Pioneer 4
Pioneer 4 on AeroVia
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Identity
- Aliases
- Pioneer 4Pioneer P-4Juno II Pioneer 4 Lunar Flyby Probe
- Name
- Pioneer 4
- Status
- completed
Details
- Astronauts
- -
- Destination
- Heliocentric orbit after a lunar flyby at approximately 60,000 km range; first U.S. spacecraft to escape Earth’s gravity and return Van Allen Belt data
- End Date
- 1959-03-06
- Outcome
- Lunar-flyby mission with a missed primary imaging objective. Pioneer 4 passed the Moon at about 60,000 km rather than the planned 32,000 km, so the imaging scanner did not function. It nevertheless returned excellent Van Allen Belt data, became the first U.S. spacecraft to reach Earth escape velocity and enter heliocentric orbit, and transmitted for 82 hours.
- Programs
- Start Date
- 1959-03-03
- Vehicle Families
Links
- Official Url
- https://science.nasa.gov/mission/pioneer-4/
Assets & Meta
- Creation Time
- August 14, 2026 at 17:41:44 UTC
- Updated Time
- September 7, 2026 at 23:13:39 UTC
Other
- Affiliations
- Space Stations
- -
- Vehicles