Posted: Fri, Jul 4 10:15 AM ET (1415 GMT)
Data collected by a NASA spacecraft as it flew past the innermost planet, Mercury, in January has confirmed that the planet is shrinking as it core cools, scientists reported Thursday. In a series of papers published in the journal Nature, scientists said that images of the planet performed by the MESSENGER spacecraft as it flew past the planet in January spotted features called lobate scarps, huge cliffs created in the planet's crust as it contracts. That contraction is caused because the planet's iron core is cooling; that core also drives a magnetic field whose existence was first discovered by the Mariner 10 spacecraft in the mid-1970s but confirmed and better analyzed by MESSENGER. Spacecraft observations also led scientists to conclude that the planet's plains were formed by volcanic activity early in its history, rather than as the result of giant impacts. An analysis of the planet's exosphere turned up evidence that the planet may have a source of water, either hidden in shadowed craters near the poles or from comet and asteroid impacts. MESSENGER will fly past the planet again in October and in 2009 before entering orbit around the planet in 2011.

Related Links:

•  SPACE.com article
•  Reuters article
•  Houston Chronicle article
•  New Scientist article
•  JHUAPL press release

Posted: Thu, Jul 3 7:45 AM ET (1145 GMT)
The possibility of a short circuit in a key instrument on NASA's Mars Phoenix Lander has led scientists to accelerate the analysis of a sample of ice-rich soil, project officials said Wednesday. Engineers are concerned about the lander's Thermal and Evolved-Gas Analyzer (TEGA), one of its key instruments, after it suffered a short circuit during operation last month. Taking a conservative approach, scientists opted to move ahead and use a soil sample thought to be rich in ice in the instrument next, in case the problem worsens and prevents future use of TEGA. The project team will be standing down Thursday through Saturday for the US Independence Day holiday, although some preprogrammed science operations will continue during the break.

Related Links:

•  Aviation Week article
•  AP article
•  Univ. of Arizona press release

Proton launches Russian military satellite
Posted: Sat, Jun 28 9:16 AM ET (1316 GMT)
A Russian Proton rocket launched a military satellite early Friday, the first Proton launch since a failure in March. The Proton K rocket lifted off...

Phoenix finds Earth-like soil
Posted: Sat, Jun 28 8:57 AM ET (1257 GMT)
The first chemical analysis of the soil at the landing site for NASA's Phoenix Mars Lander has revealed conditions not dissimilar to those of...