samedi 26 février 2011

Glonass-K Successfully Reached the Targeted Orbital Destination












GLONASS patch.

26.02.2011

Russia launched a new Glonass-K1 navigation satellite from Plesetsk space center atop Soyuz-2.1b with Fregat upper stage on February 26.

The first new-generation satellite Glonass-K of the GLONASS navigation system has been successfully put into the targeted orbit.

video

The Soyuz rocket which was lifted off from Plesetsk at 06:07 Moscow time successfully carried the satellite with the Fregat booster to orbit. It reached the planned orbit at 09:41 Moscow time. The satellite separated from the booster as planned.

GLONASS Russian GPS Constellation

High-tech Glonass-K satellite reached its intended orbit about four hours after blasting off on top a Soyuz-2 rocket from Russia's northern Plesetsk launchpad.

"We have established and are maintaining steady telemetry communications with the spacecraft," a spokesman for the Defence Ministry's Space Forces told the Interfax news agency.

Glonass-K satellite

"The on-board systems of the Glonass-K satellite are functioning normally," the official said.

The Glonass-K, which has a service life of 10 years, will beam five navigation signals - four in the special L1 and L2 bands and one for civilian applications in the L3 band.

Images, Video, Text, Credits: Roscosmos PAO / Россия 24.

Greetings, Orbiter.ch

jeudi 24 février 2011

Mars500 - "Marsonauts" Spacewalk Red Planet









ESA - ROSCOSMOS Mars500 Mission patch.

25.02.2011

On Feb 22, two of the so-called Marsonauts taking part in a 500-day Mars flight simulation experiment in Moscow have returned to their landing craft after spacewalking the conventional Martian surface for less than an hour to collect rock samples.

video
First Mars500 Marswalk  raw video

 The first 'Marswalk' by Diego Urbina and Alexandr Smoleevskiy on 14 February started at 13:00 Moscow time and lasted one hour and 12 minutes.

Alexander Smoleyevsky of Russia and Diego Urbina of Italy rehearsed an emergency situation, The Voice of Russia reports. Urbina stumbled over and dropped the bag with the samples.

 Mars500 complex situation

A launch module carrying three members of the Mars-500 experiment who recently “landed” on the Red Planet has successfully docked with the interplanetary expedition complex, The Voice of Russia.

Upon their return from the simulated Martian terrain, volunteers Alexander Smoleyevsky, Diego Urbina and Wang Yue will stay in quarantine for the next few days.

Fist "Marswalk"

Carried out at the Moscow Institute for Medical and Biological Problems (IMBP) and due to end by November 2011, the virtual flight includes three stages. These are: a 250-day “flight” from Earth to Mars, a 30- day “stay” on the Red Planet, and a 240-day “flight” home. On February 27, the crew will set out on the return journey.

Launched last June at the Moscow Institute of Medico-Biological Problems, the Mars 500 experiment will provide data needed to prepare a real-life interplanetary flight.

Images, Video, Text, Credits: ROSCOSMOS / ESA.

Best regards, Orbiter.ch

STS-133 Space Shuttle lifted off












NASA - STS-133 Mission patch.

24 February 2011

Space shuttle Discovery lifted off at 4:53 p.m. EST Thursday from NASA's Kennedy Space Center in Florida, with Commander Steve Lindsey leading the STS-133 crew to deliver the Permanent Multipurpose Module and Robonaut 2 to the space station.

video
STS-133 Astronauts Board Discovery

During space shuttle Discovery's final spaceflight, the STS-133 crew members will take important spare parts to the International Space Station along with the Express Logistics Carrier-4.

Space shuttle Discovery lifts off. Image

Steve Bowen replaced Tim Kopra as Mission Specialist 2 following a bicycle injury on Jan. 15 that prohibited Kopra from supporting the launch window. Bowen last flew on Atlantis in May 2010 as part of the STS-132 crew. Flying on the STS-133 mission will make Bowen the first astronaut ever to fly on consecutive missions.

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STS-133 Space Shuttle Launch

Space shuttle Discovery has reached orbit and is on its way to the International Space Station. "Good to be here," Discovery Commander Steve Lindsey radioed soon after the three main engines shut off and the external fuel tank was jettisoned. The official launch time was 4:53:24 p.m. EST.

The shuttle performed flawlessly on its final journey into orbit. Tomorrow, Commander Steve Lindsey and his crewmates will spend their first full day in space inspecting the shuttle thermal coverings. They'll also prepare for docking with the International Space Station on Flight Day 3.

