Free Astronomy Magazine March-April 2019

9 MARCH-APRIL 2019 systems today realistically imaginable would be able to push a spacecraft of a few tons up to a speed of about 1000 km/s, 50 times faster than that of the Voyager probes. This means that travel to the nearest extrasolar planets would last well over 1200 years, a period that largely exceeds typical human planning horizons. It is unlikely that a “launch- and-forget” mission, which requires enormous funding without bringing any benefit to those who allocate them, could be realized. Moreover, such long navigation times have to survive the life- time of the technological components, which on average would probably be less than a thousand years. Suppose that we want to be optimistic and hypothesize that the Genesis Project can actually be realized in the near fu- ture. In addition to the almost insur- mountable technical difficulties, which we leave out, there is left to solve the ethical issue linked with the desire to bring life forms where life might already exist, risking the annihilation of the au- tochthonous species. In order to avoid invading a planet that already hosts life, it would be necessary to investigate biomarkers in its atmos- phere beforehand, an operation that will be carried out within a few years through the new telescopes that are about to atmosphere of the chosen planet. According to Gros, this operation can be accomplished by using a magnetic field created by a supercon- ducting loop with a ra- dius of about 50 km, which, by attracting the free protons encountered towards the end of the travel, would transfer to those protons part of the spacecraft’s kinetic en- ergy. Equipping the latter with a device of that kind would increase the mass by about 1.5 tons, result- ing in a very strong re- duction in the maximum achievable speed. Gros estimates that the most efficient propulsion the appearance of prokaryotes, primi- tive organisms without a struc- tured nucleus. On the right, the ap- pearance of eu- karyotes, cells with a well-defined nu- cleus, from which the evolution of animals and plants occurred. [Getty/ Stocktrek Images] Above, the Cambrian explosion, during which there was an extraordinary evolu- tion and diversifica- tion of organisms thanks to the abun- dance of oxygen in the atmosphere. [Quanta Magazine]