Skip Navigation

EOS and Terra

Terra is the flagship of the Earth Observing System, a series of spacecraft that represent the next landmark step in NASA's role to observe Earth from the unique vantage point of space. Focused of key measurements identified by a consensus of U.S. and international scientists, Terra enables new research into the ways that Earth's lands, oceans, air, ice, and life function as a total environmental system. Terra was launched into sun-synchronous Earth orbit on December 18, 1999.

Terra carries five scientific instruments: ASTER, CERES, MISR, MODIS, and MOPITT. You can learn more about this mission at the Terra web site.

Specifications of the Terra Spacecraft

Launch date: December 1999
Orbit: 705 km altitude, sun-synchronous, so that at any given latitude it crosses directly overhead at the same time each day.
Orbit inclination: 98.3 degrees from the Equator
Orbit period: 98.88 minutes
Equator crossing: 10.30 a.m. (north to south)
Ground track repeat cycle: 16 days, i.e. every 16 days (or 233 orbits) the pattern of orbits repeats itself
Builder: Lockheed Martin