What goes up must come down—if you don’t do anything about it.
NASA launched the Hubble Space Telescope in 1990, and in the decades since scientists have benefitted from its unprecedented views far beyond our galaxy. And even though its successor, the James Webb Space Telescope, is now performing its own exploration even further into the cosmos, the Hubble can do plenty of useful astronomy.
But Earth’s gravity and atmosphere will inevitably pull the bus-sized telescope back to the planet, perhaps as soon as 2028. NASA will need to safely bring it back down to crash into the Pacific Ocean, or better yet: Lift it into a higher orbit so it can continue its mission, which has already cost the US about $16 billion since the idea for the telescope was conceived in 1977.
It’s a tantalizing idea for space companies of all stripes. Elon Musk’s SpaceX has partnered with Jared Isaacman, the founder of payments company Shift4, on a series of space tourism missions onboard its crewed Dragon spacecraft. One project Isaacman has proposed is flying to the Hubble and raising its orbit to keep it at work for another decade or more.
Now, two space start-ups that have emerged in SpaceX’s wake—the space servicing company Astroscale and the space tug builder Momentus—have teamed up with their own proposal to rescue the iconic observatory. The firms are developing the technology needed to fly a robot to the Hubble, have it grapple the telescope with a robotic arm, and use a water-fueled propulsion system to slowly lift it 100 km (62 miles) higher.
The difficult task of repairing spacecraft in orbit
The Hubble Space Telescope has been serviced in orbit five times before, most recently in 2009, with astronauts using the Space Shuttle and its robotic arm to latch onto the telescope. Then, they could perform space walks to install new scientific instruments, change batteries, and notably repair a damaged mirror. Humans were required because robots weren’t capable of the delicate work.
With the Space Shuttle retired, the only way to get astronauts to the Hubble is onboard the Dragon. The vehicle doesn’t have its own robotic arm, and it’s not clear exactly how it would link up to Hubble. But Dragon’s experience docking autonomously with the International Space Station gives it the tools it needs to maneuver close to the Hubble, and its propulsion system has the power to raise its orbit.
However, unlike past missions where astronauts had to get inside the Hubble, there’s no obvious reason this mission requires people in proximity—and keeping astronauts alive and comfortable in space is expensive and difficult. A robotic mission would likely be cheaper and just as effective, and the technology to robotically service satellites is now coming into its own with potential for broad use.
Notably, Northrop Grumman has used an autonomous vehicle to grapple a communication satellite and extend its life an additional five years and is developing additional missions based on that design. The US government has a national strategy to develop the kinds of complex software, sensors, and robotic systems to fix and dispose of satellites in orbit. These capabilities are seen as a precursor to more ambitious plans to manufacture goods in space.
A joint venture to rescue Hubble
Astroscale and Momentus are both working on products intended to be the infrastructure for orbital activity.
Astroscale, a Japanese company with subsidiaries in the US and UK, is focused on space debris and satellite servicing; its first mission saw its ELSA-D spacecraft rendezvous, inspect, and grapple with a target. Now, among other tasks, it is working with Japan’s space agency launch a mission to inspect a rocket body in orbit, and to develop the tools needed to service different satellites.
Momentus was founded to build orbital transfer vehicles or space tugs, which can be used to deploy satellites to specific orbits after launch, or carry payloads like sensors or communications tech as virtual satellites for other companies. It was originally founded by Mikhail Kokorich, a Russian space entrepreneur, but when Momentus went public through a SPAC transaction in 2021, Quartz reported that Kokorich was under a federal investigation and had been forced out of previous US space firms because of rules designed to protect technology with military applications from rival nations. After agreeing to a $7 million settlement with the Securities and Exchange Commission, Momentus transitioned to a new management team led by CEO John Rood, and recently completed its first orbit-raising maneuver with its Vigoride spacecraft.
That speaks to the complementary nature of the two firms’ Hubble proposal: Momentus will supply a Vigoride spacecraft and the company’s water-fueled propulsion system, which CTO Rob Schwarz says strikes a balance between the efficiency of an electric thruster and the power of a chemical rocket engine. Astroscale will add the package of sensors and software to carefully approach another spacecraft, and a robotic arm to latch onto the space telescope. Then, the vehicle could slowly lift the Hubble to a higher orbit over a period of about 64 days. The companies think they could have the mission ready in less than two years.
“A robotic solution is not only the solution that’s best suited to accomplishing the objectives of the mission cost-effectively,” Ron Lopez, the president of Astroscale US, told Quartz. “[This is] also an opportunity as a matter of good public policy to invest into this growing segment of the market of on-orbit servicing and in-space manufacturing.”
But is the price right?
SpaceX interest in the Hubble mission (and Isaacman’s apparent willingness to take it on at no cost to the government) led NASA to ask interested companies to share how they would go about boosting the Hubble—for free. NASA’s request for information notes that “[p]artner(s) would be expected to provide...the launch vehicle, spacecraft, crew if applicable to the approach, and mission operations...necessary to successfully perform the demonstration.”
Between SpaceX’s resources and Isaacman’s deep pockets, that might not be a big deal. Momentus and Astroscale, however, are still young companies with limited resources. Part of the logic of their joint venture is to share the costs of the mission, which would likely be on the order of tens of millions of dollars, far less than flying the Dragon, which costs more than $200 million for a four-person NASA mission.
For Momentus, performing the mission would be an advertisement for its capabilities and a chance to impress NASA, one of the largest buyers of space services.
“A lot of other assets that are not Hubble class would benefit from a servicing mission, but it would have to be a low-cost servicing mission. The business case can still close,” Schwarz says. “If we do invest, we get to demo our tech, get a lot of public visibility.”
Astroscale’s Lopez held out hope that NASA might be willing to invest in the mission through a public-private partnership with a fixed price contract, though he didn’t share specific figures. He noted that NASA has seen good return on investments in other commercial technology, like SpaceX’s Falcon 9 rocket, and that European and Japanese space agencies are funding more missions focused on space sustainability.
“This is an opportunity for NASA to do what it has always done,” Lopez said. “To enable and engender innovation.”