Domain: cnes.fr
Stories and comments across the archive that link to cnes.fr.
Comments · 23
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Re:How exactly is this being tested?
Basically yes. There is a brief description of the main instrument here. There was a mode detailed description with references to many papers but I can't find it anymore.
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Re:Great work, done by Americans
Where are the Europeans? Oh, I don't know... (http://www.astrium.eads.net/, http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10008/, http://www.cnes.fr/web/CNES-en/7114-home-cnes.php)
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Re:Recent Greenland Melting
Other satellites noticed Greenland's extensive surface melt because melting snow lowers the ice sheet's albedo. However, water has the same mass as a liquid or solid, so GRACE can't tell the difference between ice and meltwater. GRACE can measure how much meltwater flows into the ocean, because in that case there would be less mass on Greenland.
Also, Ambitwistor referred to the popular monthly GRACE fields, which are available as spherical harmonics and gridded fields. In addition, CNES produces 10 day solutions, and Bonn even produces (constrained) daily solutions. But the monthly fields are by far the most widely used, because the ground track coverage is more complete during a month, and the extra data increases their signal to noise ratios.
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ESA ACES
ESA will get there first, with the Atomic Clock Ensemble in Space (ACES), intended for the ISS in 2013, which should be good to ~ 10**-16 and will include a test of relativity. I believe that this is the JPL clock, which is aiming at 10**-15 stability, and a 2015 launch. (Both are fairly low earth orbits, with the JPL clock intended for an Iridium satellite.)
So, the JPL effort is cool, and I would love to see one flown to Mars or truly deep space, but this is one case where the Europeans are in the lead.
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On a related subject...
... you might have heard about PHARAO, a caesium clock which is planned to fly on the ISS in 2013. Accuracy target is 1E-16.
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Canada and USSR way ahead in this area.
The Canadian RADARSAT-I and RADARSAT-2 satellites have better data. Resolution goes down to 3 meters if desired, and is 25 meters normally. That's much better than what NASA has. Here's Ottawa seen by RADARSAT-II. Here's Paris. They did it first, too; here's RADARSAT-I's first image from 1995. RADARSAT-I was launched from the US on a Delta booster back in 1995, but RADARSAT-II was launched from Kazakhstan on a Soyuz booster
They collect amplitude, phase, and range data, so they can do processing to get false-color images which bring out terrain features. Here's Washington after processing.
RADARSAT is a commercial service. You can order images. The base price for a custom image (taken at your request, not from the archive) is $5400CN. Wait time is a week or two. If you're in a real hurry, an additional $4,800CN rush charge gets your picture taken within about 12 hours. Archival data is much cheaper, and is available from MDA Corporation. MDA also has data from Ikonos, Quickbird, Landsat, etc. Much topo data comes from those archives already.
Unlike the NASA data, this data is good enough to easily tell land from water. Better radar systems return "first and last" returns, which, over wooded areas, return both ground height and tree height, so areas of vegetation can be detected. The Washington DC false-color image shows all this.
It doesn't take all the NASA overhead of putting people in space to do this. The private sector is doing it just fine.
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Unfortunately not enough
Kepler and Corot are the missions which have been launched and will be searching for exoplanets over the next few years. WISE and Herschel are the missions that have been launched, which are not targeted at exoplanets, but instead in the IR region. WISE tends to be focused as a total sky survey mission in the near-IR while Herschel is focused more on the mid-far IR at more specific targets.
Combined they potentially give use the ability to begin the search for Matrioshka Brains. IMO, one of the primary problems with astronomy and astrophysics is that the physicists (and most physics based research activities) start with the assumption that the "Universe is dead". But what if thats not true? What if it is in fact quite "alive"? This makes things horribly more complex for the physicists and astronomers because "life", esp. advanced intelligent life, can stretch the boundaries of what is determined by the laws of physics. Even more difficult -- for a complete "Theory of Everything" it probably means the physicists and astronomers are going to have to enter into serious discussions with the biologists and sociologists (to determine the characteristics that advanced civilizations might possess.
