Rockets For a while the United States was in a real bind. The space shuttle was taken out of service and we had no way of reaching the space station. We had to go to the Russians and pay millions of dollars to them for seats on the Soyuz rocket so we could reach the space station. That was not the only problem we had, we also had to license their rocket motors and the main stay of our rockets became the Russian RD-180 engine which as of the writing of this article is still being used in some rockets. It is believed there will be six more launches with this engine and that will end its use in this country. We used that engine because it was supposed to be the most efficient. We have permission to use that engine for 18 more launches, but our vice chief of space operations, Lieutenant General David Thompson said six will be the limit. It seems the Raptor engine from SpaceX has become the best rocket engine. The engine is claimed to have a long life and a lot of power. Not being an engineer, I do not understand everything about the engine but it is said to use a full flow staged combustion cycle. This means all the oxygen powers an oxygen turbopump and all the fuel powers a methane turbopump. The reason the engine is more powerful is it uses this methane instead of kerosene or hydrogen and this also brings down the cost. It is more stable than hydrogen. Since methane is denser than hydrogen the fuel tank can be smaller. If one looks at older articles on the internet, they usually pick hydrogen as the most efficient rocket fuel. SpaceX was the first to use methane in a large rocket, the plans to develop it were announced by Musk in 2012 and it has been a huge success with several companies getting on the bandwagon. There are two basic types of propellants for rockets and both have advantages and disadvantages. One is liquid fuel and the other is solid fuel. Let’s start with solid fuel. It is much easier to store solid fuel than liquid fuel. The space shuttle had two solid fuel rockets strapped to it for boosting it into space. On the flip side they are now as powerful as liquid fuel rockets. Solid fuel is heavy. You are not able to throttle a solid fuel rocket but alternatives are being worked on. Liquid fuel has to be stored either cryogenically or the element of the fuel stored separately. That type of fuel is known as hypergolic and ignition takes place when the ingredients are mixed together. These rockets can be throttled. They can also be restarted after they are shut off. Storing the fuel is more dangerous and at times requires special cooling equipment. I am sure many of us have watched the New Shepherd rocket take off and ferry people to the edge of the atmosphere and back. The rocket is owned by Blue Origin and uses a combination of liquid oxygen and liquid hydrogen. Some of the employees of the company had said there were dangers involved with this rocket, but the government investigated and said there was no basis for the claims. It seems to me this company is far behind SpaceX who has been ferrying people and supplies back and forth to the International Space Station. Blue Origin has an engine it is testing named the BE-7. It still uses oxygen and liquid hydrogen and is said to be a lunar landing engine. As many of us realize chemical rocket engines are just a stop gap measure no matter how efficient they get. The very good ones are the most powerful and reliable, but they will never be fast enough for powering rockets to distant points in our solar system or for further trips to other solar systems, and would be worthless as crewed rockets. I guess by that statement you realize I am against putting human crews into stasis for long duration journeys. Can you imagine you are a crew member and something goes wrong and the computer crashes and you never get woken up or there is an accident and the computer wakes you far too early and you have to try and remain alive for years. It could be a situation where there is not enough food for that. I can’t help but think a human should be in charge. For this to happen we need faster vehicles and I am not talking about light speed, because even that would not be fast enough to reach the closest solar system in a reasonable amount of time. I have to wonder if any country on earth is trying to build some sort of device which will power ships so fast, we might be able to reach Alpha Centauri, the nearest solar system in a few days or faster. I also wonder if anyone is doing any meaningful experiments on worm holes. Perhaps if we could discover a way of locating one, if they really exist, we might eventually map out the wormholes in our area and eventually try to explore them and see where they would take us. The beauty of a wormhole is you don’t need a faster than light ship to travel to a distant point. That is assuming what science believes about wormholes existing and where they go is true. Let’s put things in perspective. Pluto is 0.000628 light years from the sun. If a rocket was launched from the earth traveling at about 35,400 miles per hour, it would take 9.5 years to reach Pluto. Solar sail craft used the sun’s solar wind can reach 1/10th light speed but become ineffective past Jupiter. Even if we could boost the speed of a nuclear rocket to double that of a chemical one, Pluto would still be at least a 4.75 year trip which would still be unacceptable. Speed is going to be the biggest challenge we face in space travel. Sure, there will be many other ones, but without the speed to reach a destination the rest doesn’t mean much since we would not be able to go on our trip with humans aboard anyway. Maybe some other means of transportation we have never imagined will come along, but for now we are pretty much limited to humans traveling to the moon and perhaps Mars. The New Horizons probe which flew to Pluto had the ability to get to Mars in 39 days if we sent it there.
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