Why the space telescope could simply burn up

No other research instrument is as popular around the world as the Hubble Space Telescope. For many years it has provided spectacular images of planets, stars and distant galaxies. "Hubble", which was named after the American astronomer Edwin Hubble, has made the universe tangible and aroused the interest in astronomy in many people. You could also say it revolutionized astronomy.

"Hubble" has now been in use for more than three decades. The telescope, which works in the visible wavelength range, was put into orbit in 1990 with the "Discovery" shuttle. Since then it has sent more than 1.5 million recordings to Earth.

The photos taken by "Hubble" are not only of great aesthetic appeal, they also provide the astrophysicists with relevant new insights. So far, scientists have reported on discoveries made by Hubble in more than 19,000 peer-reviewed articles.

The big advantage of "Hubble" compared to terrestrial telescopes is that it does not have to look through the earth's atmosphere into the depths of space. Neither rain clouds, dust particles nor air turbulence impair "Hubble's" crystal-clear view.

Hubble's capabilities have actually increased over time. During maintenance missions, defective parts were replaced or parts that were still working were replaced with better ones. Hubble was last serviced in 2009. Since then everything has been running smoothly and it is not at all foreseeable how long the telescope will continue to provide images.

However, "Hubble" does not have its own engine. And that means the space telescope will eventually burn up in Earth's atmosphere. Even at an altitude of 530 kilometers above the earth, there are still molecules in the earth's atmosphere that cause a little friction.

As a result, "Hubble" loses energy and enters lower orbits. The deeper the orbit, the more air particles there are and the greater the friction. So the process of descent becomes faster and faster over time. If "Hubble" is not lifted back into a higher orbit with outside help in the meantime, the telescope is likely to burn up in the earth's atmosphere in an estimated 20 years.

The question now is: Can and do we want to prevent this end? Should "Hubble" be kept operational for decades to come? In any case, the American space agency Nasa has called on space companies to make suggestions on how the famous space telescope could be saved.

It would be conceivable, for example, that a SpaceX Crew Dragon capsule could fly to "Hubble" and lift the research instrument to a higher orbit. If one were to decide on such a project, it would also have the sentimental aspect of not letting the pioneer of space telescopes burn up. After more than three decades of scientific and technical progress, it might make more sense to build a "Hubble II" with the latest measurement technology.

One of the highlights of the "Hubble" observations is the collision of an asteroid with the giant planet Jupiter. This crash could be followed live thanks to "Hubble". Without "Hubble" it would not have been possible to track the orbit of the mysterious object Ouamuamua. This interstellar asteroid paid a brief visit to our planetary system in 2017.

Hubble has discovered moons orbiting the dwarf planet Pluto and observed star births in cosmic clouds. Last but not least, "Hubble" has discovered numerous exoplanets, i.e. planets that do not orbit our sun, but a distant star.

However, the James Webb space telescope, which went into operation this year, is much better suited for exploring the atmospheres of these exoplanets. In contrast to "Hubble", it can also carry out measurements in the infrared wavelength range.

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