Capture the cosmos > Hubble Space Telescope > Q&A: Hubble Space Telescope

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Q and A:
Hubble Space Telescope & SM4
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Question
1. What is the Hubble Space Telescope?
 
Answer

The Hubble Space Telescope is a space-based telescope that was launched in 1990 from the space shuttle Discovery. From its position above Earth's atmosphere, Hubble has expanded our understanding of the universe — and of star birth, star death, galaxy evolution, and black holes in particular.

The telescope's science instruments are the astronomer's eyes to the universe. During Servicing Mission 4, in May 2009, astronauts boosted Hubble’s scientific power by installing two state-of-the-art science instruments: the Cosmic Origins Spectrograph (COS) and the Wide Field Camera 3 (WFC3). To make room for the new instruments, astronauts removed the Wide Field and Planetary Camera 2, which was installed aboard Hubble in 1993. Other Hubble science instruments include the Space Telescope Imaging Spectrograph, Near Infrared Camera and Multi-Object Spectrometer, and Advanced Camera for Surveys.

When first launched, Hubble's primary mirror had a minor flaw that made it difficult for the telescope to resolve faint objects. Because the telescope is in low Earth orbit, it can be serviced by a space shuttle; thus, the defect was corrected during the first on-orbit servicing mission.

 
 
 
Question
2. Why service the Hubble Space Telescope?
 
Answer

NASA decided early in the telescope's development to design the observatory for on-orbit servicing. Instruments were designed as modular units, comparable to dresser drawers that could be easily removed and replaced. In addition, designers equipped the telescope with handholds and other special features to make servicing tasks less difficult for astronauts wearing bulky spacesuits.

By periodically upgrading the science instruments, NASA also reasoned that it could provide the science community worldwide with state-of-the-art technology that takes advantage of Hubble's unique position high above Earth's obscuring atmosphere.

 
 
 
Question
3. What instruments and equipment did the astronauts add to the Hubble Space Telescope during Servicing Mission 4 in May 2009?
 
Answer

This mission boosted Hubble's scientific power and ensured the continued effective operation of the telescope. During Servicing Mission 4, astronauts installed two state-of-the-art science instruments: the Cosmic Origins Spectrograph (COS) and the Wide Field Camera 3 (WFC3). They also added six batteries, six gyroscopes, and a Fine Guidance Sensor.

 
 
 
Question
4. What is the Wide Field Camera 3 (WFC3), and what does it do?
 
Answer

WFC3 replaced Hubble’s “workhorse” camera, the Wide Field Planetary Camera 2 (WFPC2), which observed celestial objects for 15 years. The new camera greatly improves Hubble’s ability to image large and distant objects, such as galaxies and clusters of galaxies, as well as planets in our solar system.

Astronomers use WFC3 to make wide-field surveys of the distant universe to study how galaxies formed and evolved from about 2 billion years after the Big Bang to the present. WFC3 allows Hubble to see objects that are about five times fainter than Hubble’s landmark deep view of the cosmos, called the Hubble Deep Field, taken in 1996 with WFPC2.

 
 
 
Question
5. What is the Cosmic Origins Spectrograph (COS), and what does it do?
 
Answer

COS examines the ultraviolet light streaming from distant objects. The new instrument allows Hubble to study galaxy formation and the births of stars and planetary systems. COS completes observations much faster than Hubble’s previous spectrograph.

 
 
 
Question
6. How do Hubble’s batteries, gyroscopes, and Fine Guidance Sensors help the telescope operate effectively?
 
Answer

Normally, Hubble’s science instruments run on sunlight collected by its twin solar panels, which make the observatory look like it has wings. The batteries power Hubble’s science instruments when the telescope is in Earth’s shadow. The gyroscopes help keep Hubble steady as it orbits Earth and allow scientists to point the telescope at celestial targets. Hubble has three Fine Guidance Sensors, which also help in pointing the telescope at objects.

 
 
 
Question
7. How often are servicing missions scheduled?
 
Answer

When your car needs a tune-up, you take it to your mechanic for servicing. Engineers and scientists designed the Hubble Space Telescope with the same principle in mind. When a component breaks or a more technologically advanced instrument becomes available, astronauts install the new equipment using wrenches, screwdrivers, and power tools during periodic servicing missions.

Astronauts have serviced Hubble five times — in 1993, 1997, 1999, 2002, and 2009 — and have installed many new instruments featuring more advanced technology.

 
Hubble Space Telescope
Hubble Space Telescope
 
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Capture the cosmos > Hubble Space Telescope > Q&A: Hubble Space Telescope