Space Escape: Flying A Chair To Lunar Orbit

In the coming decades, mankind will walk on the moon once again. Right now, plans are being formulated for space stations orbiting around Lagrange points, surveys of lava tubes are being conducted, and slowly but surely plans are being formed to build the hardware that will become a small scientific outpost on our closest celestial neighbor.

This has all happened before, of course. In the early days of the Apollo program, there were plans to launch two Saturn V rockets for every moon landing, one topped with a command module and three astronauts, the other one containing an unmanned ‘LM Truck’. This second vehicle would land on the moon with all the supplies and shelter for a 14-day mission. There would be a pressurized lunar rover weighing thousands of pounds. This wouldn’t exactly be a Lunar colony, instead, it would be more like a small cabin in the Arctic used as a scientific outpost. Astronauts and scientists would land, spend two weeks researching and exploring, and return to Earth with hundreds of pounds of samples.

With this, as with all Apollo landings, came a risk. What would happen if the ascent engine didn’t light? Apart from a beautiful speech written by William Safire, there was nothing concrete for astronauts consigned to the deepest of the deep. Later in the Apollo program, there was a plan for real hardware to bring stranded astronauts home. This was the Lunar Escape System (LESS), basically two chairs mounted to a rocket engine.

While the LESS was never built, several studies were completed in late 1970 by North American Rockwell detailing the hardware that would return two astronauts from the surface of the moon. It involved siphoning fuel from a stricken Lunar Module, flying to orbit with no computer or really any instrumentation at all, and performing a rendezvous with an orbiting Command Module in less than one Lunar orbit.

A 370 Pound Plan B

The Lunar Escape System would only be used in the event of a failure of the ascent stage engine. For hopefully all missions, this rocket-powered life raft would be dead weight, and that meant shaving every unneeded ounce. There would be no computer, and some plans called for no attitude indicator. Fuel would be siphoned off from the Lunar Module, and the dry weight of the entire vehicle would weigh about 370 pounds in Earth’s gravity, or about a hundred pounds less than the lunar rover flown on Apollo 15, 16, and 17.

Like the lunar rover, the LESS would be stored on the outside of the descent stage, flat-packed, and assembled on-site. Once the LESS is deployed and fueled, the astronauts would return to the Lunar Module, repressurize the spacecraft, recharge their suits, and wait for the first launch opportunity.

Why go back to the lander? The PLSS life support system found in Apollo space suits could only support an astronaut for about four hours, but assembling, fueling, and servicing the LESS would take nearly three. Without a quick reprieve to fill up their suits, the astronauts would only have an hour to wait for the right time to launch, ride it to orbit, rendezvous, dock, and enter the command module, and finally, repressurize the spacecraft. It simply can’t be done. In fact, simply launching to orbit and reentering the command module is just barely possible in four hours.

Orbiting By The Seat Of Your Pants

While the crew of the LESS would be able to communicate with Houston and the Command Module, the LESS would not be equipped with a computer. There would be no guidance system, save for a sextant. The commander of this rescue mission would have to fly into lunar orbit by the seat of their pants.

Through the 1960s, there was significant concern someone would eventually have to launch into orbit and rendezvous with a spacecraft without the assistance of even the primitive computer control available at the time. During Apollo 9 and Apollo 10, crews experimented with flashing beacons and visual sighting of returning lunar landers, and  Buzz Aldrin’s doctoral thesis — arguably the reason he was chosen as the Lunar Module pilot for the first landing — was titled, “Line-Of-Sight Guidance Techniques for Manned Orbital Rendezvous”.

These techniques for orbiting and rendezvous with another spacecraft could not apply to the LESS. The crew would only have four hours between climbing out of a crippled Lunar Module on the Moon’s surface and climbing into an orbiting Command Module. Aldrin’s techniques of slowly closing in on an awaiting spacecraft over several orbits worked when you had a real, proper spacecraft, the ascent profile of the LESS was slightly more direct.

After assembling the LESS, climbing back into the Lunar Module, and refilling their space suits, the stranded astronauts would wait for the next launch opportunity, and possibly for the Command Module to reorient itself into a more favorable orbit.

Near the appointed time, the astronauts would climb out of the Lunar Module for the last time and strap into the LESS. The Command Module would pass overhead, and several seconds later the commander would light the engines. The LESS would take off, but only with an acceleration of about two times lunar gravity. For the first ten thousand feet, the commander would keep his eye on the attitude indicator, while the pilot would look for landmarks, ensuring that yes, they are indeed going the right way. At around ten thousand feet above the moon’s surface — a guesstimate, because there is no altimeter on this lifeboat — the LESS would begin pitching over, eventually inserting it into an orbit with an apoapsis sixty nautical miles above the moon’s surface.

