From the April 2019 issue

Who actually repaired Hubble?

No, Virginia, COSTAR did not fix Hubble.
By | Published: April 2, 2019 | Last updated on May 18, 2023
In John Ford’s classic 1962 Western, The Man Who Shot Liberty Valance, Jimmy Stewart plays Ransom Stoddard, a senator and former governor who owes his career to the moment when, as a young lawyer, he shot the villainous Liberty Valance. Of course, Stoddard did not pull the trigger at all; Tom Doniphon (John Wayne), a local rancher, did. A reporter, upon learning the truth late in Stoddard’s life, throws his notes in the fire and utters the famous words, “When the legend becomes truth, print the legend.” 

Astronomy has its own Man Who Shot Liberty Valance. It is the Corrective Optics Space Telescope Axial Replacement, or COSTAR. As most readers of Astronomy surely know, when the Hubble Space Telescope was launched, its mirror was badly flawed, turning the mission into what arguably would have been the most spectacular failure in the history of science.

Then, much like how Dr. Emmett Brown envisioned the flux capacitor in Back to the Future, the idea for COSTAR sprang into Jim Crocker’s head one day while he was in the bathroom. Hubble was saved! Or such is the legend. 

The thing is, COSTAR no more saved Hubble than Ransom Stoddard put a bullet in Liberty Valance.
What follows (edited for length) is some of my correspondence with the producers of a recent retelling of the legend, a 2015 episode of Nova celebrating Hubble’s 25th anniversary.

Perhaps in the grand scheme of things, none of this matters. Hubble went on to become one of the most impactful scientific endeavors of all time. Maybe the legend is enough. But some of us who were there still think people should know who really pulled the trigger.

NASA (2)


Dear PBS Ombudsman,

My name is Dr. Jeff Hester. I have appeared in a number of PBS productions over the years, including the NOVA Origins series. I was a member of the science teams responsible for the Wide Field and Planetary Camera (the camera that flew on the Hubble Space Telescope) and the Wide Field and Planetary Camera 2 (the camera that repaired the Hubble Space Telescope). I am also responsible for Hubble’s iconic “Pillars of Creation” image.

The recent NOVA episode “Invisible Universe Revealed” seriously misrepresents history. The most egregious error is the claim that COSTAR repaired the Hubble Space Telescope. In point of fact, roughly 70 percent of the science done with the instruments following the servicing mission (and almost 100 percent of the science that was deemed newsworthy) was carried out with WFPC2, which included its own correction and in no way depended on COSTAR. Of the remaining roughly 30 percent of the science, perhaps half of it was improved by COSTAR, while the other half was actually degraded by COSTAR because of its harmful effect on the throughput of ultraviolet light. COSTAR was at best a 15 percent solution.

Even so, in the NOVA episode nominally celebrating the 25th Anniversary of Hubble, COSTAR was represented as the “Savior of Hubble,” and those responsible for COSTAR were the stars of the show. No one involved with WFPC2 was interviewed at all. There was no mention of the Jet Propulsion Laboratory, which built the camera that fixed Hubble.

The program showed a group surrounding the monitors and celebrating the first images from Hubble after the servicing mission. It is my laugh that you hear above others in the clip. That group largely consisted of members of the WFPC2 science team and members of the WFPC2 support team at the Space Telescope Science Institute. Yet the program left viewers with the clear impression that we were seeing “post-COSTAR” images.

The idea that COSTAR repaired Hubble is a long-standing fiction promulgated by those at Goddard and elsewhere for their own reasons. The producers of “Invisible Universe Revealed” were content to listen to those inclined to further that fiction, while failing entirely to do journalistic due diligence. In my experience NOVA and PBS are typically far more responsible than this.

Best regards, 
Dr. Jeff Hester

Dear Dr. Hester,

I’m writing to let you know the status of NOVA’s “Invisible Universe Revealed” and the problems that you brought to the attention of the PBS Ombudsman over the show’s coverage of the repairs made to the Hubble Space Telescope. We’ve had extensive discussions about these issues and, as a result, we’re inserting new narration that makes it clear that as well as the ingenious fix that the COSTAR instrument represents in the show, an upgraded Wide Field Planetary Camera was designed with the corrected optics already installed, and it was this improved camera that has provided most of the stunning Hubble images that have made such a lasting impact on the public and on scientific research. The new version of the show will shortly be posted on  

Senior Science Editor