34 years since the launch of the Hubble telescope. How could we further extend its operational life?

On April 24, 1990, Space Shuttle Discovery left platform 39B at NASA’s Kennedy Space Center in Florida to begin mission STS-31, the thirty-fifth of the Space Shuttle program. The main purpose of the mission was the deployment in low Earth orbit of what, to date, is a veteran of the exploration of the cosmos: the Hubble Space Telescope.

Today, 34 years later, Hubble is still orbiting in Earth’s extremely tenuous upper atmosphere, and still observing the cosmos on a daily basis. However, over time its orbit is progressively decaying due to atmospheric resistance.

The exact date when Hubble can no longer remain in orbit will depend on how active the Sun is and its impact on the upper atmosphere. Based on current knowledge of solar activity and atmospheric drag, it is estimated that a natural atmospheric reentry for Hubble will occur between 2028 and 2040. There is currently a 50% chance that Hubble will return by 2037. In November 2021, NASA then extended the service contract for Hubble until June 2026.

In recent years, however, NASA has floated the idea of ​​launching a service mission that could take Hubble to a higher, more stable orbit. A study was actually conducted by SpaceX between 2022 and 2023 to study the feasibility of doing this with a Crew Dragon capsule.

A crazy idea. Or maybe not?

Several space officials have said they believe a relaunch mission of some kind, involving Crew Dragon or another robotic spacecraft, is feasible with current capabilities. This would help extend the life of Hubble, which is still operational and could continue doing science for at least another two decades.

There is more skepticism about the ability to repair Hubble, given the complexity of such work. Dragon, for example, lacks capabilities such as an airlock and robotic arm for maintenance, while robotic systems have yet to demonstrate the ability to perform advanced repairs in orbit. But orbital lifting would instead be absolutely evaluable.

The SpaceX project

In September 2022, NASA and SpaceX announced that they had signed an agreement to investigate the possibility of designing a mission to lift Hubble and extend its operational life possibly another 20 years.

The study involved SpaceX and billionaire astronaut Jared Isaacman and involved a privately funded mission, without any government costs. Isaacman had suggested, again at the end of 2022, this mission as the second of the Polaris Program.

The basic concept of the mission implied the docking of a Crew Dragon capsule to Hubblepossibly using a capture mechanism installed during the Space Shuttle’s last service mission in 2009, and raising its orbit.

Hubble’s orbit is currently about 525 km above the surface. The mission should have bring it back to 600 kmthe height at which it was after its launch in 1990. However, there would have been no maintenance or repair work on the telescope.

While SpaceX has extensive experience with Dragon missions to the International Space Station, it has not yet attempted any type of satellite reboot or maintenance. It would therefore be the first mission of this type. The study lasted six months and ended in early 2023, however neither NASA nor SpaceX have commented on the results or next steps.

Other proposals

SpaceX isn’t the only possibility to extend Hubble’s life, either. In fact, at the end of 2022, NASA issued a Request for Information looking for projects for commercial missions that could revive Hubble, which however the Agency would not finance.

NASA received eight different responses, including one from satellite services company Astroscale in collaboration with space transportation company Momentus. The two companies proposed working together to attach a vehicle to the telescope and raise its orbit. Their concept involved using technologies Astroscale is developing to dock with and extend the life of satellites and orbital transfer vehicles from Momentus.

In the proposal, a Momentus orbital service vehicle, launched on a small launch vehicle, would approach Hubble, docking with it with Astroscale technology. The vehicle it would increase Hubble’s orbit by 50 km before undocking, and could then be used to remove orbital debris in orbits approaching Hubble.

NASA has not yet commented on the outcome of the proposed reviews of Astroscale and Momentus, or the other projects received.

Long live Hubble

NASA’s original plan to safely deorbit Hubble was to recover it using a Space Shuttle. Most likely, Hubble would have been exhibited at the Smithsonian Institution.

This is no longer possible since the Space Shuttle fleet was retired, and would have been unlikely anyway due to the cost of the mission and the risks to the crew. Instead, NASA considered adding an external propulsion module to enable controlled reentry. In 2009, as part of the Space Shuttle Servicing Mission 4, NASA installed the Soft Capture Mechanism (SCM) on Hubble, to enable deorbit via a manned or robotic mission.

We still don’t know for sure what the American Agency’s exact plans are for the future of Hubble. However, we know that the telescope remains in good operating condition, which is still enabling important research on the cosmos, which is collaborating with its successors. And if he really still had twenty years of operation ahead of him, who knows what his work combined with that of the new generation space telescopes could make us discover…