Could astronauts travel to Jupiter

Exploration of the universe part 3: Jupiter and Saturn

Almost a second sun

In its composition, Jupiter is more like the sun than the terrestrial planets. It consists almost entirely of gases, primarily hydrogen and helium. The decisive difference to the sun lies in the mass. Stars like the sun release radiant energy over a long period of time by converting hydrogen to helium. Very high temperatures and extreme pressure are required for this nuclear fusion. Stars have such a large mass that these conditions are met. Although the pressure and temperature in Jupiter's atmosphere also increase sharply with increasing depth, the mass of the planet is not sufficient to achieve the values ​​required for nuclear fusion processes. In order for nuclear fusion processes to start at all, a celestial body must combine at least thirteen Jupiter masses and hydrogen fusion does not start until at least 80 Jupiter masses. Our sun has a mass of 1,048 Jupiter, making it an average star.

A bright point in the night sky

From Earth, Jupiter can also be seen in the night sky with the naked eye. Most nights it is the third brightest object after the moon and Venus. In the telescope, Jupiter does not appear as a circular disk, but rather has a clear flattening at the poles. The reason for this are the centrifugal forces that arise from the extremely fast rotation of the planet. Jupiter only needs ten hours to complete one revolution, making it the planet in our solar system that rotates the fastest on its own axis. Jupiter completes one orbit around the sun in eleven years, 315 days and three hours.

The pronounced banding of its atmosphere can be seen on better-resolved images of the planet. The bands are wind structures that orbit the planet with different relative flow speeds parallel to the equator. The bands are divided into lighter zones and darker belts. In addition to the zones and belts, there are also smaller local structures, the most noticeable of which is the so-called Great Red Spot. This is a huge cyclone that has existed for at least 300 years. It is so large that it can also be seen in amateur telescopes, and it is believed that wind speeds of over 600 kilometers per hour are reached at its edges.

Dangerous radiation

Jupiter has the largest magnetic field of all planets in our solar system. On the side facing away from the sun, it protrudes as a long tail a good 700 million kilometers into space and thus almost as far as Saturn's orbit. On the side facing the sun, the magnetic field interacts with the solar wind consisting of charged particles and is compressed in the process. Nevertheless, its extension in the direction of the sun is still over seven million kilometers. The radiation belt that surrounds Jupiter is correspondingly large. The extended magnetic field constantly traps charged particles from the solar wind and Jupiter's moons. Once trapped, particles follow the magnetic field lines on spiral paths and swing back and forth between the poles at high speed. Due to their high energy, they are able to knock electrons out of atoms or molecules. The radiation belt therefore poses a danger to space probes.

Jupiter probes

Jupiter has already been visited by several space probes. The majority of the probes only completed fly-bys or carried out measurements during a swing-by maneuver on the way to other destinations. The first Jupiter orbiter was NASA's Galileo probe, which orbited the planet for more than seven years. During this time she collected a rich treasure trove of data, which due to a malfunction of the primary antenna could only be partially transmitted to earth. Part of the mission was also an entry capsule that was immersed in the planet's atmosphere and provided information about temperature, pressure, wind speed and chemical composition.