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Friday, 15 May 2009

News from Mars and around it, April, 2009

First of all, check this site-it's live video from the International Space Station. That's awesome!!!


Update: I no longer can watch the ISS live, I don't know why. Eh, well...
Today:
  1. ESA designs its smallest ever space engine to push back against sunshine
  2. GOCE launch: Mapping the Earth’s gravity as never before
  3. Report: Images from Mars lander show liquid water
  4. Mars Orbiter's Computer Reboots Successfully
  5. Mars orbiter glitch stalls Red Planet science
The most intriguing are the last two articles which tell us that both Mars Reconnaissance Orbiter and Mars Odyssey had problems?! Aliens, anyone :)

ESA designs its smallest ever space engine to push back against sunshine

March 10th, 2009

(PhysOrg.com) -- This month an ESA team is preparing to test the performance of the smallest yet most precisely controllable engine ever built for space, sensitive enough to counteract the force of incoming sunshine.

Measuring only ten centimetres across and emitting a faint blue glow as it runs, the (FEEP) engine produces an average equivalent to the force of a single falling hair. But despite its low power, FEEP's thrust range and controllability are far superior to more forceful thrusters, holding the key to future success of an ambitious ESA science mission.

"Most propulsion systems are employed to get a vehicle from A to B," explains Davide Nicolini of ESA's Scientific Projects Department, in charge of the FEEP project. "But with FEEP the aim is to maintain a in a fixed position, compensating for even the tiniest forces perturbing it to an accuracy that no other engine design can match."

Observing how objects behave when separated from all outside influences is a long-time ambition of physicists, but it is impossible to achieve within Earth's gravity field. So a next-decade mission called LISA Pathfinder will fly 1.5 million km to an area in space called Lagrange Point 1 (L1), where the Sun and Earth's gravities cancel each other out, so that the behaviour of a pair of free-floating test masses can be precisely monitored. However, to detach the experiment fully from the rest of the Universe there will still be some remaining to overcome, most notably the slight but continuous pressure of sunlight itself.

Which is where FEEP comes in. It operates on the same basic principle as other flown aboard ESA's SMART-1 Moon mission and other spacecraft: the application of an electric field serves to accelerate electrically-charged atoms (known as ions), producing thrust.

But while the thrust of other engines is measured in millinewtons, FEEP's performance is assessed in terms of micronewtons - a unit one thousand times smaller. The engine has a thrust range of 0.1 - 150 micronewtons, with a resolution capability better than 0.1 micronewtons in a time response of 190 milliseconds or better.

A total of three sets of four FEEP thrusters clustered together will be mounted on the hull of LISA (Laser Interferometer Space Antenna) Pathfinder. Operating together with a separate NASA-designed propulsion system, the FEEP thrusters should yield directional control at least two orders of magnitude more accurate than any spacecraft before it, down to a millionth of a millimetre. This month's ESTEC tests are intended to qualify the FEEP development model before the construction of the final flight hardware begins.

Nicolini says that ESA testing of the FEEP cluster assembly subsystem - developed over the last seven years under ESA contract by Italian companies Alta and Galileo Avionica and Astrium-Toulouse in France and Oerlikon in Switzerland - represents a kind of coming home for the technology: "FEEP was invented at ESTEC but the technology was put aside for a time due to its low power output, until interest in it revived for space applications that require very stable positioning. FEEP remains the sole space propulsion system entirely conceived and developed in Europe."

Once it has been proven, the FEEP technology has been earmarked for a broad range of other missions, including precision formation flying for astronomy, Earth observation and drag-free satellites for mapping variations in Earth's gravity. source

My comment:Cool. As a European lover, I love the idea of Europe-made systems. And this would be so useful for LISA. It's adorable how fundamental physics get along with sophisticated engineering. As I often say, investing in science is always beneficial for civilisation. Even when the experiment fails, the technology involved with it stays and finds thousands of uses.

GOCE launch: Mapping the Earth’s gravity as never before

March 9th, 2009

(PhysOrg.com) -- ESA is about to launch the most sophisticated of Earth Observation satellites to investigate the Earth’s gravitational field with unprecedented resolution and accuracy.

GOCE data will be crucial for obtaining accurate measurements of and sea-level change, both of which are affected by climate change. The data will help to better understand processes occurring inside the Earth which are linked to volcanoes and earthquakes.

ESA’s 1-tonne spacecraft carries a highly sensitive to measure the variations of the in three dimensions. The data collected will provide a high-resolution map of the 'geoid' (the reference surface of the planet) and of . Such a map will not only greatly improve our knowledge and understanding of the Earth’s internal structure, but will also be used to provide much better reference data for ocean and climate studies and ocean circulation. Practical mission applications will also include construction, planning & surveying as well as providing reference data on sea levels.

To make this mission possible, ESA, together with a consortium of 45 European companies led by Thales Alenia Space and the science community had to overcome some impressive technical challenges. The spacecraft had to be designed to orbit the Earth at close enough quarters to gather high-accuracy gravitational data while being able to filter out disturbances caused by the remaining traces of the atmosphere in low Earth orbit (at an altitude of only 260 km). This resulted in a slender 5-m long arrowhead shape for aerodynamics with low power ion thrusters to compensate for atmospheric drag.

GOCE is the first of a series of Earth Explorer satellites to be placed in orbit. The Earth Explorer missions have been designed by ESA to promote research on the Earth’s atmosphere, biosphere, hydrosphere, cryosphere and interior.

Two other Earth Explorer missions are also scheduled for launch in 2009: SMOS (summer) to study soil moisture and ocean salinity and CryoSat-2 (late autumn) to measure ice sheet thickness.source

My comment: You can't blame me for being impartial. But I really love GOCE, but not only because it's an European project. Most of all, because it will study gravitational anomalies, because we think we know a lot about our Planet, but I think we might be very very surprised. Just because nobody looked at something, it doesn't mean there's nothing to be learnt from it. So, I can't wait to see the data.

Report: Images from Mars lander show liquid water

March 11th, 2009

(AP) -- Did NASA's Phoenix Mars lander find evidence of liquid water before it froze to death?

Some scientists think so. In a provocative new paper, 22 members of the mission argue that seen on Phoenix's leg were from that splashed during landing.

Scientists propose that the perchlorate salts near the landing site acted as an antifreeze by lowering the freezing point of ice, causing it to melt into a salty liquid. When Phoenix landed in the arctic plains, some of that liquid splashed onto its leg, they said.

Scientists point to images taken by the lander that show some of the droplets merged with each other and grew in size, behavior that is consistent with liquid water, they said.

But other team members say the images are too fuzzy to support the extraordinary claim.

Phoenix landed near the in May and spent five months digging into the soil and ice.

It confirmed the presence of ice at its landing site and became the first robotic probe to taste it by melting it. It also discovered an abundant amount of the chemical perchlorate, a highly oxidizing , in dirt samples.

The current environment is too cold and its atmosphere too thin to support liquid water on the surface. source

My comment: Yes, but we actually we know too little about the Mars environment to be sure whether it really is too cold to support liquid water under the soil. And if you see the pictures, you might wonder... In any case, it's quite cool that we now know for sure there is water on Mars and it's accessible water. I mean we didn't know that 1-2 years ago!

Mars Orbiter's Computer Reboots Successfully

March 12th, 2009

(PhysOrg.com) -- NASA's Mars Odyssey orbiter properly followed commands today to shut down and restart, a strategy by its engineers to clear any memory flaws accumulated in more than five years since Odyssey's last reboot.

The procedure also restored Odyssey's onboard set of backup systems, called the spacecraft's "B side," allowing its use in the future when necessary.

Odyssey has been orbiting Mars since 2001 and has never switched from its primary set of components, the "A side," to the backup set, which includes an identical computer processor, navigation sensors, relay radio and other components. In March 2006, the B-side spare of a component for managing the distribution of power became inoperable. Analysis by engineers identified a possibility that rebooting Odyssey might restore that component, which proved to be a side benefit of today's procedure to refresh onboard memory.

The Odyssey team began a series of steps after the reboot to carefully return the spacecraft to full functioning over the next few days. Following that path, the science instruments will be back to studying Mars by next week.

An unexpected rise in temperature of the star camera in Odyssey's navigation system on March 9 had prompted a postponement of the rebooting originally scheduled for the next day. Engineers identified the cause as a heater circuit that was temporarily stuck "on." The circuit was turned off before today's reboot. source

My comment: I start thinking that there is something odd on Mars. Because the instruments there tend to live longer and to make weird problems. The truth is that this is the first planet we are on besides our own, so this is really a great new experiences. But still, the weird reboots of Spirit, now this heater circuit, it's like someone is playing with us.

Mars orbiter glitch stalls Red Planet science

updated 1:35 p.m. ET Feb. 26, 2009

NASA's Mars Reconnaissance Orbiter has suffered an apparent glitch that has left the spacecraft in a protective safe mode and stalled science observations as it circles the Red Planet, the space agency announced late Wednesday.

The malfunction occurred on Monday when the orbiter unexpectedly rebooted its main computer and entered safe mode, an automatic safeguard designed to protect the spacecraft from further damage when it detects a glitch.

NASA engineers are reviewing potential causes for the malfunction aboard the Mars Reconnaissance Orbiter, or MRO, in the hopes of resuming its science observations of the red planet.

The Mars orbiter's malfunction occurred Monday at about 7:25 a.m. ET, when the spacecraft was flying behind the Red Planet as seen from Earth. While MRO has suffered glitches that put it in safe mode five times since its 2005 launch, Monday's malfunction does not resemble any of those earlier glitches, NASA officials said.

An initial analysis suggests that the malfunction may have been caused by the detection of a power surge that lasted between 200 nanoseconds and 41 seconds. The power surge may have been real, or it could have been a phantom reading, mission managers said.

One theory is that the MRO spacecraft may have been hit by a cosmic ray, causing an erroneous power surge reading for about nine microseconds, more than enough time to trigger the computer reboot, mission managers said.

MRO flight engineers managed to bring about a partial revival of the spacecraft late Monday, when they boosted its communication rate from 40 data bits per second to a level some 10,000 times faster. The spacecraft's batteries are charged, and its expansive solar wings are generating electricity, mission managers said.

Launched in August 2005, the MRO spacecraft is NASA's youngest orbiter in a fleet of spacecraft circling the Red Planet. It arrived in orbit around Mars in October 2006 to begin a planned two-year mission. The spacecraft's initial $720 million mission has since been extended by two more years to 2010.

During its time at Mars, MRO has beamed home stunning vistas of the Red Planet and has tracked NASA's twin rovers Spirit and Opportunity during their exploration of the Martian surface.

The spacecraft has also used its high-resolution camera to scout for future Martian landing sites and spotted NASA's most recent probe — the Phoenix Mars Lander — as it parachuted down to a pinpoint landing on the planet's arctic plains in May 2008. source

My comment: If you're confused by the names of the Mars orbiters, you can read about them here. Now, isn't it weird that both orbiters experienced problems in the same month?I think it's weird.

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