ESA declares end of mission for Envisat
From the European Space Agency:
PR 15 2012 – Just weeks after celebrating its tenth year in orbit, communication with the Envisat satellite was suddenly lost on 8 April. Following rigorous attempts to re-establish contact and the investigation of failure scenarios, the end of the mission is being declared.
A team of engineers has spent the last month attempting to regain control of Envisat, investigating possible reasons for the problem.
Despite continuous commands sent from a widespread network of ground stations, there has been no reaction yet from the satellite.
As there were no signs of degradation before the loss of contact, the team has been collecting other information to help understand the satellite’s condition. These include images from ground radar and the French Pleiades satellite.
With this information, the team has gradually elaborated possible failure scenarios. One is the loss of the power regulator, blocking telemetry and telecommands.
Another scenario is a short circuit, triggering a ‘safe mode’ – a special mode ensuring Envisat’s survival. A second anomaly may have occurred during the transition to safe mode, leaving the satellite in an intermediate and unknown condition.
Although chances of recovering Envisat are extremely low, the investigation team will continue attempts to re-establish contact while considering failure scenarios for the next two months.
The outstanding performance of Envisat over the last decade led many to believe that it would be active for years to come, at least until the launch of the follow-on Sentinel missions.
Last image before loss of contact
However, Envisat had already operated for double its planned lifetime, making it well overdue for retirement.
With ten sophisticated sensors, Envisat has observed and monitored Earth’s land, atmosphere, oceans and ice caps during its ten-year lifetime, delivering over a thousand terabytes of data.
An estimated 2500 scientific publications so far have been based on this information, furthering our knowledge of the planet.
During those ten years, Envisat witnessed the gradual shrinking of Arctic sea ice and the regular opening of the polar shipping routes during summer months.
Together with other satellites, it monitored the global sea-level height and regional variations, as well as global sea-surface temperatures with a precision of a few tenths of a degree.
Years of Envisat data have led to a better understanding of ocean currents and chlorophyll concentrations.
In the atmosphere, the satellite observed air pollution increase in Asia and its stability in Europe and North America, and measured carbon dioxide and methane concentrations. Envisat also monitored the Antarctica ozone hole variations.
Over land, it mapped the speed of ice streams in Antarctica and Greenland. Its images were used regularly to update the global maps of land use, including the effects of deforestation.
Using its imaging radar, Envisat mapped ground displacements triggered by earthquakes and volcanic eruptions, improving understanding of tectonics and volcanic mechanisms.
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 were used for supporting civil protection authorities in managing natural and man-made disasters.
Envisat has also contributed valuable information to the services within Europe’s Global Monitoring for Environmental Security (GMES) programme, paving the way for the next generation of satellites.
Now with the end of the mission, the launch of the upcoming GMES Sentinel satellites has become even more urgent to ensure the continuity of data to users, improve the management of the environment, understand and mitigate the effects of climate change and ensure civil security.
… whereas the lead-post story says:
“Old?”; It would indeed seem so …
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This isn’t 1950 (or even 1960 or 1970); there is more than sufficient capacity on fiber (fibre ?) running around the world, not to mention the lower latency (spell that: “propagation delay time”) mentioned by ‘Echo’ ‘Mike’ Smith above.
Geostationary satellite latency and time delay
http://www.satsig.net/latency.htm
“The Internet’s undersea world” courtesy of The Guardian (map may be a few years old):
http://image.guardian.co.uk/sys-images/Technology/Pix/pictures/2008/02/01/SeaCableHi.jpg
Modern history – Optical telephone cables
http://en.wikipedia.org/wiki/Submarine_communications_cable#Modern_history
‘Novel’ technique of ‘laying cable’ off the coast of Africa (as a means to prevent disruptions thta land-based circuits might otherwise see due to … ‘political complications’):
http://en.wikipedia.org/wiki/EASSy_(cable_system)
Dated doc on “SUBMARINE CABLE INFRASTRUCTURE” covering some data capacities circa the year 2000 with extrapolation going forward:
http://www.rand.org/content/dam/rand/pubs/monograph_reports/MR1395/MR1395.appi.pdf
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_Jim
May 10, 2012 at 12:45 pm
BZZT! Wrong answer. 10 year life is a joke despite the lefty spin of the article. BTW, 15 years in aerospace, most working on NASA satellites. The projects I worked on, other than the one that was smeared across the surface of Mars, are still working just fine. In fact, some of the stuff my dad worked on 15 years before is still working.
“Outstanding Performance” sounds like a phrase from the performance review of a sycophant.
I’m not a big fan of this kind of statement.
Setting low expectations has become the SOP of the post-modern big-spending pseudo-Scientific era. And this applies to many fields that have nothing at all to do with Science as well.
I for one have high expectations for things purchased with my tax dollars.
