The famous night launch of the Saturn V carrying the Apollo 17 spacecraft on December 7, 2017
Apollo 17 Lunar Module Pilot and Geologist Harrison H. (Jack) Schmitt has posted a new item on his web site: the beginning of a reminiscence of his historic flight, which departed for the Moon 44 years and 11 months ago today (December 7, 1972). Although only one chapter is posted so far, it is a great read, describing the busy last month of training, simulation and constant work before the launch of an Apollo crew. I urge readers of this blog to visit his site and enjoy Chapter 4 – Thirty Days and Counting… I eagerly look forward to the next installment.
On a related note, my good friend Bill Mellberg, who passed away this year, wrote an essay recalling his attendance at the launch of Apollo 17 (which includes a guest appearance by Wernher von Braun). Bill’s essay can be found at Jack’s web site, HERE.
Interesting details about the emergency jumper cables for the lunar module ascent engine system: I remember reading that Armstrong actually proposed a purely mechanical actuator lever and was overruled.
As a former helicopter aircrewman I was also interested in the autorotation training and this does relate to the whole subject of lunar landers which is discussed regularly here.
It is one thing to specify techniques like “propulsive landing” and landing back rocket stages but another thing entirely to make them a standard practice. When humans are not involved it is simply a matter of money but if it is going to be “human-rated” then going cheap is not an option.
The commercial airline industry was used as the model for the space shuttle and this was…a disaster. What is so misunderstood about airliners is their extremely conservative design and how every part of the aircraft is subject to strict quality controls and frequent maintenance, inspections, and checks. A rotary wing is a different animal and has never been easy to make money transporting people with because everything that goes for airplanes goes double or triple for helicopters. Making a profit becomes problematic when even the smaller models with half a dozen seats cost well over a thousand dollars an hour to operate.
The Apollo lunar lander could, during landing, jettison the lower stage at any time and ignite the entirely separate ascent stage as an emergency abort option. As related by Jack, there was not much that could go wrong with the pressure-fed hypergolic ascent engine. The descent stage engine was also a pressure-fed hypergolic with no regenerative cooling but being variable thrust there was more to it.
When singing the praises of the liquid hydrogen/oxygen “reusable” lunar lander that will seemingly make landing on the Moon no big deal it must be understood such a machine would be a far, far, different animal than the Apollo lander. There is no cheap.
Now I have some reading for the weekend to do!
It is great to hear the accounts of the astronauts, as well as the technicians, from those memorable times. We could all use insight from the lessons learned.
“-Service Propulsion System (SPS) rocket burns required for Lunar Orbit Insertion (LOI).”
“-two short SPS burns, called Descent Orbit Insertions (DOIs), necessary to lower the orbit of the docked spacecraft so that Challenger could carry more landed payload than otherwise possible.”
The AJ-10 hypergolic engine first flew in 1958 and has been used on Apollo, the Shuttle, and now Orion (de-rated to about a third of the power of the Apollo version). It is hypergolic and pressure-fed but unlike the Lunar Lander engines it features regenerative cooling and at over 20,000 pounds of thrust was about twice as powerful as the Lunar Lander descent engine.
Again, these hypergolic engines do not require troublesome cryogenic propellant storage or turbopumps which make them an order of magnitude simpler and of course more reliable. This allowed for the multiple firings without worrying about spinning up turbopumps or maintaining cryogenic propellants. When considering the type of engine for a future lander there is a list going from the simplest, which would be the Apollo ascent engine to the most complex, an example of which would be the BE-3 hydrogen and oxygen (cryogenic propellants), turbopump-fed regeneratively cooled design.
One compromise between the two poles of engine design might be methane propellant as it is easier to store and transfer than hydrogen. Lunar ice will likely have volatiles trapped in it that allow for methane production. Modifying the BE-3 to burn methane may or may not require extreme modification of the design. Another design feature worth considering might be a pair of smaller engines mounted separate from the landing arrangement and main engine allowing for a cargo payload and most of the lander to be jettisoned in an emergency- somewhat like the Apollo lunar lander.
All the ices and rocks for processing have to be found and accessed. If the regolith could be used for oxygen and hydrogen, a processor and digger would be the first things there as close to the base as possible.