Images, Videos, Text, Credits: NASA / KSC.

Cheers, Orbiter.ch

Europe’s ATV supply ship docks safely with Space Station












ESA - ATV2 Johannes Kepler Mission patch.

24 February 2011

Eight days after launch, ESA’s latest Automated Transfer Vehicle, Johannes Kepler, completed a flawless rendezvous and docking with the International Space Station at 17:08 CET (16:08 GMT) to deliver essential supplies.

The approach and docking were achieved autonomously by its own computers, closely monitored by ESA and French space agency (CNES) teams at the ATV Control Centre in Toulouse, France, as well as the astronauts on the Station.

ATV-2 just before docking with ISS

ATV's own second set of sensors and computers provided an independent check.

Although both ATV and the ISS orbit at 28 000 km/h, the relative speed during final approach remained below 7 cm/s and the accuracy within a few centimetres.

Johannes Kepler closed in on the ISS from behind in order to dock with Russia's Zvezda module.

At close range, the 20-tonne unmanned spaceship computed its position through sensors pointed at laser reflectors on the Station to determine its distance and orientation relative to its target.

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European Cargo Ship Docks to ISS

ATV’s docking probe was captured by the docking cone inside Zvezda’s aft end at 16:59 CET (15:59 GMT). The closure of hooks completed the docking sequence some nine minutes later.

"With this smooth docking, Johannes Kepler proves to be a great example of the wave of innovation 'made in Europe'. We are more ready than ever to head into an era of autonomy in space exploration," said Simonetta di Pippo, ESA's Director for Human Spaceflight.

ATV-2 closing in

"Thanks to its flexibility, we can think of a wide variety of new space vehicles. ATV could evolve into a future reentry spacecraft to support future orbital infrastructures and exploration missions, carrying people and supplies to lunar orbit," added Mrs Pippo.

"This is very important for us and for all our partners in the ISS programme since, after the withdrawal of the Space Shuttle, ATV will be the largest servicing vehicle left to support the Station and it is our responsibility to deliver a proper service."

"What is happening up there is a lot more than the combination of space agencies, the engagement of ESA Member States and the dedication and 'savoir faire' of European Industry," said Jean-Jacques Dordain, ESA's Director General.

"We are contributing to the largest international cooperation ever conducted in the field of science and technology.

"We have a lot to learn here, not only through scientific research conducted onboard, but also with the ongoing space operations, in order to meet the challenges of tomorrow.

"The succession of vehicles recently launched to the ISS gives an idea of the level of joint operations the Station generates now that it is fully operational."

ATV Johannes Kepler was launched by an Ariane 5 from Europe's Spaceport in Kourou, French Guiana, on 16 February. It will remain docked to the Station until June, serving as an additional module, providing a shirtsleeve environment for the astronauts and reboosts to move the complex to a higher altitude.

Europe’s ATV Johannes Kepler supply ship on its way to Space Station

In the coming hours, the Station crew will open the hatch and enter ATV's pressurised cargo module to unload some 1760 kg of dry cargo, including food, clothes and equipment. They will also pump 860 kg of propellant and 100 kg of oxygen into Zvezda's tanks. ATV can carry about three times as much payload as Russia's Progress cargo ships. However, most of this load on Johannes Kepler is propellant for its own thrusters for periodic Station reboosts to compensate for atmospheric drag.

If required, ATV will also provide Station attitude control or even move the outpost out of the way of potentially dangerous space debris.

ISS astronauts prepare for ATV docking

The docking of Johannes Kepler will be followed by NASA's docking of Space Shuttle Discovery, carrying the European-built Leonardo Permanent Multipurpose Module. With Europe's ATV and Leonardo, the US Shuttle, Japan's HTV-2 and two Russian Soyuz and one Progress docked simultaneously to the Station, the orbital outpost will set a new record for a manned space vehicle: it will provide more than 1000 cubic metres of pressurised volume and total more than 500 tonnes.

Related links:

International Space Station: http://www.esa.int/esaHS/iss.html

EADS Astrium: http://www.astrium.eads.net/

Arianespace: http://www.arianespace.com/index/index.asp

Images, Video, Text, Credits: ESA / S. Corvaja / NASA.

Greetings, Orbiter.ch

ESO - Planet Formation in Action?












ESO - European Southern Observatory logo.

