Transcript Interdisciplinary Evolution of the Hubble Space Telescope

The Interdisciplinary
Evolution of the Hubble
Space Telescope
An Historical Examination of Key
Interdisciplinary Interactions
Greg Carras, Jerry Cordaro, Andrew Daga, Sean Decker, Jack Kennedy, Susan Raizer
University of North Dakota, Department of Space Studies
24 April 2006
The Hubble Space Telescope: An Overview
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An orbiting telescope that collects light from celestial
objects in visible, ultraviolet, and near-infrared
wavelengths
Launched 24 April 1990 aboard the Space Shuttle
Discovery
Dimensions: Cylindrical 24,500 lb (11,110-kg), 43 ft
long (13.1 m ) and 14.1 ft (4.3m) wide
Orbital period: 96 minutes
Primarily powered by the sunlight collected by its two
solar arrays
The telescope’s primary mirror is 2.4 m (8 ft) in
diameter
Was created by NASA with substantial and
continuing participation by ESA
Operated by the Space Telescope Science Institute
(STSI) in Baltimore, MD
Named for Edwin Powell Hubble
"The Hubble Space Telescope is the most productive telescope since Galileo's"
- Robert Kirshner, President of the American Astronomical Society
Reference: Image and data: STSI (www.hubblesite.org)
The evolution of HST may be best approached by
understanding the interaction of four factors:
The Social and
Political Conditions
The Historical Context
(and the post WWII trend
toward “Big Science”)
The Participants
(People and Agencies)
The Technological
Dimension
Hubble’s Historical Context
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At the beginning of the 20th Century, scientists had a remarkably limited view of
the physical universe – many believed that our galaxy was the only galaxy.
Before WWII most astronomy was conducted by individuals or small groups,
and astronomical observatories were funded by private philanthropists
(example: Carnegie) or by an individual astronomer (example: Percival Lowell).
By the 1920’s this view was being rapidly revised, in part due to the
observations of Edwin Hubble and Milton Humason in the 20’s and 30’s who
saw many other galaxies, and that these galaxies were moving away from each
other (which leads to the concept of an expanding universe and the Hubble
Constant).
During WWII, the federal government teamed up with
industry and the scientific community to form working
partnerships. People learned how to develop
transformational projects quickly and “Big Science” is
born.
Some scientists learn how to play the game and extend
themselves to be activists for important programs.
One of these, an astronomer, is Lyman Spitzer, Jr.
Hubble’s Historical Context (continued)
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In 1946 Spitzer publishes “Astronomical Advantages of an Extra-Terrestrial
Observatory,” for RAND. It lays out in detail for the first time the enormous
advantages of a space-based telescope. This report remains classified for years.
The US Army has been experimenting with captured V2 rockets, some of which
have been equipped with scientific payloads.
In 1950, at a dinner party in his home, physicist James Van Allen and several
scientists consider the idea for a third International Polar Year – this will become
the IGY. An increasing number of scientists are looking at the space environment
and new space age technologies to further scientific exploration.
Other scientists and engineers are also speculating about the new realm of
possibilities for science, including Wernher von Braun, who describes a manned
orbital telescope in 1952.
1955: In response to growing pressure from scientists, the US National Academy
of Sciences and National Science Foundation jointly agree to seek approval to
orbit a scientific satellite during the upcoming IGY (to be 1957-1958).
During this period, many scientists remain unconvinced of the idea to take
science into space. Nevertheless a scientific advocacy emerges, and it learns to
become politically savvy.
The paradigm has shifted to Big Science.
Hubble’s Historical Context (continued)
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In 1958 (and following Sputnik), the Space Science Board
of National Academy of Sciences calls for and receives
hundreds of suggestions for follow-on projects to IGY.
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These are forwarded to NASA's Space Science Working
Group on "Orbital Astronomical Observatories (OAOs)"
President Eisenhower enthusiastically supports.
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In the Cold War climate, NASA is interested in
demonstrating what it can do. In 1960-61 it issues first
RFP’s for OAO series.
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The contentious relationship between NASA and the
science community takes form with the OAO project.
Scientists who have been used to taking complete charge
of their science projects will now have to contend with a
loss of control to NASA.
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On the positive side: With OAO, the idea of a Guest
Observer is introduced – breaking from the idea of strict
control by a single Principal Investigator.
This will have later implications as key scientists will insist
that the new Large Telescope be a National Facility (open
to all)
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On the negative side: 2 of 4 OAO missions fail – in large
part because NASA did not communicate well with the
scientists and the technology was too complicated.
Reference: Smith, Robert W, et al. The Space Telescope: A Study of NASA, Science, Technology, and Politics. New York: Cambridge Univ. Press, 1989
Social and Political Conditions
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As NASA begins to seriously contemplate a Large Space Telescope, the financial and
budgetary condition of the nation weighs heavily. This factor, and how the various
participants perceive it, will prove to be critical in defining Hubble’s scientific potential,
management, ultimate cost, and schedule.
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By the mid-1970’s the federal budget has been overstressed by the expenses of war and
the Great Society programs, and the economy is stagnating.
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NASA senior management is concentrating on the new Space Shuttle and the political
climate for new expensive projects is hostile.
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NASA continues to pursue an LST by using available funds (not needing congressional
approval) to fund “Phase A” studies, forcing Marshall Space Flight Center to compete
with Goddard Space Flight Center to become the lead center.
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NASA Administrator Fletcher finds the Phase A cost estimates politically untenable – and
orders MSFC to limit the program cost to $300M.
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Finally, throughout the 1960’s and 70’s, the DoD has been building a series of
increasingly sophisticated reconnaissance satellites, and it forces controls on NASA that
severely limit NASA’s access to the technology to protect secrecy.
Ironically, the same companies that know how to build the recon satellites are ultimately
selected to build Hubble.
