Spacewalkers restore some power to Mir.

In another installment of the world's longest-running space drama, cosmonaut Anatoly Solovyev and astronaut Mike Foale took a 6-hour walk outside Mir late last week, realigning two solar arrays on the beleaguered Russian space station. The new orientation enables the arrays to capture more sunlight and convert it into electricity for the power-starved craft.

During the remainder of their time outside Mir, however, Foale and Solovyev were unable to locate holes or tears in the craft's Spektr module, which suffered heavy damage when a resupply vehicle rammed into it on June 25 (SN: 7/5/97, p. 6).

One of a string of mishaps that has beset Mir since February, the June collision was a potentially life-threatening event that bent solar arrays and crumpled radiators attached to Spektr and punctured the module's skin. The entire craft lost pressure until the crew managed to sea] off the module, a maneuver that severed electric cables from the arrays and halved the amount of power available to the craft. On Aug. 22, Solovyev and Pavel Vinogradov crawled through Spektr's hatch and reconnected the cables, restoring about 25 percent of the lost power.

The Sept. 6 realignment of two of the three solar arrays still working on Spektr recouped another 15 percent of the power, estimates James Van Laak, deputy director of the Mir-space shuttle program at NASA's Johnson Space Center in Houston. A day later, that success was tempered by another, albeit temporary, malfunction. For the third time since mid-July, Mir's main computer shut down, causing the craft to disconnect its automatic navigation system and go into free drift, a mode in which the arrays can gather sunlight only intermittently.

By Sept. 8, the crew had replaced a central processing unit in the computer and solved the problem, but the malfunction prompted once again questions that have been raised repeatedly all summer: Is it time for Mir to retire or at least for NASA to curtail its involvement with the 11-year-old craft?

"At what point do you leave a marriage?" asks John M. Logsdon, a space policy analyst at George Washington University in Washington, D.C. "Nothing has happened in the last month that significantly diminishes my belief that it's worth moving forward with a very prudent and careful recognition of all the problems."

NASA has taken crew and supplies to Mir since 1995, in part to gain experience the agency predicts will prove invaluable aboard the international space station, whose construction is scheduled to begin in mid-1998. According to the current plan, a space shuttle will dock with Mir on Sept. 27, carrying repair equipment for Spektr along with astronaut David Wolf, who will replace Foale for a 4-month stay.

"The bottom line is very simple," says Charles P. Vick, an analyst at the Federation of American Scientists in Washington, D.C. "We've got to learn this technology before the international space station or before we do lunar and Mars missions in the future. What if you're halfway to Mars and you have a [puncture]--what are you going to do then? You're going to have to deal with it right then and there, and it's better to learn it now than later."

Says Marcia S. Smith of the Congressional Research Service in Washington, D.C., "If they have to keep powering down because a computer blows up ... obviously that further reduces the science yield, so you end up justifying the astronaut's presence on Mir really on the basis of operational experience and these intangibles of building better relationships with the Russians and living up to our commitments.

"It's not clear to me what the direct relationship will be between [the experience] an astronaut gets on Mir versus the international space station." Smith notes that Russia plans to contribute a core module resembling that of Mir, "but the rest of the international space station is based on very different technology."