24 February 2011

Astronomers may have found the first object clearing its path in the natal disc surrounding a young star

Artist’s impression of the disc around the young star T Cha

Using ESO’s Very Large Telescope an international team of astronomers has been able to study the short-lived disc of material around a young star that is in the early stages of making a planetary system. For the first time a smaller companion could be detected that may be the cause of the large gap found in the disc. Future observations will determine whether this companion is a planet or a brown dwarf.

The young star T Cha in the constellation of Chamaeleon

Planets form from the discs of material around young stars, but the transition from dust disc to planetary system is rapid and few objects are caught during this phase [1]. One such object is T Chamaeleontis (T Cha), a faint star in the small southern constellation of Chamaeleon that is comparable to the Sun, but very near the beginning of its life [2]. T Cha lies about 350 light-years from the Earth and is only about seven million years old. Up to now no forming planets have been found in these transitional discs, although planets in more mature discs have been seen before (eso0842, heic0821).

A Wide-field view of the sky around the young star T Cha

“Earlier studies had shown that T Cha was an excellent target for studying how planetary systems form,” notes Johan Olofsson (Max Planck Institute for  Astronomy, Heidelberg, Germany), one of the lead authors of two papers in the journal Astronomy & Astrophysics that describe the new work. “But this star is quite distant and the full power of the Very Large Telescope Interferometer (VLTI) was needed to resolve very fine details and see what is going on in the dust disc.”

A Wide-field view of the sky around the young star T Cha (annotated)

The astronomers first observed T Cha using the AMBER instrument and the VLT Interferometer (VLTI) [3]. They found that some of the disc material formed a narrow dusty ring only about 20 million kilometres from the star. Beyond this inner disc, they found a region devoid of dust with the outer part of the disc stretching out into regions beyond about 1.1 billion kilometres from the star.

Nuria Huélamo (Centro de Astrobiología, ESAC, Spain), the lead author of the second paper takes up the story: “For us the gap in the dust disc around T Cha was a smoking gun, and we asked ourselves: could we be witnessing a companion digging a gap inside its protoplanetary disc?”

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ESO - Flying around the young star T Cha (artist's impression)

However, finding a faint companion so close to a bright star is a huge challenge and the team had to use the VLT instrument NACO in a novel and powerful way, called sparse aperture masking, to reach their goal [4]. After careful analysis they found the clear signature of an object located within the gap in the dust disc, about one billion kilometres from the star — slightly further out than Jupiter is within our Solar System and close to the outer edge of the gap. This is the first detection of an object much smaller than a star within a gap in the planet-forming dust disc around a young star. The evidence suggests that the companion object cannot be a normal star [5] but it could be either a brown dwarf [6] surrounded by dust or, most excitingly, a recently formed planet.

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ESO - Zooming into the star T Cha

Huélamo concludes: “This is a remarkable joint study that combines two different state-of-the-art instruments at ESO’s Paranal Observatory. Future observations will allow us to find out more about the companion and the disc, and also understand what fuels the inner dusty disc.”

Notes:

[1] The transitional discs can be spotted because they give off less radiation at mid-infrared wavelengths. The clearing of the dust close to the star and the creation of gaps and holes can explain this missing radiation. Recently formed planets may have created these gaps, although there are also other possibilities.

[2] T Cha is a T Tauri star, a very young star that is still contracting towards the main sequence.

[3] The astronomers used the AMBER instrument (Astronomical Multi-BEam combineR) and the VLTI to combine the light from all four of the 8.2-metre VLT Unit Telescopes and create a “virtual telescope” 130 metres across.

[4] NACO (or NAOS–CONICA in full) is an adaptive optics instrument attached to ESO’s Very Large Telescope. Thanks to adaptive optics, astronomers can remove most of the blurring effect of the atmosphere and obtain very sharp images. The team used NACO in a novel way, called sparse aperture masking (SAM) to search for the companion. This is a type of interferometry that, rather than combining the light from multiple telescopes as the VLTI does, uses different parts of the mirror of a single telescope (in this case, the mirror of the VLT Unit Telescope 4). This new technique is particularly good for finding faint objects very close to bright ones. VLTI/AMBER is better suited to studying the structure of the inner disc and is less sensitive to the presence of a distant companion.

[5] The astronomers searched for the companion using NACO in two different spectral bands — at around 2.2 microns and at 3.8 microns. The companion is only seen at the longer wavelength, which means that the object is either cool, like a planet, or a dust-shrouded brown dwarf.

