PRIVATE stylefile:c:!temp!~pr00000b2c0001001ffb91005.STY PHOENIX — Now that NASA has settled on Lockheed Martin to build the Orion spacecraft that will ferry astronauts back to the Moon next decade, agency officials are mulling a new fleet of vehicles to monitor potentially hazardous space storms that could turn such a mission into disaster.

The Solar Sentinels mission, only in an early discussion phase, would provide important data on heavy doses of solar radiation that can threaten astronauts and the electronic components of their spacecraft.

An astronaut on a spacewalk could become very sick, or even be killed, by radiation from a large solar flare, scientists say. Advance warning of such storms will be crucial to anyone on the Moon or Mars, enabling them to take cover in time.

A solar storm observed in 1859 and another in 1972 — the latter sandwiched between two Apollo missions — both could have been harmful or even deadly, according to a NASA statement issued Sept. 1.

Solar activity waxes and wanes in a roughly 11-year cycle. Right now the sun is in a quiet period, but solar cycle 24 is just beginning and will peak between 2010 and 2012.

“NASA astronauts are scheduled to return to the Moon around 2020,” Robert Lin, a solar physicist at the University of California, Berkeley, said in the NASA statement. “We’ve got only one solar maximum left to learn what we need to know” to ensure the safety of astronaut crews, he said.

Lin led a NASA commission that in 2004 began looking into the potential need for Solar Sentinels. Additional eyes in space are indeed needed, the group concludes in a new report. The report, “Solar Sentinals: Report of the Science and Technology Definition Team,” was released in August.

The NASA-European Space Agency Solar and Heliospheric Observatory spacecraft already watches radiation storms lifting off the sun, and the soon-to-launch Solar Terrestrial Relations Observatory, or Stereo, mission will provide a better view in 3-D.

But some scientists say more study and observations are needed to learn about the radiation threats to future explorers, who would be in space for months and venture beyond the relative protection offered by Earth’s magnetic field to crews aboard the international space station.

One glaring hole is the far side of the sun, where a solar storm can head out undetected toward Mars during certain portions of that planet’s orbit — such as when Mars and Earth are on opposite sides of their parent star.

Solar Sentinels is a proposed architecture of spacecraft that would consist of three main components representing different vantage points for viewing the sun:

● Inner Heliospheric Sentinels, consisting of four identical probes stationed inside the orbits of Venus and Mercury to sample energetic solar particles close to the sun.

● Near-Earth Sentinel, a probe that would observe the sun’s atmosphere from Earth orbit.

● Far-side Sentinel , a probe to watch the far side of the sun.

The spacecraft would use existing technology to make them relatively easy to build quickly. NASA’s Science Mission Directorate “is considering the Sentinels recommendations,” the agency said in its Sept. 1 statement.

“NASA needs reliable forecasts of space weather,” David Hathaway, a solar physicist at NASA’s Marshall Space Flight Center, Huntsville, Ala., said in the NASA statement. “The problem is, scientists are still learning to make these forecasts. It’s often said that space weather forecasting is 50 years behind Earth-weather forecasting. We need to catch up.”