Subscribe free to our newsletters via your
. 24/7 Space News .

Subscribe free to our newsletters via your

Global Positioning Keeps Tabs On Satellites

Microsat programs like UoSat-12 by Surrey Satellite Technology are benefiting from lower cost navigation systems that rely on the GPS network
Paris - Dec. 6, 2000
The growing population of satellites flying above our planet can now be guided by global satellite navigation systems just as easily as by ground-based systems, thanks to the pioneering work of ESA and two leading European satellite manufacturers and operators.

ESA has helped develop two new GPS (Global Positioning System) space receivers, the TOPSTAR 3000 in conjunction with the French-based company Alcatel and the SGR in collaboration with Surrey Satellite Technology in the UK.

Both receivers will bring more accurate, affordable satellite tracking to the commercial user. The TOPSTAR 3000 is designed for telecommunication and observation commercial missions with strong reliability requirements, and the SGR is ideal for use with the smallest type of satellites, weighing from a few hundred to just 5 kg.

Already, the world's ground-based communication networks -- such as sea navigation, air traffic management and various forms of mobile communication -- rely on the accuracy of GPS, a constellation of 24 United States satellites which transmit signals from an altitude of 20 000 km to small receivers on Earth.

Now, the precise position and orientation of low-Earth orbiting satellites travelling just 650 km above the Earth's surface can also be determined using GPS data through the new generation of space GPS receivers.

"These small satellites are travelling at speeds of 7.5 km per second, so tracking can be a difficult and tricky business," says Dr Martin Unwin, of the Surrey Space Centre, who has worked closely with ESA on the SGR project.

"Low-Earth orbiting satellites are used in a multitude of applications, from high resolution photographic monitoring of the Earth's surface to scientific and remote sensing experiments,and experimental communication systems in remote areas."

Most big satellite users and operators rely on a network of ground stations which bounce signals back and forth to determine position and orientation, or they use tracking data that originate from the US Space Command tracking facilities.

"The new space receivers will mean that the monitoring of satellites will become easier and cheaper for smaller operators," says Dr Unwin.

The SGR and TOPSTAR 3000 can both use multiple antennae, a feature that puts them at the forefront in a new league of GPS space receivers and allows the calculation not only of the orbital location but also of the orientation of the satellite (often referred to as the satellite's attitude).

Experimental and commercial missions have already been carried out for the receivers in both low and geostationary orbits. The TOPSTAR 3000 has been delivered to the STENTOR programme (a French space agency project for advanced research in space technology) for use in geostationary orbit as well as several commercial observation missions in low Earth orbits from 400 to 1400 km.

The SGR has successfully used GPS data to control and correct the orbit of the UoSat 12 mission and is due to go through experimental procedures on board ESA's Proba mission due for launch in the second half of 2001.

The attitude determination capabilities of the new receivers will be of particular importance to future science and remote sensing missions, where it is important to know exact orientation to achieve accurate scientific measurements.

Satellites carrying cameras will also benefit. "For example, a discrepancy of just one degree in attitude can throw a satellite off its target on Earth by about 14 km -- obviously the difference between the success and failure of any commercial satellite based system," added Dr Unwin.

Related Links
GPS At US Naval Observatory
Surrey Satellite Technology
Search SpaceDaily
Subscribe To SpaceDaily Express

Euro GPS System Gets A Road Test
Turin - Nov. 6, 2000
A Fiat car is putting a European satellite navigation system through its paces in Turin, Italy this week. EGNOS, which is being developed by a collaboration led by the European Space Agency, will be monitoring the car's position on a map with an accuracy of close to one metre.

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once

credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly

paypal only

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.