Would an Internal Combustion Engine work in space? Could an Internal Combustion Engine (ICE) power a spaceship? That's what this fascinating article from MotorTrend discusses.
I hadn't thought of it before, but to begin with, there's a difference between an "engine" and a "motor". An engine creates its power, but a motor requires external power.
An ICE forces pistons down to rotate the crankshaft, whereas, in rockets, the combustion is expelled propelling the rocket. ICEs create rotation, rockets create thrust.
ICE combustion occurs when fuel is burned with oxygen. Since oxygen is required for an ICE to work, and there is no oxygen in space, how could it possibly work? The answer is you would need an oxygen injector and a closed assembly unit in space.
Spark plugs ignite the fuel/oxygen mixture in an ICE. More fuel and larger torch igniters are used in liquid-fuel rocket engines. Both can be done in a vacuum, but different engine materials are necessary because, in space, cold-welding occurs. That's when clean, flat surfaces of similar metals bond without the need for heat.
Interestingly, it's gravity that helps the flow of fuel for launching a rocket, but in space, it's the momentum that keeps the flow going. Other considerations, such as backpressure and compression stroke are looked at, but the main point is that being in a vacuum really isn't an issue.
"If fuel is hot enough to reach ignition with its oxidizer, it will ignite and expand until it hits something and moves that object or stops because that object requires more force than that expansion is producing."
So, why don't the ISS and other spacecraft use ICE generators? That comes down to weight. To refuel in orbit would mean carrying fuel to space, and the weight is prohibitive. That's why solar power and other nuclear options win. (The ISS uses solar, and the Mars rovers use Radioisotope Thermoelectric Generators.)
There's also the issue of exhaust. If an ICE was used on the ISS, for example, part of its mechanism would need to be exposed to space, and that would add layers of complexity to the design of any spacecraft. Even using alternative fuel would still produce byproducts to be dealt with.
In summary, the article concludes, "While it is possible to run an internal combustion engine in the vacuum and cold environment of space, the reality is that it's just not feasible." This is a fairly long article, I'd say about 20 minutes to read.
NASA has a program to fund research and proposals into various early-stage concepts. That program is called the NASA Innovative Advanced Concepts ("NIAC") program. (I've covered several of their research selections before.)
One of the recent proposals that caught my eye is the Cosmic Radiation Extended Warding using the Halbach Torus ("CREW HaT") grant. Proposed by Dr. Elena D’Onghia of the University of Wisconsin's Madison Research Group, this proposal is intended to build a prototype space radiation shield to protect astronauts.
It is suggested that a "Halbach array" might work. A "Halbach array" is, basically, an arrangement of an array of magnets that enhances the magnetic field on one side of the array while cancelling it on the other side. Dr. D'Onghia explains: "This configuration produces an enhanced external magnetic field that diverts cosmic radiation particles, complemented by a suppressed magnetic field in the astronaut’s habitat."
As explained in another interview with Dr. D'Onghia (embedded below), this idea is not entirely new. The problem in the past has been the weight of the magnets that would be required. New "superconductive tapes" can reduce the magnetic coils from 300 tons down to 3 tons, making deployment and construction (of the array in space) much easier.
This post links to NASA's February 18, 2022 press release from Dr. Elena D'Onghia explaining what her CREW HaT proposal hopes to accomplish.
NASA February 25, 2022 press release announcing NIAC awards, including Dr. Elena D’Onghia, University of Wisconsin–Madison, CREW HaT proposal ...
Dr. Elena D’Onghia's UW Madison Research Group website, "Mad Astrodynamics" ...
Dr. Elena D'Onghia's YouTube interview with Fraser Cain. She explains the issues with space radiation ...
FYI: May 2 - May 6, 2022 was NASA's Black Hole Week. Here is a link to everything about Black Holes from NASA's Goddard Media Studios …