Spaceflight Now: Breaking News

Space shuttles that repair technical glitches on the fly
Posted: January 7, 2001

Ever stop and think about the millions of dollars spent on fancy space equipment that breaks down once it becomes airborne? If you are millions of miles away orbiting the Earth, there's no repairman available to fix the problem.

Researchers at the University of Michigan College of Engineering think they may have the answer: machines that are smart enough to learn from experience, detect problems, and fix themselves.

A view of Atlantis docked to the international space station. Photo: NASA
Atlantis docked at the International Space Station in September, carrying MACE II, an on-orbit demonstration of self-reliant, adaptive-control technologies, which is the first scientific experiment aboard the space station. This week, MACE II begins its mission: to detect problems with the spacecraft's hardware and onboard technologies and correct those problems as they arise.

"This new technology will allow the space station and other space systems to operate as if they had a human operator, taking note of any glitches and fixing those problems on the fly," said Prof. David Hyland, chair of U-M's Department of Aerospace Engineering. Hyland developed the adaptive-control technology used in the MACE II project. "Problems can be fixed on the spot, so unexpected hardware failures won't threaten the life of a space mission," he said. "The assistance of ground control will only be required to perform tasks at the very highest level."

This technology should create significant cost savings for future space missions because it reduces the need for an extensive ground control staff to track and repair errors that occur in the hardware and onboard technologies.

"Building spacecraft that are more autonomous and reducing the human factor now required for spacecraft management will inherently result in lower costs and permit more flexible and reliable missions," said Rory Ninneman of the Air Force Research Laboratory's (AFRL) Space Vehicles Directorate. The AFRL is leading the first science team on the MACE II project.

MACE II relies on algorithms that enable it to adapt to changing conditions and correct problems without using a ground controller to exchange messages with the space shuttle. This technology, known as frequency domain expert control, is an advance beyond MACE I, which was able to test and fix gained controls but unable to adapt to unforeseen changes or to detect faults and failures in the hardware and technology.

"Since communications in space aren't instantaneous, we wanted to develop a technology that would eliminate the need for directions from ground control," said Hyland. "The improvements made in MACE II accomplish that goal and allow us to fix problems quickly without human intervention."

Experimental testing of MACE II will begin this week now that astronauts have attended to their many space station readiness and check-out tasks. A variety of tests will be performed using the MACE hardware which, originally developed by the Massachusetts Institute of Technolog (MIT), is a scaled model of a large space platform containing precision- pointing antennas and control actuators.

"Although we conducted several experiments in similar conditions on the ground, we are excited to see how MACE II will perform in space," Hyland said. "There are subtle change from one "g" to zero "g" -- such as the rattling of the structure's joints -- so we will test the algorithms that we have written to make sure everything works once it's up in space."

After the experiments are completed and algorithms for the technology are finalized, researchers hope to use MACE II in future space missions conducted by NASA and the U. S. Air Force.

There are two science teams involved in the MACE II project. The first science team is led by the AFRL and includes the U-M, Virginia Polytechnic Institute and State University, Melbourne Controls Group, Payload Systems, Inc., Planning Systems, Inc., and Sheet Dynamics Ltd. The second team is led by MIT.

The project was funded by a Small Business Innovative Research (SBIR) contract, an Educational Partnership Agreement, and a Cooperative Research and Development Agreement.

The U-M College of Engineering is ranked among the nation's top five engineering schools according to a recent U. S. News and World Report study. The College's graduate programs are ranked number four, and its undergraduate programs are ranked fifth. The aerospace engineering graduate program are ranked fourth in the nation and its undergraduate program is ranked second.