Reference: Smith, Robert W, et al. The Space Telescope: A Study of NASA, Science, Technology, and Politics. New York: Cambridge Univ. Press, 1989
Hubble’s Participants – Key People and Agencies
The four key participants in the development lifecycle of Hubble:
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Space Agencies
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NASA Headquarters – the Office of Space Science believes the LST is a major priority, but senior
management were reluctant to propose any new program.
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MSFC – it had no astronomy expertise and was threatened with closure at the time of the LST
Phase A competition; it wanted the LST badly and said so.
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GSFC – it had the experienced people and know-how to build astronomical sats (it was lead for
OAO), but was overburdened with project work; it’s Director was ambivalent about the project.
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JSC, KSC and JPL would play important roles in the program too. JSC’s astronauts would prove
essential. JPL designed and built the WF/PC (and the $60M spare).
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Astronomers and other scientists within NASA would play a pivotal role in coordinating with the
science community, of these Dr Robert O’Dell (Chief Project Scientist at MSFC) and Dr Nancy
Roman of NASA HQ were crucial.
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ESA – It wanted a substantial space science program but could not do it on its own, and NASA
needed to satisfy Congress while reassuring domestic scientists that they would not sacrifice control
as a price for ESA’s involvement
Executive and Legislative Branches of Government
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Executive Branch – despite budget constraints imposed by the Ford administration, the OMB and
President Ford were generally supportive, as were officials in the Carter and Reagan
administrations.
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Congress – Hubble will face stiff opposition from key congressional committees forcing major delays
and economic limits. Congress will ultimately mandate international cooperation. The most
prominent opponents of Hubble were Representative Edward P. Boland (D-MA) and Senator William
Proxmire (D-WI).
Reference: Smith, Robert W, et al. The Space Telescope: A Study of NASA, Science, Technology, and Politics. New York: Cambridge Univ. Press, 1989
Key People and Agencies (continued)
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Scientists and Advocates
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Individual scientists will come to save the telescope by rallying their community and aggressively
lobbying congress.
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Of these, the most influential will be Lyman Spitzer and John Bahcall, both of Princeton. Their
collaboration with Robert O’Dell (at MSFC) in lobbying Congress will come to be called the
“Princeton-Huntsville Axis.” O’Dell actively promotes the project in scientific journals and
presentations.
Industry
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Many companies contributed to LST/HST, including all major aerospace firms, most in
subcontractor roles to Lockheed Missiles and Space Company (CA) for the SSM, and to PerkinElmer (CT) for the OTA.
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Lockheed and P-E had substantial experience working on highly classified PHOTOINT satellites.
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Other firms were contracted by the universities to build elements of the Scientific Instruments.
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At various times, corporate competitors worked together and with NASA and outside scientists to
lobby congress at critical junctures.
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Importantly, since both Lockheed and P-E were operating as “associate contractors” – no
company was fully charged with systems engineering authority, and NASA was unable to perform
this role adequately.
Reference: Smith, Robert W, et al. The Space Telescope: A Study of NASA, Science, Technology, and Politics. New York: Cambridge Univ. Press, 1989
Hubble’s Evolution – Consolidated Summary
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In the context of big science and Cold War tensions and technology advancements,
NASA and the scientific community find common purpose in proposing a large (3m)
reflecting telescope in Earth orbit. Astronomers know it will be revolutionary; NASA
and several presidents agree.
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As Apollo concludes, NASA is under fire and fighting to keep field centers open. It
develops an LST program but forces GSFC to compete with MSFC to lead the
program. The compromise sets up antagonism between the centers.
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With Marshall in the lead, the program is believed to be untenable politically – an
artificial limit of $300M is imposed, and the DoD demands limits on contractor
penetration of the two key defense contractors.
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With constant cost overages, NASA management demands reductions, forcing tradeoff studies of capability versus cost. In this process the 3m primary mirror will be
reduced to 2.4m. The scientists are always pushing back.
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When the program is proposed to Congress, the House appropriations subcommittee
rejects it, forcing NASA to appeal to the Senate in hopes of effectuating a resolution,
and NASA considers holding off on the program.
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It is at this point that university scientists, key NASA staffers and scientists, and
contractors, begin to collaborate to lobby congress.
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From this emerges a partial victory, leading to the restoration of some funding and the
mandate that NASA collaborate with ESA. NASA begins talks with ESA.
Hubble’s Evolution – Consolidated Summary
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As the program moves into the design and development phase (C/D), a
manpower cap and the limited budget restrain Marshall’s ability to manage the
program. NASA depends on two associate contractors to do their own systems
engineering. MSFC saw itself in this role, but was not able to do it.
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During this period the relationship between MSFC and GSFC is antagonistic
and even hostile. Goddard is charged with developing the scientific instruments
and eventually operating the telescope, but only reluctantly takes direction from
MSFC. Marshall objects to Goddard’s interference, and Marshall’s project
scientist (O’Dell) takes the initiative away from GSFC.
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As the project moves ahead, even with ESA’s 15% contribution, the LST runs
out of money. Faced with the prospect of severely reducing the scientific
capability and delaying the launch, NASA management concedes to extend the
launch date and returns to congress for more money.
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Status 1980: From it’s inception, LST has been underfunded and consequently,
its capabilities were oversold (Smith, 1989). In 1980, the program is in crisis but
still at a design stage where NASA considers cutting back on certain
technologies to save money.
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During this time, scientists are working to create the methodologies that will be
needed to operate HST at the STSI. A entire new star reference system is
created to help guide the telescope.
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In 1983, the program hits another crisis – NASA finally recognizes that changes
need to be made, the launch date extended, and NASA HQ demands new
managers and appoints its own project manager. NASA works with OMB and
Congress begins to infuse much more money. Things begin to change.
Hubble’s Evolution – Consolidated Summary
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Between 1983 and 1986, the program is disciplined and turned around. New
managers at NASA do not feel tied to the unrealistic promises that the program
has made. Launch is scheduled for 1986.
