Hubble has more time

In the article “Electric propulsion of spacecraft ” by Igor Levchenko, Dan Goebel, and Katia Bazaka (Physics Today, September 2022, page 38), the authors mistakenly refer to the Hubble Space Telescope’s “hydrazine thrusters.”

As project scientist for Hubble from 1972 to 1983—the period of its creation as a real piece of hardware, its design, and its early phases of construction—I clearly recall that thrusters of any sort were not incorporated. That was because UV performance could potentially be lost through contamination by any gas used in thrusters.

Levchenko, Goebel, and Bazaka mention that “the telescope could potentially spiral back to Earth by 2028.” Without a dedicated mission of another spacecraft to raise the orbital altitude of Hubble, the telescope will eventually decay into the upper atmosphere of Earth. That will cause Hubble to lose control of its pointing before finally making a fiery return. That is well in the future, with project leaders now estimating that there is a 10% chance that reentry will occur by October 2034, a 50% chance by July 2037, and a 90% chance by October 2045.