Featured Research

from universities, journals, and other organizations

Satellites Flying In Formation To Help Improve Understanding Of Earth

Date:
December 5, 2008
Source:
European Space Agency
Summary:
Based on the outstanding success of the first tandem mission between ERS-2 and Envisat last year, ESA has paired the two satellites together again to help improve our understanding of the planet.

Geocoded sea ice displacement map. The green areas correspond to an observed displacement of about 160 m in 28 minutes. The image brightness corresponds to the backscattering of the Envisat image.
Credit: ESA - GAMMA REMOTE SENSING

Based on the outstanding success of the first tandem mission between ERS-2 and Envisat last year, ESA has paired the two satellites together again to help improve our understanding of the planet.

ERS-2, ESA’s veteran spacecraft, and Envisat, the largest environmental satellite ever built, both carry Synthetic Aperture Radar (SAR) instruments that provide high resolution images of the Earth's surface.

By combining two or more SAR images of the same site, slight alterations that may have occurred between acquisitions can be detected. This technique, known as SAR interferometry or InSAR, has proven to be very useful for applications such as glacier monitoring, surface deformation detection and terrain mapping.

ESA engineers configured the first SAR tandem mission, which took place from September 2007 to February 2008, and the current one, which began on 23 November, to ensure that the satellites both acquire data over the same area just 28 minutes apart.

This short time separation allows for changes that occur quickly to be detected. Fast-moving glaciers, for instance, move more than 200 m per year and can move as much as 1 cm in 30 minutes. The ability to detect these small changes occurring on the ground between acquisitions is also allowing scientists to understand better and improve the quality of the SAR interferometry technique.

The current tandem mission, scheduled to run until 27 January 2009, is continuing the work of the first tandem mission with respect to measuring the velocity of fast-moving glaciers, detecting land-ice motion and developing elevation models over flat terrain.

However, based on the first mission’s proven ability to provide precise elevation information over flat regions, data from the current mission will also be used to identify natural carbon sources and sinks in Kazakh Steppe and wetlands in permafrost regions.

A challenging configuration

ESA engineers had to overcome many challenges in order to put Envisat and ERS-2 into a tandem flight configuration. For instance, in 2001 ERS-2 lost the ability to be manoeuvred in the usual way by onboard gyroscopes, navigational tools that allow mission controllers to maintain the correct position of satellites.

The operational lifetime of satellite missions is normally determined by the functioning of onboard gyroscopes. Without them, the ESA team had to work out a way of positioning the spacecraft by operating onboard sensors in a new way.

Part of their creative solution involved using a device called the Digital Earth Sensor (DES), which is designed to provide the horizon line to allow basic checks on the spacecraft’s position, and analysing Doppler frequency shifts in the signals of ERS-2’s radar instruments.

ERS-2, launched in 1995, and Envisat, launched in 2002, have exceeded the time they were intended to stay in orbit. Since they remain operational and continue to provide quality data about our planet, engineers are trying to use as little fuel as possible so as not to shorten their lifetimes.

"The strategy is to align the tandem start date with an Envisat manoeuvre. Therefore, there is no need to spend extra hydrazine for Envisat. For ERS, the manoeuvre to place it in tandem position is such that the satellite drifts back to its nominal orbit without additional manoeuvre after the tandem campaign," ESA Mission Planner Manager Sergio Vazzana said.


Story Source:

The above story is based on materials provided by European Space Agency. Note: Materials may be edited for content and length.


Cite This Page:

European Space Agency. "Satellites Flying In Formation To Help Improve Understanding Of Earth." ScienceDaily. ScienceDaily, 5 December 2008. <www.sciencedaily.com/releases/2008/12/081203133821.htm>.
European Space Agency. (2008, December 5). Satellites Flying In Formation To Help Improve Understanding Of Earth. ScienceDaily. Retrieved April 19, 2014 from www.sciencedaily.com/releases/2008/12/081203133821.htm
European Space Agency. "Satellites Flying In Formation To Help Improve Understanding Of Earth." ScienceDaily. www.sciencedaily.com/releases/2008/12/081203133821.htm (accessed April 19, 2014).

Share This



More Earth & Climate News

Saturday, April 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drought Concerns May Hurt Lake Tourism

Drought Concerns May Hurt Lake Tourism

AP (Apr. 18, 2014) Operators of recreational businesses on western reservoirs worry that ongoing drought concerns will keep boaters and other visitors from flocking to the popular summer attractions. (April 18) Video provided by AP
Powered by NewsLook.com
Man Claims He Found Loch Ness Monster With... Apple Maps?

Man Claims He Found Loch Ness Monster With... Apple Maps?

Newsy (Apr. 18, 2014) Andy Dixon showed the Daily Mail a screenshot of what he believes to be the mythical beast swimming just below the lake's surface. Video provided by Newsy
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com
Ark. Man Finds 6-Carat Diamond At State Park

Ark. Man Finds 6-Carat Diamond At State Park

Newsy (Apr. 18, 2014) An Arkansas man has found a nearly 6.2-carat diamond, which he dubbed "The Limitless Diamond," at the Crater of Diamonds State Park. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins