2005-014A
48 kg NASA/Orbital experiment, Demonstration of Autonomous Rendezvous Technology. Mass 350 kg, size 1.8m long 1.0m dia. The DART AVGS payload is attached to the HAPS fourth stage of the Pegasus launch vehicle and has propulsion, AVGS, RCS, batteries, and communications. DART is an MSFC project which grew out of the VGS experiment on the Spartan-201 satellite carried on STS-87 and STS-95.
HAPS capacity is 57 kg prop and has three 220N thrusters. The AVGS bus has 16 cold-gas 3.5N, Isp=60s N2 thrusters with 23 kg prop capacity. It is 0.6m dia 0.6m long (0.9m long with GPS antenna etc) while HAPS is 1.0m dia 1.0m long.
Rendezvous with MUBLCOM at 150m R-bar stationkeep. The entire mission is preprogrammed, without ground command during flight. The misson was monitored at VAFB's DART Mission Ops Center. After reaching 95m to MUBLCOM, DART detected that it was unexpectedly low on fuel and moved away to abort the mission. Post-flight analysis revealed that DART had collided with MUBLCOM due to multiple software and algorithmic problems.
The TLEs for DART show it in the MUBLCOM orbit until Apr 18; no TLEs for MUBLCOM exist for Apr 16-18. OSC reports the DART safing burn was on Apr 16; I conclude that the DART TLEs for Apr 17-18 actually belong to MUBLCOM.
| DART | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 2005 Apr 15 | 1627 | L-1011 T/O from VAFB | |
| 1726:50 | Drop | ||
| 1726:55 | T+0:05 S1 burn 11.5 km 0.442 km/s | ||
| 1728 | T+1:17 S1 off 63.1 km 1.606 km/s | ||
| 1728 | T+1:35 S2 on 88.0 km 2.429 km/s | ||
| 1728 | T+1:50 Fairing 108.6 km 2.710 km/s | ||
| 1729 | T+2:48 S2 off 216.1 km 5.428 km/s | ||
| 1735:21? | Stage 2 sep | ||
| 1735:30 | T+8:40 S3 on | ||
| 1736:35? | T+9:45? S3 off 7.545 km/s 0.0 deg | 400 x 547 x 97.7 | |
| On orbit checkout in phasing orbit 1 | |||
| 1738:41? | S3 sep | ||
| 1738:45? | HAPS burn 1 | ||
| 1739:20? | HAPS cutoff | 500 x 756 x 97.7 | |
| Phasing orbit 2 | |||
| 2005 Apr 16 | HAPS burn 2 | ||
| 0055? | T+7:29:00 HAPS burn 2 cutoff | 739 x 742 x 97.7 | |
| T+7:29:00 DART 40 km behind and 7.5 km below MUBLCOM | |||
| T+7:55:42 DART CW Transfer burn 1A?, to range 3 km | |||
| T+8:36:49 DART stationkeep at 3 km | |||
| T+8:51:49 DART CW transfer burn 2A?, to range 1 km | |||
| T+10:08:05 DART stationkeep at 1 km | |||
| 0340? | T+10:13:05 Approach to 95m | 740 x 746 x 97.7 | |
| X-1:23 Collision avoidance activated | |||
| 0418:46 | X+0:00 Impact MUBLCOM | ||
| T+11hr, X+0:03:49 Retreat to 300m | |||
| 1047 | 740 x 751 x 97.7 | ||
| 2005 Apr 16 | 1715:45 | Retirement burn | |
| 1724:11 | Safed | ||
| 1753:09 | Transmitter on to deplete battery | ||
| 2005 Apr 18 | 394 x 746 x 97.7 | ||
| Planned DART proxops | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| T+11:10:34 -Vbar rendezvous at 15m | |||
| T+12:59:20 Stationkeep at 15m on target docking axis | |||
| T+13:06:31 Approaches to 5m with avoidance tests | |||
| T+13:43:12 Retreat to -100m on Vbar | |||
| T+14:21:35 Simulated avoidance | |||
| T+14:29:53 Retreat to -200m on -Vbar | |||
| T+15:23:48 Flyaround to +Rbar (nadir) at 150m | |||
| +Rbar approach to 100m | |||
| +Rbar retreat to 300m | |||
| Flyaround to +Vbar, -Rbar, -Vbar | |||
| Second -Vbar approach to 200m | |||
| Flyaround to +Rbar, rerendezvous | |||
| T+19:59:23 Second +Rbar approach to 100m | |||
| Retreat to 300m | |||
| T+20:22:26 HAPS Retirement burn, lower perigee | |||
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