Launched in 1990, the Hubble Space Telescope continues to serve the scientific community today, not to mention the impact it continues to have on the general public. But in addition to the technical problems caused by advanced age and the loss of altitude caused by interaction with the atmosphere, researchers using the Hubble Space Telescope to make scientific measurements face a new problem: constellations of satellites in low Earth orbit that affect observations of space telescope

After being launched into orbit, the Hubble Space Telescope was visited by shuttle crews during 5 servicing missions. The first such mission made it usable because the telescope was launched with a problem with the main mirror. The last such mission took place in 2009, just two years before the space shuttles were finally retired. During these missions, the telescope was repaired and upgraded, and docking with the space shuttle allowed the telescope’s orbit to be raised each time at the end of the maintenance missions, thus counteracting the effects of atmospheric friction.

Even at an altitude of 650 km, at which the telescope was originally placed, this effect is felt, and the height at which the telescope is located decreases with time. Since the Hubble telescope has no engines on board, this means that it cannot raise its altitude on its own, so its orbit will continue to deteriorate, and sometime after 2030, if no action is taken, it will plunge destructively into the atmosphere. That is unless another technical failure renders it unusable by then, because in recent years there have been some problems with the gyroscopes that keep the telescope oriented around its center of mass.

Currently, according to data provided by the North American Aerospace Defense Command (NORAD), the Hubble Space Telescope is at an altitude of about 530 km, which is 100 km closer to Earth than its original altitude. This in itself would not be a problem, but in 1990 no one anticipated the problems that modern satellite arrays, especially Starlink, are causing today.

Starlink satellites are initially launched at an altitude of just over 200 km, from where they use their onboard ion thrusters to slowly but surely reach a nominal operating altitude of 550 km. That is, at an altitude of 20 km above the orbit of the Hubble Space Telescope, there are thousands of Starlink satellites in the sky (half of the active satellites in orbit today are Starlink satellites).

Added to these are several hundred OneWeb satellites already in orbit (at an altitude of 1200 km), without mentioning the future launches of satellites in low Earth orbit (I mean the Kuiper satellites, as well as the Chinese Constellations and the Europeans that will be launched ). This means that this problem will worsen in the future.

Sandor Kruk, a Romanian astrophysicist and researcher at the European Space Agency (ESA), draws attention to this problem in an article recently published with a group of researchers in the journal Nature Astronomy (and also picked up by the New York Times ): according to statistics, currently almost 6 of 100 images taken by the Hubble telescope were affected by satellites that pass through the frame and leave light trails on the pictures taken by the telescope, compared to almost 4 affected images in 100. captured, from 2009-2020. And these numbers will become larger and larger in the future, when new constellations will appear in low Earth orbit.

One solution that SpaceX and NASA are currently working on is a mission to the Hubble Space Telescope, which will raise its orbit to its original altitude, that is, to an altitude of more than 650 km. This would temporarily solve one of the problems by placing the telescope above the layer of Starlink satellites, but it would not solve the problem of other constellations that might choose higher orbits (such as the current OneWeb satellite orbits).

Billionaire Jared Isaacman (former member of the private Inspiration-4 mission) is also involved in this mission, and it is possible that the SpaceX crew will visit the Hubble Space Telescope as early as next year with NASA’s permission in one of the Isaacman-funded Polaris Missions.

But the problem is not only with the Hubble Space Telescope, but also with any space telescope placed in low Earth orbit (Hubble is not the only one, but only the most famous). Later this year, China will launch its own Hubble-like Xuntian Space Telescope, which will probably be placed at an altitude of 400 km, near the Chinese space station (from where it will be visited periodically by taikonauts). . Fortunately, the James Webb Space Telescope is safe, located at the L2 Earth-Moon Langrange point, well above the Starlink and OneWeb satellites. Also, a future NASA telescope named Nancy Grace Roman will be launched towards this Lagrange point.

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