JAPAN QUAKE MAY HAVE SHORTENED EARTH DAYS, MOVED AXIS

The March 11, magnitude 9.0 earthquake in Japan may have shortened the length of each Earth day and shifted its axis. But don't worry you won't notice the difference. Using a United States Geological Survey estimate for how the fault responsible for the earthquake slipped, research scientist Richard Gross of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Applied a complex model to perform a preliminary theoretical calculation of how the Japan earthquake the fifth largest since 1900 affected Earth's rotation. His calculations indicate that by changing the distribution of Earth's mass, the Japanese earthquake should have caused Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds (a microsecond is one millionth of a second).

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DISCOVERY MAKES LAST MISSION A FLIGHT TO REMEMBER

The crew of STS-133 closed out space shuttle Discovery's roster of accomplishments with a virtually flawless 13-day flight to attach a new module to the International Space Station and help the residents there outfit the orbiting laboratory for continued research.

Commander Steve Lindsey, Pilot Eric Boe and Mission Specialists Alvin Drew, Michael Barratt, Nicole Stott and Steve Bowen lifted off aboard Discovery on Feb. 24, 2011, from NASA's Kennedy Space Center in Florida to begin the spacecraft's pursuit of the station.

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NASA'S HUBBLE RULES OUT ONE ALTERNATIVE TO DARK ENERGY

Astronomers using NASA's Hubble Space Telescope have ruled out an alternate theory on the nature of dark energy after recalculating the expansion rate of the universe to unprecedented accuracy.

The universe appears to be expanding at an increasing rate. Some believe that is because the universe is filled with a dark energy that works in the opposite way of gravity. One alternative to that hypothesis is that an enormous bubble of relatively empty space eight billion light-years across surrounds our galactic neighborhood. If we lived near the center of this void, observations of galaxies being pushed away from each other at accelerating speeds would be an illusion.

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MESSENGER POISED FOR MERCURY ORBIT INSERTION

After more than a dozen laps through the inner solar system, NASA's MESSENGER spacecraft will move into orbit around Mercury on March 17, 2011. The durable spacecraft carrying seven science instruments and fortified against the blistering environs near the sun will be the first to orbit the innermost planet.

At 8:45 p.m. EDT, MESSENGER having pointed its largest thruster very close to the direction of travel will fire that thruster for nearly 14 minutes, with other thrusters firing for an additional minute, slowing the spacecraft by 862 meters per second (1,929 mph) and consuming 31 percent of the propellant that the spacecraft carried at launch. Less than 9.5 percent of the usable propellant at the start of the mission will remain after completing the orbit insertion maneuver, but the spacecraft will still have plenty of propellant for future orbit correction maneuvers.

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THE FAR SIDE OF THE MOON AND ALL THE WAY AROUND

Because the moon is tidally locked (meaning the same side always faces Earth), it was not until 1959 that the farside was first imaged by the Soviet Luna 3 spacecraft (hence the Russian names for prominent farside features, such as Mare Moscoviense). And what a surprise  unlike the widespread maria on the nearside, basaltic volcanism was restricted to a relatively few, smaller regions on the farside, and the battered highlands crust dominated. A different world from what we saw from Earth.

Of course, the cause of the farside/nearside asymmetry is an interesting scientific question. Past studies have shown that the crust on the farside is thicker, likely making it more difficult for magmas to erupt on the surface, limiting the amount of farside mare basalts. Why is the farside crust thicker? That is still up for debate, and in fact several presentations at this week's Lunar and Planetary Science Conference attempt to answer this question.

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NASA AND OTHER SATELLITES KEEPING BUSY WITH THIS WEEK'S SEVERE WEATHER

Satellites have been busy this week covering severe weather across the U.S. Today, the GOES-13 satellite and NASA's Aqua satellite captured an image of the huge stretch of clouds associated with a huge and soggy cold front as it continues its slow march eastward. Earlier this week, NASA's Tropical Rainfall Measuring Mission satellite captured images of severe weather that generated tornadoes over Louisiana.

Today the eastern third of the U.S. is being buffered by a large storm that stretches from southeastern Minnesota east to Wisconsin and Michigan, then south through the Ohio Valley and all the way down to eastern Louisiana. That massive storm system was captured in an image by the Geostationary Operational Environmental Satellite called GOES-13.

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PROLIFIC NASA ORBITER REACHES FIVE-YEAR MARK

NASA's versatile Mars Reconnaissance Orbiter, which began orbiting Mars five years ago on March 10, has radically expanded our knowledge of the Red Planet and is now working overtime.

The mission has provided copious information about ancient environments, ice-age-scale climate cycles and present-day changes on Mars. The orbiter observes Mars' surface, subsurface and atmosphere in unprecedented detail. The spacecraft's large solar panels and dish antenna have enabled it to transmit more data to Earth 131 terabits and counting, including more than 70,000 images than all other interplanetary missions combined. Yet many things had to go well for the mission to achieve these milestones.

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