|
US satellite protection scheme poses global communications threat A proposed If activated, the envisaged “radiation belt remediation” system would significantly alter the upper atmosphere in the short term, seriously disrupting high frequency (HF) radio wave transmissions and GPS navigation around the globe, says the group’s lead researcher, Dr Craig Rodger of the University of Otago Physics Department. |
|
|
The remediation system aims to protect hundreds of low earth-orbiting satellites from having their onboard electronics ruined by charged particles in unusually intense radiation belts “pumped up” by high-altitude nuclear explosions or powerful solar storms, says Dr Rodger. The approach, which is being considered by the US Air Force and the US Defense Advanced Research Projects Agency, involves using very low frequency radio waves to flush particles from belts and dump them into the upper atmosphere over either one or several days. |
Cartoon
of a radiation belt remediation system in operation [After Mozer]. |
|
“We’ve calculated that Earth’s upper atmosphere would be dramatically affected by such a system, causing unusually intense HF blackouts around most of the world,” he says. “Airplane pilots and ships would
lose radio contact and some GPS would likely also suffer large-scale disruptions, as signals between ground users and satellites were scrambled by the ionosphere, he added. The disruptions result from a deluge of dumped charged particles temporarily changing the ionosphere from a “mirror” that bounces high frequency radio waves around the planet to a “sponge” that soaks them up, he says. In their paper, just published in the
August edition of the international journal Annales
Geophysicae, the Otago researchers and The researchers also calculated the likely effect of remediation on the ozone layer, but found that ozone depletion would be short-lived and similar to that resulting from natural processes such as large solar storms and volcanic eruptions. The paper, titled: “The atmospheric
implications of radiation belt remediation” was co-authored with Otago
colleague Associate Professor Neil Thomson and researchers from the British Antarctic Survey, and the Sodankylä
Geophysical Observatory in The full paper reference, including a link to the Annales Geophysicae website
containg the publication : The
atmospheric implications of radiation belt remediation. Rodger, C. J. , Clilverd, M. A.,
Ulich, Th., Verronen, P. T., Turunen, E., and Thomson, N. R., Annales Geophysicae, Page(s)
2025-2041. SRef-ID: 1432-0576/ag/2006-24-2025,Volume 24, Number 7, 2006. |
|
Notes and Background - Satellites For more information on the threats to satellites posed by high altitude nuclear explosions visit: http://www.cndyorks.gn.apc.org/yspace/articles/nuclear_explosions.htm The site features a copyrighted article which originally appeared in Scientific American magazine in June 2004 entitled "Nuclear Explosions in Orbit", and has been reprinted with the permission of the author. The article ends with several additional information sources. It has been suggested that a
nuclear airburst at high-altitude would significantly
shorten the operational lifetime of Low Earth Orbiting satellites. Even a
"small" detonation (~10-20 kilotons) occurring at altitudes of
125-300 km, could lead to the loss of 90% of all low-earth-orbit
satellites within a month. In 2004 there were approximately 250 satellites
operating in low-Earth orbit (LEO). These satellites fulfil a large
number of roles, including communications, navigation, meteorology, military
and science. In the event of a nuclear airburst at high-altitude, or an
unusually intense natural injection, this large population of valuable
satellites would be threatened. Due to the lifetime of the injected
electrons, the manned space programme would need to be placed on hold for a
year or more. |
|
|
In the earliest days of the Space Age, the US "Starfish Prime" HANE, a 1.4 Megaton detonation occurring at 400 km above Johnston Island in the central Pacific Ocean on 9 July 1962, damaged 3 of the 5 satellites which operating in space at the time. This included the world's first active communications satellite, Telstar, which failed due to radiation exposure, even though the satellite was launched after the Starfish Prime explosion. |
|
|
Notes and Background – HF
Communications HF radio frequencies are very important because of their wide uses. Many developed countries use HF for radiocommunications to and from aircraft and ships, international broadcasting, amateur operations, and for fixed long-distance radiocommunications. While little use is made of HF radiocommunications in developed countries for domestic communications, lesser developed countries still find HF cost-effective for their domestic radiocommunications needs, such as for national broadcasting, mobile, and fixed point-to-point communications. Notes and Background – GPS The Global Positioning System,
usually called GPS, is the only fully-functional satellite navigation system.
A constellation of more than 24 GPS satellites broadcasts precise timing
signals by radio to GPS receivers, allowing them to accurately determine
their location (longitude, latitude, and altitude) in any weather, day or
night, anywhere on Earth. GPS has become a vital global utility,
indispensable for modern navigation on land, sea, and air around the world,
as well as an important tool for map-making and land surveying. GPS also
provides an extremely precise time reference, required for telecommunications
and some scientific research. The operation of an RBR
system would lead to serious GPS degradation at mid latitudes, a new and
unexpected experience for mid-latitude GPS users.
The University of Otago is New Zealand's oldest university. Located in Dunedin, Otago is the
southern-most University of the country, with more than 17,800 students and 3300 staff. In
New Zealand, universities are institutions where teaching is primarily undertaken by those
engaged in research and scholarship. As New Zealand's oldest university, Otago has a long
established tradition of research excellence. Since its foundation in 1869, the University
has steadily increased its teaching and research activities, while building on its original
strengths, including Physics. More information on the University of Otago can be found at:
www.otago.ac.nz.
British Antarctic Survey is a world leader in research into global issues in an
Antarctic context. It is the UK's national operator and is a component of the Natural
Environment Research Council. It has an annual budget of around £40 million, runs nine
research programmes and operates five research stations, two Royal Research Ships and five
aircraft in and around Antarctica. More information about the work of the Survey can be
found at: www.antarctica.ac.uk
The Sodankylä Geophysical Observatory is an independent research department of the
University of Oulu, located in Lapland, and established in 1913 by Finnish Academy of
Science and Letters to perform geophysical measurements and research based on the
observation results. More information on Sodankylä Geophysical Observatory can be found at:
www.sgo.fi.
The Finnish Meteorological Institute is the agency responsible for gathering and
reporting weather data and forecasts in Finland. The Institute is an impartial research and
service organisation with expertise covering a wide range of atmospheric science activities
other than gathering and reporting weather data and forecasts. The main research subject of
the Finnish Meteorological Institute is the Earth's atmosphere. Other research topics
include the study of near space and solar influence on the planet's atmospheres. More
information on the Finnish Meteorological Institute can be found at: www.fmi.fi
|