Page 2 of 2 THINGS THAT GO BUMP IN SPACE, Part
1 Collision puts new Asian satellites at risk
By Peter J Brown
collisions of everything it tracks, but [SOCRATES] does," said Dr Gregory
Kulacki, senior analyst and China Project Manager at the UCS. "SOCRATES listed
these two satellites as ones that would pass close to each other - it gave an
estimated distance of about 0.5 kilometers. Such close conjunctions happen all
the time between satellites and large pieces of space junk, but the chance of
them actually colliding is very small. If Iridium moved its satellites every
time there was a conjunction, it would run its satellites out of fuel more
quickly. So apparently Iridium decided to take its chance and got unlucky."
Keep in mind that although the SOCRATES algorithms are
accurate, the data set it has for the analysis - the public so-called "Two Line
Element" catalog distributed by US Air Force Space Command - is inherently
imprecise, according to Robert Hall, AGI's technical director.
"The SOCRATES results were not provided directly to Iridium. Iridium had access
to the SOCRATES analysis results - they are available for anyone to see on the
web, updated twice daily. On that website [4], all of the results are provided
in a searchable fashion," said Hall.
"To see an example, go to the website and you will see a couple of 'top 10'
listings and you will also see a search function. You can type in the name of
any satellite - like Iridium - and get the listing for all Iridium events."
Li Yan, a correspondent for People's Daily in France, reported that: "Philippe
Goudy, deputy director of France's space center in Toulouse [which is operated
by CNES] thinks that the cause might have been careless monitoring by US
operators. They had really underestimated the "destructive power" of flying
debris in outer space." [5]
This and other Chinese press reports seem to imply that the US is not doing
enough to monitor debris in orbit, and this journalistic slant is highly
questionable, according to Dr Joan Johnson-Freese, chair of the National
Security Decision Making Department at the US Naval War College.
"That [report] seems rather ironic given that China has been the largest
single-event contributor to the debris. Further, while the event certainly has
raised awareness of the debris issue, hopefully it will also raise awareness
that it is an international issue, not one that is solely the responsibility of
the United States," she said.
"This is clearly at least a three-step problem. First, stopping the deliberate
creation of debris, and minimizing that created through the routine use of
space. This is where an international Code of Conduct is key. Second, there is
a need for better SSA and sharing of data - and that is not the responsibility
of one country. And third, more long term, cleaning up what is already in
space. All these are international issues."
China's Purple Mountain Observatory (PMO), which operates the space monitoring
network for the Chinese Academy of Sciences, began tracking the debris
immediately, PMO staff member Zhao Changyin told the People's Daily. However,
the collision happened above northern Siberia, which is well beyond "the
observational airspace of existing Chinese observation stations". Space expert
Pang Zhihao later told Xinhua that he predicted that the "debris' flying speed
may reach 7.8 kilometers per second, or even faster, and may remain in space
for decades".
The operational status of the entire Iridium constellation certainly affects
China. More than decade ago, Hong Kong-based Iridium China Ltd emerged as a
wholly-owned subsidiary of China Aerospace, the parent company of China Great
Wall Industries Corporation which launched several early Iridium satellites on
its Long March rockets. Then in 2007, China Space Mobile Satellite
Telecommunications (China Spacecom) activated an Iridium satellite gateway in
Beijing to enhance iridium service throughout China.
The timing was fortunate indeed as China came to rely heavily on Iridium
sat-phones immediately after the massive May 2008 earthquake which effectively
wiped out many if not most telecommunications networks throughout the
earthquake zone. Several major cities were left entirely without any phone
services, including cell phones, as hundreds of cellular base stations ceased
to work in Sichuan and neighboring provinces. Local Chinese officials and
disaster response personnel scrambled to obtain sat-phones in much the same way
as US personnel reacted after Hurricane Katrina in 2005. [6]
Today, Iridium sat-phones are used routinely by the Chinese at home and abroad.
For example, in late December, one of the first things that a Xinhua state news
agency reporter did as he was preparing to cover the Chinese naval deployment
in the Indian Ocean was to "de-bug" his laptop, his maritime satellite link and
his Iridium satellite phone after going on board the Chinese Navy destroyer
Wuhan. [7]
That reporter, like thousands of other sat-phone users worldwide, depended on
the integrity and reliability of the Iridium network.
"Why Iridium was not informed of a possible collision by the SSN is perplexing.
Maybe the SSN is not so well organized or reliable," said one Japanese space
expert who asked not to be identified.
"I find it incredible that Iridium received no warnings. I have heard a couple
of trial balloons floated to try to explain this: close encounters happen so
often as to be unremarkable - that turns out to be not true - and that it is so
time consuming to calculate these approaches as to be prohibitive. That also is
false," Forden said.
Notes
[1] http://www.armscontrolwonk.com [2]
http://www.asmmag.com/news/satellite-collision-panics-remote-sensors [3]
http://www.centerforspace.com/ [4] http://www.celestrak.com/SOCRATES [5]
http://news.xinhuanet.com/english/2009-02/17/content_10835968.htm [6] (See
"Crisis On The Gulf Coast: When Satellite Was The Only Game In Town" by Peter
J. Brown; Via Satellite magazine, January, 2006 -
http://www.satellitetoday.com/via/features/18.html) [7]
http://news.xinhuanet.com/english/2008-12/26/content_10563160.htm)
Part 2 will examine legal issues, and significant attempts to develop a
viable international solution to the growing problem of space debris.
Peter J Brown is a satellite journalist from Maine USA.
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