Assuming unpowered flight, what were the significant differences between the STS orbiter and the Buran in:

  • re-entry trajectory?
  • re-entry guidance?
  • navigation during re-entry (inputs and algorithms - there was no Glonass for the Russians back then)?
  • terminal area energy management (TAEM)?
  • $\begingroup$ Neat documents: STS - JSC-11746 (Entry Guidance and Entry Autopilot), Jan. 1980, and Buran - Trajectories of BURAN Orbiter's Descent and Landing Algorithms of the Automatic Guidance and Control. Hope someone writes up an answer... $\endgroup$ – Deer Hunter Aug 19 '13 at 21:19
  • $\begingroup$ Good question. Somehow, the Russians managed to build Buran in a way, that it could perform a fully automated re-entry and landing. This is an impressive capability, which the shuttle could not match - not even at the end of its 'career'. I do not know how the 'auto-pilot' of Buran worked, but I would love a good explanation on that. $\endgroup$ – s-m-e Aug 19 '13 at 21:26
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    $\begingroup$ @ernestopheles the Soviet space program has always been much bigger on the use of autopilots instead of The Right Stuff than the American ones. $\endgroup$ – Dan Neely Aug 20 '13 at 3:51
  • $\begingroup$ The STS Guidance link: wayback.archive-it.org/all/20100515203820/http://ntrs.nasa.gov/… $\endgroup$ – Deer Hunter Aug 20 '13 at 9:46
  • $\begingroup$ I remember an anecdote that the US shuttles would be capable of fully automated reentry and landing but the astronauts protested against making them entirely redundant - and so, the operation of lowering the landing gear remained "manual only". Anyone care to confirm? $\endgroup$ – SF. Sep 1 '13 at 8:22


The Buran's computer is cadenced à 4MHz (3 MHz for STS), consisting of 4 independent units and 5 independent units on the shuttles. the dead memory is stored on magnetic tapes, the memory of the Buran's computer is 819 200 words of 32 bits and for shuttle 106 496 words of 16 bits which give buran a better calculation power. Shuttles used FORTAN algorithms whereas for Buran new computer science languages were developed (high and down level). It's more powerful because it uses all the power of the hardware but needs more time to make the language and needs more time for the engineers and technicians to be fully ready to work on it.


enter image description here

During re-entry , the orbiter encounters the main air of the atmosphere and is able to fly like an airplane. It is designed as a lifting body design with swept back "delta" wings which can generate lift with a small wing area. flight computers fly the orbiter. The orbiter makes a series of S-shaped, banking turns to slow its descent speed as it begins its final approach to the runway. The commander picks up a radio beacon from the runway (Tactical Air Navigation System) when the orbiter is about 140 miles (225 km) away from the landing site and 150,000 feet (45,700 m) high. At 25 miles (40 km) out, the shuttle's landing computers give up control to the commander. The commander flies the shuttle around an imaginary cylinder (18,000 feet or 5,500 m in diameter) to line the orbiter up with the runway and drop the altitude. During the final approach, the commander steepens the angle of descent to minus 20 degrees


The difficulty in creating algorithms for automatic traffic control was the fact that the conditions orbiter should be able to point out any areas of admissible initial conditions of entry into the atmosphere at an altitude of 100 km in a time just over 30 minutes to land at a given airport located at a distance of more than 8000 km, while paying off the flight speed to 28,000 km / h to zero.

  • part of the descent N = 100 to 20 km;
  • site of pre maneuvering H = 20 to 4 km
  • approach segment and landing N = 4 to 0 km.

enter image description here

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    $\begingroup$ As we've explained in the past, you need to use the correct formatting when posting direct quotes from sources. Please adhere to this in the future. $\endgroup$ – user29 Aug 27 '13 at 15:02
  • $\begingroup$ Hash, I suppose you'll get the bounty halved if the answer stays like this. I'd like more in-depth analysis based on the sources I mentioned for both systems. $\endgroup$ – Deer Hunter Aug 29 '13 at 21:12

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