|   Launch of Saturn AS-104  | |
| Mission type | Spacecraft aerodynamics; micrometeoroid investigation  | 
|---|---|
| Operator | NASA | 
| COSPAR ID | 1965-039B | 
| SATCAT no. | 1385 | 
| Mission duration | 8,810 days [1] | 
| Distance travelled | 3,282,050,195 kilometers (2.039371443×109 mi) | 
| Orbits completed | ~79,790 | 
| Spacecraft properties | |
| Spacecraft |  Apollo BP-26 Pegasus 2  | 
| Launch mass | 1,451.5 kilograms (3,200 lb) | 
| Start of mission | |
| Launch date | May 25, 1965, 07:35:01 UTC | 
| Rocket | Saturn I SA-8 | 
| Launch site | Cape Kennedy LC-37B | 
| End of mission | |
| Decay date | July 8, 1989 [1] | 
| Orbital parameters | |
| Reference system | Geocentric | 
| Regime | Low Earth orbit | 
| Perigee altitude | 511 kilometers (318 mi) | 
| Apogee altitude | 739 kilometers (459 mi) | 
| Inclination | 31.7 degrees | 
| Period | 97.2 minutes | 
| Epoch | 4 July 1965 [2] | 
AS-104 was the fourth orbital test of a boilerplate Apollo spacecraft, and the second flight of the Pegasus micrometeoroid detection satellite. It was launched by SA-8, the ninth Saturn I carrier rocket.
The primary mission objective was to demonstrate the launch vehicle's iterative guidance mode and to evaluate system accuracy. The launch trajectory was similar to that of mission AS-103.
The Saturn launch vehicle SA-8 and payload were similar to those of mission AS-103, except that a single reaction control engine assembly was mounted on the boilerplate service module (BP-26). The assembly was instrumented to acquire additional data on launch environment temperatures. This assembly also differed from the one on the AS-101 mission in that two of the four engines were of a prototype configuration instead of all engines being simulated.
This was the first nighttime launch in the Saturn I series. A built-in 35 minute hold was used to ensure that launch time coincided with the opening of the launch window.
AS-104 was launched from Cape Kennedy Launch Complex 37B at 2:35:01 a.m. EST (07:35:01 GMT) on May 25, 1965. [3] The launch was normal and the payload was inserted into orbit approximately 10.6 minutes after lift-off. The total mass placed in orbit, including the spacecraft, Pegasus B, adapter, instrument unit, and S-IV stage, was 34,113 pounds (15,473 kg). The perigee and apogee were 314.0 and 464.1 miles (505 and 747 km), respectively; the orbital inclination was 31.78'. The 1397 kilogram (3080-pound) Pegasus 2 satellite was also carried to orbit by SA-8, being stowed inside the boilerplate's service module, and remaining attached to the S-IV stage.
The actual trajectory was close to the one predicted, and the spacecraft was separated 806 seconds after lift-off. Several minor malfunctions occurred in the S-I stage propulsion system; however, all mission objectives were achieved. [4] [5]
 This article incorporates  public domain material  from websites or documents of the  National Aeronautics and Space Administration .