Vanguard 2
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| Vanguard 2 | |
|---|---|
| Name | Vanguard 2 |
| Mission type | Earth science |
| Operator | United States Naval Research Laboratory |
| COSPAR ID | 1959-001A |
| SATCAT | 00011 |
| Mission duration | 19 days (active transmission) |
| Manufacturer | Naval Research Laboratory |
| Launch mass | 10.8 kilograms (23.8 lb) |
| Launch date | February 17, 1959, 15:55 UTC |
| Launch rocket | Vanguard SLV-4 |
| Launch site | Cape Canaveral LC-18A |
| Last contact | March 8, 1959 |
| Orbit reference | Geocentric orbit |
| Orbit regime | Medium Earth orbit |
| Orbit semimajor | 7,722.7 kilometers (4,798.6 mi) |
| Orbit eccentricity | 0.1659 |
| Orbit periapsis | 559 kilometers (347 mi) |
| Orbit apoapsis | 3,320 kilometers (2,060 mi) |
| Orbit inclination | 32.88 degrees |
| Orbit period | 125.8 minutes |
| Orbit epoch | 17 February 1959 |
Vanguard 2. It was the world's first weather satellite, designed to observe Earth's cloud cover distribution. Launched by the United States as part of the Project Vanguard program, it was a significant, though partially successful, step in the early Space Race against the Soviet Union. The satellite demonstrated the feasibility of using spacecraft for meteorological observation from orbit.
Overview
The mission was developed by the United States Naval Research Laboratory under the broader International Geophysical Year initiative. Its primary objective was to test a new method of observing global weather patterns, a concept championed by scientists like Harry Wexler of the United States Weather Bureau. The launch occurred from Cape Canaveral Air Force Station using a Vanguard launch vehicle, following the earlier, pioneering Vanguard 1 satellite. This mission represented a direct application of space technology for practical Earth science, distinct from earlier satellites focused on cosmic rays or geopolitical demonstration.
Spacecraft design
The spacecraft was a 50.8-centimeter (20.0 in) magnesium sphere, weighing 10.8 kilograms (23.8 lb). Its most critical instrument was a pair of photoelectric cell sensors, designed to scan the Earth's surface by measuring reflected sunlight. Power was supplied by mercury batteries, and it transmitted data via a 60-milliwatt radio transmitter operating at 108.03 MHz. The satellite was spin-stabilized, intended to rotate at 50 RPM for stable scanning. Key collaborators in its design included the Naval Research Laboratory and the Army Ballistic Missile Agency, utilizing expertise from programs like the Jupiter-C.
Mission and results
Launched on February 17, 1959, the satellite achieved orbit but suffered from an imperfect spin. The resulting wobble caused its optical scanners to point intermittently at space instead of Earth, severely compromising data quality. Despite this, it transmitted for 19 days and provided some crude cloud-cover observations, proving the basic concept of orbital weather monitoring. The mission is considered only a partial success due to the technical issues, but it paved the way for the fully operational TIROS-1 launched by NASA in 1960. Data analysis was conducted by teams at the Naval Research Laboratory and the United States Weather Bureau.
Legacy
It established the foundational principle for all subsequent weather satellites, directly influencing the design of the TIROS program and modern systems like the Geostationary Operational Environmental Satellite series. The mission's challenges provided critical engineering lessons on spacecraft stabilization and sensor design for Earth observation. Its launch was a notable American achievement during the intense competition of the Space Race, following Soviet milestones like Sputnik 1. The satellite remains in orbit, a historical artifact of early space exploration.
Category:Artificial satellites orbiting Earth Category:Project Vanguard Category:Spacecraft launched in 1959 Category:Weather satellites of the United States