Despite the fact that 60 years have passed since humanity entered the space age, progress in space expansion is very insignificant. Even less progress has been made in the speed of travel through our solar system.
Modern rocket engines make it possible to reach the Moon within an acceptable time frame. The flight to the planets of the solar system takes years, and some missions to study them become the work of several generations of people.
An illustrative example is the Voyager and Pioneer programs, whose probes have been surfing the vastness of the solar system for half a century.
Why is that? Firstly, the Universe is huge, and secondly, movement in outer space has a number of fundamental limitations that do not contribute to the conquest of space at all.
Even if we do not take into account biological factors, but operate purely technical ones, the projects of interplanetary travel seem to be very limited.
Today, one of the methods of movement in outer space implemented in practice is jet propulsion. According to Newton's third law (the force of action is equal to the force of reaction), in order to push off from emptiness and start moving, it is required to discard part of its own mass. Alas, there is no other effective way to travel far from massive celestial bodies (stars and planets) today.
To effectively move around the solar system, we use gravity assist around the planets. This gives the spacecraft more speed with minimal energy and fuel consumption. But still, flights to the outer planets of the solar system last for years.
In general, during jet propulsion there is a direct dependence on the rate of fuel flow and its mass. The greater these physical quantities, the greater the speed the spacecraft will develop.
Here we have one way out - to increase the rate of fuel expiration: the higher it is, the less fuel will need to be taken with us.
The physical processes that take place during the chemical oxidation reactions that are used in today's rocket engines to create thrust are limited by the flow rate of 5 km per second (specific thrust).
It turns out that spacecraft of gigantic proportions with huge amounts of fuel are required to travel through the solar system in a reasonable time. This is completely unacceptable in terms of the cost of resources for this trip.
But the principles of jet propulsion can be implemented not only by classical chemical rocket engines, but also by many others.
For example, thrust in ion engines is created due to the outflow of charged particles - ions. They are accelerated thanks to the electromagnetic field, and the rate of ion outflow is tens of times higher than that of chemical engines.
Ion engines are very energy efficient and consume little fuel. The disadvantages are very small traction.
However, the ratio of the amount of fuel on board to the useful mass of the ship and the speed that it can develop is in favor of the ion engine.
For example, the "Deep Space 1" space probe with a mass of 373.7 kg reached a speed of 4.3 km / s, while consuming 74 kg of xenon.
The spacecraft "Dawn" in an arc accelerated to 41 km / sec. Its ion engine consumed only 280 grams of xenon (working fluid) per day.
Fuel efficiency is excellent, but the spacecraft acceleration time (an increase in speed of 97 km / h every 4 days of operation of the engines) is still too long for the effective expansion of the solar system.
But here, too, there is one encouraging fact: a small increase in engine specific thrust leads to a significant reduction in fuel consumption.
According to Tsiolkovsky's formula, with the same mass of the spacecraft, a speed of 16 km / second (the minimum speed for free travel in the solar system) will be achieved by consuming 1300 tons of fuel at a specific thrust of 3400 m / s, and 380 tons at a specific thrust thrust of 4550 m / s.
The record for ion expiration in ion engines today is 210 km / sec, which is 50 times more than today's chemical rocket engines. In other words, an ion engine is 50 times more efficient than chemical rocket engines in terms of weight, size and fuel economy.
Next in terms of efficiency is one of the varieties of electrostatic rocket engines - a stationary plasma engine.
The plasma engine has a higher concentration of ions in the working chamber, which gives more thrust with the same mass-dimensional characteristics with the ion engine. And the energy can be supplied to them thousands of times greater power. And this already makes it possible to effectively use the plasma engine as a propulsion engine for a spacecraft.
Work on such engines is already underway. An example of this is the American VASIMR plasma engine with a capacity of 200 kW and the Russian "BPRD" with a capacity of 100 kW.
The thrust of these engines is already enough for a spacecraft weighing 1 ton to reach Mars in 41 days. Agree, this is already better than flying for 6-12 months on a chemical rocket engine.
However, such engines are already very energy-demanding, and megawatts of electrical energy are needed to implement the concept of flight on plasma engines.
And today it is the only realizable technology that will provide manned travel to the planets of the solar system in a reasonable time frame.
So, according to calculations to Jupiter and back, "Zeus" on ion engines "ID-500" will consume only 2 tons of fuel (taking into account the use of gravity assist maneuvers).
The flight of "Zeus" to Mars on a plasma engine of the "BPRD" or "VASIMR" type, according to calculations, will take only 1.5 months (with full deceleration in its orbit), and the fuel supply (10 tons) will be enough to return back to Earth. In this case, the crew will be independent of the so-called
flight window, which opens every 2 years for a flight to Mars. In the worst case, the flight will take 3-4 months instead of 1.5.
At the same time, the fuel efficiency is simply amazing. So, for example, if we use all the matter in the universe (10 to the 53 power of kg) as fuel, for example, for the usual chemical rocket engine Elon Musk "Raptor", then "Starship" will develop a speed of only 500 km / s and then fuel will end.
"Zeus" will develop a similar speed, having spent only 12,000 tons of fuel.