NRL PL170B

Re-entered 20 Sep 1989

NRL PL170B (NORAD 4958, COSPAR 1971-012D) was a US satellite that re-entered Earth's atmosphere on 20 Sep 1989, launched on 17 Feb 1971 on the DAPP Block 5A F-3 mission. It was operated by NRL as part of the NRL Cal programme. The spacecraft was built by NRL on the NRL 10" bus, with a mass of 1 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

1989

re-entered

years on orbit

kg mass

Lifecycle

Launched17 Feb 1971 · on the DAPP Block 5A F-3 mission

Operational17 Feb 1971 · entered service

Retired17 Feb 1971 · end of operational service

Re-entered20 Sep 1989 · atmospheric re-entry — object destroyed

Specifications

NORAD ID4958

COSPAR1971-012D

TypeSatellite

OperatorNRL

Country / StateUS

ManufacturerNRL

BusNRL 10"

Mass1 kg

ProgrammeNRL Cal

CategoryCAL

OrbitLEO (LEO/S)

Altitude760 × 831 km

Inclination98.8°

Frequently asked questions

What happened to NRL PL170B?

NRL PL170B re-entered Earth's atmosphere on 20 Sep 1989, 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 NRL PL170B re-enter the atmosphere?

NRL PL170B re-entered on 20 Sep 1989, according to Orbital Radar's historical catalogue records.

Who operated and built NRL PL170B?

NRL PL170B was operated by NRL and built by NRL (US).

Launched together

DMSP Block 5A F-3NORAD 4953 NRL PL170ARe-entered 1989 NRL PL170CRe-entered 1990

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

Browse the live satellite directory → Re-entered satellites archive → Launch record: DAPP Block 5A F-3 → What is space debris? →