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In 1986, just as the program is being readied for its final round of thermalvacuum chamber testing, the Shuttle fleet is grounded with the Challenger
disaster. NASA is afraid to lose the technical skills it needs to finish the
program, so work continues to fix lingering problems and complete the thermalvacuum testing. HST goes into protected storage.
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In 1990, HST is launched and very quickly put into service. Soon, it will be
discovered that there is a flaw in the optics, which will be traced to a
manufacturing error at P-E (which P-E knew about for 10 years).
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In 1993, in a dramatic series of EVA’s during the first servicing mission (SM),
HST’s optics are corrected and a new era of space astronomy finally begins.
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Since 1993, there have been 3 additional SM’s, each one replacing and
upgrading HST to state-of-the-art technology. Hubble has generated data of
unprecedented quality in vast quantities since – and continues to do so. With
more demand for observing time than can be filled, and the ability to be
extended indefinitely, Hubble has turned out to be everything and more than its
supporters ever claimed.
References: Smith, Robert W, et al. The Space Telescope: A Study of NASA, Science, Technology, and Politics. New York: Cambridge Univ. Press,
1989, and personal interview, Dr David Leckrone, Goddard Space Flight Center, 10 April 2006.
Hubble’s Technological Dimension
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The Hubble Space Telescope was designed with many constraints – both technical and
cost.
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This technology section will cover the technology components of Hubble and the
rationale that drove decisions on its design.
Index to Technology Slides
Hubble Components
- Overall Components
- Power Systems
- Spacecraft Systems
- Mirrors and Baffles – Mirror Problem
- Sensors
- Actuators
- Scientific Instruments
Most Difficult Technical Challenge – Pointing Control System
“Get the Cost Down”
Initial Deployment Components and Servicing Missions
Hubble Technology
Overall Components – Exploded View
Hubble Technology
Power Systems
Solar Arrays:
(2) 40-foot (12-meter) panels that convert
sunlight into 2400 watts of electricity in
order to power the telescope.
Batteries:
- 6 nickel-hydrogen (NiH) batteries
- Power storage capacity is equal to 20 car batteries
- Power usage: 2,800 watts
Hubble Technology
Power Systems
http://hubble.nasa.gov/technology/summary.php
Hubble Technology
Spacecraft Systems
Communications antennae (2)
Transmit Hubble's information to communications satellites called the Tracking & Data Relay
Satellite System (TDRSS) for relay to ground controllers at the Space Telescope Operations
Control Center (STOCC) in Greenbelt, Maryland.
Computer support systems modules
Contains devices and systems needed to operate the Hubble Telescope. Serves as the master
control system for communications, navigation, power management, etc.
Electronic boxes
Houses much of the electronics including computer equipment and rechargeable batteries.
Aperture door
Protects Hubble's optics in the same way a camera's lens cap shields the lens. It closes when
Hubble is not in operation to prevent bright light from hitting the mirrors and instruments.
Light shield
Light passes through this shaft before entering the optics system. It blocks surrounding light from
entering Hubble.
Pointing control system
This system aligns the spacecraft to point to and remain locked
on any target.
The telescope is able to lock onto a target without deviating more than 7/1000th of an arcsecond,
or about the width of a human hair seen at a distance of 1 mile.
Hubble Technology
Spacecraft Systems
Hubble Technology
Spacecraft Systems
Hubble Technology
Spacecraft Systems
Hubble Technology
Spacecraft Systems
Hubble’s Spacecraft Systems – the OTA
Hubble Technology
Communications
Hubble data path to the Goddard Space Flight Center.
Hubble Technology
Pointing Control System
The Pointing Control System (PCS) aligns Hubble so that the telescope points to and
remains locked on a target. The PCS is designed for pointing to within .01 arcsec and is
capable of holding a target for up to 24 hours while Hubble continues to orbit the Earth at
17,500 mph. If the telescope were in Los Angeles, it could hold a beam of light on a dime in
San Francisco without the beam straying from the coin's diameter.
Hubble Technology
Mirror and Baffles
Primary Mirror
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Primary Mirror Diameter: 94.5 in (2.4 m), Weight: 1,825 lb
(828 kg).
Hubble's two mirrors were ground so that they do not
deviate from a perfect curve by more than 1/800,000ths of
an inch. If Hubble’s primary mirror were scaled up to the
diameter of the Earth, the biggest bump would be only six
inches tall.
Secondary Mirror
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Secondary Mirror Diameter: 12 in (0.3 m), Weight: 27.4 lb
(12.3 kg).
Focal Plane
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Mirrors focus starlight on the Focal Plane.
Baffles:
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Keep out stray light.
• Main baffle
• Central baffle
• Secondary mirror baffle
The telescope's primary mirror
(2.4 m diameter) being hoisted up
Hubble Technology
Mirror and Baffles
Hubble Main Mirror
Workers study Hubble’s main, eight-foot (2.4 m) mirror. Hubble, like all telescopes, plays a kind of
pinball game with light to force it to go where scientists need it to go. When light enters Hubble, it
reflects off the main mirror and strikes a second, smaller mirror. The light bounces back again, this
time through a two-foot (0.6 m) hole in the center of the main mirror, beyond which Hubble’s
science instruments wait to capture it. In this photo, the hole is covered up.
Hubble Technology
Mirror and Baffles
Hubble Technology
Mirror and Baffles
Hubble Technology
Mirror and Baffles
Hubble Technology
Mirror and Baffles
Mirror Problem
The mission controllers made progress and by 21 May began receiving the first
optical images from the telescope.
These views of a double star in the Carina system, scientists believed, were
much clearer than those from ground-based telescopes. Such success left
project officials surprised on the weekend of 23–24 June when the telescope
failed a focus test. The controllers had moved the telescope’s secondary mirror
to focus the light, but a hazy ring or “halo” encircled the best images.
Subsequent tests determined that the blurry images resulted from the
“spherical aberration” of the primary mirror; spherical aberration reflected
light to several focal points rather than to one. It occurred because PerkinElmer had removed too much glass, polishing it too flat by 1/50th of the
width of a human hair. This seemingly slight mistake, however, prevented the
telescope from making sharp images.
