A Tour of the Universe with the Hubble Space Telescope

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A Tour of the Universe with the Hubble Space
Telescope

• Duncan A. Forbes
• Centre for Astrophysics Supercomputing,
  Swinburne University

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Why a Space Telescope ?

• Putting a telescope in orbit above most of the
  atmosphere has two main advantages
• 1. It is unaffected by seeing (atmospheric
  turbulence) which tends to smear out the detail
  in astronomical objects.
• 2. It can observe at wavelengths which are
  absorbed by the Earths atmosphere e.g. UV and
  infrared wavelengths.

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Telescope Description

• The HST has a 2.4m primary operating at f/24. It
  is in a cyclindrical shape 13.1x4.3m.

The instruments are located in bays behind the
primary mirror. Telescope movement comes from
internal gyros.
HST Schematic
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How much does it cost ?

• The Hubble Space Telescope was 85 paid for NASA
  and 15 by ESA. Below we guesstimate how much
  HST cost to develop and maintain. For comparison
  a typical 2.4m ground-based telescope would cost
  US15m.

USmillion Initial Research
and Development 2,000
1st Service mission (inc WFPC2)
500 2nd Service mission (inc STIS,
NICMOS) 600 3rd Service mission
(inc Gyros)
400 Total to date
3,500
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Liftoff of the Space Shuttle

• On the 24th April 1990, the Space Shuttle
  Discovery blasted off from Cape Canaveral with
  HST onboard.

At an altitude of 600 km (then a record height
for the Shuttle), HST was placed into orbit. The
event was recorded with IMAX cameras. After an
initial systems check the Shuttle returned to
Earth. The first images would be taken later.
Discovery enroute to orbit.
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The Initial Instruments

• HST was launched with 5 instruments.
• WFPC1 Wide Field Planetary Camera 1
• FOC Faint Object Camera
• GHRS Goddard High Resolution Spectrograph
• FOS Faint Object Spectrograph
• HSP High Speed Photometer

HST also included the FGS (Fine Guidance Sensors)
necessary for the acquisition and locking-on to
guide stars.
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Houston we have a problem

• Shortly after HST was turned-on it was realised
  that the images were out of focus. The mirror
  suffered from spherical aberation. So although it
  was polished to the required degree of smoothness
  it was made to slightly the wrong shape. This
  affected all of the science instruments to
  varying degrees. Some science objectives were
  just no longer possible.

A tiger team was formed to fix the problem. They
considered bringing the telescope back to Earth
but eventually opted for corrective optics (later
called COSTAR).
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Perfect but Wrong !
Ground image
Actual HST image
Expected HST image
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STS61

• Lasting almost 11 days, STS61 (launched 2nd Dec.
  1993) was one of the most ambitious shuttle
  missions to be flown

The astronaunts, which included an astronomer,
had to carefully remove the HSP replace it with
the corrective optics (COSTAR), swap WFPC2 for
WFPC1, and fix the malfunctioning solar arrays.
HST in the cargo bay of Endeavour
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Before and After

• Right is an image of M100 taken with WFPC1.

Lets see how it looks with WFPC2, and its
improved optics.
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Wide Field Planetary Camera 2

• Although similar to WFPC1, the new WFPC2 had
  several improvements (including internal
  corrective optics), such as better CCD detectors
  and new filters.

WFPC2 consists of 4 separate CCDs. Three (WF
CCDs) are arranged in an L shape with the fourth
(PC) in the bend of the L. The WF CCDs have 0.1
arcsec pixels and 75x75 sq. arcsec field-of-view.
The PC has 0.045 arcsec pixels and 34x34 sq.
arcsec fov. This L shape layout was chosen to
save money.
Schematic layout of the four WFPC2 CCDs.
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Future Instrumentation

• Future HST servicing missions are planned for
  late 2001 (STS109) and 2003. As well as continued
  maintanance, these servicing missions will
  install new instruments.
• Scheduled instruments include the Advanced Camera
  for Surveys (ACS) in 2001, Cosmic Origins
  Spectrograph (COS) in 2003 and possibly the Wide
  Field Camera 3 (WFC3).

It is hoped that HST will remain active and have
at least a few years overlap with the planned 8m
New Generation Space Telescope due for launch
around 2010.
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End of the Tour
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New Online Shortcourse
Searching for Extrasolar Planets and
Extraterrestrial Life
Http//www.swin.edu.au/astronomy/sao/shortcourse