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OSO H

Re-entered 9 Jul 1974

OSO H (NORAD 5491, COSPAR 1971-083A) was a US satellite that re-entered Earth's atmosphere on 9 Jul 1974, launched on 29 Sep 1971 on the OSO H mission. It was operated by GSFC as part of the OSO programme. The spacecraft was built by BALL on the OSO bus, with a mass of 642 kg. Like most satellites in low orbits, it was gradually slowed by atmospheric drag until re-entry. Historical record from Orbital Radar's satellite archive, cross-referenced with the live satellite catalogue.

1971
launched
1974
re-entered
3
years on orbit
642
kg mass

Lifecycle

Launched29 Sep 1971 · on the OSO H mission
Operational9 Jul 1974 · entered service
Retired9 Jul 1974 · end of operational service
Re-entered9 Jul 1974 · atmospheric re-entry — object destroyed

Specifications

NORAD ID5491
COSPAR1971-083A
TypeSatellite
OperatorGSFC
Country / StateUS
ManufacturerBALL
BusOSO
Mass642 kg
ProgrammeOSO
CategoryAST
OrbitLEO (LLEO/I)
Altitude324 × 569 km
Inclination33.1°

Frequently asked questions

What happened to OSO H?

OSO H re-entered Earth's atmosphere on 9 Jul 1974, ending a mission that began with its launch in 1971. Objects in low orbits are gradually slowed by atmospheric drag until they fall back and burn up on re-entry.

When did OSO H re-enter the atmosphere?

OSO H re-entered on 9 Jul 1974, according to Orbital Radar's historical catalogue records.

Who operated and built OSO H?

OSO H was operated by GSFC and built by BALL (US).

Launched together

ERS 33Re-entered 1978
Historical record from the Orbital Radar satellite archive. Sources & methodology: data sources. Accessed 2026-09-06.