# Explorer 49

> satellite launched by NASA for long range radio astronomy

**Wikidata**: [Q1781732](https://www.wikidata.org/wiki/Q1781732)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Explorer_49)  
**Source**: https://4ort.xyz/entity/explorer-49

## Summary
Explorer 49 (also known as Radio Astronomy Explorer-B or RAE-B) is a NASA lunar orbiter satellite designed for long-range radio astronomy observations. Launched in 1973, it was part of the Explorers Program and operated from lunar orbit to study low-frequency radio emissions from celestial sources.

## Key Facts
- **Launch Date**: June 10, 1973, at 14:13 UTC from Cape Canaveral Space Launch Complex 17B.  
- **Launch Vehicle**: Delta 1000 series (specifically Delta D-095).  
- **Operator**: National Aeronautics and Space Administration (NASA).  
- **Mission Type**: Lunar orbiter for radio astronomy.  
- **Alternative Names**: Radio Astronomy Explorer-2, RAE-B, RAE-2, Explorer 38.  
- **COSPAR ID**: 1973-039A.  
- **NSSDCA ID**: 1973-039A.  
- **Part of**: Explorers Program.  
- **Country of Origin**: United States.  

## FAQs
### Q: What was the purpose of Explorer 49?
A: Explorer 49 was designed to study low-frequency radio emissions from celestial objects, leveraging its lunar orbit to minimize interference from Earth's ionosphere.

### Q: When was Explorer 49 launched?
A: It was launched on June 10, 1973, from Cape Canaveral Space Launch Complex 17B using a Delta 1000 rocket.

### Q: Is Explorer 49 still operational?
A: No, Explorer 49 completed its mission decades ago and is no longer operational.

## Why It Matters
Explorer 49 was significant for advancing radio astronomy by providing unprecedented data on low-frequency radio emissions from space. Its lunar orbit allowed it to avoid Earth's ionospheric interference, enabling clearer observations of cosmic phenomena. This mission contributed to understanding galactic and extragalactic radio sources, laying groundwork for future space-based radio telescopes. Its success also demonstrated the viability of using lunar orbits for scientific missions, influencing later projects.

## Notable For
- **First dedicated lunar orbiter for radio astronomy**: Pioneered long-range radio observations from lunar orbit.  
- **Part of the Explorers Program**: Contributed to NASA's long-running series of low-cost scientific missions.  
- **Unique positioning**: Used the Moon's orbit to avoid Earth's radio interference, a novel approach at the time.  

## Body
### Mission Overview
- Explorer 49, also designated RAE-B, was launched to study low-frequency radio waves (below 1 MHz) from space.  
- It followed its predecessor, Explorer 38 (RAE-A), which operated in Earth orbit.  

### Technical Specifications
- **Launch Vehicle**: Delta 1000 series (Delta D-095).  
- **Launch Site**: Cape Canaveral Space Launch Complex 17B.  
- **Orbit**: Lunar orbit, chosen to minimize Earth's radio interference.  

### Scientific Contributions
- Provided data on galactic and extragalactic radio sources.  
- Helped map low-frequency radio emissions across the sky.  

### Legacy
- Demonstrated the utility of lunar orbits for radio astronomy.  
- Influenced later missions like the Lunar Radio Telescope concept.

## References

1. Jonathan's Space Report
2. Freebase Data Dumps. 2013