[6] Brown dwarfs are objects between stars and planets in size. They are not massive enough to fuse hydrogen in their cores but are larger than giant planets such as Jupiter.
More information

This research was presented in two papers: Olofsson et al. 2011, “Warm dust resolved in the cold disk around TCha with VLTI/AMBER”, and Huélamo et al. 2011, “A companion candidate in the gap of the T Cha transitional disk”, to appear in the journal Astronomy & Astrophysics.

The team is composed of J. Olofsson (Max-Planck-Institut für Astronomie [MPIA], Heidelberg, Germany), M. Benisty (MPIA), J.-C. Augereau (Institut de Planétologie et d’Astrophysique de Grenoble [IPAG], France) C. Pinte (IPAG), F. Ménard (IPAG), E. Tatulli (IPAG), J.-P. Berger (ESO, Santiago, Chile), F. Malbet (IPAG), B. Merín (Herschel Science Centre, Madrid, Spain), E. F. van Dishoeck (Leiden University, Holland), S. Lacour (Observatoire de Paris, France), K. M. Pontoppidan (California Institute of Technology, USA), J.-L. Monin (IPAG), J. M. Brown (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany), G. A. Blake (California Institute of Technology), N. Huélamo (Centro de Astrobiología, ESAC, Spain), P. Tuthill (University of Sydney, Australia), M. Ireland (University of Sydney), A. Kraus (University of Hawaii) and G. Chauvin (Université Joseph Fourier, Grenoble, France).

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and VISTA, the world’s largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

    * Research papers (Olofsson, J. et. al., Huélamo, N. et. al.):
http://www.eso.org/public/archives/releases/sciencepapers/eso1106/eso1106a.pdf
http://www.eso.org/public/archives/releases/sciencepapers/eso1106/eso1106b.pdf

    * Photos of the VLT: http://www.eso.org/public/images/archive/category/paranal/

Images, Videos, Text, Credits: ESO / L. Calçada / IAU and Sky & Telescope / Digitized Sky Survey 2. Acknowledgment: Davide De Martin / Video: ESO/L. Calçada / S. Brunier / A. Fujjii/Digitized Sky Survey 2. Music: John Dyson (from the album Moonwind). Acknowledgment: Davide De Martin.

Greetings, Orbiter.ch

Superfluid in Neutron Star's Core












NASA - Chandra X-Ray Observatory logo.

02.23.11

 
This composite image shows a beautiful X-ray and optical view of Cassiopeia A (Cas A), a supernova remnant located in our Galaxy about 11,000 light years away. These are the remains of a massive star that exploded about 330 years ago, as measured in Earth's time frame. X-rays from Chandra are shown in red, green and blue along with optical data from Hubble in gold.

At the center of the image is a neutron star, an ultra-dense star created by the supernova. Ten years of observations with Chandra have revealed a 4% decline in the temperature of this neutron star, an unexpectedly rapid cooling. Two new papers by independent research teams show that this cooling is likely caused by a neutron superfluid forming in its central regions, the first direct evidence for this bizarre state of matter in the core of a neutron star.

The inset shows an artist's impression of the neutron star at the center of Cas A. The different colored layers in the cutout region show the crust (orange), the core (red), where densities are much higher, and the part of the core where the neutrons are thought to be in a superfluid state (inner red ball). The blue rays emanating from the center of the star represent the copious numbers of neutrinos -- nearly massless, weakly interacting particles -- that are created as the core temperature falls below a critical level and a neutron superfluid is formed, a process that began about 100 years ago as observed from Earth. These neutrinos escape from the star, taking energy with them and causing the star to cool much more rapidly.

This new research has allowed the teams to place the first observational constraints on a range of properties of superfluid material in neutron stars. The critical temperature was constrained to between one half a billion to just under a billion degrees Celsius. A wide region of the neutron star is expected to be forming a neutron superfluid as observed now, and to fully explain the rapid cooling, the protons in the neutron star must have formed a superfluid even earlier after the explosion. Because they are charged particles, the protons also form a superconductor.

Using a model that has been constrained by the Chandra observations, the future behavior of the neutron star has been predicted . The rapid cooling is expected to continue for a few decades and then it should slow down.

Images, Text, Credits: X-ray: NASA/CXC/xx; Optical: NASA / STScI; Illustration: NASA / CXC / M.Weiss.

Read more / access larger images: http://chandra.harvard.edu/photo/2011/casa/

Cheers, Orbiter.ch

mardi 22 février 2011

Soyuz -2.1b/Glonass-K Prelaunch Processing Continues at Plesetsk












Glonass logo.