Hubble Technology
Mirror and Baffles
COSTAR
Corrective Optics Space Telescope Axial Replacement
Although the primary mirror was not one of the replaceable units, its aberration
could be corrected, much like the way an eye doctor corrects poor vision with
spectacles, by modifications to “second generation” scientific instruments.
COSTAR, the corrective optics Space Telescope axial replacement, would
replace the high speed photometer and use relay mirrors mounted on
movable arms to focus the scattered light.
Hubble Technology
Optical Camera Channel and Baffles
Four Optical Camera Channel and Baffle assemblies from the
Wide Field and Planetary Camera (WF/PC) 1 recovered from the
Hubble Space Telescope during HST Service Mission
Hubble Technology
Optical Camera Channel and Baffles
Faint Object Camera (FOC) M1 Field
Mirror Mechanism that was ultimately
installed as part of the COSTAR (Corrective
Optics Space Telescope Axial Replacement)
payload during Space Shuttle Mission STS61 (Hubble Service Mission 1) to correct
errors in the primary mirror onboard the
Hubble Space Telescope.
The error was the result of a residual
aberration polished into the primary due to a
mis-assembled nulling apparatus; the error
resulted in the Hubble's primary mirror
being ground about 2 micrometers too flat
(1/40 the thickness of a human hair).
Scientists and engineers devised COSTAR
with four small mirrors, about the size of
dimes and quarters. The small mirrors were
intentionally produced with a flaw identical
to and opposite the flaw on the primary
Hubble mirror.
Hubble Technology
Sensors
Fine Guidance Sensors (3)
These sensors are locked onto two guide stars to keep Hubble in the same relative position of
these stars.
Coarse Sun Sensors (2)
Measure Hubble's orientation to the sun. Also assist in deciding when to open and close the
aperture door.
Magnetic Sensing System
Measure Hubble position relative to Earth's magnetic field.
Rate Sensor Unit
Two rate sensing gyroscopes measure the attitude rate motion about its sensitive axis.
Fixed Head Star trackers
An electro-optical detector that locates and tracks a specific star within its field of view.
Hubble Technology
Actuators
Reaction Wheel Actuators (4)
The reaction wheels work by rotating a large flywheel up to 3000 rpm or braking it to exchange
momentum with the spacecraft which will make Hubble turn.
Magnetic Torquers (4)
The torquers are used primarily to manage reaction wheel speed. Reacting against Earth's magnetic
field, the torquers reduce the reaction wheel speed, thus managing angular momentum.
Hubble Technology
Actuators
Hubble Technology
Scientific Instruments
Axial bays (4)
Four instruments are aligned with the main optical axis and are mounted just behind the primary
mirror. As of the year 2000 they consisted of:
ACS (Advanced Camera for Surveys)
The newest camera (2002) with a wider field of view, and better light sensitivity. It effectively
increases Hubble's discovery power by 10x.
NICMOS (Near Infrared Camera and Multi-Object Spectrometer)
Infrared instrument that is able to see through interstellar gas and dust.
STIS (Space Telescope Imaging Spectrograph)
Separates light into component wavelengths, much like a prism.
COSTAR
Contains corrective optics for spherical aberration in the primary mirror.
Radial bay (1)
Wide Field/Planetary Camera 2 (WFPC2) is housed here. Taking images that most resemble
human visual information, WFPC2 is responsible for taking nearly all of Hubble's famous pictures.
Fine guidance sensors (3)
The sensors lock onto guide stars and measure relative positions, providing data to the
spacecraft's targeting system and gathering knowledge on the distance and motions of stars.
Hubble Technology
Scientific Instruments
Hubble Technology
Scientific Instruments
Space Telescope Imaging Spectrograph (STIS)
Engineers in a clean room at Ball Aerospace in Boulder, Colo., work on one of
Hubble’s instruments, the Space Telescope Imaging Spectrograph (STIS), in
1996. The instrument, installed in Hubble in 1997, breaks light into colors,
giving scientists an important analytical tool for studying the cosmos. STIS has
been used to study such objects as black holes, new stars, and massive
planets forming outside our solar system.
Hubble Technology
The Most Difficult Technical Challenge – Pointing Control System
The Problem:
A major problem for NASA and its contractors was the means to guide and stabilize the telescope. If
the completed telescope was to perform to the negotiated requirements, it would have to be capable
of being aimed at an astronomical target with a pointing stability of 0.005 seconds of arc, an
angle on the sky about 360,000 times smaller than the angle that is subtended by the diameter
of the full moon. So taxing was this requirement that it was widely viewed in NASA and outside as
the most difficult technical challenge the designers and builders had to overcome.
The telescope not only had to be pointed extremely accurately, means also had to be devised to
keep it locked on its astronomical targets. This task was crucial because there would inevitably
be tiny disturbances that would act to move the spacecraft away from its targets, disturbances known
as "jitter". Jitter might arise from the motions of the gyroscopes in pointing, for example. Should
the entire spacecraft be moved if small corrections in its position were needed (a method known as
body pointing)? Or should the secondary mirror of the Large Space Telescope be shifted to
compensate for the spacecraft's minor motions (a method known as image motion
compensation)?
Hubble Technology
The Most Difficult Technical Challenge – Pointing Control System
The Answer:
During Phase A, Bendix had performed studies for Marshall that argued that body
pointing alone was sufficient. Marshall, however, was not convinced. Hence the
center's Phase A design concept also incorporated a movable secondary mirror. But
more studies persuaded Marshall that control moment gyroscopes could point and
stabilize the telescope. If so, a moving secondary would not be essential, even though
Perkin-Elmer argued that it promised to give the best performance.
Marshall's basic engineering approach was to use the simplest available
systems where possible, and for pointing and control that would mean using
either control moment gyroscopes or reaction wheels alone, but preferably not
the two in combination.
Hubble Technology
“Get the Cost Down”
The Problem:
Financial pressure pushed the Center’s design activities and often forced it to
relinquish conservative engineering principles. The Center’s March 1972 project
plan called for three telescopes, an engineering model, a “precursor” flight unit,
and the final LST. Design and development would cost between $570 and
$715 million. Headquarters believed this was too expensive. In a December
1972 meeting, NASA Administrator Fletcher “emphasized that the current
NASA fiscal climate was not conducive to initiation of large projects” and suggested
$300 million as a cost target.
Hubble Technology
“Get the Cost Down”
A “proto-flight” approach would eliminate the engineering and precursor units; a single
spacecraft would serve as test model and flight unit. The proto-flight approach had
been successfully tried for Department of Defense projects, and the Center
expected it to reduce costs—which would please Congress—and speed progress
to operations—which would please the astronomers.
The telescope maintenance strategy also changed. Rather than designing for extensive
repair in orbit inside a pressurized cabin, Marshall suggested a design that would eliminate the
cabin and minimize repairs in orbit. The new design assumed the Space Shuttle could
return the telescope to Earth for major repairs. These changes simplified the
overall LST design and development scheme.
Hubble Technology
“Get the Cost Down”
By December 1974 the Program Development task team had downsized the telescope.
As before the team had to balance cost and performance and devise a design pleasing to
Congress and the astronomers. Team leader Downey said the Agency wanted “to procure
the lowest cost system that will provide acceptable performance” and would “be willing to
trade performance for cost.”
Working with the LST science groups and contractors, the team reduced the telescope’s
primary mirror from a 3-meter aperture to 2.4 meters. This major change mainly
resulted from new NASA estimates of the Space Shuttle’s payload delivery
capability; the Shuttle could not lift a 3-meter telescope to the required orbit. In
addition, changing to a 2.4-meter mirror would lessen fabrication costs by using
manufacturing technologies developed for military spy satellites. The smaller mirror would
also abbreviate polishing time from 3.5 years to 2.5 years.
The redesign also reduced the mass of the support systems module from 24,000
pounds to 17,000 pounds; the SSM moved from the aft of the spacecraft to one-third of
the way forward and became a doughnut around the primary mirror. These changes
diminished inertia and facilitated steering of the spacecraft, thus permitting a smaller
pointing control system. The astronomers chose to reduce the number of scientific
instruments from seven to four. Finally, the Marshall team believed that designing for
repair would allow for lower quality standards.
Hubble Technology
Initial Deployment Components and Servicing Missions
1990 Initial Complement at Deployment:
WFPC (1) - Wide Field/Planetary Camera - First-generation imaging camera. WFPC (1) operated in
either Wide Field mode, capturing the largest images, or Planetary mode with higher resolution.
GHRS - Goddard High Resolution Spectrograph - First-generation spectrograph. GHRS was used
to obtain high resolution spectra of bright targets.
FOS - Faint Object Spectrometer - First-generation spectrometer. FOS was used to obtain spectra of
very faint or faraway sources. FOS also had a polarimeter for the study of the polarized light from
these sources.
FOC - Faint Object Camera - First-generation imaging camera. FOC is used to image very small field
of view, very faint targets. This is the final, first-generation instrument still on Hubble.
HSP - High Speed Photometer - First-generation photometer. This instrument was used to measure
very fast brightness changes in diverse objects, such as pulsars.
FGS - Fine Guidance Sensors - Science/guidance instruments. The FGS's are used in a "dualpurpose" mode serving to lock on to "guide stars" which help the telescope obtain the exceedingly
accurate pointing necessary for observation of astronomical targets. These instruments can also be
used to obtain highly accurate measurements of stellar positions.
Hubble Technology
Initial Deployment Components and Servicing Missions
1993 Servicing Mission 1:
WFPC2 - Wide Field Planetary Camera 2 - Second-generation imaging camera. WFPC2 is an upgraded
version of WF/PC (1) which includes corrective optics and improved detectors.
COSTAR - Corrective Optics Space Telescope Axial Replacement - Second-generation corrective optics.
COSTAR is not an actual instrument. It consists of mirrors which refocus the abbreviated light from Hubble's
optical system for first-generation instruments. Only FOC utilizes its services today.
Restoring Hubble's Vision
As the first in a series of planned visits to the orbiting Hubble Space Telescope, the First Servicing Mission
(STS-61) in December 1993 had a lot to prove and a lot to do. The mission's most important objective was to
install two devices to fix Hubble's vision problem. Because Hubble's primary mirror was incorrectly shaped,
the telescope could not focus all the light from an object to a single sharp point. Instead, it saw a fuzzy halo
around objects it observed.
Once astronauts from the space shuttle Endeavour caught up with the orbiting telescope, they hauled it into the
shuttle's cargo bay and spent five days tuning it up. They installed two new devices—the Wide Field and
Planetary Camera 2 (WFPC2) and the Corrective Optics Space Telescope Axial Replacement (COSTAR).
Both WFPC2 and the COSTAR apparatus were designed to compensate for the primary mirror's incorrect
shape.
Also installed during the First Servicing Mission were:
• New solar arrays to reduce the "jitter" caused by excessive flexing of the solar panels during the telescope's
orbital transition from cold darkness into warm daylight
• New gyroscopes to help point and track the telescope, along with fuse plugs and electronic units.
• This successful mission not only improved Hubble's vision — which led to a string of remarkable discoveries
in a very short time — but it also validated the effectiveness of on-orbit servicing.
Hubble Technology
Initial Deployment Components and Servicing Missions
Servicing Mission 2:
STIS - Space Telescope Imaging Spectrograph - Second-generation imager/spectrograph. STIS is used to obtain high
resolution spectra of resolved objects. STIS has the special ability to simultaneously obtain spectra from many
different points along a target.
NICMOS - Near Infrared Camera/Multi-Object Spectrometer - Second-generation imager/spectrograph. NICMOS is
Hubble's only near-infrared (NIR) instrument. To be sensitive in the NIR, NICMOS must operate at a very low
temperature, requiring sophisticated coolers. Problems with the solid nitrogen refrigerant have necessitated the
installation of the NICMOS Cryocooler (NCC) on SM3B to continue its operation.
The light from the most distant galaxies is shifted to infrared wavelengths by the expanding universe. To see these
galaxies, Hubble needed to be fitted with an instrument that could observe infrared light.
During the 10-day Second Servicing Mission (STS-82) in February 1997, the seven astronauts aboard the space shuttle
Discovery installed two technologically advanced instruments. The Near Infrared Camera and Multi-Object
Spectrometer (NICMOS) would be able to observe the universe in the infrared wavelengths. The second instrument—
the versatile Space Telescope Imaging Spectrograph (STIS)—would be used to take detailed pictures of celestial
objects and to hunt for black holes.
Both instruments had optics that corrected for the flawed primary mirror. In addition, they featured technology that wasn't
available when scientists designed and built the original Hubble instruments in the late 1970s—and opened up a
broader viewing window for Hubble.
The new instruments replaced the Goddard High Resolution Spectrograph and the Faint Object Spectrograph.
Also installed during the Second Servicing Mission were:
• A refurbished Fine Guidance Sensor—one of three essential instruments used to provide pointing information for the
spacecraft, to keep it pointing on target, and to calculate celestial distances
• A Solid State Recorder (SSR) to replace one of Hubble's data recorders (An SSR is more flexible and can store 10
times more data)
• A refurbished, spare Reaction Wheel Assembly—part of the Pointing Control Subsystem.
Hubble Technology
Initial Deployment Components and Servicing Missions
Servicing Mission 3a:
On December 19, 1999, seven astronauts boarded the space shuttle Discovery to pay the Hubble Space Telescope
a special holiday visit. After a successful launch and several trips around Earth, the crew caught up with Hubble
and hauled it into the shuttle's cargo bay. Six days and three 6-hour spacewalks later, the crew had successfully
completed Part A of the two-part Third Servicing Mission, which had them replacing worn or outdated equipment
and performing several critical maintenance upgrades.
Servicing Mission 3A (STS-103) was a busy one. The most pressing task was the replacement of gyroscopes,
which accurately point the telescope at celestial targets. The crew, two of whom were Hubble repair veterans,
replaced all six gyroscopes-as well as one of Hubble's three fine guidance sensors (which allow fine
pointing and keep Hubble stable during observations) and a transmitter.
The astronauts also installed an advanced central computer, a digital data recorder, an electronics
enhancement kit, battery improvement kits, and new outer layers of thermal protection. Hubble was as
good as new.
Hubble Technology
Initial Deployment Components and Servicing Missions
Servicing Mission 3b:
On March 1, 2002, NASA launched the space shuttle Columbia into an orbit 360 miles above Earth, where its sevenmember crew met with the Hubble Space Telescope to perform a series of upgrades. Servicing Mission 3B, also
known as STS-109, was the fourth visit to Hubble. NASA split the original Servicing Mission 3 into two parts and
conducted the first part – Servicing Mission 3A – in December 1999.
The highly-trained astronauts performed five spacewalks. Their principal task was to install a new science instrument
called the Advanced Camera for Surveys, or ACS. The first new instrument to be installed in Hubble since 1997,
ACS brought the nearly 12-year-old telescope into the 21st century. With its wide field of view, sharp image quality,
and enhanced sensitivity, ACS doubled Hubble’s field of view and collects data ten times faster than the Wide Field
and Planetary Camera 2, the telescope’s earlier surveying instrument.
Hubble gets its power from four large flexible solar array panels. The 8-year-old panels were replaced with smaller
rigid ones that produce 30 percent more power. Astronauts also replaced the outdated Power Control Unit, which
distributes electricity from the solar arrays and batteries to other parts of the telescope. Replacing the original unit,
which has been on the job for nearly 12 years, required the telescope to be completely powered down for the first time
since its launch in 1990.
Reaction Wheel Assembly: Four Reaction Wheel Assemblies like this one are needed to point the telescope.
Astronauts will replace one of them.
During the last spacewalk astronauts installed a new cooling system for the Near Infrared Camera and Multi-Object
Spectrometer, or NICMOS, which became inactive in 1999 when it depleted the 230-pound block of nitrogen ice that
had cooled it since 1997. The new refrigeration system, which works much like a household refrigerator, chills
NICMOS’s infrared detectors to below –315° F (–193° C). NICMOS Cooling System: An experimental refrigeration
technology will make it possible to restore Hubble's infrared vision.
New Steering Equipment: Astronauts replaced one of the four reaction wheel assemblies that make up Hubble's
pointing control system. Flight software commands the reaction wheels to “steer” the telescope by spinning in one
direction, which causes Hubble to spin in the other direction.
The Science of Hubble
It is not even remotely possible to cover all the science that Hubble has done in a single presentation. Tens of
thousands of papers and hundreds of books have been written based on HST data, and every day generates 20 GB of
data. Astronomers will be mining this resource for generations to come.
Exceeding Expectations
•
“It should be emphasized, however, that the chief contribution of such a radically new and more
powerful instrument would be, not to supplement our present ideas of the universe we live in, but
rather to uncover new phenomena not yet imagined, and perhaps modify profoundly our basic
concepts of space and time.” - Lyman Spitzer, Jr.
•
“[T]his mechanism …has succeeded in opening the universe to us in ways never dreamed
possible.”
Petersen, Carolyn C. and Brandt, John C. Hubble Vision: Further Adventures with the Hubble Space Telescope, 2nd
ed., Cambridge University Press, Cambridge UK
The Science of Hubble
•
Even before Hubble was launched, it had changed the science of astronomy. Because of its
exacting pointing requirements, the Guide Star Catalog had to be created to allow its fine
guidance sensors to be used to their full capacity. The GSC now contains almost a billion objects
and is a valuable resource for astronomers worldwide.
First Light
“First light” images from Hubble showed
that, even with the spherical aberration of the
main mirror, good science could still be
done. The image on the left is from a groundbased telescope; the right is from Hubble.
A Busy Ten Years
•
In its first decade of operation, Hubble refined and reshaped our knowledge of Mars,
Jupiter, star formation, globular clusters, black holes, and the age of the universe.
•
After only five years of “20/20 vision,” Hubble had studied the atmosphere of Mars,
imaged Venus, studied the weather of Jupiter, discovered new moons, studied
comets and asteroids, mapped Pluto, and forever changed our picture of the Solar
System.
Livio M. et al, eds, A Decade of Hubble Space Telescope Science, Cambridge University Press, Cambridge UK 2003.
Petersen, Carolyn C. and Brandt, John C. Hubble Vision: Further Adventures with the Hubble Space Telescope, 2nd ed.,
Cambridge University Press, Cambridge UK
Hubble’s Top 10 Scientific Discoveries
1. Hubble’s studies of supernovas helped to show the existence of
dark energy
2. Determining the age of the universe
3. Snapshots of the early universe via the Hubble Deep Field
Surveys (image seen here)
4. First direct measurement of an extrasolar planet’s atmosphere
(further work is halted due to STIS failure)
5. Discovering black holes in the hearts of galaxies
6. Sources of gamma ray bursts – the collapse of massive stars in
distant galaxies
7. Showing that quasars are the hearts of distant galaxies
8. Showing that protoplanetary disks are common
9. The 1994 impacts of comet Shoemaker-Levy 9 on Jupiter
10. Studies of planetary nebulae yielded more information on how
stars die.
Handwerk, Brian, “Hubble Space Telescope Turns 15,” National Geographic, April 25, 2005, viewed at
http://news.nationalgeographic.com/news/2005/04/0425_050425_hubble.html
Interview with Dr. David Leckrone, Goddard Space Flight Center, April 10,2006.
The Future?
•
HST Service Mission 4 is currently being studied; if carried out, it will install batteries, gyros, one
fine guidance sensor, and two new science instruments, repair STIS, and extend the telescope’s
lifespan by at least five years. One instrument, WFC3, would allow astronomers to measure the
universe’s rate of expansion over time with unprecedented accuracy.
•
If SM4 is not carried out, Hubble is expected to shut down by 2008.
•
James Webb Space Telescope (JWST) is slated for launch in 2013. It is expected to have finer
resolution and concentrate more on IR than HST. Hubble can detect faint IR smudges at the very
edge of resolution; JWST should be able to reveal what those smudges are (probably some of the
very first stars and proto-galaxies to form.)
Interview with Dr. David Leckrone, Goddard Space Flight Center, April 10, 2006
Funding and Economics
Hubble: Large Space Telescope,
Astronomical Price Tag
Overview of an Overrun
• Original budget: $475 million
• OTA: $69.4 million
• Actual cost: In 1986, when it was first assembled
for launch, it cost $1.6 billion, and had several
technical problems. Four years of tinkering and
improvements later, it is finally launched – at $2.2
billion (not counting the $0.5 billion for the
launch!)
• Percentage overrun: 463%
Players
NASA
-MSFC:
engineering and
construction
-GSFC: scientific
instruments and
mission operations
-JSC: launch and
astronaut training
Science Interests
-STScI: created to
oversee the
interests of the
outside scientific
community
-AURA:
international group
of 31 educational
and nonprofit
entities
Contractors
Lockheed: SSM
Perkin-Elmer: OTA
Secondary
contractors: almost
two dozen
companies
throughout the
aerospace industry
Costs Plus
• Mirror discovered to have spherical aberration –
only seeing about 21% of the light it is supposed
to.
• SM-1: repaired faulty optics, replaced gyros, solar
panels, and memory banks.
• SM-2, SM3A, SM3B: $0.5 billion plus
• Proposed fifth mission: $1.7-2.4 million (not
counting $2.2 billion for Shuttle rehab)
Hubble’s Policy, Legal,
and International
Ramifications:
Lessons Learned
Political incrementalism is
reflected in studies on
congressional decision-making as
it relates to Big Science (largescale) NASA programs like the
Hubble Space Telescope.
Astronomers in the
mid-to-late 1970s
were very effective
in using the growing
pluralistic political
interest group,
single-issue oriented
politics, to advance
the development of
the Space Telescope.
Civil space officials
formulate international
agreements with
foreign officials, in
part to expand their
base of support.
An international
agreement with a
foreign government
provides a layer of
extra protection not
afforded a pure
domestic program.
Some of the technology
of the Hubble Space
Telescope was developed
initially for satellite
reconnaissance programs
of the DoD.
It has been suggested
that the initial telescope
problems could have been
mitigated had the DoD
been more forthcoming
with NASA Marshall.
Today International
Traffic in Arms Regulation
(ITAR) limits international
cooperation through
exclusion or added
burden of bureaucratic
waiver paperwork upon
scientists working with
international space
telescope projects.
Technology transfer
issues remain a vexing
political and legal issue.
The Hubble Space Telescope
Management & Operations
Early Years of the Program
•
After Apollo, NASA considered both MSFC & GSFC to manage its
proposed Large Telescope program.
•
GSFC had the scientific expertise & MSFC more experience in managing
a large program and had a large idle staff.
•
In 1971, NASA divides the program between the two centers causing
rivalry and animosity that lasted for most of the program
•
NASA gave lead to Marshall in 1972, as well as too many responsibilities,
making it, in effect a prime contractor (without the experience to be one),
that led to serious management and technical problems.
•
By 1976, this rivalry threatened program, with Goddard’s role viewed as
that of a sub-contractor.
•
Rivalry abated when NASA threatened to give entire program to Marshall.
Marshall and the Associate Contractors
•
•
•
•
•
•
•
In 1977, Marshall chose Lockheed Martin to build the support craft and Lockheed in
turn chose Perkin-Elmer for the mirror.
Marshall was wary of Perkin-Elmer because their low bid did not include proper
testing of the mirror polishing computer program. This concern proved to be
prophetic.
European Space Agency becomes partner in program to provide camera a solar
panels in exchange for 15% of observation time.
MSFC also prevented from sufficient staff and management penetration at PE due to
its DoD work.
Once NASA removed personnel cap in 1979, Marshall took more active role at PE, it
was too late to make changes.
Marshall had to step in to help finish the mirror’s shaping as PE was over budget &
behind schedule. MSFC felt that PE was ‘good at testing … but nothing else’.
By 1982, Marshall was increasingly dissatisfied with PE & had to increase its own
staff in Danbury because Perkin-Elmer lacked competent management and
inadequate operating procedures.
More Problems and New Solution
•
Marshall fully managing at PE, better progress was made.
•
Management, scheduling and cost problems at Lockheed that Marshall
had to rectify
•
Marshall finally informed NASA of the worsening situation at PE and
NASA reports it to Congress.
•
Communications breakdown caused by NASA’s lack of experience at
managing multiple centers for same project and Marshall’s naiveté in
hoping problems would correct themselves.
•
Science community had lobbied for independent institute to operate
telescope; finally got their wish in 1981, with the establishment of the
Space Telescope Science Institute, located on the campus of Johns
Hopkins University.
Program Management Prior to Launch
Management and Operations Today
•
Hubble is operated on behalf of NASA by AURA (the Association of Universities for
Research in Astronomy, Inc.), Goddard Space Flight Center and the European
Space Agency.
•
Operations are monitored by staffers (including 15 from the ESA) at both GSFC
and STSI
•
STSI operates 24/7; it is manned in rotating shifts (3-4 at a time)
•
Operations are divided into Engineering and Science foci
•
Engineering responsibility is spacecraft performance. By communicating in real
time, engineers are able to tell HST what to do and how to focus.
•
Science Operations encompass observation scheduling, science hardware,
interpreting the raw data, as well as maintaining the data and disseminate the data
to end users.
•
Dr. David Leckrone (lead STSI Hubble scientist) explained that there is an
oversubscription of proposals (5:1 at present; 8:1 before STIS failed) with no sign
of lessening. To date HST viewings have generated over 5,000 science papers.
Operations (continued)
•
Once images are taken, the data (more than
several million bits daily are taken by HST’s
high gain antennas) is returned to Earth several
times a day.
•
The data is then sent as digital signal to White
Sands, NM, the HST ground station via a
TDRSS satellite.
•
The data then goes to GSFC for accuracy
determinations either immediately or are stored
on tapes for later review.
•
STSI gets the data next for processing and
distribution to the requesting astronomer who
has exclusive rights to the data for one year.
•
Each orbit lasts about 95 minutes, with
scheduled downtime to allow for maintenance,
repositioning, target acquisition, etc.
Conclusions and Lessons Learned
What does this investigation of Hubble’s
integrated evolution teach us?
Conclusions and Lessons Learned
•
•
Hubble has been a stunning scientific and technological success.
The LST/HST history can be described as an example of how not to conduct a large national
science program. The contributing detrimental factors in its development can be
summarized as follows:
– The sources of trouble were multiple, but the overarching problem was money. The
promise of the program was great, but NASA did not believe it could ask Congress for
the money MSFC had estimated the project would cost.
– Competition was misplaced. In the case of NASA’s management, the forced
competition between two co-equal NASA centers was detrimental.
– NASA was faced with the threat of having one or more centers closed – this was one
factor in the selection of MSFC as the lead.
– The decision to use two associate contractors (not a prime with real authority to do
systems management) was a critical error since MSFC did not have the resources to
perform this function.
– NASA HQ had too few people to watch over the program and left it to the field centers
to manage until 1983. By then, the program was faced with intractable problems.
– Congress was opposed to the project and key legislators fought it. We can learn from
this that efforts to unrealistically limit a program’s budget by forcing limits can, over
time, force a program to cost more, not less.
– An overestimation of the Space Shuttle’s capabilities was a factor.
– The influence of the DoD in limiting NASA penetration of key contractors was a major
factor which exacerbated the problem.
– Perkin-Elmer was unqualified to handle the OTA.
– NASA did a poor job of communicating not just within the program, but in effectively
describing the potential value of the project.
Conclusions and Lessons Learned
On the positive side, we have also learned the following;
– Large national space science programs do work, and can lead to enormous
gains for the nation. More should be done to explain the accomplishments
effectively.
– Hubble demonstrated the idea of a National Facility, breaking from the
paradigm of a single Principal Investigator.
– The scientific community was a hero in the story of the HST
– HST demonstrated that multiple countries can cooperate effectively on a
major science program in space.
– The role of astronaut servicing on orbit was validated by Hubble – without it,
we would not have this program. With it, we have an orbital observatory that
can be upgraded and extended for decades.
(On this point, we have good reason to see concordance between the
advocates of both manned and unmanned space exploration.)
Perhaps the lasting lesson of Hubble is that we should allow ourselves to be challenged
by potentially transformational projects. At the height of the Cold War, Hubble’s builders
allowed themselves to dream of a telescope in space that they did not know how to build.
It would be able to point at galaxies while flying through space; it would be operated by
multiple nations; tended by astronauts; and for all this, its results were unpredictable.
Team Hubble Huddle
Professor Shan de Silva PhD
Team and Component Research Areas:
Greg Carras (Technology)
Jerry Cordaro (Science)
Andrew Daga (Evolution and History)
Sean Decker (Funding and Economics)
Jack Kennedy (Policy, Law, and International Cooperation)
Susan Raizer (Management and Operations)
With appreciation to the Space Telescope Science Institute in Baltimore, MD; Dr David Leckrone and the staff and
personnel of NASA Goddard Space Flight Center, Greenbelt, MD; and to the Boeing Company, Seattle, WA
Submitted in partial fulfillment of the requirements of Space Studies 502 (with associated Evolutionary Chart and References)
Department of Space Studies, University of North Dakota, April 24 2006