NASA and SpaceX assessing possible Hubble altitude boost
NASA and SpaceX will study the feasibility of a commercial Crew Dragon flight to increase the altitude of the aging Hubble Space Telescope and even whether a limited servicing mission of some sort might be possible to help extend the observatory's useful lifetime, officials announced Thursday.
The six-month study will be carried out at no cost to taxpayers and will include input from Jared Isaacman, who commanded the first commercial SpaceX mission — Inspiration 4 — and who is financing another program called Polaris that includes two Crew Dragon flights and a piloted mission aboard SpaceX's new Starship rocket.
Isaacman said his team first thought about a Hubble reboost mission as a potential goal for the second Polaris mission.
But during a teleconference with reporters to announce the study, officials stressed no actual flights are being planned, saying the study is primarily focused on determining whether a Crew Dragon reboost mission, either piloted or uncrewed, is possible while ensuring the safety of the iconic telescope.
"There could be something that comes out of the study that says, 'Hey, it does not make sense to have a human mission going to do this,'" said Jessica Jensen, SpaceX vice president of customer operations and integration. "So we're going to look at all the different options. At this point, everything is on the table."
Isaacman already is planning a Polaris flight in 2023 that will carry him and three crewmates to a record high altitude for a piloted Earth orbit mission and include the first commercial spacewalk.
But the second Polaris mission does not yet have any announced mission objectives and could serve as a Hubble reboost mission if the study concludes such a flight is technically feasible using a Crew Dragon capsule.
"There are specific objectives that we're trying to achieve with each mission," Isaacman said. "Certainly, the idea of boosting and servicing Hubble, should the feasibility study support it, would be a logical second mission."
Unlike the now-retired space shuttle, which featured a 60-foot-long cargo bay and a 50-foot-long robotic arm, SpaceX Crew Dragon capsules have no external appendages. Hubble, however, was equipped with a grapple fixture during its final servicing mission, and SpaceX engineers may be able to come up with a mechanism that would allow a Crew Dragon to lock on.
"The inclusion of the soft capture mechanism in Servicing Mission 4 certainly makes a mission like this much more feasible and easier to talk about," said Patrick Crouse, Hubble Space Telescope project manager at NASA's Goddard Space Flight Center. "Part of the feasibility study is to see how that adapter is useful and what kind of accommodations may have to be made."
Like all spacecraft in low-Earth orbit, Hubble is subjected to atmospheric drag as it plows through atoms and molecules in the ultra-thin but still-present extreme upper atmosphere at 17,000 miles per hour.
When launched in 1990, the telescope was released into a 380-mile-high orbit — but over time, the altitude slowly but steadily dropped, or "decayed." During subsequent shuttle servicing missions, it was periodically reboosted.
At the end of the final shuttle servicing mission in 2009, Hubble's altitude was about 350 miles. Since then, it has dropped to an altitude of about 330 miles. If nothing is done, the telescope likely will plunge back into the lower atmosphere and break up in the mid to late 2030s.
"One of the things we'll look at is what is the maximum boost we could achieve?" said Crouse. "The preliminary assessment has been on the order of 40 to even, say, 70 kilometers (more than 40 miles) of boost."
"Certainly, if we were to get back to 600 kilometers, that's essentially the altitude we were at in 1990, so you'd add easily 15 to 20 years of orbital life to the mission if you could achieve that altitude," Crouse added.
Orbital altitude is not the only factor affecting Hubble's longevity. Only three of its six stabilizing gyroscopes are still fully operational, and other components and instruments are showing signs of age-related wear and tear. Along with studying reboost options, the NASA-SpaceX study also will consider whether a commercial mission offers an opportunity to carry out limited servicing.
Because the telescope does not have a propulsion system, an uncontrolled re-entry could result in debris hitting the ground and posing a possible threat to the public. Without a reboost of some sort, Crouse said NASA likely would start exploring options later this decade to attach a thruster to the telescope so it could eventually make a targeted end-of-life re-entry over a remote stretch of ocean.
In the meantime, NASA sees the joint SpaceX study as a model for coming up with innovative solutions, not just for Hubble but possibly for other spacecraft as well.
"We're super excited for the opportunity to conduct this feasibility study with NASA," said Jensen. "One of our main goals out of the study is going to be to take a closer look at how Dragon can safely rendezvous, dock, boost and therefore extend the Hubble Space Telescope operations."
"We obviously have a lot of experience (with) rendezvous and docking with the International Space Station," Jensen added. "So we want to use that as our foundation, but then innovate upon that. ... Really, we're just looking forward to studying what's possible and what's needed and working all this in coordination with NASA."