23.02.2011

Sunday Feb. 20 was a working day at Plesetsk, Nothern Russia. At 7 a.m., Soyuz-1.2b with Fregat upper stage and Glonass-K spacecraft was rolled out from the assemble building, and at 10 a.m. it was erected on the launch pad. Space Forces began L-3 operations. The launch is slated for Feb. 24.




Glonass-K is the first new-generation spacecraft developed by Reshetnev ISS, with increased lifetime of 10 years, which is to be included into Russian navigation system GLONASS.








Designed and produced by TsSKB-Progress, Soyuz-1.2b is also a new modification of famous Russian Soyuz rocket. The launch of Feb 24 will be the 4th for Soyuz-1.2b, the most reliable rocket in the world.




On Feb 22, experts of the Space Forces performed visual inspection of the LV, tests of the upper stage, preparations for integrated tests. Roscosmos specialists took part in the activities. The launch is slated for Feb. 24.

Images, Text, Credit: Roscosmos PAO.

Greetings, Orbiter.ch

Shenzhou 8 Mission Could Top Three Weeks










CNSA logo.

23.02.2011

The next flight of China's Shenzhou spacecraft will last somewhere between 20 and 22 days, according to German sources. The information was relayed to SpaceDaily by a communications officer at DLR, Germany's equivalent of NASA. German researchers will fly a collection of biological experiments on the mission, which is expected to launch in the second half of this year.

The Shenzhou 8 spacecraft will fly with no crew on board, and will be sent to rendezvous and dock with China's Tiangong 1 space laboratory, expected to be launched at some time before Shenzhou 8 flies. The descent module of Shenzhou 8 will return to Earth at the end of the flight, carrying the experiment package.
The duration of the mission is noteworthy. This will be the longest flight ever for a Shenzhou spacecraft in its full capacity. It also gives clues to how China will send astronauts to the Tiangong 1 laboratory, and other space laboratories to follow.

Shenzhou 7

The primary purpose of the Shenzhou 8 mission is to test rendezvous and docking procedures in space. It's also a dress rehearsal for the Shenzhou 9 mission, which is expected to carry astronauts to the Tiangong 1 laboratory in 2012. Thus, we can expect the overall mission plans to match each other fairly closely.
China has openly discussed its plans for sending astronauts to its first space laboratory for years, but has released few specific details on the missions.

One question that has preoccupied analysts is the expected duration of an expedition to Tiangong. The space laboratory is fairly small, and offers little room for astronauts to inhabit. Questions have also been raised about the logistics of such a mission.

The Tiangong laboratory and the Shenzhou spacecraft that will dock with it have fairly limited room for supplies. Issues of food, water and oxygen supplies would almost certainly rule out a long stay aboard the laboratory.

This writer, along with other analysts, has previously suggested that a crewed flight to Tiangong of roughly two weeks was likely. Some analysts suggested around three weeks. A three-week mission for Shenzhou 8 supports all these estimates, but still doesn't tell us exactly how long the Shenzhou 9 mission will last.

If Shenzhou 8 is meant to be a shakedown cruise for a crewed expedition, it will try to be thorough in its testing. This means that we can expect this to cover all of the normal requirements for a crewed mission, plus a bit more. So Shenzhou 8 is probably going a bit further with its endurance, to prove that it's spaceworthy for a long time.

This mission is probably designed to last a few days more than will be required for a crewed flight, just for good measure.

Shenzhou 7 (Artist's view)

If this is the case, then astronauts will probably stay aboard Tiangong 1 for roughly two weeks. A stay of around two and a half weeks is possible. At this stage, it is unclear how long Shenzhou 8 will fly alone at the start of its mission, while it approaches Tiangong 1. It's possible that they will copy current Russian strategies, and cruise for about two days to the laboratory.

However, China is also introducing a more powerful version of the Long March rocket to launch this mission, and may opt for a more direct trajectory. If crew consumables are scarce, it makes more sense to get to the laboratory as quickly as possible. Then again, Shenzhou 8 is doing this for the first time, and it's also a modified vehicle. There will probably be a solo "shakedown cruise" in orbit before the spacecraft is cleared to move on to the docking phase of its mission.

On a crewed flight, the time spent in transit will influence the time available on the laboratory. But we can't be sure if Shenzhou 8's cruise will match that of Shenzhou 9. So, we can probably say for sure that crewed expeditions to Tiangong 1 will last no longer than three weeks. Exactly how much time will be spent on board the laboratory is unclear. But the mission plan suggests that China is determined to get as much crew time on the laboratory as it can, given the resources available.

