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 appreciate
the tremendous support that NASA and other government agencies have
given us in this effort," said Paul Sasaki, vice president and general
manager 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.
