1968-025A
Apollo CSM 020 flew the AS-502 mission, or Apollo 6. The spacecraft used CM 020 and SM 014. The mission was to test launch vehicle and spacecraft compatibility, Saturn stage separations, and Apollo propulsion, guidance and control, and electrical systems. The S-IVB was to insert Apollo 4 in orbit and reignite to place it
in a high apogee trajectory of 224 x 513752 km. The CSM would then have separated and made a retro burn to a 35 x 22194 km orbit, followed prior to reentry with a second SPS burn to 39 x Inf with a reentry velocity of 11.12 km/s. The S-IVB would have carried on to the vicinity of the Moon and presumably made a flyby to solar orbit. However, all this was not to be.
The launch of the second Saturn V, SA-502, was the only serious failure of the Saturn program. The rocket lifted off at 1200 on 1968 Apr 4. The first stage underwent `pogo' oscillations which shook the stack. At 1202:14 part of the SLA adapter broke away. Two engines on the Saturn S-II stage shut down only 4 minutes into second stage burn. The Instrument Unit automatically commanded the stage to burn its three remaining engines for an extra minute to make up. At S-IVB ignition, the rocket's attitude was incorrect and the guidance system commanded the stage to point downward towards the Earth. Then it pitched up, and detected that it had developed more speed than planned, so started to try and cut the speed - it actually went into orbit thrusting backward. The orbit achieved was 172 x 395 km instead of the planned 175 x 175 km one.
The S-IVB failed to restart properly on the second orbit, and as a backup plan the CSM separated in the low orbit and ignited its own SPS engine, reaching an apogee of 22225 km. A second planned SPS burn was cancelled due to lack of fuel. The Service Module, SM-014, was jettisoned and CM-020 reentered the Earth's atmosphere at 10.0 km/s. It splashed down successfully in the Pacific.
| Apollo CSM 020 Mission Log | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 1968 Apr 4 | 1200:00 | Launch of SA-502 | |
| 1968 Apr 4 | 1202:05 | Pogo oscillations in S-IC stage for 10s | |
| 1968 Apr 4 | 1202:13 | T+2:13 SLA-9 -Z panel debris breaks off, 46 km | |
| 1202:24 | IECO | ||
| 1202;28 | OECO 59 km | -6009 x 109 x 32.21 | |
| 1968 Apr 4 | 1202:29 | S-IC separation, S-II ignition | |
| 1202:59 | Interstage | ||
| 1203:04 | LES jettison | ||
| 1968 Apr 4 | 1206:53 | S-II engines 2 and 3 shut down | |
| 1968 Apr 4 | 1209:36 | S-II cutoff | |
| 1209:37 | S-II staging | -2475 x 202 x 32.74 | |
| 1968 Apr 4 | 1209:37 | S-IVB ignition | |
| 1968 Apr 4 | 1212:27 | S-IVB cutoff, Earth orbit insertion | 89.92 178 x 367 x 32.63 (T3-I) |
| 90.04 178 x 373 x 32.74 (T.3-II) | |||
| 1220:51 | S-II impact | ||
| 1968 Apr 4 | 1513:35 | 90.01 183 x 370 x 32.63 | |
| 90.40 191 x 397 x 32.74 (T.3-II) | |||
| 1513:35 | S-IVB reignition | ||
| 1513:50 | S-IVB cutoff | 90.50 191 x 406 x 32.73 | |
| 1968 Apr 4 | 1514:27 | CSM separated from S-IVB | 90.52 191 x 408 x 32.73 |
| 1968 Apr 4 | 1516:06 | SPS-1 burn (7:22) to high apogee orbit | |
| 1523:28 | SPS-1 cutoff 517 km | 384.8 33 x 22260 x 32.58 | |
| 386.60 29 x 22373 x 32.65 | |||
| 1968 Apr 4 | 1828:58 | Apogee at 22225 km | |
| 2129:19 | RCS +X translation | ||
| 2130:09 | RCS +X cutoff | 389.33 33 x 22533 x 32.66 | |
| 1968 Apr 4 | 2136:57 | SM-014 separation 238 km | |
| 1968 Apr 4 | 2138:29 | Reentry 10.0 km/s -5.85 deg | 35 x 22618 x 32.73 |
| 2140 | Begin skip, 58 km | ||
| 2143 | Skip apogee, 67 km | ||
| 2145 | Descending at 58 km | ||
| 2151:27 | Drogue parachute deployed | ||
| 1968 Apr 4 | 2157:20 | Splashdown | |
| 1968 Apr 4 | 2330 | Recovered by USS Okinawa. | |
