Spaceflight Now STS-100

'Mighty Mouse' computer saves the day aboard station

Posted: April 26, 2001 at 2:35 p.m. EDT

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A camera in Endeavour's payload bay shows the international space station. The Raffaello cargo module the main feature seen in this view. The Spacelab pallet is also visible on the end Canadarm2 near the shuttle's nose. Photo: Spaceflight Now/NASA TV
Flight controllers regained at least partial control of one of the international space station's critical command computers today after a computer in a different part of the station launched an emergency program called "Mighty Mouse" in a last-ditch bid to save the day.

The aptly-named program did its job, automatically turning power to the command computers off and back on again, one at a time, to force one of the machines to reboot from scratch without loading any possibly corrupted software.

That apparently did the trick and command-and-control computer No. 2 - C&C-2 - booted up normally. Flight controllers did not realize what had happened, however, until the station's crew woke up early today and used a laptop computer to check the health of the C&C system.

To the surprise - and relief - of exhausted flight controllers, Susan Helms reported C&C-2 appeared to be operating normally. The ground team then downloaded the machine's memory to look for clues as to what had gone wrong in the first place and began implementing procedures to eventually recover a second C&C machine.

At a 12:30 p.m. news briefing, station flight director John Curry said it appeared C&C-2 was healthy. But around 1:30 p.m. - just minutes after the briefing ended - station astronaut James Voss reported half the lights in the Destiny laboratory module had suddenly gone out.

A few moments later, astronaut Charlie Camarda in mission control reported "all indications appear we have good cooling, ventilation and power and the computers are OK. We still do not know why we went into (an electrical) load shed but we are checking that on the ground."

As it turned out, the lights were dimmed as a consequence of work to reconfigure the station's computer system and not because of a problem.

In the meantime, the astronauts are wrapping up work to unload an Italian cargo module docked to the station's Unity module. Astronaut Scott Parazynski, operating Endeavour's robot arm, likely will undock the module later today or early Friday and restow it in the shuttle's cargo bay for return to Earth.

The other top priority of the mission is to complete delayed tests of the station's new Canadian-built robot arm. The arm can be operated with just a single C&C computer, but flight controllers want a backup on line in case of additional problems. As a result, additional arm work is off until Friday at the earliest.

An artist's concept shows the historic "handshake" between the station and shuttle robotic arms as the Spacelab pallet is handed from Canadarm2 to Endeavour's crane. Photo: CSA
Mission managers are debating the possibility of extending Endeavour's flight one day to complete all of the crew's initial objectives. A decision is not expected before early Friday, after engineers have had more time to assess the health of the station's computer system.

Shuttle flight director Phil Engelauf said Endeavour has enough supplies, fuel and electrical power to extend its mission by up to two full days.

The Russians, meanwhile, are scheduled to launch a new Soyuz lifeboat spacecraft to the station Saturday. The ship's three-man crew, including U.S. millionaire space tourist Dennis Tito, is scheduled to dock Monday.

Engelauf said if Endeavour's flight is extended one day, the Soyuz would still be able to take off on time. The only impact would be a short turnaround for the station's on-board crew. But a two-day mission extension for the shuttle would force the Russians to delay the Soyuz launch by at least one day.

Engineers suspect a problem with the complex, inter-related software on board the station caused the computer problem that has disrupted the crew's schedule.

Even though C&C-2 appeared to be working normally, the team decided not to immediately reload various software packages that might be suspect, including the new space crane's control software, programs that operate the station's main Ku-band antenna and others, on the assumption a bug somewhere in the code triggered the initial failures.

Instead, engineers are studying the programs for signs of trouble and will reload them in an incremental fashion, after a second C&C computer is online and operational.

The Mighty Mouse software that saved the day for the station crew is loaded on computers in the Unity module. Those computers were programmed to keep tabs on the operation of the command computers in the Destiny module as a last-ditch backup.

If it ever discovered all three C&C machines were out of action, the node computer system was programmed to automatically launch a routine called Mighty Mouse. The Mighty Mouse program then would begin turning power to the C&C computers off and back on again to force one of the machines to reboot.

Flight controllers were unaware Mighty Mouse had been invoked early today because they did not have telemetry from the station until Helms, commanding through her laptop, enabled it.

So here's the chronology to this point:

1. C&C-1 drops off line Wednesday night after experiencing hard disk access problems. C&C-2 automatically takes over, switching from backup to primary mode. C&C-3 switches to standby.

2. C&C-2 operates normally for several hours and then experiences hard disk errors Wednesday morning.

3. Flight controllers send commands ordering C&C-3 to take over as the primary computer in the command set.

4. C&C-3 suffers hard disk problems and drops off line, taking the station's communications system down with it.

5. Engineers upload commands late Wednesday, shutting C&C-3 down in a bid to force C&C-2 back into action. That appears to work, but 40 minutes later C&C-2 fails again.

6. With all three computers down, the node software launches Mighty Mouse to power cycle all three C&C computers.

7. C&C-2 reboots normally and appears healthy.

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