December 13

NASA's Odyssey spacecraft is busy at work circling Mars. One of the probe's investigations, the Martian Radiation Environment Experiment (MARIE) show that the radiation dose equivalent at Mars is two to three times greater than that aboard the International Space Station (ISS).

The differences between Mars and the ISS are primarily due to the magnetic field surrounding the Earth, which provides considerable shielding to astronauts in orbit. Mars lacks a strong magnetic field and is therefore more exposed to the harshest elements of space radiation.

This week at the annual meeting of the American Geophysical Union in San Francisco, new radiation and weather data gleaned by Odyssey is being presented.

"The Martian Radiation Environment Experiment has observed very different space weather near Mars than has been seen during the same period by satellites near Earth," said Cary Zeitlin, principal investigator for

that experiment at the National Space Biomedical Research Institute in Houston, Texas.

"Variations in space weather are caused by solar activity, including solar flares. To help us understand these events, we compare data from Odyssey to data from similar instruments in orbit around Earth. The recent observations are particularly exciting because Earth and Mars have been on opposite sides of the Sun," Zeitlin said.

-- Leonard David

December 12

Nothing to Hear from NEAR

Word has it that not a peep has been heard from the Shoemaker Near Earth Asteroid Rendezvous (NEAR) spacecraft from its resting spot on asteroid Eros.

An attempt to hear from Shoemaker NEAR was undertaken by NASA's Deep Space Network (DSN), from late Tuesday until early Wednesday morning. At first, engineers were in a listening mode. That was followed by sending commands to the spacecraft's computers to trigger the probe's transmitter for data, but to no response.

Chances were slim to begin with, but engineers wanted to see if the plucky probe had some electronic staying power. Knowing how robust the spacecraft's electronics, instruments, and subsystems were is an important data point, specific to what temperatures and temperature swings such equipment can tolerate.

As example, since landing on the space rock in February 2001, the craft experienced temperatures that plunged to as low as -274 degrees Fahrenheit, said Helen Worth, a spokeswoman for the Applied Physics Laboratory (APL) in Laurel, Maryland. APL built the highly successful NEAR spacecraft for NASA.

"The reasons we tried now, twenty-two months after landing," Worth said, "is that Eros is now less than half the distance from Earth than it was when we landed on the asteroid. So even weak signals had a better chance of being picked up. Also NEAR's solar panels had been in the Sun for the last three months, so power would again be available."

Attention now turns to the lost-to-space Comet Nucleus Tour (CONTOUR) probe. After its onboard rocket motor fired last August, the probe fell silent. Attempts to make contact with CONTOUR are set for next week.

-- Leonard David

December 11

Missile Defense Test Failure Reported

The U.S. Missile Defense Agency (MDA) announced today an unsuccessful intercept of a long-range ballistic missile target over the central Pacific Ocean.

The test shot went awry when the exoatmospheric kill vehicle (EKV) interceptor and the booster rocket failed to separate, preventing the EKV from engaging the target warhead in space.

The test involved a modified Minuteman II intercontinental ballistic missile (ICBM) carrying the target warhead launched from Vandenberg Air Force Base, California. The booster rocket carrying the EKV was launched approximately 20 minutes later from Kwajalein Atoll in the Republic of the Marshall Islands.

This test was conducted in support of research and development efforts for the Ground-based Midcourse Defense (GMD) program.

Beginning next spring, two new booster designs for hurling EKVs on future intercept flights are to undergo flight tests. The GMD program in all future intercept tests starting late 2003 will use one or both of the new boosters, the MDA stated in a press release.

This was the eighth intercept test of the GMD research and development program.

The score card to date: The first test on Oct. 3, 1999, resulted in the successful intercept of a ballistic missile target. The second test took place on Jan. 19, 2000, and did not achieve an intercept due to a clogged cooling pipe on the EKV, but did successfully test the integrated system of elements. The third test, on July 8, 2000, did not result in an intercept due an unsuccessful separation of the EKV and the booster rocket. The fourth test, on July 14, 2001, achieved a successful intercept of a ballistic missile target, as did tests on Dec. 3, 2001, and March 15, 2002. The successful test on Oct. 14, 2002 included the use of a ship-based SPY-1 radar for the first time to track a long-range target missile.

