Repeated attempts to re-establish radio contact with NASA's Earth-orbiting Lewis spacecraft since it entered a slow spin on Aug. 26 have been unsuccessful. Due to increasing atmospheric drag, the spacecraft's orbit is deteriorating. Unless contact is regained early next week, it is expected to re-enter and burn up between Sept. 23-30, with Sept. 27 as the current most likely re-entry date, according to program officials.
"Based on our previous experience with this type of spacecraft, we expect Lewis to burn up in the atmosphere. The probability that any part of it will survive is very low, and it presents no significant threat to people on the ground," said Samuel Venneri, Chief Technologist at NASA Headquarters, Washington. "The potential loss of this mission is an obvious disappointment. However, the process of designing and building the spacecraft taught us a great deal about how to integrate cutting-edge technology into small missions and how to prepare the associated science teams, and we will apply those lessons to future projects."
Lewis was launched on Aug. 22 (Aug. 23 EDT) from Vandenberg Air Force Base, CA, aboard a Lockheed Martin Launch Vehicle (LMLV-1). Built by TRW Space & Electronics Group, Redondo Beach, CA, the 890-pound Lewis satellite is part of NASA's Small Spacecraft Technology Initiative.
"We are aggressively applying the company's resources in our ongoing attempt to recover the satellite, and we greatly appreciatethe tremendous support that NASA and other government agencies havegiven us in this effort," said Paul Sasaki, vice president and generalmanager of the TRW Civil & International Systems Division.
Initial operations and check-out of Lewis were proceeding satisfactorily until telemetry received early August 26 indicated that the spacecraft was spinning at approximately two revolutions per minute. Preliminary indications are that unbalanced thruster firings occurred on the spacecraft, inducing a spin rate that went unchecked as Lewis remained in a previously commanded safehold.
The solar arrays on Lewis were unable to generate significant power due to the spinning motion and their alignment with the Sun, and thus the spacecraft's batteries became almost fully discharged. Initial hopes that sunlight would "trickle charge "the batteries sufficiently to allow the spacecraft's transmitter and computer to be accessed were not borne out by subsequent operations.
An independent Lewis spacecraft anomaly review board, to be chaired by a non-NASA official, is being established. It is expected to report its findings approximately 60 days after re-entry.
Outfitted with advanced technology Earth-imaging instruments and subsystems intended to push the state-of-the-art in scientific and commercial remote sensing, Lewis featured remote-sensing instruments designed to split up the spectrum of light energy reflected by Earth's land surfaces into as many as 384 distinct bands. Potential commercial applications included pollutant monitoring, analysis of endangered species habitats, estimation of forest and agricultural productivity, soil resources and crop residue mapping and assessments of environmental impacts from energy pipelines.
The total cost to NASA of the Lewis mission, including its launch vehicle and one year of planned orbital operations, is $64.8 million. NASA incurred an additional cost of $6.2 million for storage and maintenance of the spacecraft during a one-year delay due to launch vehicle issues.
Lewis is part of NASA's Mission to Planet Earth enterprise, a long-term research program designed to study the Earth's land, oceans, air and life as a total system. Upcoming Mission to Planet Earth spacecraft such as the New Millennium program's Earth Orbiting-1 mission, due for launch in June 1998, should help scientists address some of the planned applications of Lewis data.
EDITOR'S NOTE: The U.S. Space Command in Colorado Springs, CO, will perform its normal orbital tracking duties as the orbit of Lewis degrades. Updated re-entry forecasts are available from its public affairs office at 719/554-6889.
Materials provided by National Aeronautics And Space Administration. Note: Content may be edited for style and length.
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