By: Lea S. ‘20

The Hubble Space Telescope launched in 1990. On April 24th, 2018, Hubble ushered its 28th birthday. During these twenty-eight years, it opened a window to observe the universe. It gave us a chance to travel through the mystical cosmic world. In people’s mind, Hubble is not only a telescope, it is also a sign, a legend, an era that many people can’t forget. At twenty-eight years old, the Hubble era is almost reaching an end. During its time in service, Hubble met many failures, such as aging equipment. So far, the astronauts have completed five high-profile repairs. Although the Hubble Space Telescope is a high-spending project, in many researchers’ opinions, the brilliant life of Hubble is also the golden age of astronomy research because, after each mission, people have had significant astronomical discoveries through the Hubble Space Telescope. Let’s recall our memory about the five-servicing mission completed for Hubble.Shortly after the Hubble was deployed in 1990, the observatory’s primary mirror was discovered to have an aberration that affected the clarity of the telescope’s early images. In that case, correcting the optics of the flaw in Hubble’s primary mirror was a task of top priority. The seven astronauts who were chosen for their mission received intensive training. As we know, the Hubble is the largest telescope in the world. Its size is equivalent to four big telephone kiosks and four pianos. As a result, it’s very difficult to repair. More difficult, the astronauts need to repair it in a weightless environment. The astronauts launched in December 1993. Then, new instruments were installed, and the major problem was solved. In addition, this servicing mission was the first time they conducted planned maintenance on the telescope. One of the most important things during SM1 is that COSTAR, which is the instrument designed to correct Hubble’s spherical aberration for light, replaced the High-Speed Photometer. Another significant thing is that the Wide Field and Planetary Camera 2 (WFPC2) was replacing the telescope’s original camera. In a nutshell, these two replacements have resulted in a dramatic increase in the clarity of the photos the Hubble takes. The success of this mission not only brought extremely high praise to NASA, but also gave astronomers a telescope which is fully competent for space exploration.

Although the subsequent servicing missions have not been as dramatic as the first one, each time new capabilities have been added to the Hubble. The SM2 was launched in February 1997. It happened four years after the first mission and greatly improved the Hubble’s productivity from two aspects. First, they installed some new instruments which extended the Hubble’s wavelength range, allowing us to probe more distant reaches of the universe. Second, the replacement of failed or degraded spacecraft components increased efficiency and performance.

In November 1999, when the fourth of six gyroscopes failed, the Hubble temporarily closed its eyes on the universe. Gyroscopes are important because they measure the rate of motion as the Hubble moves and help the telescope retain correct pointing during observations. Without working gyroscopes, the Hubble “went to sleep” while it waited for help. As soon as possible, NASA decided to split the Third Servicing Mission into two parts, SM3A and SM3B. Through SM3A, Hubble became more fit and capable than ever before. They gave Hubble a big update, including six fresh gyroscopes, a more powerful and faster main computer, and many other new and improved equipment. SM3B was launched in March 2002. It was the fourth visit to Hubble. In this mission, Advanced Camera for Surveys (ACS) replaced the previous camera. This is a milestone in the study of astronomy because the Hubble would give people superb quality images through this camera. It means ACS would have ten times more discovery power than the camera it replaced. More importantly, it gave astronomers an opportunity to study the nature and distribution of galaxies in order to understand how our universe evolved.

The last servicing mission was launched in May 2009. During SM4, two new scientific instruments were installed – the Cosmic Origins Spectrograph (COS) and Wide Field Camera 3 (WFC3). With these efforts, Hubble has been brought to the apex of its scientific capabilities.

After these five servicing missions, the Hubble Space Telescope has become the largest and most accurate telescope ever built. It can take pictures of hundreds of stars with more than ten times the sharpness of a terrestrial astronomical telescope. The achievements of the Hubble are indelible. The Hubble is the faithful recorder of this charming universe. It is the eye for human beings to see the fascinating universe. Astronomers believe that the Hubble telescope will still deliver the goods and complete its historic mission until it is eventually replaced by the James Webb Space Telescope. Let us all witness the miracle that the Hubble will create for us for the rest of the year!

Happy Birthday, Hubble!