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The Student Nitric Oxide Explorer (SNOE) project was the first satellite to be launched in NASA's Student Explorer Demonstration Initiative (STEDI) program. STEDI, managed for NASA by USRA, is a pilot program to demonstrate that high-quality space science can be carried out with small, low-cost (<$4.4 million) free-flying satellites on a time scale of two years from go-ahead to launch. The scientific objectives of the Student Nitric Oxide Explorer were a detailed study of variations in nitric oxide (NO) in the Earth thermosphere. NO is an important minor constituent that strongly affects the ion composition of the ionosphere and the thermal structure of the thermosphere. Specific objectives were to: (1) determine how variations in the solar soft X-radiation produce changes in the density of nitric oxide in the lower thermosphere; and, (2) determine how auroral activity produces increased nitric oxide in the polar regions.

The spacecraft was a compact hexagonal structure, approximately 0.9 m high and 1 m across it widest dimension, weighing a maximum of 100 kg. It was launched into a sun-synchronous circular orbit at 530-580 km altitude and 97.7 degrees inclination. It span at 5 rpm with the spin axis normal to the orbit plane and carried three instruments: an ultraviolet spectrometer to measure nitric oxide altitude profiles, a two-channel auroral photometer to measure auroral emissions beneath the spacecraft, and a five-channel solar soft X-ray photometer. SNOE also carried a GPS receiver for accurate orbit and attitude determination.

The SNOE spacecraft and its instrument complement were designed, built, and operated entirely at the Laboratory for Atmospheric and Space Physics (LASP) of the University of Colorado at Boulder.

SNOE re-entered the atmosphere on 2003-12-13 at 09:34Z +/- 6 minutes, descending over 2.9 deg S, 273.8 deg E, on orbit 32248, after 5 years and 290 days.

Alternate Names

  • 25233
  • Explorer 72
  • STEDI-2
  • Student Nitric Oxide Explorer

Facts in Brief

Launch Date: 1998-02-26
Launch Vehicle: Pegasus XL
Launch Site: Vandenberg AFB, United States
Mass: 120 kg
Nominal Power: 37 W

Funding Agency

  • NASA-Office of Space Science (United States)


  • Space Physics
  • Solar Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. Dieter K. Bilitza



NameRoleOriginal AffiliationE-mail
Dr. Charles A. BarthMission Principal InvestigatorUniversity of
Dr. Scott M. BaileyDeputy Mission Principal InvestigatorUniversity of

Other SNOE Data/Information at NSSDCA

SNOE data

Other Sources of SNOE Data/Information

SNOE Project

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