Tuesday, February 06, 2007

Orbiting Junk, Once a Nuisance, Is Now a Threat-Update

For decades, space experts have worried that a speeding bit of orbital debris might one day smash a large spacecraft into hundreds of pieces and start a chain reaction, a slow cascade of collisions that would expand for centuries, spreading chaos through the heavens.

In the last decade or so, as scientists came to agree that the number of objects in orbit had surpassed a critical mass — or, in their terms, the critical spatial density, the point at which a chain reaction becomes inevitable — they grew more anxious.

Now, experts say, China’s test on Jan. 11 of an antisatellite rocket that shattered an old satellite into hundreds of large fragments means the chain reaction will most likely start sooner. If their predictions are right, the cascade could put billions of dollars’ worth of advanced satellites at risk and eventually threaten to limit humanity’s reach for the stars.

You can read the whole story by William J. Broad online at:

More debris has been cataloged by U.S. Space Command associated with the Chinese ASAT test conducted last month. The debris is from the target of the test - the Fengyun 1C polar orbiting weather satellite.

Here is a catalog of the known objects as of 6 Feb 2007 at 1200 UTC:
International Designator / SSC#
1999-025E / 29716 to 1999-025AM / 29747 [Original pieces cataloged]
1999-025AN / 29748 to 1999-025LZ /29999 [2nd set of debris cataloged, released 1/28/07]1999-025MA / 30001 to 1999-025WS / 30233 [2nd set of debris cataloged, released 1/28/07]
1999-025WT / 30234 to 1999-025ZZ / 30312 [3rd set of debris cataloged, released 2/2/07]1999-025AAA / 30313 to 1999-025AAK / 30322 [4th set of debris cataloged, released 2/5/07]
1999-025AAL / 30325 to 1999-025ACB / 30364 [4th set of debris cataloged, released 2/5/07]

Information for the latest debris listed above is from Dr. TS Kelso's celestrak website. As of the time listed above, nothing past 1999-025ZZ was listed on the 7 day report on the Space track website.

The 1999-025 ASAT test still ranks as the second highest on orbit debris event in space history as the table below shows.

Rank / SSN / Int Designator / Pieces
4 / 27721 / 1965-082UT / 474
3 / 27596 / 1986-019VN / 493
2 / 30325 / 1999-025ACB / 642
1 / 29036 / 1994-029AET / 714

In a related note regarding the UPI story below that the ISS had been maneuvered to avoid the 1999-025 debris field, Greg Williams reported on the SEESAT-L newsgroup over the weekend that NASA had not moved the orbit of the ISS. Greg wrote:

"According to a source on a NASA forum, ISS was not moved and no orbital change was made. The following is from the forum. Here's the details -- pass around as you like:

"UPI's Moscow bureau sent out a news story Friday PM that the space station had to change orbit to avoid collision with a fragment of a Chinese rocket that was destroyed last month in the anti-satellite test.

"The entire story is here:

"The story is NOT true, and should be disregarded.

"There has been no maneuver in space, and none are currently planned -- I verified with NASA spokesman John Ira Petty in Houston.

"The UPI story claims it is based on a 'Novosti' news agency story. I found the story, in English, and it DOES say that "We are diverting the orbit of the ISS to prevent a possible collision
with large fragments of space debris, a decision the Russian Mission Control took together with the Johnson Space Center in Houston," a Russian Mission Control spokesman told Novosti Friday. http://en.rian.ru/world/20070202/60105727.html

"Sort of.

"Novosti botched the translation, and UPI didn't realize it -- and didn't try to verify with NASA.

"Here's the original Russian story: http://rian.ru/technology/cosmos/20070202/60093948.html

"Not to show off or anything .... I get by in Russian, and here's the much more accurate translation of the verb tenses: "In order to protect ISS from the possibility of collision with big
pieces of space junk, we conduct a maneuver of avoidance to lead the station to the side.

"The Russian MCC takes the decision of carrying out this maneuver together with the Johnson space center in Houston."

"The Russian expert at Moscow Mission Control is speaking HYPOTHETICALLY. This is, he explains, what we DO in order to keep the station safe from space junk.

"It's NOT what we have just DONE, today. It has nothing to do with actual events today. The verb tenses indicate that.

"It's kind of scary how an alarming story can blast off, on such a volatile and frightening subject, based on misunderstanding.

"So it's only fair that the story has been featured on Drudge Report all day Saturday!!"

So now you know the rest of the story. Thanks Greg and 73 de N5FPW.