Hello all, I’d like to cover a pretty cool interesting topic today.
I’ve already addressed rocket engines, which are very useful for getting into space, but what happens if you don’t want to go to space anymore?
What I mean is this: If something goes horribly wrong with your mission, you need a way to safely go home.
Section 1: Pad Aborts
The easiest way to get out of space is to not go to space in the first place. Many launches are stopped from launching while they are still on the launchpad because something appeared to be wrong. The best part about aborting on the launchpad is that you usually get to reuse your spacecraft, i.e. it doesn’t explode and you don’t need to build a new one.
This may sound really boring, but there are some cool examples of it happening.
The Space Shuttle ignites its liquid fueled engines 6.6 seconds before it lifts off from the launchpad in order to let them spool up. Liquid fueled engines can be shut off at anytime just be cutting off the fuel, so those 6.6 seconds allow the Shuttle to perform some final checks. At T-0 seconds, the solid rocket boosters ignite, and there is no turning back.
A couple of missions have aborted extremely close to the 0 second mark. One example is STS-68, where the Space Shuttle’s onboard computer detected a minor problem and aborted the launch only 1.9 seconds before liftoff. Had there been a serious issue and the computer not stopped the countdown, things might have gone differently that day.
Section 2: Launch Escape Aborts
This is one of the cooler ones. If you’ve ever seen crewed rockets, you will usually see a long rod coming off the top of the rocket. This is called the Launch Escape System or LES.
The purpose of the LES is to pull the capsule with the people off of the rocket while it is in flight. Here is a demo featuring SpaceX’s Dragon 2 crew vehicle.
The LES in the video is essentially built-in with the Dragon 2 spacecraft. Those engines are actually dual-purpose; they can also be used for powered landings on Earth. However, for most rockets, like the Soyuz, the LES is a large tower at the very top of the rocket.
The LES usually uses a couple of big rockets near the middle of the tower to pull the crew away from the main rocket, and a couple of smaller rockets near the top to steer the assembly, as pictured below.
The only case of any LES being used for real happened in 1983, and it’s a cool story.
3 cosmonauts were prepared to launch on a Soyuz rocket, known as Soyuz 7K-ST No. 16L on September 26, 1983.
Around 90 seconds before liftoff, the bottom of the rocket caught fire. The crew was unable to see this, since they were in a completely closed capsule – they could however feel that something was wrong.
The crew is unable to activate the LES – only the control tower can do so. However, by the time they decided to abort, the cable that gave commands to the rocket on the ground had burned. They eventually activated it by radio, and the crew was saved from the explosion that happened a few seconds after.
The crew was accelerated at around 15gs (15 times the gravitational force that you usually feel) and were very startled. It is said that they intentionally turned off the radio to mission control at that point because they were swearing so much inside the capsule.
When they landed, two crew members were found to be bruised, but the crew was safe. They were given shots of vodka afterwards to relax. A truly Russian mission.
This was an example of the LES being used on the pad, but the LES is also designed to be used in flight.
The problem, however, is that the LES is thrown away once you get to space because it can be very heavy. So what happens if you need to abort from space?
Section 3: MOOSE
The MOOSE system was a proposal in the 1960s to get someone out of space if their spacecraft fails for some reason. MOOSE stands for Man Out Of Space Easiest – which does not inspire much confidence in terms of safety.
In essence, it was suitcase-sized kit which let an astronaut return from orbit.
First, there would be a huge garbage bag that you wrap yourself around. Then you sprayed some foam which would expand and harden. This would become the heat shield that protects you from reentry. You would then use a rocket motor strapped to your chest to deorbit, and turn yourself around in space using the equivalent of a fire extinguisher. After reentry, you would parachute down to safety.
Due to how ridiculous this sounded, the system never actually made it to space (thankfully).
Section 4: Apollo LESS
We know that MOOSE would allow you to get home from Earth orbit, but what if you were stuck on the moon?
During the Apollo program. NASA feared that the lunar lander would not be able to get back to lunar orbit and bring the astronauts back to Earth. They were worried that the return stage of the lunar lander would fail to work, and leave the astronauts stranded on the Moon.
Their solution would be an emergency system that would allow the astronauts to get to orbit without the lander. However, because of how limited their space margins were, the system would need to be lightweight and be able to fit in a small space.
Obviously a full spacecraft would not work – so NASA downsized – A LOT.
The resulting design – the Lunar Escape System (LESS) – was a bit more than a lawn chair with some rockets strapped to it.
The design had to be foldable and be able to fit on the side of the lunar lander. The craft had no pressurized pod, no life support (air, temperature), steering, or computer. Everything was cut down to the bare minimum for escape.
To start, the astronauts would suit up in their spacesuits to launch. This gave them only 4 hours to reach orbit and get to the main Apollo spacecraft- the CSM. The fuel tanks would be empty, and would use fuel from the lunar lander itself. The astronauts would need to siphon rocket fuel from the lander into the LESS.
In terms of guidance, the astronauts could not determine their altitude or speed because computers would be too heavy. They would instead need to fly according to features on the surface of the Moon, like mountains and craters.
In terms of flying, some designs of LESS would have astronauts physically lean back and forth to steer it. Others had more rational designs, such as gimballing the engine or by changing the balance of thrust across multiple engines.
Fortunately, the design never needed to be used, and never even went to space. All of project Apollo’s missions were short enough that NASA didn’t need to worry about lunar lander failure.
A potential extension of the LESS idea was the “Long Range Flyer“, which would let astronauts fly across the Moon on their rocket-powered lawn chair rather than go to orbit. Though they already had the rover, they the LRF could have doubled or tripled their range on the Moon. Overall, even though the LESS was never needed for the Apollo program, an emergency escape system will still be needed when we eventually return to the Moon.
Escape systems in spaceflight are cool but sometimes also ridiculous. However, it is certain that these systems have saved the lives of many. The next generation of escape systems, such as the one on Dragon 2, will hopefully be more efficient by taking on multiple roles, as demonstrated by Dragon 2.
Thanks for reading!
Stay tuned and stay sciency,