Friend, I still have ‘gear’ (albeit not space qualified nor operating under ‘harsh’ conditions such as space) first manufactured (fabricated, including active semiconductors/transistors) in the 1960’s … so, ten years, ten schmeeers …. normally fans (‘mechanicals’) and electrolytic (power supply) caps ‘give out’ first but as you know in space different ‘things’ can happen (you recall the dendritic tin whisker growth [1] that has taken out birds in past years like Galaxy IV satellite in 1998? I joined an employer shortly after that event in ’98 … they had *just* engaged in a major ‘all-hands on-deck’ scramble to re-orient all their earth-station antennas at the *many* terrestrial sites they hd in their large system across the contiguous-48 to a different bird in the satellite belt after that outage.)
Space, being a somewhat harsher environment than a ‘radio hut’/environmental building coupled with zero-G can do strange things not to mention the zero bar atmosphere and effects that can have on lubricants. As you should know, the ‘lifetimes’ are also negotiated figures; different parties (from the insurer, the platform contractor/integrator, individual instrument manufacturers, etc) have different interests in that ‘lifetime’ number.
Now, the capper: What has been the mean life on our GOES series of satellites? And what kind of distribution in ‘lifetimes’ have we seen across the series?
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[1] http://nepp.nasa.gov/whisker/background/index.htm
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Despite a steadfast assertion to the contrary, I’m finding multiple cites of the “5 year” lifetime in multiple technical ‘white papers’, such as here:
ENVISAT ASAR – Design & Performance with a View to the Future
by Michael Hutchinson, Michael D. Gibbons
http://ftp.rta.nato.int/public//PubFullText/RTO/MP/RTO-MP-061///MP-061-34.pdf
(bolding mine) and:
Precision Non-Conservative Force Modelling For Low Earth Orbiting Spacecraft
by Anthony John Sibthorpe
http://www-research.cege.ucl.ac.uk/gnrg/PhD/Ant_Sibthorpe_PhD.pdf
Where we find:
What then ensues are calculations (and related) which also consider the decreasing fuel load (a ‘heat sink’ locally and thermal conductor internal to the satellite) and increasing output heat-load internally that this low earth-orbit (LEO, 800 km) satellite was designed at some ‘level’ or magnitude to endure.
There is also a reference to the following for analytical purposes:
BOL: Friday March 1, 2002. At 01:07.59
EOL: Thursday March 1, 2007. At 01:08.00
the difference being the assumed 5 year lifetime …
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_Jim says:
May 10, 2012 at 3:35 pm
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Ok so what? The Europeans don’t know how to build satellites. We already knew that. The bird was designed for 5 years and it only lasted twice that? I’m sorry, but that is not impressive by US standards. Meeting expectations is NOT something worthy of praise. That people think it is, is just more indication of the destruction to our society caused by the pervasiveness of a Marxist world-view.
BTW, one of the papers was written by someone who clearly has as much knowledge of satellite design as Hanson has about atmospheric physics. He made a statement that is blatantly wrong. Big FAIL!
_Jim says:
May 10, 2012 at 2:17 pm
Space, being a somewhat harsher environment than a ‘radio hut’/environmental building coupled with zero-G can do strange things not to mention the zero bar atmosphere and effects that can have on lubricants. As you should know, the ‘lifetimes’ are also negotiated figures; different parties (from the insurer, the platform contractor/integrator, individual instrument manufacturers, etc) have different interests in that ‘lifetime’ number.
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Guess you did not get the fact that I spent 15 years of my life with the qualification of space hardware, including stuff that is now on running around on Mars. You also mentioned the Purple Plague. Hell, there was absolutely no excuse for hardware to succumb to a problem that had been well known and characterized for 30 YEARS! I know because my dad was one of the guys who was involved with characterizing it. If you want to talk about strange failure modes, talk about phosphor-glass passivisation, not some that could have been prevented with a little pit of silver. And GOES suffers, like everything else from the drive towards the mediocrity that the lefties love so much. “Cheaper, faster, better”, yay right! NASA lost all of its good engineers 20 years ago when the Democrats made it a lefty only shop. I worked on GOES 9. The stuff my company did is still working just fine. It was designed for three, used for over 10, and placed in a parking orbit while STILL functional. The main problem that it had was with parts made by major lefty donor Loral( We sell secrets to the chinese) Space Systems. My company which had one field failure 40 years (due to die NASA bought us) was driven out of business because we were not lefties.
In space, nobody can “Press F1 to continue”…
DY;
Yeah, Lefty technology is a de facto oxymoron. Unfortunately, it produces huge collateral damage when employed.
Is anyone really surprised that tropospheric temperatures would rise when there are indications that sea surface temperatures are rising? Acknowledging the problems with Levitus et al, after three decades of atmospheric warming it seems unsurprising that the oceans, with three orders of magnitude more heat capacity would lag the atmosphere in any change of trend. Yet it seems another ridiculous material property of H2O is the inability of the liquid state to absorb long wave photons much deeper than the wavelength, i.e. a few angstroms.
The bottom line, within the rather narrow confines of our understanding, is that heat exchange between the ocean and the atmosphere is pretty much a one way street, with the ocean almost always warming the atmosphere.