-- Leonard David

Icebergs - Off the Shelf Warning

NASA's Terra satellite has been monitoring the Ross Ice Shelf in Antarctica. Being observed is Mother Nature's equivalent of "chips off the old block". However, what is unusual is the size of the icebergs breaking free and floating slowly through the Ross Sea.

Called "calving", the huge icebergs are formed by a natural process. Ice shelves are created when slow moving glaciers on land flow into the sea. The stiff ice stretches out on the sea as a thick sheet. The faster ice is fed to the shelves, the larger they become. The ice shelf gradually grows thinner farther from shore until cracks within the ice and tidal forces succeed in breaking off pieces, creating icebergs.

Some of these icebergs over the years have made their way out into the Pacific Ocean to melt, others continue to shift and float slowly through the Ross Sea.

The Terra spacecraft captured in a November 17 image three icebergs. Two of the giant ice slabs are identified as B-15A and C-16, both of which could become dislodged as the weather warms.

On one hand, experts point out, the calving of these icebergs does not cause the seas to rise since the ice shelf already floats on the sea.

Yet these giant mountains of ice are troublemakers. Scientists are concerned about the overall stability of the Ross Ice Shelf and disintegration rates.

There is evidence to suggest that ice shelves act as a brake for the glaciers that pour into them. Without the Ross Ice Shelf in place, the glaciers that feed it may begin pumping ice into the sea at a faster rate, which could raise sea levels.

Continued satellite observations of the Ross Ice Shelf will track the movements of the loose icebergs as summer approaches in the Antarctic.

-- Leonard David

December 10

European Satellite Plunges Into Ocean

MOSCOW (AP) -- The world's largest communications satellite was sent plunging into the Pacific Ocean Tuesday two weeks after a Russian booster rocket failed to put it into the correct orbit, Russia's space forces said.

European mission control used the Astra-1K's engines to push it back into the earth's atmosphere and plunge it into the southern Pacific Ocean, said space forces spokesman Vyacheslav Davidyenko.

The French-made Astra-1K was rendered useless following its Nov. 26 launch on a Russian proton rocket, when a Russian-made booster unit failed to push the satellite into its intended orbit.

Its owners later established partial control over the satellite but said it would never be able to fulfill its main mission of handling signals for radio, television, mobile telephones and the Internet.

The failure marked another setback for Russia's satellite-launching program, which Moscow sees as a potential cash cow for its depressed space industry. It followed the Oct. 15 explosion of a Russian Soyuz-U rocket, also carrying a satellite, half a minute after liftoff.

The Astra-1K, manufactured by France's Allocate Space corporation for Society European Des Satellites of Luxembourg, weighed nearly six tons and was the largest communications satellite ever built.

December 9

Eclipse Photographed from ISS

Science officer Don Pettit photographed the Dec. 4 total solar eclipse from out the window of the International Space Station.

The photo shows a broad dark shadow, cast by the Moon, along the horizon of Earth. The eclipse was caused by the Moon lining up perfectly between the Sun and Earth.

The eclipse crossed Angola, Zambia, Zimbabwe, South Africa and Mozambique before it headed across the Indian Ocean toward southern Australia.

The shadow was racing across the Indian Ocean at the time this picture was made.

The Mars Society's Mars Desert Research Station in southern Utah is adding on an astronomical observatory.

Celestron -- a major telescope-making firm -- and an anonymous donor are sponsoring the observatory. The initial sky-watching gear to be housed at the site involves Celestron's high-quality computerized Nexstar 11 GPS telescope.

Construction of the Mars Society Desert Observatory is slated to begin later this month. "We anticipate that first light will be seen by the observatory by Christmas, with regular operations beginning shortly after the New Year," said Robert Zubrin, President of the Mars Society.

Zubrin told SPACE.com that, once up and running, the Mars Society Desert Observatory will be available on many nights for students, amateurs, and professional astronomers around the country to control via communication to the crew over the Internet. Eventually, direct Internet control of the observatory from remote sites will be implemented.

The telescope addition to the Mars Desert Research Station provides both recreational and scientific purposes for teams living and working at the simulated Mars habitat, Zubrin said.

Dark skies are promised at the Utah site, some 3.5 hours south of Salt Lake City.

Observing time will be publicly available starting in January. Schools, professional astronomers, or amateur astronomy groups wishing to obtain observing time should send their requests by email to astronomy@marssociety.org.

-- Leonard David

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