Weather Report from the Sun

When the first U.S. astronauts make a lunar landing in late 1968 or 1969, many of the world's telescopes will be focused on their activities. But there will be some important exceptions. In seven small observatories scattered around the world from the Manned Spacecraft Center near Houston to Carnarvon, Australia, small groups of NASA astronomers will be devoting their full attention to the sun. What they see might well determine the success or failure of the Apollo moon mission.

Eleven-Year Cycle. The astronomers will be part of a "solar patrol" established to warn astronauts against possible danger from the sun, which by 1968 or 1969 should reach a peak in its eleven-year cycle of activity. During these years, great storms will erupt on the solar surface; there will be a dramatic increase in the number of dark sunspots and bright flares. Using both optical and radio telescopes, the patrolmen will be particularly anxious to spot the flares, for they always accompany the sun's violent expulsion of swiftly moving atomic particles.

As these particles--mostly protons and electrons--approach the earth, most are caught in its magnetic field or absorbed by its atmosphere. They cause long-distance communications blackouts and set off vivid displays of northern lights, but they do no harm to humans. The moon, however, has no atmosphere or magnetic field to stop the particles; they reach its surface at velocities great enough for -the heavier protons to penetrate space suits and the thin walls of a Lunar Excursion Module (LEM). Caught on the surface of the moon, astronauts might receive a fatal dose of proton radiation before they could return to their orbiting Apollo vehicle, which will be substantial enough to withstand the most severe solar bombardment yet recorded.

One-Hour Trip. Not all solar flares are accompanied by dangerous proton outbursts, and the solar patrol will have to take care not to set off a false alarm that might unnecessarily abort a costly Apollo mission. But on the basis of past observations, the patrolmen know that if a flare is large and bright enough, if it is located close enough to a sunspot and is the source of strong radio signals over a wide range of frequencies, its appearance almost always heralds a hail of high-energy protons.

Once an ominous flare is sighted, word will have to be flashed quickly to the lunar astronauts. Speeding outward from the sun, 93 million miles away, the first deadly protons could begin hitting the moon an hour after the first flare sighting. The lethal rain would become increasingly strong, reaching a maximum about six hours later. Long before that maximum, though, if all went well, the astronauts would have blasted off in their LEM to rendezvous and found safety within the protective skin of the orbiting Apollo.

This file is automatically generated by a robot program, so reader's discretion is required.