During office hours, the average Dutch person looks at an uninspiring industrial estate. How different is it for astronauts? The space photo of the week is the view taken by astronaut Jeffrey Hoffman during the first Hubble service mission in 1993.

The Hubble telescope is a space telescope that has been hovering above the Earth’s surface for more than thirty years. Over the past decades, the telescope has been visited and/or maintained by astronauts a total of six times. The first time was in 1990 (STS-31) when Hubble was orbited from the space shuttle. The last time was in 2009.

Hubble needs glasses

Shortly after its launch in 1990, scientists discovered a problem with Hubble’s mirror. The telescope could not be focused and all photos were therefore less good than expected. An analysis revealed that the mirror had been polished to the wrong shape. The deviation should not be more than ten nanometers, but in the end the outer edge turned out to be 2,200 nanometers too flat. The cause of the error: an incorrectly adjusted null corrector. A null corrector is an optical instrument used for testing large aspherical mirrors. A lens of this null corrector was found to be installed 1.3 millimeters off the correct position and as a result the mirror was ground incorrectly. A costly mistake.

Error fixed

During the first service mission (ST-61) in 1993, astronauts installed two brand new instruments: the Wide Field & Planetary Camera 2 (WFPC2) and the Corrective Optics Space Telescope Axial Replacement (COSTAR). These two devices corrected the primary mirror problem, allowing astronomers and many more amateur astronomers to finally enjoy pin-sharp images of space.

For example, a year later the Hubble telescope took the famous and now iconic photo of the so-called pillars of creation, or the pillars of gas in the Eagle Nebula. In the decades that followed, thousands of other beautiful photos followed.

Can James Webb be repaired in space?

While the Hubble Space Telescope was designed to be repaired in space, the James Webb Telescope is not. This space telescope was launched at the end of last year and will start its scientific observations this summer. While the Hubble Space Telescope hovers about 550 kilometers above the Earth’s surface, the distance to the James Webb Telescope is 1.5 million kilometers. It is impossible for astronauts to visit this telescope and fix any mistake. After reading this you will probably understand why James Webb’s mirrors have been retested and checked many times and why the launch has been delayed several times in recent years.

Incidentally, the Hubble Space Telescope is no longer being repaired. The service mission in 2009 was also the last maintenance. More and more instruments are expected to fail in the coming years and the telescope will burn up in the atmosphere sometime between 2028 and 2040. This ends an era.

Over the past decades, space telescopes and satellites have captured beautiful images of nebulae, galaxies, stellar nurseries and planets. Every weekend we remove one or more impressive space photos from the archive. Enjoy all the photos? View them on this page.