The Hubble Space Telescope - Out of the Ordinary...Out of this World

Hubble Space Telescope History:

Lyman Spitzer Jr.

Although the Hubble Space Telescope has been in orbit since 1990, its origins date long before that. After World War II, the first concepts of a space-based optical observatory began. In 1946, Lyman Spitzer, a professor and researcher at Yale University, described how a telescope actually in space would enable us to have much better images. He published his work, Astronomical Advantages of an Extra-Terrestrial Observatory, which explained that the Earth's atmosphere causes distortion of light coming in from the stars, it also "prevents most forms of light from reaching the ground at all" (8). Even the most technologically advanced telescopes positioned on Earth couldn't produce as good of a picture as one in space could. Also, X-rays emitted from high-temperature phenomena in stars and other objects are blocked by the Earth's atmosphere, so they cannot be detected by instruments on the Earth's surface. A space telescope would be the solution to overcoming these problems. (1)(7)

In the mid-1960s, NASA and its contractors conducted multiple studies to decide whether or not such a project could be completed. Over time, NASA could see the probability of building this telescope was possible and necessary. In 1971, George Low, NASA's Acting Administrator, gave approval to the Large Space Telescope Science Steering Group to conduct studies to decide how this may come true. (1)

In 1972 design of the telescope began. Perkin-Elmer Corporation was chosen to construct the mirror and optical assembly and the Lockheed Missiles and Space Company to construct the spacecraft and its support systems. The Europeans were chosen to develop the solar array that would power Hubble while in orbit. The most important aspect of the telescope, the mirror, would be completed by a computer-based laser grinding system used by Perkin-Elmer. (1)

Edwin Hubble

The space telescope was named the Hubble Space Telescope, after American astronomer Edwin Hubble, who proved that the universe was expanding through is discoveries of "fuzzy patches" which were actually other distant galaxies. Hubble's launch was scheduled for October 1986 but on January 28, 1986, the Space Shuttle Challenger exploded almost immediately after take-off. Shuttle flights ceased for two years. The finished telescope parts were moved into storage. During this time, those working on the Hubble improved its parts and made technical tweaks. On April 24, 1990, Hubble finally launched into orbit aboard the Space Shuttle Discovery. The telescope carried five instruments: The Wide Field/Planetary Camera, the Goddard High Resolution Spectrograph, the Faint Object Camera, the Faint Object Spectrograph and the High Speed Photometer, which are all mentioned below. (3)

Hubble...We Have a Problem:

The Hubble Mirror

When the HST was launched, we now had a new eye in the universe. Once in orbit, all seemed well with the telescope and all seemed to be working properly. The first pictures were taken on May 20, 1990. The photographs transmitted back to Earth successfully, yet experienced astronomers found the images to be somewhat blurry. Engineers attempted to adjust the lens, but after several weeks after not solving the problem, they realized the problem must be in the mirror. After engineers inspected an identical backup mirror they discovered than the central region of the mirror was too flat by just a few nanometers. This mistake unfortunately reduced the resolution of the telescope so that when focused, it wasn't able to gather the 80 percent of light needed to produce a clear image, but only 15 percent. The mistake was devastating to the $1.5 billion project. The mirror itself could not be repaired or exchanged deep in space, so NASA engineers went to work to develop corrective optics for Hubble's mirror. Astronauts were actually sent up into space to go fix the problem, and the mission was a total success. (2)

The Telescope:


Every 97 minutes, Hubble completes a revolution around Earth, moving at the speed of about five miles per second (8 km per second) — fast enough to travel across the United States in about 10 minutes. While in orbit, the Hubble's mirror captures light and directs it into its several science instruments listed below. Hubble is a type of telescope known as a Cassegrain reflector, a type of reflector telescope. Light hits the telescope's primary mirror and then bounces off the primary mirror and encounters a secondary mirror. The secondary mirror focuses the light through a hole in the center of the primary mirror that leads to the telescope's science instruments. As in anyone familiar with telescopes could tell you, the magnification is the least important part of a telescope. Instead, we want to gather as much light as possible. The larger a telescope's mirror, the more light it can collect, and the better its vision. Hubble's primary mirror is 94.5 inches (2.4 m) in diameter. This mirror is small compared with those of current ground-based telescopes, which can be 400 inches (1,000 cm) and up. However, as Spitzer had explained, Hubble's location beyond the atmosphere gives it remarkable clarity. Once the mirror captures the light, Hubble's science instruments work together or individually to provide the observation. Each instrument is designed to examine the universe in a different way. Let's take a closer look... (3)

Path of Light in the Hubble


When light strikes the concave primary mirror of the Hubble Space Telescope, it is reflected to the convex secondary mirror, then back through a hole in the center of the primary mirror. There, the light comes to the focal point and passes to one of Hubble's instruments. (4)


The Wide Field Camera 3

The Wide Field Camera 3 (WFC3) sees three different kinds of light: near-ultraviolet, visible and near-infrared, though not simultaneously. Its resolution and field of view are much greater than that of Hubble's other instruments. WFC3 is one of Hubble's two newest instruments, and will be used to study dark energy and dark matter, the formation of individual stars and the discovery of extremely remote galaxies previously beyond Hubble's vision. (4)

Cosmic Origins Spectrograph

The Cosmic Origins Spectrograph (COS), Hubble's other new instrument, is a spectrograph that sees exclusively in ultraviolet light. Spectrographs acts something like prisms, separating light from the cosmos into its component colors. This provides a wavelength "fingerprint" of the object being observed, which tells us about its temperature, chemical composition, density, and motion. COS will improve Hubble's ultraviolet sensitivity at least 10 times, and up to 70 times when observing extremely faint objects. (5)

Advanced Camera for Surveys

The Advanced Camera for Surveys (ACS) sees visible light, and is designed to study some of the earliest activity in the universe. ACS helps map the distribution of dark matter, detects the most distant objects in the universe, searches for massive planets, and studies the evolution of clusters of galaxies. ACS partially stopped working in 2007 due to an electrical short, but was repaired during Servicing Mission 4 in May 2009. (6)

Image taken using the Imaging Spectrograph

The Space Telescope Imaging Spectrograph (STIS) is a spectrograph that sees ultraviolet, visible and near-infrared light, and is known for its ability to hunt black holes. While COS works best with small sources of light, such as stars or quasars, STIS can map out larger objects like galaxies. STIS stopped working due to a technical failure on August 3, 2004, but was also repaired during Servicing Mission 4. (3)

Uranus as seen through the NICMOS

The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is Hubble's heat sensor. Its sensitivity to infrared light — perceived by humans as heat — lets it observe objects hidden by interstellar dust, like stellar birth sites, and gaze into deepest space. (3)

Installation of the FGS

Finally, the Fine Guidance Sensors (FGS) are devices that lock onto "guide stars" and keep Hubble pointed in the right direction. They can be used to precisely measure the distance between stars, and their relative motions. (3)

The Solar Arrays are the wing-like structures

All of Hubble's functions are powered by sunlight. Hubble sports solar arrays that convert sunlight directly into electricity. Some of that electricity is stored in batteries that keep the telescope running when it's in Earth's shadow, blocked from the Sun's rays. (3)

Collecting Data

Several antennas on the telescope send and receive information between Hubble and the Flight Operations Team at the Goddard Space Flight Center in Greenbelt, Md. Directions and commands are achieved through satellite communication. The telescope has two main computers and a number of smaller systems. One computer collects the data, the other sends the data back to Earth. The Space Telescope Science Institute (STScI) staff translates the data into units such as wavelength or brightness and archive the information. Astronomers can download archived data via the Internet and analyze it from anywhere in the world. At Goddard, people monitor the telescope's health while they maneuver it as well as control its instruments. (3)


The Hubble Control Station

Hubble Discoveries

Other Cool Stuff!

Interactive Hubble Website!

Images taken by the Hubble!


(1). Gabriel Okolski, A Brief History of the Hubble Space Telescope. (2008). Retrieved November 25th, from http://history.nasa.gov

(2) Chapter 5 - Hubble, (2011). Retrieved November 27th, from http://www.scienceclarified.com

(3). Hubble Essentials, (2010), Retrieved November 27th, from http://hubblesite.org

(4) Wide Field Camera 3, (2009), Retrieved Nov. 25th, from http://sci.esa.int

(5) Cosmic Origins Spectrograph, (2009), Retrieved Nov. 25th, from http://www.stsci.edu

(6) Advanced Camera for Surveys, (2009), Retrieved Nov. 25th, from http://www.stsci.edu/hst/acs/

(7) Philip Plait, Bad Astronomy, 2002, John Wiley & Son's, Inc. New York.

(8) The Cosmic Perspective, 2010, Pearson Education, Inc. San Francisco, California, p. 185.

All Videos are linked to YouTube.com

All Pictures are credited to http://hubblesite.org