The Hubble Space Telescope was launched in 1990 aboard the Space Shuttle Discovery and is one of the most significant telescopes in the history of astronomy.
However, its future is uncertain because NASA will not realize any further maintenance missions, and without intervention, it will re-enter Earth's atmosphere sometime in the 2030s.
Repair
The first repair occurred in December 1993, as the primary mirror had an aberration, and Hubble was therefore fitted with 'eyeglasses.' This repair involved spacewalks by astronauts during the STS-61 mission, carried out by the Space Shuttle Endeavour.
Space Telescope
Four antennas send and receive information between the telescope and the Flight Operations Team at the Space Telescope Science Institute.
Flanking the telescope's tube are two thin, blue solar arrays. Each wing-like array contains a solar cell 'blanket' that converts the Sun's energy into 2,800 watts of electricity.
Some of the energy generated is stored in onboard batteries, allowing the telescope to operate while it is in Earth's shadow, which occurs for about 36 minutes of each 97-minute orbit. Fully charged, each battery contains enough energy to sustain the telescope in normal science operations mode for 7.5 hours, or five orbits.
Designers of the Hubble Space Telescope had to consider the conditions in which it would operate. Hubble would face the challenges of zero gravity and temperature extremes—fluctuations of more than 100 degrees Fahrenheit during each orbit around Earth. To accommodate these conditions, Hubble was equipped with a 'skin,' or blanket, of multilayer insulation (MLI), which protects the telescope from temperature extremes. Beneath the MLI is a lightweight aluminum shell, which provides an external structure for the spacecraft and houses its optical system and science instruments.
Hubble's optical system is supported by a truss (supporting 'skeleton') measuring 5.3 m in length and 2.9 m in diameter. The 114 kg truss is made of graphite epoxy—a material also used in many sports equipment like golf clubs, tennis racquets, and bicycles. Graphite epoxy is stiff, strong, and lightweight, and resists expansion and contraction in extreme temperatures.
Optics
Hubble's 'eyes' comprise the Optical Telescope Assembly, which includes two mirrors, support trusses, and the instruments' apertures (openings).
Color Pictures
Taking color pictures with the Hubble Space Telescope is much more complex than with a traditional camera. Hubble doesn’t use color film—indeed, it doesn’t use film at all. Instead, its cameras capture light from the universe with special electronic detectors, producing images in shades of black and white.
Finished color images are actually combinations of two or more black-and-white exposures to which color has been added during image processing.
The colors in Hubble images, which are assigned for various reasons, aren't always what we'd see if we were able to visit the imaged objects in a spacecraft. We often use color as a tool, whether it is to enhance an object's detail or to visualize what ordinarily could never be seen by the human eye.
Astronomical pictures from Hubble often look different from what the naked eye would see.
Light from astronomical objects comes in a wide range of colors, each corresponding to a particular kind of electromagnetic wave. Hubble can detect all the visible wavelengths of light plus many more that are invisible to human eyes, such as ultraviolet and infrared light.
Astronomical objects often look different in these different wavelengths of light. To record what an object looks like at a certain wavelength, Hubble uses special filters that allow only a certain range of light wavelengths through. Once the unwanted light has been filtered out, the remaining light is recorded.
Many full-color Hubble images are combinations of three separate exposures—one each taken in red, green, and blue light. When mixed together, these three colors of light can simulate almost any color of light that is visible to human eyes.
Instruments:
Advanced Camera for Surveys (ACS)
Cosmic Origins Spectrograph (COS)
Space Telescope Imaging Spectrograph (STIS)
Wide Field Camera 3 (WFC3)
Fine Guidance Sensor (FGS)
Near Infrared Camera and Multi-Object Spectrometer (NICMOS)
Construction
NASA’s Marshall Space Flight Center was given responsibility for the design, development, and construction of the telescope, while the Goddard Space Flight Center was given overall control of the scientific instruments and ground control center for the mission.
History
In early 1986, the planned launch date of October that year looked feasible, but the Challenger disaster brought the US space program to a halt, and the launch of Hubble was postponed for several years.
Mission Results:
Discovering the Runaway Universe: Our cosmos is growing, and that expansion rate is accelerating.
Tracing the Growth of Galaxies: Hubble is instrumental in uncovering the various stages of galactic evolution.
Studying the Outer Planets and Moons: Hubble’s systematic observations chart the ever-changing environments of our solar system's giant planets and their moons.
Seeing Light Echoes: Like ripples on a pond, pulses of light reverberate through cosmic clouds forming echoes of light.
Monster Black Holes are Everywhere: Supermassive black holes lie at the heart of nearly every galaxy.
Exploring the Birth of Stars: Hubble’s near-infrared instruments see through the gas and dust clouds surrounding newborn stars.
The Death Throes of Stars: From colliding neutron stars to exploding supernovae, Hubble reveals details of some of the mysteries surrounding the deaths of stars.
Shining a Light on Dark Matter: Hubble observations have made key discoveries that characterize the structure and evolution of the universe, galaxies, nebulae, stars, exoplanets, and our solar system neighbors.
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