Roentgen / ROSAT Hit Earth: Somewhere Around Southeast Asia

"Dead ROSAT Satellite Reenters Over South-East Asia"
Ian O'Neill, Discovery News (October 23, 2011)

"The German Aerospace Center and NASA have confirmed the defunct Roentgen Satellite, or ROSAT, has met its doom, most likely somewhere over SE Asia. German officials have said that the reentry occurred some time between 9:45 p.m. and 10:15 p.m. EDT on Saturday night.

"Fortunately, there are no reports of falling debris or damage, which means the surviving satellite bits -- around 30 pieces -- most likely crashed safely into the Bay of Bengal, somewhere between the the east coast of India and Indonesia. The location has yet to be confirmed, however.

"If it did come down in the Bay of Bengal, the satellite would have been approaching heavily populated cities in China before it started to tumble through the Earth's atmosphere, a fall that would have taken up to 15 minutes.

"Although the likelihood of the 2.4 ton X-ray satellite causing death and destruction was low (at 1-in-2,000), these odds were higher than last month's NASA Upper Atmosphere Research Satellite (UARS) crash. The likelihood of UARS hitting someone on Earth was set at 1-in-3,200, even though UARS was a larger piece of kit than ROSAT...."

What made ROSAT particularly dangerous was its mirror: almost three feet across, and weighing 880 pounds. Odds are pretty good that most of it came down in one piece. Even if the mirror broke up during reentry, and the largest piece was only half the size of the original: that'd still be 440 pounds of mirror. Definitely not the sort of thing anyone would want hitting the roof.

As of last night, it looks like nobody got hurt. That's good news.

The bad news is that ROSAT wasn't the only piece of space junk spinning around our planet. The Lemming's no Luddite, and thinks that communications satellites, GPS systems, and all the rest are useful. On the other hand, it's gotten crowded up there: and folks on Earth can't count on being lucky each time something comes in.

Maybe someone will work out a way to make money by salvaging out-of-service satellites. The Lemming's pretty sure that the more earnest folks Earthside would have fits over such capitalistic plots, and there'd have to be some sort of air traffic control (space traffic control?) for the salvage operations. But the Lemming also thinks a 'private sector' solution like that would probably cost less, and might work more effectively than some massive bureaucracy.

Think about it: if Earth goes the 'government' route, the United States, Japan, Russia, China, and India - at minimum - would insist on having full control of the program. The United Kingdom, France, Germany - you get the idea.

Yes, the Lemming thinks 'Ralph's Rockets and Orbital Salvage' would probably work better. Particularly since Ralph would have plenty of competition to keep up with.

And that's another topic.

Slightly-related posts:

• "Space Junk, Lasers, and Diplomacy"
  (March 21, 2011)
• "European Space Agency Inheriting Huge Satellite, and Trouble to Match"
  (July 27, 2010)
• "Over Four Dozen Space Agencies (and Growing?)"
  (February 28, 2010)
• "Bigelow Aerospace: Space to Rent or Lease, in Orbit"
  (January 20, 2010)
• "Asteroid Threat: Good News, We Have the Technology; Bad News - "
  (April 28, 2009)

Two Decades Later: Voyager 1 Flyby of Triton, August 21, 1989

"Aug. 21, 1989: Voyager 2 Reaches Triton"
This Day in Tech, Wired (August 21, 2009)

"1989: Twelve years and one day after liftoff, Voyager 2 reaches Triton, the largest of Neptune's eight moons and the coldest, most unusual satellite in our solar system.

"Launched from Cape Canaveral on Aug. 20, 1977, Voyager 2, as the name suggests, was the second of two identical deep-space probes originally dispatched by NASA to gather data on Jupiter and Saturn. Their primary mission completed, Voyager 2 continued on to make observations of Uranus and Neptune, while Voyager 1 hightailed it toward the edge of the solar system. Voyager 2’s flyby of Triton was the spacecraft's last contact with a major heavenly body before heading off in the direction of Voyager 1 and interstellar space...."

That was 20 years ago, today. This short Wired article gives a brief overview of the Voyager 1 flyby of Triton and the two Voyager missions. A day over 32 years after Voyager 1's launch, both spacecraft are still active, coasting through the outer parts of our sun's heliopause, and expected to keep sending data until 2025.

NASA has a bit more information about Triton: "Neptune: Moons: Triton;" a more complete description of that color image displayed by Wired; and a 26-image gallery, including a few artistic composites and quite a number of images.

Including this color image, which seems to be the original of Wired's version:

"PIA00317: Global Color Mosaic of Triton "


"Global color mosaic of Triton, taken in 1989 by Voyager 2 during its flyby of the Neptune system. Color was synthesized by combining high-resolution images taken through orange, violet, and ultraviolet filters; these images were displayed as red, green, and blue images and combined to create this color version. With a radius of 1,350 (839 mi), about 22% smaller than Earth's moon, Triton is by far the largest satellite of Neptune. It is one of only three objects in the Solar System known to have a nitrogen-dominated atmosphere (the others are Earth and Saturn's giant moon, Titan)...."

U.S. Navy Targets Spy Satellite Fuel Tank

"U.S. missile strikes spy satellite"
International Herald Tribune (February 21, 2008)

"Navy Hits Satellite With Heat-Seeking Missile "
Space.com (February 20, 2008)

It was pretty good shooting: The satellite (USA-193, AKA NROL-21) was about the size of a bus; the Navy was aiming at, and apparently hit, a fuel tank on the satellite.

Now, the biggest pieces of the satellite are about the size of a football.

The fuel tank was a real concern. It was made of titanium and had about a thousand pounds of hydrazine¹ inside. Hydrazine is a rocket fuel that's sincerely unhealthy to breath.

CNN has a pretty good video of the satellite being hit. That video includes part of a press conference with General James Cartwright of the Joint Chiefs of Staff: also clips from "Armageddon" and "Deep Impact," and some mildly-tongue-in-cheek interviews with New Yorkers.

The Space.com article includes a claim by an "MIT physicist and space expert" that there's a 3.5% chance that the tank will hit someone². Numbers with a decimal point are always impressive, but that's a crazy-high chance: and the Space.com article doesn't go into why the MIT expert decided to use that number.

---

¹That's hydrazine, not hydrogen, as I heard an expert say. In fairness, he might not have had enough sleep the night before.
²Even when you take into account America's 'obesity epidemic.' :)

Fifty Years after Sputnik, Satellites are Everywhere

"What's your Sputnik moment?" is a very good look at what's happened in the last fifty years.

The author, Chris Rowan, points out that in the sixties New Zealand was on the other side of the world, as far as people back in England were concerned. Well, they still are, actually: the point is that communication was effectively limited to mail, and that could take weeks to months.

I remember Sputnik, and lived through the explosion of information technology: If you did, to, this post is a good review.

If you didn't, you really ought to read it: and learn how much a few few tin cans being launched into space changed the world.