The Kepler and Corot missions, because they are focused on stellar photometry (brightness) can detect transients of other objects in front of stars. So they may be able to provide some limits on the abundance of various "dark objects" orbiting between our solar system and those stars (the planet searches are obviously looking for repeats, but the data, once public could be scanned for transient occultations (i.e. one time apparent occultations which indicate something between us and the star, be it a nearby asteroid or a more distant Matrioshka Brain). Freeman Dyson has suggested that the study of stellar occultations would be useful (presumably recognizing that not every stellar occultation indicates a planet around the star -- some might represent intervening objects transiting across the field of view. Know the size of the object being viewed, and one can set limits on sizes/distances of what is being viewed). (And Jupiter Brains or Matrioshka Brains clearly fall outside of the realm of classical (read acceptable to the "realm of comfortability" of most astrophysicists). [I have been to several conferences of gravitational microlensing astronomers -- this statement is made on the basis of direct experience -- they think in terms of hard data and they will only reluctantly acknowledge ideas which conflict with those in which they have been trained).
Now the WISE and Herschel missions are more interesting from the perspective that they begin to allow us to ask the fundamental question of "What is the rate at which Stars go dark?", i.e. what is the rate at which civilizations migrate from a pre-Kardashev type I level civilization (where we are now) to a Kardashev type II level civilzation (which does not require but is significantly enabled by the development of mature molecular nanotechnology [in the robust Drexler/Merkle/Freitas framework]. So the possible development rate could be measured in anything from months (which is feasible within our solar system, to decades, to centuries (solar system development has varying degrees of "difficulty")). And one measures that rate at that which a solar system goes "dark", with a slow conversion of visible light radiation (an undeveloped star) into an IR star (that being intelligently harvested) (i.e. the star effectively goes "dark"). We are just posed on this transition point ourselves, so it is not unworthy of study or discussion. Perhaps most importantly, the currently launched missions enable the setting of limits on the abundance of Advanced Extraterrestrial Civilizations. And it is useful to
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Re:Tiny effect
You've heard of humidity, right? Something about water in air? 20 Tera-anything multiplied by even a tiny absorption coefficient still adds up to an awful lot of absorption. This graph shows how bad a problem atmospheric absorption can be: water vapor alone can cause 1-10dB of absorption. That's 4 to 18 TW of power being dissipated in the atmosphere. Worst case at 100dB: only 2 kW reaches the ground.
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ORFEO Toolbox
Another possibility in the line of open source software is the orfeo toolbox
sponsored by the French Space Agency (CNES). Have a look at http://smsc.cnes.fr/PLEIADES/lien3_vm.htm or or the blog at http://blog.orfeo-toolbox.org/ -
Re:FSA?
No. The French, Italians, Dutch etc all have their own space agencies in addition to ESA. (However I have never seen the acronym FSA used for the French one: it's the CNES, the Centre National d'Etudes spatiales.)
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Re:Link seems broken
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Why do melting icebergs raise sea level?The pure water from a melting iceberg is less dense than sea water. How much less dense depends on temperature. The water from a melting iceberg will probably be around 1Celsius. Pure water at 1C is 2.5% less dense than sea water at 1C.
Imagine you could contain the pure water from a fully melted iceberg inside a sphere. In the same way an iceberg floats and sticks out of the sea, the ball of pure water would float in the sea with 2.5% of its volume sticking out above the sea surface. If you let the water out of the sphere, the 2.5% volume of pure water that was above the sea level inside the sphere will spread out across the planet's oceans, raising the global sea level.
The iceberg mentioned in the article was 40metres thick and 66 square kilometres in area, so the ice volume is 2.6 billion cubic metres. Ice is 8.3% less dense than pure water liquid , so when the iceberg melts, the volume of pure water will be 2.4 billion cubic metres and 2.5% of that is 60 million cubic metres. The world has 360 million square kilometers of ocean, so adding 60 million cubic metres of pure water will raise average global sea level by 0.17 microns (thousandths of a millimetre)!
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Hmm...
Well the english on that site is really poor and I never trust Israeli tech sites to be accurate.
According to this press release, it's a multispectral sensor in VNIR with only 12 bands. I don't know where they get "super-spectral," I've never heard that term before. The IsraCast article has an AVIRIS image with it. AVIRIS is a hyperspectral (hundreds of bands) sensor but it's not on any satellite. It flies on planes. The only impressive thing about this seems to be the spatial resolution.