The Command Module pilot would track the LESS on ascent. Once the LESS made a stable orbit after firing its engines for eight minutes or so, the CM pilot would enter the relevant angles and times from visual and radar tracking into the Apollo Guidance Computer. The computer would, in turn, tell the pilot how long to fire his engines to enter a higher, intercept orbit. After nearly an entire orbit around the moon and two hours, the Command Module would again fire its engines to put it in the same orbit as the LESS. From here, it was a simple matter of rendezvous from a few nautical miles away. Studies demonstrated the Command Module pilot could spot the LESS from ten or fifteen miles away, with radar guidance available beyond those ranges.

At this point, the studies for the LESS break down somewhat. At the time the LESS studies were completed, orbital rendezvous was well understood, but the question of how the astronauts would get back inside remained. Plans for inflatable probes were floated, and there was the possibility of a small, simplified docking adapter that would latch onto the front of the Command Module. Because of the bulk of the life-support backpacks, the astronauts would have to enter through the main hatch instead of the front service tunnel of the Command Module, and there had to be considerations for an incapacitated astronaut. Really, though, after flying a rocket chair into lunar orbit, dealing with tethers and hand holds isn’t that big of a deal.

The Legacy of the LESS

Shortly after the study for the LESS was complete, Congress canceled Apollo 18, 19, and 20. The Apollo Applications Program would result in Skylab, but plans for extended stays on the Moon and flybys of Venus were thrown out. Without plans for an LM truck supporting extended Lunar missions, there was no space on later Apollo missions for a nearly four-hundred pound lifeboat. In any event, the LESS would take nearly three years to develop, and the last footsteps on the moon would be just twenty-six months after the LESS study was published.

Nevertheless, the engineers behind the LESS were thinking ahead. The LESS could reach Lunar orbit, but that also means it could lift off from its initial touchdown point, land thirty miles away, and return to the Lunar Module. This was the inspiration for the Long-Range Flyer (LRF). This was simply a slightly more robust LESS, equipped with landing gear, that would also be able to perform the LESS rescue mission.

The LRF would have been used for scouting, research, and extending the range of how far astronauts could travel during their stay on the Lunar surface. Of course, this vehicle was never flown, but in the coming decades, when mankind returns to the moon, we’ll want a fast, easy way to get around quickly on the Lunar surface. Here, we’ll probably be looking over fifty-year-old studies from aerospace companies that don’t exist anymore, and creating a small, rocket-powered chair. There are a lot of benefits, and if the main lander breaks, it can be used to fly up to a waiting Command Module.

55 thoughts on “Space Escape: Flying A Chair To Lunar Orbit

    1. Exactly my thought. I’ll be trying this in KSP. But orbital rendevouz without computer guidiance sounds to hard for me… Oh, btw I accidentally reported your comment when I intended to reply. My apologies…

      1. That’s the beauty of it. If you understand orbital mechanics, all you need is to look at the tiny glimmer of light, or pixel in this case, and compare its motion against the horizon. The relative motion tells you where it’s going. When it’s finally standing still just slightly above the horizon, your orbits are aligned and you’re on an intercepting path. If it’s under the horizon it means you’re falling behind, or looking in the other direction, it’s catching up on you. If it’s exactly on the horizon, it means you’re on the same orbit and not moving relative to one another.

        Thing is, getting to within 15 miles where you can see the object is a really lucky shot without instrumentation. The other vehicle must collaborate

  1. Wasn’t the ascent engine fueled with hypergolic propellants? If all you had to do was mix two fuels together, I’d think redundant valves and firing circuits would make for an overall safety margin that would actually be higher than what you’d get having to account for the extra weight of this (combined with the chances that the whole rescue scenario would actually work all the way the first time it was called upon).

    1. Indeed it was, and the LM engines are considered among the most reliable ever flown. I suspect the LESS project was more about a failure of the LM computer or power system, which would have been more likely and more catastrophic than an engine failure in the normal run of things.

      1. It’s interesting to note that, due to the nature of the hypergolic engine, it couldn’t be test fired. The first time each LM ascent engine was fired was on the Moon. So definitely a lot riding on that particular piece of hardware.

    1. I wonder, if you were going to die on the Moon, would you keep your suit on as you died? Or depressurise it at the last moment?

      The first option means you get to hopefully die gradually, but will end up turned to slime by your internal bacteria. The second way might be a bit violent (though hopefully the vacuum would make you pass out quickly), but at least your body would be preserved mostly intact. The cold and the lack of air would kill most of your bacteria pretty quickly, and the rest wouldn’t last long.

      Personal comfort vs what sort of mess you want to leave to infinity. Might be nice to leave a good-looking corpse with just a sheen of frost on it.

