest approach, so it has enough momentum to evade the danger zone. For now.
Looking a little further into the future, McDowell said the next large object of concern is NASA's Rossi X-ray Timing Explorer (RXTE) satellite, a 3-ton (2.7 metric tons) craft launched in 1995 to capture X-ray emission data from white dwarfs, neutron stars, black holes and other X-ray-emitting objects. It was switched off in 2012 and, for the past six years, has been zooming around Earth as space junk, he said. RXTE could re-enter sometime around mid-April, McDowell said.
"That's a re-entry that, if you're underneath it, you'll see a nice fireball in the sky," McDowell said. "There might be some small pieces that reach the surface."
Jonathan McDowell's catalogue of satellites from Sputnik to whatever launched last week: link.
The above reentries went by, and there wasn't a peep anywhere online. No one will care until a really BIG piece of rocket wipes out a rich asshole on the Florida coast or somesuch.
Re: Space Junk (Tiangong-1 and others) thread
Posted: Sat Apr 14, 2018 3:59 am
by Strelnikov
ericbarbour wrote:The above reentries went by, and there wasn't a peep anywhere online. No one will care until a really BIG piece of rocket wipes out a rich asshole on the Florida coast or somesuch.
The problem is that we are beginning to wall ourselves off from space with all the fragments of long dead rockets, satellite junk from collisions, Mike Collins' lost Hasselblad camera from that Gemini mission, etc. There are plans to deal with it using junk-grabbing robots, but no ideas about dealing with the tiny, high-velocity stuff. It's like the asteroid problem; academic until we spot a large one heading straight for us.
Re: Space Junk (Tiangong-1 and others) thread
Posted: Sat Apr 14, 2018 5:09 am
by ericbarbour
And so far, the only public debate of this has been in occasional hand-wringing magazine articles, a few science-fiction stories, one overdramatic movie, and a popular anime series. It would be prohibitively costly to actually do it so it's not "seriously discussed" I assume.
Not much will be done until people start to die, guessing.