Solar flares could force shuttle crew to take cover on space station

August 03, 2005|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

Space weather forecasters are watching the development of a large spot on the sun - a region on the solar surface with a potential to hurl dangerous solar particles toward the crews of the shuttle Discovery and the International Space Station.

They say the sunspot has been active in recent days, and new eruptions are possible.

Some would pose no risk. But a blast of high-energy protons could force the two crews to seek shelter in one of the space station's protected Russian modules, solar scientists say.

That has happened to shuttle and station crews several times in the past, most recently in 2003.

This time, at least so far, "we haven't had to adjust any of our operations," said NASA spokesman Allard Beutel. "If there is a need, we have space weather experts, people who are a part of mission control, that monitor these kinds of activities. ... That's their job."

One of those experts is Francis A. Cucinotta, radiation health officer for the astronauts. He discounted the risk from the new sunspot. "It's not that unusual," he said. "Historically, we never see a large event at this part of the [11-year] solar cycle. You might see an event of just low-energy protons that don't penetrate [the spacecraft]."

So the "radiation room" at NASA's Johnson Space Center in Houston has not been put on call, he said. "It's just normal operations."

Others are watching the sprawling sunspot 792, as it has been designated, including the federal Space Environment Center in Boulder, Colo.

"Yeah, there's quite a bit of eyeballing this right now. ... It could do something in the next few days that would have folks talking about it," said Sgt. Rick Jacobsen, a liaison to the center for the Air Force Weather Agency.

So far, he said, sunspot 792 hasn't produced "extremely high energy levels. ... But the potential for that exists."

Last week, while it was on the far side of the sun, the region generated several coronal mass ejections - huge blasts of billions of tons of solar matter. "They were pretty impressive," Jacobsen said.

On Saturday, the sunspot generated a powerful "X-class" flare. "X flares are pretty uncommon," Jacobsen added. "When you get to the X-level, you're talking about fairly significant energy levels being spewed into space."

Even aimed mostly away from the Earth, Saturday's flare produced increased levels of solar protons, a potential hazard to astronauts. Now the spot faces the Earth, so any eruptions would be aimed more directly at us.

Solar flares are surface eruptions of magnetic energy that heat the solar atmosphere to tens of millions of degrees and release huge amounts of electromagnetic energy. The radiation can reach the Earth in minutes - the electrons and protons in a few hours.

Living things have been safe from this solar radiation for eons because the Earth's magnetic field traps most if it and provides a shield, as does the atmosphere.

"But if you're outside the Earth's protective cocoon, in orbit around the Earth a couple of hundred miles up as the astronauts are ... then you are liable to be zapped by solar flares or particles in the coronal mass ejection in a more significant way," said Jay M. Pasachoff, a professor of astronomy at Williams College, in Williamstown, Mass.

Cucinotta said astronauts aboard shuttles or the space station are sheltered by the Earth's magnetic field during most of their orbits. And spacewalks such as the one scheduled for this morning are timed for the safest intervals.

"It's completely different when you go outside Earth's magnetic field," he said, especially on flights to the moon.

An Apollo crew that walked on the moon in 1972 narrowly missed a potentially lethal dose of radiation from a solar storm that struck soon after the crew left.

Flight surgeons worry most about high-energy solar protons, which can penetrate deep into the body. Severe exposure can cause radiation sickness, increased cancer risks or death.

Mission controllers closely watch events on the sun.

If a major flare does threaten, Beutel said, "they tell crews to take shelter in the space station's heavily shielded Russian service module, which can accommodate both station and shuttle crews until the danger has passed.

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