Images, Text, Credits: CNSA / Space Daily / Roscosmos / China Defense Mashup.

Best regards, Orbiter.ch

ESA - Bridge to PARIS: testing Earth monitoring via satnav






ESA logo with flags.

22 February 2011

Every space mission has to begin somewhere. The Zeeland motorway bridge on the Dutch coast is the starting point for PARIS: testing here has confirmed the concept behind this proposed ESA mission to perform Earth monitoring using reflected satnav signals.

As traffic zoomed past, engineers extended a double-sided antenna out from a walkway on the bridge’s edge, 17 m above the coastal waters. This antenna can pick up satnav signals from above and below it simultaneously.

Testing off the Netherlands' longest bridge

By combining the initial, overhead signal with the same signal reflected off the water – employing a process called interferometry – the extra travel time of the reflected beam could be determined, and the sea height calculated to within five centimetres. 

Signal reflections are something of a nuisance for everyday satnav users, causing false locks and positioning errors. But on a larger scale, these bounced-back beams may become a scientific resource.

Intercepted by dedicated satellites, these returning signals could build up global maps of sea-surface height and wind and wave measurement over the ocean, ice extent and thickness above icecaps and soil moisture and biomass across land.

PARIS mission, detecting reflected satnav

The Passive Reflectometry and Interferometry System (PARIS) would involve a constellation of 10 satellites, each tracking 12 to 16 satnav signals. This ocean-focused constellation would be able to detect a moving tsunami within less than half an hour.

Even ship detection would be possible: the Zeeland experiment showed deflected signals when boats passed under the bridge.

“Today, there are lots of teams worldwide looking into the use of reflected satnav signals,” explained ESA’s Manuel Martin-Neira, who invented PARIS back in 1993.

“What is particularly significant about our test campaign is that it proves experimentally for the first time that interferometry does indeed allow the correlation of original and reflected satnav beams, attaining the highest possible accuracy.

“It means, in addition, that any or all of the various signals from different countries’ systems can be employed, because we extract all the measurements we need through signal correlation.

“We are not reliant on any of the securely-coded positioning data embedded in the signals themselves.”

Two-sided antenna

Interferometry is an advanced technique typically harnessed for high-precision physics, chemistry and astronomy measurements: when beams are combined, the resulting interference pattern identifies any difference in the travel time of the two beams.

By contrast, satnav reflectometry has so far operated in the same way that standard satnav receivers work: once a signal is picked up, the receiver generates a replica signal based on public access codes stored within the receiver. It is this replica signal that is then compared to the fainter reflected beam.

The problem is that the results are constrained by accuracy limits set on open-access satnav.

PARIS for ocean altimetry

“This other method is simpler to achieve with a much more streamlined antenna,” explained Manuel. “But our testing shows it to be an order of magnitude less accurate.

“PARIS instead requires a more elaborate two-sided high-gain antenna with multiple elements. This presents satellite designers with a greater challenge, but offers a much better science return.”

video
Zeeland Bridge PARIS experiment video

The Zeeland bridge test took place last July. Having proved the concept successful, the next step is to develop spaceworthy prototypes, in preparation for a proposed PARIS demonstration mission. In parallel, airborne testing is also planned.

Images, Video, Text, Credits: ESA / IEEC (Institute of Space Studies, Barcelona, Spain).

Greetings, Orbiter.ch

lundi 21 février 2011

Dmitry Kondratiev Tells about EVA of Feb 16












ISS - Expedition 26 Mission patch.

22.02.2011

ISS cosmonaut Dmitry Kondratiev published photos of the space walk which he and his colleague Oleg Skripochka made on Feb 16, in his blog in Roscosmos web.

Dmitry describes the space walk as hard job, though interesting. Both Dmitry and Oleg had cameras, so they made a lot of photos:






The most difficult task was to open RK-21 monoblock for the experiment aimed to monitor ocean salinity, Earth surface and atmosphere.




During the operation, the cosmonauts had no foothold, due to the size of the block, which is rather unusual during EVAs.




Despite of this difficulty, Kondratiev and Skripocka completed all tasks successfully.

video
Russian EVA 28 (time lapse) [with overview]
 
Images, Video, Text, Credits: Roscosmos PAO / Dmitry Kondratiev / Youtube.

Greetings, Orbiter.ch