And to all of you paranoid androids, yes, there are legitimate and very useful applications of multi-spectral remote sensing for agriculture and environmental monitoring. Also, a 5.3m spatial resolution is not going to impress any spies. You couldn't even make a out a house reliably with the resolution.
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Re:Look, Ma, there are two of them!
"Ya, I'd think there should be a blur in there somewhere, but aparently there isn't."
There is no blur, but there is deformation. The second picture, at left, taken from farther and "with a slower relative motion", is very visibly less large than the first one.
This deformation is due to the motion of the spacecraft while you slowly acquire its image line-after-line.
Incidentally, of this I deduce the line acquired here are vertical (ie, one vertical line is taken, then the following one)
A couple of years ago the french (earth) imaging satellite SPOT similarly managed to take a picture of another satellite (ERS-1): the details of why you get a deformation, and images (before/after correction) are given at http://spot4.cnes.fr/spot4_gb/im-ers-0.htm -
Re:Not first stereographic, but first hi-res stere
SPOT 5 is able to generate hi-res stereo pairs.
Sample movie of the Vesuvio: here -
Re:Excellent News!
The main problem with repairing hubble is the fact that ther is no longer any shuttle capable of containing it in it's hold
This is only a problem if you want to return HST safely to the ground in a Shuttle cargo hold. As you say, there is no longer a shuttle in which it will fit, because the external airlock for ISS makes the bay too short.
However, for a repair mission, HST does not have to fit in the cargo bay; it is mounted inside the bay sticking straight up out of it. -
NETLANDER mission
Curiously, there was something similar idea the Europeans had called NETLANDER, which would have landed a network of 4 geophysical stations on the surface of mars. Unfortunately, the project was cancelled in 2003.
Links:
http://smsc.cnes.fr/NETLANDER/
http://ganymede.ipgp.jussieu.fr/GB/projets/netland er/ -
Obvious questionSo if the ability to detect magnetic storms is so important, why in the world is there a single point of failure? I am a little disappointed that the article did not mention about who built it, and what it would take to replace it. The article makes it seem like once SOHO is gone, we are SOL.
After a little digging I found that SOHO was built in Europe. From the web site...
The SOHO satellite was built in Europ by an industrial consortium lead by Matra, while the scientific instruments were provided by European and American scientists and funded by their national institutions.
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Re:Two payloads lostFrom Eutelsat:-
"HOT BIRD(TM) 7, Eutelsat's new broadcast satellite readies for launch on Ariane 5 ECA
I guess they're still hoping that the bird miraciously escaped the huge engulfing fireball that even vapourised the air, it will take a while to sink in!
Eutelsat's HOT BIRD(TM) 7 broadcasting satellite is ready for launch by Arianespace in the night of December 11 to 12."
Expect a statement in the morning along the lines of "We're fucked, we've run out of transponder space for the fast growing European satellite porn market, but we're not as fucked as SES with their Astra 1K."
And what CNES have to say about their experimental Stentor communications satellite :-"12 December - The launch of "10-ton" Ariane 5 failed about 3 minutes after the liftoff.
The reasons are still unspecified.
For more informations, see the website"Translation, OMG, their fucking fault, ask them about it! French tax payers money was proudly burnt on a French rocket" -
Wrong, Frequency is not critical this time.Dragging Quantum levels in here is just a red herring or grandstanding. Of course the engergy and frequency of a photon is related by quantum levels; even the kinetic energy being converted as heat must be absorbed and dumped in quantum units, but that's irrelevant to the question at hand. The poster who said frequency was irrelevant was basically correct, there is no resonance involved; that was the key point.
(For other things like cellphones, the ratio of wavelength to body-part size could be critical to efficiency of heating, so frequency can be critical, and is so frequently.)
"FAQs About Water and Steam" (The International Association for the Properties of Water and Steam)
"Sometimes you may hear that the microwaves are interacting with a resonant frequency of the water molecule (like a radio gets tuned to a frequency), but that is actually not the case. Anything with a dipole moment will absorb microwave radiation, so microwave ovens will also heat fats and sugars, for example. "
FAQ or cache
Has link to How Microwaves works sites with more links.The wavelength of the microwaves needs to be comparable to the size of the object which then gets an induced alternating electrical field. That alternating field drives the molecules as little syncronous induction-motor rotors. Heat being just molecular kinetic energy, it is felt as, and cooks, as, any other heat source, but inside-out.
