A Delta II rocket launched the Spitzer Space Telescope two decades ago, boosting it into an Earth-trailing orbit, where it flies away from our planet at a speed of about 15 million kilometers per year. It was the last of four NASA “Great Observatories” that were placed in space from 1990 to 2003.
During its planned five-year life, the infrared space telescope has done its job well, helping astronomers discover new stars, observe exoplanets, and study galaxies. After more than seven years, as scientists expected, the on-board supply of liquid helium ran out. Without this coolant, some of Spitzer’s scientific instruments would be unusable. So its operators switched to “warm mission” mode, gathering data from two of its shortwave channels.
The space telescope continued to operate until about three years ago, when the spacecraft began to overheat whenever it had to point back to Earth for communications. At this time, as it moves away from Earth, it is almost opposite the Sun. This means that running the telescope, and having it on the house phone from time to time, will irreversibly damage the rest of Spitzer’s scientific instruments.
So in January 2020, after more than 16 years of service, the Spitzer Space Telescope was deactivated—consigned to fly in a heliocentric orbit until the fiery expansion of the Sun at the end of its life a few billion years from now .
Or is it?
A small space technology company, Rhea Space Activity, says it has plans to revive Spitzer. Last week said the company it won a $250,000 grant from the US Space Force to continue studying a robotic rescue mission for the spacecraft, which is now about two astronomical units—or twice Earth’s distance from the Sun.
The plan is a bit daring, but it has some serious backers, including the Smithsonian Astrophysical Observatory, the Johns Hopkins University Applied Physics Laboratory, Blue Sun Enterprises, and Lockheed Martin.
“When it comes to robotic space servicing, this is going to be the most ambitious thing ever,” said Shawn Usman, an astrophysicist who is the founder and chief executive of Rhea Space Activity, in an interview with Ars. “I mean, it’s literally sending a satellite to the other side of the Sun to resurrect the last Great Observatory. So I think it’s a little ambitious, but it would be really great if we could do it.”
The “Spitzer Resurrector” mission will be a small spacecraft that can fit into a 1-meter-by-1-meter box and will be ready to launch as soon as 2026, Usman said. It will take about three years to travel to the telescope, during which the spacecraft will make observations of solar flaring.
“We plan to be busy from the very beginning of the mission,” said Howard Smith, an astronomer at the Center for Astrophysics, run by Harvard University and the Smithsonian, which is involved in the proposed rescue flight.
Once the resurrector spacecraft reaches the telescope, it will fly at a distance of 50 to 100 km to determine Spitzer’s health. It will then attempt to establish communications with the telescope and begin transmitting information back and forth between the ground and the telescope. This will allow scientists to restart observations.
Rhea Space Activity, named after the Greek goddess and currently has fewer than 10 employees, is seeking a larger grant from the military and, eventually, full funding for a mission expected to cost about $350 million.
“This is a wonderful collaboration between a private space company, academic research institutions, and the US Space Force,” said Giovanni Fazio, a Harvard University astronomer who is the principal investigator of the Infrared Array Camera at Spitzer.
Rhea Space’s effort is part of an emerging trend in the commercial space industry. Northrop Grumman is developing and launching a series of “mission extension” vehicles to service satellites in geostationary orbit. Billionaire Jared Issacman is working with SpaceX and NASA to use a Crew Dragon vehicle to extend the life of the Hubble Space Telescope.
The autonomous satellite technology developed by Rhea Space could have many applications for moving and servicing satellites in low-Earth and geostationary orbit. It is for in-space servicing, assembly, and manufacturing capabilities that the Department of Defense is interested in. Last year the White House published a report stating that advancing government and commercial capabilities in these areas is a priority for the United States.
Usman said the company has already had discussions with NASA about the mission, and the agency is likely to sign off on a rescue attempt. The space agency would welcome Spitzer’s return not only for scientific purposes, but to help identify the threat posed by near-Earth asteroids.
But is Spitzer healthy after all this time? It’s been two decades since Spitzer was launched, and the Resurrector mission won’t reach it until the end of this decade.
“Solar cells can be damaged, and there can be meteorite impacts,” Fazio said. “So it’s an uncertainty as to what condition the telescope is in. But our best estimate is that it’s still in an operating condition.”