Image: Artist’s impression of the Ramjet propulsion system
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Photo credit: NASA
There is a problem in science fiction stories about contact with extraterrestrial civilizations: what propulsion system could be used to bridge the enormous distances between the stars? This is not possible with ordinary rockets such as those used to go to the moon or Mars. To this end, many more or less speculative ideas were put forward – one of them is the “buzzard collector” or “ramjet drive”. Protons are captured in interstellar space and then used for a nuclear fusion reactor.
Peter Schattschneider, physicist and science fiction author, has now analyzed this concept in more detail together with his colleague Albert Jackson from the USA. For fans of interstellar travel, the result is unfortunately disappointing: It cannot work as Robert Bussard, the inventor of this drive system, thought up in 1960. The analysis has now been published in the journal Acta Astronautica.
The hydrogen collection machine
“The idea is definitely worth investigating,” says Prof. Peter Schattschneider. “In interstellar space there is very dilute gas, mainly hydrogen – about one atom per cubic centimeter. If one were to collect the hydrogen in front of the spaceship like in a magnetic funnel with the help of huge magnetic fields, one could operate a fusion reactor and accelerate the spaceship. “In 1960 Robert Bussard published a scientific paper on this subject. Nine years later, such a magnetic field was described theoretically for the first time “Since then, the idea has not only excited science fiction fans, but has also met with great interest in the technical and scientific space community,” says Peter Schattschneider.
Half a century later, Peter Schattschneider and Albert Jackson have taken a closer look at the equations. Unexpectedly, software developed as part of a research project at TU Wien for the calculation of electromagnetic fields in electron microscopy proved to be extremely helpful: the physicists were able to show that the basic principle of magnetic particle falling actually works. Particles can be collected in the proposed magnetic field and fed into a fusion reactor. In this way, considerable accelerations can be achieved – up to relativistic speeds.
Huge dimensions
However, when the size of the magnetic funnel is calculated, hopes of visiting our galactic neighbors quickly fade. In order to achieve a thrust of 10 million Newtons – this corresponds to the double main drive of the space shuttle – the chimney would have to have a diameter of almost 4,000 kilometers. A technically advanced civilization might be able to build something like this, but the real problem is the necessary length of the magnetic fields: the funnel would have to be around 150 million kilometers long – that is the distance between the sun and earth.
After half a century of hoping for interstellar travel in the distant future, it is now clear that ramjet propulsion, while an interesting idea, will only remain part of science fiction. If one day we want to visit our cosmic neighbors, we have to come up with something else.
diary
Space Act
Research method
Data / statistics analysis
Research subject
Inapplicable
Article heading
Visited the fishback ramjet again
Publication date of the article
14-December-2021
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