NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header




The Ionosphere Sounding Satellite was developed as part of Japan's contribution to the International Magnetospheric Study (IMS). Its objectives were to accumulate data for study of the topside ionosphere and to survey radio noise at four frequencies, from both earth and cosmic sources. It was planned to prepare worldwide maps of f2 critical frequency from the ionosphere sounding data. The ISS was a small observatory with four experiments on board. The spacecraft, a right cylinder 82-cm long and 93.5-cm in diameter, was spin stabilized at about 10 rpm with the spin axis normal to the ecliptic plane. Two pairs of crossed dipole antennas extended from the central part of the satellite and lay perpendicular to the spin axis. These antennas, 36.8- and 11.4-m long, were unfurled in orbit and were shared by ionospheric sounding and radio noise experiments. A spherical retarding potential trap sensor was mounted on a boom perpendicular to the spin axis. A magnetic attitude sensor was mounted on a similar boom on the opposite side of the spacecraft. The remaining experiment involved a Bennett-type mass spectrometer with two sensors flush mounted on opposite ends of the spacecraft. Spacecraft attitude was determined by means of a magnetometer, a solar sensor, and an earth horizon sensor. Small telemetry and command antennas extended from the spacecraft. The spacecraft was powered from a battery-solar-cell system with solar cells covering most of the cylindrical surface. One tape recorder on board permitted spacecraft operation in either a recorded (for up to 112 min) or real-time mode. Readout and real-time operation were planned to be from Kagoshima, Japan, and Soywa station, Antarctica.

Alternate Names

  • 08709
  • Ionosphere Sounding Sat
  • JISS
  • ISS1

Facts in Brief

Launch Date: 1976-02-29
Launch Vehicle: Nu
Launch Site: Tanegashima, Japan
Mass: 135 kg

Funding Agencies

  • Radio Research Lab (Japan)
  • National Space Development Agency (NASDA) (Japan)


  • Space Physics

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Yoshiharu OgataProject ManagerRadio Research Laboratory
Dr. Kazuhiko TaoProject ScientistRadio Research Laboratory
[] NASA Logo -