Focus on space debris: Envisat

Oct 11, 2012
Envisat Advanced Synthetic Aperture Radar coseismic interferogram from descending track 347, processed by JPL/Caltech ARIA project. Data acquired on 19 February and 21 March 2011, spanning the main shock of the magnitude 9 earthquake and several aftershocks that occurred in Japan on 11 March 2011 and the following days (until 21 March). One colour cycle represents 50 cm of motion in the satellite line of sight (approximately east at 41 degrees from the vertical), i.e. about 35 cm of motion on the ground. The seismicity plot is from the US Geological Survey. Credits: Based on ESA data - JPL/Caltech ARIA project (E. Fielding, Principal Scientist JPL/Caltech; S. Yun, Research Scientist JPL/Caltech; P. Agram, KISS Postdoctoral Fellow Caltech)

(Phys.org)—Space debris came into focus last week at the International Astronautical Congress in Naples, Italy. Envisat, ESA's largest Earth observation satellite, ended its mission last spring and was a subject of major interest in the Space Debris and Legal session.

was planned and designed in 1987, a time when space debris was not considered to be a serious problem and before the existence of mitigation guidelines, established by the UN in 2007 and adopted the next year by ESA for all of its projects. Only later, during the post- operational phase, did Envisat's orbit of about 780 km become a risky debris environment, particularly following the Chinese antisatellite missile test in 2007 and the collision between the and the Cosmos satellites in 2009.

Lowering Envisat to an orbit that would allow reentry within 25 years, however, was never an option because of its design and limited amount of fuel.

Even if controllers had lowered the satellite immediately after launch in 2002, there would not have been enough fuel to bring it down low enough – to around 600 km – where it could reenter within 25 years.

In 2010, part of the remaining fuel was used to lower the satellite slightly into a less crowded orbit at 768 km, while keeping enough reserve to provide for several years.

The lower orbit also ensured continuity of crucial until the next generation of satellites – the Sentinels – are fully operational in 2013.

Focus on space debris: Envisat
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard Envisat can map the atmospheric concentrations of more than 20 trace gases, including ozone, as well as the pollutants that attack it. This animation shows the ozone hole over the Antarctic during 13–20 September 2011. Credits: ESA

In April 2012, however, contact with Envisat was suddenly lost, preventing ESA from controlling the spacecraft and disrupting data provision to the international user community.

ESA is strongly committed to reducing space debris. Today, the deorbiting of missions is taken into consideration during the development of future satellites, and during the operations of current satellites when technically feasible.

Indeed, ESA decided to terminate operations of the 16-year-old ERS-2 satellite in 2011 because there was still enough fuel to lower its orbit to about 570 km, allowing it to reenter well within 25 years.

During the last years of Envisat, ESA began to investigate new technology to deorbit space debris in a controlled fashion.

The problem of debris in low orbits is of paramount importance. ESA space debris represents about 0.5% of the more than 16 000 objects catalogued by the US surveillance network.

ESA is working together with other agencies to reinforce international cooperation in monitoring and to study mitigation and remediation measures that will ensure the future of space endeavours.

During its extended operational lifetime, Envisat provided crucial Earth observation data not only to scientists, but also to many operational services, such as monitoring floods and oil spills.

Its data supported civil protection authorities in managing natural and man-made disasters.

An estimated 2500 scientific publications so far have been based on the data provided by the satellite during its ten-year life.

Explore further: Rosetta measures comet's temperature

add to favorites email to friend print save as pdf

Related Stories

Envisat still going strong after five successful years

Feb 28, 2007

Launched from Kourou in French Guiana on the night of 28 February 2002, ESA’s Envisat spacecraft marks its fifth year in space. Having orbited Earth more than 26 000 times, the world’s largest and most ...

Pioneering ERS environment satellite retires

Jul 06, 2011

After 16 years spent gathering a wealth of data that has revolutionized our understanding of Earth, ESA's veteran ERS-2 satellite is being retired. This pioneering mission has not only advanced science, but ...

The new home of Envisat

Oct 28, 2010

ESA’s Earth-observing satellite Envisat has moved to a lower orbit in order to conserve fuel and extend its life by three years, and is once again delivering invaluable data to thousands of scientists.

Space junk: Ideas for cleaning up Earth orbit

Jul 12, 2012

Space may be big — vastly, hugely, mind-bogglingly big — but the space around Earth is beginning to get cluttered with space junk. This poses a threat, not only to other satellites, space stations ...

Investigation on Envisat continues

Apr 23, 2012

(Phys.org) -- Optical, radar and laser observations of the Envisat satellite show that it is still in a stable orbit. Efforts to regain contact with the satellite have been under way since 8 April, when it ...

Recommended for you

Rosetta measures comet's temperature

59 minutes ago

(Phys.org) —ESA's Rosetta spacecraft has made its first temperature measurements of its target comet, finding that it is too hot to be covered in ice and must instead have a dark, dusty crust.

How Rosetta arrives at a comet

3 hours ago

After travelling nearly 6.4 billion kilometres through the Solar System, ESA's Rosetta is closing in on its target. But how does a spacecraft actually arrive at a comet?

Lunar occultation of Saturn

3 hours ago

On the night of Monday August 4, mainland Australia will see Saturn disappear behind the moon. It's the third time this year that the moon and Saturn will perfectly line up, as viewed from our part of the ...

SHERLOC to micro-map Mars minerals and carbon rings

5 hours ago

(Phys.org) —An ultraviolet-light instrument on the robotic arm of NASA's Mars 2020 rover will use two types of ultraviolet-light spectroscopy, plus a versatile camera, to help meet the mission's ambitious ...

NuSTAR celebrates two years of science in space

6 hours ago

(Phys.org) —NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, a premier black-hole hunter among other talents, has finished up its two-year prime mission, and will be moving onto its next phase, ...

User comments : 0