Page 1 of 2 THINGS THAT GO BUMP IN SPACE, Part
1 Collision puts new Asian satellites at risk
By Peter J Brown
On February 10, Iridium 33 - one of more than 60 US satellites in the Iridium
satellite constellation used primarily for worldwide satellite phone services -
and an uncontrollable Cosmos 2251, a lifeless Russian communications satellite
that had been drifting in space for over several years, collided approximately
790 kilometers above Siberia.
Space experts like Dr Geoffrey Forden, senior research associate at the
Massachusetts Institute of Technology's Program on Science, Technology, and
Society, are still calculating the amount of debris that has been created, as
well as its potentially
harmful effects. The safety of satellites in the Iridium constellation is now
questionable.
"As of Friday, February 20, 2009, there were 212 pieces of debris from that
collision cataloged [144 associated with the Cosmos satellite and 68 with
Iridium]. Both groups of debris are starting to spread out along their initial
satellite trajectories. And this is just the first pieces that have separated
from the swarm," Forden wrote on a website where he shares his ongoing
assessment of the situation. [1] "All the Iridium satellites pass through both
debris tubes twice per orbit. That's four times of dramatically increased
chances of another collision [this time between a satellite and a piece of
debris] every 100 minutes, roughly."
"Unfortunately, it just makes it a sort of continuous danger," Forden added.
According to "Colliding Satellites: More Space Junk in Exactly the Wrong
Place", a backgrounder issued by the Massachusetts-based Union of Concerned
Scientists (UCS) on February 12: "Prior to this collision, there were some
3,000 objects larger than 10 centimeters in the region between 450 and 500
miles in altitude [700 to 900 kilometers]. The China [anti-satellite] ASAT test
created about 2,500 debris particles of this size around an altitude of 530
miles [850 kilometers], roughly a third of which may be in this altitude band."
In Vienna, quite by coincidence, a large meeting of scientists, space experts
and government officials was just getting underway as the collision occurred.
The subject of space debris mitigation was already on the agenda at the 46th
session of the Scientific and Technical Subcommittee of the United Nations
Committee on the Peaceful Uses of Outer Space (COPUOS), which ended on February
20.
Besides reviewing the implementation of the recommendations of the Third United
Nations Conference on the Exploration and Peaceful Uses of Outer Space
(UNISPACE III), one of the first events at this session was an International
Astronautical Federation (IAF) symposium on the role of earth observation
satellites in assessing climate change.
On the list of many new earth observation satellites that could be affected by
the debris is the Japan Aerospace Exploration Agency's (JAXA) Greenhouse Gases
Observing Satellite (GOSAT), also called "Ibuki", which was launched in
January. It orbits at an altitude of about 670 kilometers where it monitors
carbon dioxide and methane levels. Also in orbit at an altitude of around 660
kilometers is Maido No 1, one of several small satellites which accompanied
Ibuki on the same JAXA H2 rocket. It observes electromagnetic waves emitted
during thunderstorms.
"Based on the data [provided] by NASA NORAD [the North American Air Defense
Command based in Colorado], JAXA has been tracking our satellites to avoid
debris collision. Our control center continues to monitor a possible debris
impact that might be caused by this current accident," said a JAXA spokesman.
"JAXA is not going to execute evasive maneuvers for now. However, if and when
obvious collision possibilities occur, we will carry out an evasion plan such
as altering the orbit of our satellite."
Next week, Ibuki will be joined by the Orbiting Carbon Observatory (OCO),
another greenhouse gas-hunting satellite which NASA will deploy at an altitude
of 690 kilometers above Earth. OCO will be the sixth and final satellite in
NASA's so-called "Afternoon Constellation" or "A-Train". It was the Ozone
Monitoring Instrument on Aura - another one of the six "A-Train" satellites -
that helped to demonstrate how successful China's air pollution control measure
had been during the 2008 Summer Games in Beijing, for example.
In his address to the 46th session, Wang Keran, deputy secretary-general of
China's Secretariat of Asia-Pacific Multilateral Cooperation in Space
Technology and Applications and head of the Chinese Delegation, specifically
mentioned China's growing fleet of five meteorology satellites - including the
latest of the Fengyun-3 Series launched in May, 2008. However, while he talked
about how these weather satellites could help China "to prevent and mitigate
disasters and adapt to climate change", he did not comment on the fact that
these new polar orbiting Chinese meteorology satellites are now at a somewhat
greater risk of a collision with space debris.
He did emphasize China's efforts to enhance cooperation in all space-related
matters. Besides mentioning the Sino-Russian joint explorations to Mars, he
brought up the China-Brazil Earth Resources Satellite (CBERS) and others as
important examples of China's ongoing bilateral ties in space.
Yellow caution lights are now flashing for these CBERS satellites, which occupy
an orbit at an altitude of approximately 770 kilometers. Chinese Yaogan
military radar surveillance satellites and Haiyan maritime surveillance
satellites operate in roughly the same neighborhood. Yellow caution lights are
flashing for other satellites as well, including the Hubble Space Telescope and
the Communication / Navigation Outage Forecasting System (C/NOFS) spacecraft
which was launched last year to take measurements in the ionosphere - C/NOFS
circles in an elliptical orbit ranging from 375 to 710 kilometers. There are
also fears for the $500 million new GeoEye-1 satellite, which was launched in
September and only commenced commercial operations in early February - it can
focus in on objects as small as 16 inches from its perch 695 kilometers above
Earth.
Speaking at the MapWorld Forum in India shortly after the collision, a GeoEye
spokesperson said the company was "extremely concerned" about its new GeoEye-1
spacecraft. [2]
Operators of the joint Small MultiMission Satellite (SMMS), which was launched
in September, also need to be more vigilant. The SMMS space imaging team
includes Thailand, China, Iran, Pakistan, Mongolia, Bangladesh and South Korea.
The SMMS is in a sun-synchronous polar orbit at an altitude of 650 kilometers.
"Based on the increased number of debris created by the Chinese ASAT test in
2007 at [their] altitude, the chances of [satellites like Ibuki and Maido No 1
to name just two] being struck increased from somewhere between 1.5 to two
times what it was before - which for any specific satellite is still pretty
small, on the order of one in a thousand over three years," said Forden.
Updates on satellites confronting near misses, which are known as
"conjunctions", flow from two different sources, the SOCRATES database and the
US Strategic Command's Joint Functional Component Command for Space, which
oversees the US Joint Space Operations Center. This is home to the US Space
Surveillance Network (SSN) which consists of more than two dozen space
surveillance sensors including radar and optical telescopes. All of these
updates form the Space Catalog, a comprehensive listing of the numbers, types,
and orbits of well over 18,000 man-made objects in space.
Since 2004, according to the Center for Space Standards and Innovation (CSSI)
and Pennsylvania-based Analytical Graphics Inc (AGI) joint website [3], the
free online "conjunction" advisory service known as SOCRATES.
Since May
of 2004, CSSI has been providing free online conjunction advisory services -
SOCRATES - to the satellite community, using AGI tools, to help the space
community develop a better understanding of the magnitude of the problem with
satellite close approaches in Earth orbit. Since February 2008, CSSI has worked
closely with geostationary satellite operators to find ways to improve the
accuracy of the data used for these analyses in an effort to reduce the number
of false alarms and thereby reduce the risk of a potential collision," says the
website.
Iridium did not respond to questions from Asia Times
Online and issued its last press advisory on February 13 saying, "it has
completed its service hole patch in relation to its recent satellite loss".
Iridium has publicly stated that it received no warning of any impending
collision.
"The SSN has a list of priority items it spends more effort in tracking, but
neither of these satellites would have been on that list. As a result, the
tracking data probably had an uncertainly of a kilometer or two. The US
military doesn't check for possible
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