      1. I would be inclined to stay in the LEM, to keep out of the sun, even if there is no atmosphere, the couple of hundred degrees in the sun wouldn’t do your body any favors over time. Then, I would get out of my suit and depressurize the LEM, slowly if possible. You would quickly go hypoxic and even possibly feel euphoric before you pass out. From there, let nature take its course knowing the LEM is keeping you cool and out of the sun, while your body stays preserved waiting for someone in the future to come and bring you home.

      2. I don’t know how good-looking the corpse would be, since you’d pretty much evacuate all your bodily fluids on depressurization. Instant nose bleed, vomit and brown pants, as the gasses in your intestines expand and escape.

        Your body can expand to twice its size under vacuum as the fluids start to boil.

  2. This seems like something out of Major Matt Mason, but in fact there wasn’t such a vehicle.

    There was a juvenile science fiction novel, “The Planet Strappers” by Raymond Z. Gallun, where space launches were common, and reasonably cheap. So people would bootstrap, build their own “vehicles” which were more like collapsible bubbles, and other supplies. The rocket would get them into space, then thy ere on their own. Puts exploration, and exploitation, into everyone’s hands. It used to be that way, but getting off earth is a problem. The book is at Gutenberg.

    Michael

    1. Depending on how much stability assist would it have, “going up” would probably be the easiest and most fun part.
      It’s the randervouz that would be terrifying, with no computer and no radar/lidar, you have to do EVERYTHING manually and the smallest fuckup (especially early on) would either cause you to “dock” with the target too fast (damaging/destroying both you and it) or miss it altogether and die in lunar orbit because you’d run out of lifesupport.

      My personal guess would be that if the remaining Apollo missions weren’t canceled, they would come up with a way for the command module to provide at least some form of guidance assist, possibly even do all the guiding remotely using a datalink, a set of gyros, servos and a radio link wouldn’t be all that big, heavy or power hungry even in the 70s…

        1. Even getting into a stable orbit and particularly one the command module is able maneuver into and “dock” in time (remember that the astronauts riding the rocket lawn chair only have the suits, you can’t just wait a day or two for things to align) would require guidance, and since it would already have to be guided, might as well try use all the fuel so that the significantly lighter spacecraft does most of the maneuvering.

  3. As it happens much of this came up in a book by Von Braun. It’s a compilation of his excellent articles that he wrote for one of the Popular et cetera magazines. I didn’t know about the flying lawn chairs, but the LEM as a cottage on the Moon is in there.

  4. Eternal damnation to all the bean counting politicians that canceled mankinds march to space in the 70’s and 80’s. So much potential wasted. We are finally recovering and going back but I probably won’t live to see a permanent presence on the moon or a non research space station. My generation has to hope that the kids will fulfill their dreams.

  5. Wow, great article. I thought I knew a reasonable amount about Apollo but never heard of LESS.
    I wonder what would be scarier to ride – LESS or MOOSE (Man Out Of Space Easiest). Probably MOOSE.

    1. There was also Project Moonray. It was to put an amateur radio repeater on the moon, the selling point was that it could provide backup communication for the moon mission. I recall someone had found an otherwise empty space to fit it in (which set the dimensions of the project), I think a lunar “car”. Obviously it was for a later moon mission.

      There were articles in the ham magazines, but I could never tell from them how much of it was proposal and how much reality. They were talking about a nuclear power source if I recall. But I don’t know how much if any of the overall project got built.

      But it seemed to end when the main person involved died. And the moon missions were ended early, which definitely ended the project, however for along it might have been. It’s never been clear if NASA had plans for it, or if asking tem was on the list of thongs to do.

      For Skylab, some effort was made to get a ham transceiver on-board. Owen Garriott was part of the crew, and he’d long had a ham license Some work was done, there was a transceiver, but in the NASA declined, the explanation I remember was that NASA didn’t want uncontrolled communication. That changed later with the space station, NASA fully behind ham radio in space.

      Michael

      1. Yea, but it is mostly repeater and SSTV; I wish they would put the packet BBS mode on more often, IMHO it is the most useful mode even if it is a scramble to get everything running before you LOS the ISS.

        1. Used to quite enjoy playing with sstv. I used to record the wave forms onto audio cassette tape and decode them with a dos machine. I even got around to making my own audio files to transmit but since I “only” had one computer back then, that was as far as I got. Mothballed along with 10k other projects.

  6. Today a LESS could be made much lighter by using composites, and guidance electronics would only add a few ounces. A Raspberry Pi Zero and another one for backup ought to be able to handle everything.

    1. I thought it wasn’t so much height, as speed. You have to get up to some ridiculous speed to stay in orbit, otherwise it’s a ballistic flight, up and back down again. So starting a couple of miles higher doesn’t really help.

      1. Yes, it would. You would have a lot less drag. The issues are.
        The rocket would still be pretty big.
        The ballon would be huge.
        Control would be really hard.
        Some small sounding rockets have been launched but not any orbital ones.

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