A $5 million University of Colorado at Boulder satellite
dubbed the “Little Satellite That Did” now is expected to re-enter
the atmosphere and burn up in early December following a successful
six-year mission.

The Student Nitric Oxide Explorer, or SNOE, is carrying
instruments that have measured nitric oxide in the upper atmosphere
that affects Earth’s ozone layer, the intensity of X-rays from the
sun and ultraviolet light from Earth’s aurora. Developed at
CU-Boulder’s Laboratory for Atmospheric and Space Physics by
students, engineers and faculty, the mission has been controlled from
LASP’s CU Research Park facility 24 hours a day by students and
faculty since early 1998.

“The SNOE satellite has been determining the influence of the
sun on Earth’s upper atmosphere by measuring the amount of nitric
oxide in the atmosphere,” said Charles Barth, former LASP director
and principal investigator of SNOE. Produced when solar X-rays are
absorbed into the atmosphere, nitric oxide destroys naturally
produced ozone when injected into the stratosphere 30 to 50 miles
above Earth.

“NASA’s latest predictions indicate that SNOE will re-enter
the atmosphere on Dec. 5,” he said. “However, we are anticipating
more solar storms in the next few days that may cause it to come in
earlier. We still are studying the effects of the solar storms on
the atmosphere, so any large storms in the next several days will be
good news for our scientific studies and bad news for the lifetime of
the satellite.”

Orbiting at more than 300 miles above Earth, SNOE has helped
CU-Boulder scientists and students map the effect of global X-rays on
the atmosphere. SNOE data have shown that nitric oxide levels in the
mesosphere correlate with the 27-day cycle of solar X-rays coming
from the sun.

In addition, the researchers discovered that when charged
particles sent rocketing to Earth by solar storms slam into Earth’s
magnetic field and are injected into the polar regions, they produce
both Aurora Borealis and Aurora Australis. “The same particles that
cause the aurora also produce the nitric oxide in the upper
atmosphere,” said Barth. This helps CU researchers determine how
much energy is injected in the polar regions, he said.

Roughly 60 students from disciplines ranging from business,
film studies and computer science have participated in the on-campus
control of SNOE, said Randy Davis, LASP’s mission operations
director. LASP currently controls five satellites.

SNOE’s design and construction phase involved more than 100
students, primarily undergraduates, said Davis. SNOE was one of
three spacecraft selected for flight by the Universities Space
Research Association in 1994 as part of NASA’s Student Explorer
Demonstration Initiative. CU’s spacecraft was the first to launch.

“It is remarkable to me how successful SNOE has been,” said
Davis. “The reasons we built SNOE in-house was the opportunity of
involving more than 100 students in the project from design and
construction to satellite control and the tremendous science SNOE was
capable of doing. We have extremely competent and enthusiastic
students here.”

From 1981 to 1989, CU students and faculty controlled the
Solar Mesosphere Explorer satellite from campus, the first NASA
satellite ever entirely operated and controlled by a university.
SNOE was the second.

The three-foot-diameter, 220-pound spacecraft was launched on
a Pegasus expendable-launch vehicle built by Orbital Sciences Corp.
of Dulles, Va. The Pegasus carried the satellite to an altitude of
40,000 feet by jet aircraft and dropped into a five-second free fall.
SNOE then ignited horizontally and began ascending, placing it in a
circular orbit about 340 miles above Earth within 10 minutes.

CU students tapped into the expertise of engineers from Ball
Aerospace Corp. — which built the Solar Mesosphere Explorer
satellite — and the National Center for Atmospheric Research,
working side by side with them in all phases of the project.

The operations were supported in part by a special excellence
award from the Colorado Commission on Higher Education, said Davis.

“During the final months of SNOE’s lifetime, the students
formed a SNOE re-entry team to carefully monitor the satellite’s
performance,” said Barth. “This has been a truly unique experience
for CU-Boulder students to participate in from launch to re-entry.”

The SNOE research team expects almost all of the satellite to
burn up during re-entry, with perhaps a few small fragments falling
into the ocean.

Additional information on the SNOE project can be found on
the Web at