. It is because of the frequency of the microwave photon.
NO! If you check standard texts, you will find that microwave oven performance is largely insensitive to variation in frequency, and indeed may vary within the ISM band. Domestic microwave ovens are at about 2.5GHz in the Industrial Scientific and Medical (ISM) Band out of historical coincidence (existing allocation, existing equipment) only. Note that has a wavelength of 12cm, a bit long for a molecular resonance. This is very close to the 2.4G part-15 data and part-97 ham bands. The water and water-vapor absorption is quite weak, being on the flank of the 22GHz weak resonance. Any competent microwave design book, whether for data, radio-astronomy, or diathermy, will have the tables and charts. See for example,
"resonance lines of water [are] at 22 GHz and a very very strong line at 183 GHz. "
CEOS or cacheYou can see in the diagram there that absorption does decrease from 1G to 2.5G, it's nothing like a resonance, it's considered an edge of the low "window". In the 10GHz range, we consider clouds to be lenses not opaque absorbers, and that's higher up that peak's flank.
Under the terms of my ARS radio license, I know I have to abide by federal human/radio safety standards (which will prevent me from anywhere near our full authorized power on 2.4G any time soon! Just thinking about 5W on 10G with feed and dish gain is enough to worry about.). The scarier thing is those who don't know about them are supposed to too.
The Federal standard for human / radio absorption safety is available from FCC OET RF Safety Home page ; their Consumer Facts watered down version is Human Exposure To Radio Frequency Fields Federal Communications Commission
73 de radio n1vux
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There WILL be some environmental effects...A couple details about wave energy.
For one thing, a wave coming ashore doesn't simply END, it reflects some of its energy back into the ocean. When I was younger, I used to help my father with LandSat and SeaSat data (1970s satellites) and specifically plotting wave patterns in the Chesapeake Bay and the ocean around the mouth of the Bay. The view-from-space wave patterns miles around the Bay mouth, and in fact any land feature, clearly show that the wave doesn't just dissipate upon hitting the shore. This system would tend to absorb some sizable fraction of that otherwise reflected energy. That WOULD affect wave patterns for miles around.
Here's a
;sa mple image of ocean wave patterns in the Galapagos Islands - the reflection is clearly visible.Secondly, waves carry sediment. When you slow down a wave, or absorb its energy, you cause the suspended sediment to drop out ("sedimentation"). Particles drop out near where you absorb the energy, starting with the larger particles. Also, changes induced in the underwater current flow near the shore would change the erosion patterns. The practical effect of this is that the shoreline and the underwater topography around the generators would begin to change.
Many beachfront communities already deal with this phenomenon - putting up jettys and breakwaters tend to cause sand buildup or erosion in strange locations - sometimes miles away along the shore, sometimes at the breakwater. It's not completely understood yet, but what IS understood is that wave-absorbing devices cause sedimentation and erosion problems that must be addressed.
In summary, placing this system would certainly not be free of erosion, sedimentation or other environmental effects. Naturally there is also a corresponding effect on the long-term efficiency of the generator. If you build this system, you commit to large-scale dredging - or moving the generators periodically. And who knows whether that nearby beachfront condo will survive the next ten years? Not quite as "renewable" as it first sounds.
The overriding principle: Nature tends to mold itself around obstacles. If we create obstacles, we end up having to fight natural processes that want to remove them. This system would be no different.
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Its latest mission
The latest Mir mission was for its inhabitants to beat the record of days in space
This last mission was funded mostly by the European Space Agnecy.
Another big part of the fund for this last mission came from France Space Center. Btw the name of this mission was perseus (many nice photos even if the site is in french) -
Its latest mission
The latest Mir mission was for its inhabitants to beat the record of days in space
This last mission was funded mostly by the European Space Agnecy.
Another big part of the fund for this last mission came from France Space Center. Btw the name of this mission was perseus (many nice photos even if the site is in french)