How to travel inside our Solar system

Planets of the Solar System

Planets of the Solar System (Photo credit: Wikipedia)

In the previous post we focus our attention about the needs for low-gravity and short-distance transports, recovering the “Eagle” concept from the beloved TV serial “Space:1999“. Basically that was a kind of spaceship that we can build even today, using ion engines or chemical engines for propulsion. The limit for such a ship and for everything else we put out in space until now, is that it’s slow. Six months or more to reach Mars, much more to reach the other planets (or bodies) in our Solar system.

A voyage measured in many months or a few years could be acceptable for automated vehicles, such as “Cassini” or “New Horizons“, but it’s absolutely inappropriate when it comes to manned missions. Too much time in space, exposed to radiations and to the damages of zero-gravity, too high the resource level needed to keep alive our astronauts. Looking at the near future, when we will need fast and reliable way to transport people and goods to and from distant bases, we will need another way to power our spaceships.

Basically we have two options on the table. Nuclear-powered propulsion, based on next-generation reactors (that means, fusion reactors) and plasma engines, such as VASIMR.

None of them is at the ready right now. The path to the fusion reactor,although is the key of our future, is still a long road to run. Maybe we will have such a reactor by 2050, that if in the meanwhile we will be able to overcome a lot of technical issues. The ITER project is actually the most advanced in the field, but it’s an experimental reactor – something really different from a feasible power plant.


Plasma engines could be seen as a very interesting reality right now. The concept is in development since the end of the ’70s and the most recent version of the engine, as seen in the Ad Astra VX-200SS, looks good for long-term performance. The output power could be seen as modest, with few hundreds of Watts available, but this output will be very useful for the aforementioned needs of low gravity environments. A small number of VASIMR units will be enough to reduce mission time for almost every spacecraft actually in development, with all the obvious benefits.

So we have three different ways of propulsion to be used for our manned missions. Traditional chemical rockets, to be used to overcome the Earth’s gravity and put our astronauts in LEO, and two different systems to be used in low gravity: ion engines and VASIMR. A few days ago NASA granted ten USD millions to the Ad Astra company, in order to finance their projects. It’s a good omen for the future of this propulsion system but it’s still spare change.

What’s needed it’s a huge investment plan, aimed to multiply our efforts to create a habitat in the Earth-Moons system and to conduct manned missions to Mars and to the Asteroid Belt. We don’t have that much time to waste, nor we have better chances. Ready or not, we have to go.


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