| AS-104 | |
| Mission Type: | Spacecraft aerodynamics; micrometeoroid investigation |
| Operator: | NASA |
| Cospar Id: | 1965-039B |
| Satcat: | 1385 |
| Mission Duration: | 8,810 days |
| Orbits Completed: | ~79,790 |
| Distance Travelled: | 3282050195km (2,039,371,443miles) |
| Spacecraft: | Apollo BP-26 Pegasus 2 |
| Launch Mass: | 1451.5kg (3,200lb) |
| Launch Date: | UTC |
| Launch Rocket: | Saturn I SA-8 |
| Launch Site: | Cape Kennedy LC-37B |
| Decay Date: | [1] |
| Orbit Epoch: | 4 July 1965[2] |
| Orbit Reference: | Geocentric |
| Orbit Regime: | Low Earth orbit |
| Orbit Periapsis: | 511km (318miles) |
| Orbit Apoapsis: | 739km (459miles) |
| Orbit Inclination: | 31.7 degrees |
| Orbit Period: | 97.2 minutes |
| Apsis: | gee |
| Previous Mission: | AS-103 |
| Next Mission: | AS-105 |
| Programme: | Apollo program |
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]