STS-71 was a crewed spaceflight that was the third mission of the US/Russian Shuttle-Mir Program. The mission began on June 27, 1995, with the launch of Space Shuttle Atlantis from launchpad 39A at the Kennedy Space Center in Florida. Atlantis became the first Space Shuttle to dock with the Russian space station Mir, delivering a relief crew of two cosmonauts Anatoly Solovyev and Nikolai Budarin to the station and recovering Increment astronaut Norman Thagard. Atlantis returned to Earth on July 7 with a crew of eight. It was the first of seven straight missions to Mir flown by Atlantis, and the second Shuttle mission to land with an eight-person crew after STS-61-A in 1985.
During the five days the Shuttle was docked to Mir, the combined spacecraft became the largest in orbit at the time. STS-71 marked several key achievements: it was the first Shuttle docking with a space station, the first crew exchange between a Shuttle and a station, and the 100th crewed space launch by the United States. The mission carried Spacelab and provided logistical resupply for Mir. The joint US/Russian crews conducted various life science investigations using Spacelab and performed the Shuttle Amateur Radio Experiment-II (SAREX-II).
I want to note that even today, no spacecraft (I ain't counting ISS) can match this crew capacity:
Now about that historic docking:
Docking occurred at 9 am EDT, June 29, using R-Bar or Earth radius vector approach, with Atlantis closing in on Mir from directly below. R-bar approach allows natural forces to brake the orbiter's approach more than would occur along standard approach directly in front of the space station; also, an R-bar approach minimizes the number of orbiter jet firings needed for approach.
The manual phase of the docking began with Atlantis about a half-mile (800 m) below Mir, with Gibson at the controls on aft flight deck. Stationkeeping was performed when the orbiter was about 75 meters (246 ft) from Mir, pending approval from Russian and U.S. flight directors to proceed. Gibson then maneuvered the orbiter to a point about 10 meters (33 ft) from Mir before beginning the final approach to station.
Closing rate was close to the targeted 0.1 foot per second (30 mm/s), being approximately 0.107 foot per second (33 mm/s) at contact. Interface contact was nearly flawless: less than 25 millimeters (0.98 in) lateral misalignment and an angular misalignment of less than 0.5 degrees per axis. No braking jet firings had been required.
Turns out, John Young had some involvement:
I discussed several ways that we could upgrade flight crew knowledge so that STS-71 would approach Mir in the best possible way and arrive there for docking at only 0.1 feet per second. STS-71 Atlantis was the third mission in the U.S.-Russian shuttle/Mir program, but it was to be the first docking. After a lot of practice in the shuttle engineering simulator, I reported that the orbiter could readily dock at 0.1 fps. That velocity would provide the 230,000-pound orbiter with six times less energy than the normal 16,000-pound Soyuz or Progress.
...Orbital mechanics was something I knew a little bit about, so in 1996 I reminded the space station folks that because rendezvous was taking two or three days, from one-fifth up to one-third of the time in orbit was being used just to rendezvous. To the year 2000, that would mean that the seventeen shuttle missions for assembly, test, and checkout of the space station would spend 34 to 51 days just with the orbiter chasing the space station. That seemed crazy! I recommended we look at ways to start doing on-time launches and to rendezvous in four or fewer orbits. We had done that in Gemini and Apollo; we eventually even did it in one orbit. It should have been easy for the shuttle to do with GPS, but it never did manage to do it that way.
These days, the default for Crew Dragon is still 1-2 days for rendezvous/docking at ISS (gives astronauts time to adjust to microgravity, test systems, and conserve fuel), although there is a fast track option of several hours that both Dragon and Soyuz can perform. The latter has even pulled off a 2-orbit ultrafast approach in about 3 hours. Regardless of technique, it is a lovely, tricky ballet.
<exits, humming Blue Danube>
No comments:
Post a Comment