STS-51-F Abort-to-Orbit (1985)

STS-51-F Abort-to-Orbit (1985)(en.wikipedia.org)

10 points by schoen 3 hours ago | 3 comments

Today I learned that one Space Shuttle flight (in 1985) successfully used the Abort-to-Orbit recovery plan (changing its flight path in real time in response to an engine failure during ascent). The overall mission continued, accomplished its other objectives, and was considered a success despite the engine failure.

Some 2015 coverage of this mission:

https://www.americaspace.com/2015/07/25/going-to-spain-30-ye...

https://www.americaspace.com/2015/07/26/cola-and-solar-wars-...

EvanAnderson 1 hour ago |

My "favorite" Space Shuttle abort mode is the Return to Launch Site (RTLS) abort[0] because of the complex energy management procedure necessary to pull it off.

As I understand it the energy management of an RTLS is tenuous because, ultimately, the orbiter is an unpowered glider (with a glide ratio similar to a brick). The limits of stress on the orbiter's airframe are a factor, too.

The orbiter's mass, energy (altitude), and downrange position all have to be in a reasonably tight envelope to make the landing without coming up short or overshooting (there's only so much energy you can bleed off doing S turns).

John Young[1] described an RTLS abort working thru "continuous miracles, interspersed with acts of God".

Somebody made a fun (if you like this kind of stuff) simulation of an RTLS abort[2] in Kerbal Space Program.

[0]: https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Retu...

[1]: https://en.wikipedia.org/wiki/John_Young_(astronaut)

[2]: https://www.youtube.com/watch?v=Vx94b9nHTHg

dabluecaboose 1 hour ago |

This mission also illustrates how confusing the old STS mission numbering scheme used to be.

STS-51-F is the only exercised launch abort, and the Challenger was the orbital vehicle.

STS-51-L, which occurred the following year, is the famous Challenger disaster.

Originally, the numeral in the mission designation indicated the federal fiscal year of the mission and the launch site (51 being 1985 and launch site 1 (KSC, 2 would have been used for Vandenberg). The letter indicated the sequential launch index, so A=1m, B=2, etc.

This was originally done after STS-12. Superstition around Apollo 13 created the desire to avoid an STS-13. The numbering system returned to a strictly sequential schema after STS-51-L, with STS-26.

GMoromisato 1 hour ago |

> Booster Systems Engineer Jenny M. Howard acted quickly to recommend that the crew inhibit any further automatic RS-25 shutdowns based on readings from the remaining sensors,[6] preventing the potential shutdown of a second engine and a possible abort mode that may have resulted in the loss of crew and vehicle (LOCV)

Incredible that human action during ascent (when everything is usually automated) potentially saved a crew. One of probably dozens of cases, is my guess.

STS still has the record for most astronauts killed. I don't believe we will surpass that grim record until Starship starts carrying humans.