Bonn, Germany (SPX) Jul 19, 2010
On its launch date, 21 June 2010, roughly 16,000 kilometres separated TanDEM-X from its twin satellite, TerraSAR-X. Now, that distance has shrunk to just 2000 kilometres. The time has come for the relative movement between the two satellites to be slowed down, and for them to be set up for formation flying.
To accomplish this, the Flight Dynamics Group at the German Space Operations Center (GSOC) will carry out a total of 10 orbital manoeuvres over the next eight days.
The orbit of TanDEM-X was set shortly after its launch to an altitude some 4.6 kilometres lower than that of TerraSAR-X, meaning that TanDEM-X has a slightly higher orbital speed.
This means that the two satellites have been approaching one another at a rate of approximately 630 kilometres per day - not much, when you consider that they are flying at a speed of 27,000 kilometres per hour. Without alterations to its orbit, TanDEM-X will overtake its twin within the next three days.
However, the radar instrument team wants to achieve a large-separation formation; one in which TanDEM-X follows TerraSAR-X at a distance of 20 kilometres, covering the same track across the surface of the Earth. This formation will be retained until September, to allow the radar to be calibrated.
Setting up the formation must take place in stages. On the one hand, the satellite only has four one-newton propulsion units - which equates to the force of four bars of chocolate on a set of kitchen scales. Given that it weighs in excess of 1300 kilograms, it follows that these propulsion units have to operate for a long time to effect small changes in speed.
The manoeuvre, for example, will last for 421 seconds, and will alter the orbital speed by 1.14 metres per second. That might not sound like much, but it is enough to raise the mean orbit altitude by 2000 metres. A longer manoeuvre would have a negative impact on the effectiveness of the orbital correction.
On the other hand, it is necessary to eliminate any risk of the two satellites colliding with one another. To accomplish this, the relative speed will be reduced in small steps. This means that by 18 July the satellites will only be approaching one another at the rate of about 140 kilometres each day.
In the event that it proves impossible to carry out the final deceleration manoeuvre on 18 July, as a consequence of problems on the ground or on the satellite, the two satellites would move past one another at a safe distance of more than 250 metres.
After this deceleration process, a further five manoeuvres are envisaged to precisely adjust the orbit's plane and ellipsoidal shape. If everything runs on schedule, it should be possible to start the next calibration phase for the radar instrument on 22 July.
Share This Article With Planet Earth
German Space Operations Center (GSOC)
Space Technology News - Applications and Research
Solar storm created 'zombie' satellite
Washington (UPI) Jul 13, 2010
U.S. scientists say they've identified a massive solar storm that reached Earth and caused a satellite to malfunction, turning it into a "zombie satellite." A NASA sun-watching spacecraft observed the explosion of plasma and magnetic energy, called a coronal mass ejection, on April 3, SPACE.com reported Tuesday. Charged particles in the solar storm disabled the Galaxy 15 communic ... read more
One Tiny Satellite In Space, Whiz Kids Plan Two More|
iPad and other gadgets drain Asia of electronic components
Art In Space - Or, How To Set Up A Formation
Tokyo trials digital billboards that scan passers-by
Savi Ships Compact Mobile Tracking Systems For Marine Afghan Forces
Army Plans Network Integration Exercise
Gilat To Provide Broadband Satellite For Homeland Security In Asia
Critical Design Review For U.S. Navy CSD Program
Sea Launch Signs Launch Agreement With AsiaSat
PSLV Launch Successful With 5 Satellites Placed In Orbit
ISRO To Launch More Satellites This Year
ILS Successfully Launches The Echostar XV
Lockheed Martin Unveils GPS Exhibit At UN
Tracking System Leads Rescuers To Birds Caught In Gulf Of Mexico Oil Spill
New System Helps Locate Car Park Spaces
Skyhook Wireless Partners With Samsung Electronics For Leading Location System
China jumbo jet maker picks GE, Eaton as suppliers
Swiss solar plane makes history with round-the-clock flight
Solar Impulse plane packed with technology
Piccard dynasty roam unknowns in sky, sea, sun
Acer, Asus and Lenovo lead pack as PC sales surge
Intel posts 'best quarter' ever
Cloud Computing Problems Can Spot Before They Start
India's poor scrape a dangerous living in new 'e-waste' jobs
NASA Goddard Was In The Earthquake Zone
A Puzzling Collapse Of Earth's Upper Atmosphere
Britain unveils Google Earth map showing temperature rises
GOES Brings Hurricane Alley Live To The Wireless
Experts fear long oil effect on marine life, food chain
Hope peeks out over oil-weary Gulf Coast
$4 million in fines for polluting company
Greenpeace slams 'destruction' of the Spanish coast
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal 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 SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement|