SOLRAD 1 (GREB)
Country: United States of America
Live Position
Ground Track · Last 90 Minutes
Upcoming Passes · Over Your Location
About This Satellite
SOLRAD 1 studied how solar activity affects the ionosphere and radio communication. Launched in June 1960, it carried measurements above the atmosphere to investigate the connection between solar X-rays and radio fade-outs. Its scientific product was a record of radiation, rather than visible-light photographs of the Sun or a map of terrestrial transmitters.
A solar flare connected space measurements with radio behaviour
NRL credits SOLRAD 1 with confirming the role of solar X-ray emissions in solar-related radio fade-outs. Its historical account describes an August 6, 1960 flare lasting eighteen minutes, of which the satellite recorded six and sent the information to a NASA tracking station. Those six minutes are a partial observation, not continuous coverage of the entire event.
Later SOLRAD achievements belong to later spacecraft
The programme subsequently supported astronaut radiation monitoring, including Apollo-era work. That does not make this 1960 spacecraft the source of every later SOLRAD measurement. The mission number and observation date matter when tracing a scientific result through a long-running satellite series.
Mission reference: NRL: SOLRAD I solar-radiation measurements and historical results. Editorial review: .
SOLRAD and GRAB describe different payload roles
NRL dates the launch to June 22, 1960 and identifies a second, originally classified role: GRAB, short for Galactic Radiation and Background, collected electronic intelligence. The public solar experiment and the classified payload shared the spacecraft. They were not two independent satellites merely passing through the same orbit, nor should the solar measurements be confused with the intercepted radio signals.
Reference: NRL history timeline: June 22, 1960 SOLRAD/GRAB launch and payload identities.
Declassification changed the public history, not the orbit
The NRL timeline explains that the intelligence role was declassified decades after launch. This helps explain why historical accounts emphasize different names and purposes for the same object. A catalog identifier connects those accounts to a physical spacecraft, while the payload description tells the reader which experiment or collection activity a particular source is discussing.
Reference: NRL history timeline: public science mission and later disclosure of GRAB.
Reading this orbital snapshot
Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 567 km at perigee to 852 km at apogee, a difference of 285 km. The orbital period is about 99.0 minutes. Eccentricity 0.02008 shows why a single altitude cannot describe the whole path. In a two-body approximation, perigee speed is 1.04 times apogee speed. These are mean-element estimates, not instantaneous measurements. Distance per orbit uses an ellipse approximation.
Saved build snapshot. If a valid TLE is retrieved, this explanation and the orbit panel update together. Otherwise this dated snapshot is retained.
Ground track is not sensor coverage
An inclination of 66.69 degrees implies approximate geocentric ground-track limits of 66.7 degrees north and south. This is a prograde orbit, moving in the same general direction as Earth rotation. The plotted line marks the point beneath the object. It does not represent camera coverage, radio reception, or a guaranteed visible pass.
Accuracy and missing information
The introductory record describes the build snapshot. The orbital snapshot explanation and orbit panel share any successfully retrieved TLE; check the displayed epoch. Reentered objects retain historical data only. Mission history is not rewritten by TLE updates. TLE/SGP4 positions are predictions and can change after maneuvers or updated observations. The 14-day stale-data cutoff is a display safeguard, not an accuracy guarantee. Local passes are geometric predictions, not a visibility forecast. No verified operator or mission status means unknown, not active. Do not use this catalog for collision avoidance or operational flight decisions.
Catalog sources: CelesTrak SATCAT: NORAD 46 · GCAT: S00046 (source update 2026 Sep 4 2345:57). Supplementary metadata: SatNOGS DB, retrieved 2026-09-05T12:57:25.375Z. Page assembled 2026-09-15. GCAT phase codes describe trajectory phases, not mission health.
Learn more: TLE data · Perigee and apogee · Ground tracks · JOT (Jewawud Live Orbital Map)