Return to Hubble: Servicing Mission 4

Dr. Frank SummersSpace Telescope Science Institute

April 2, 2009

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A Space Telescope

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Artist’s Illustration

WRONG

Photograph

CORRECT

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Size of Earth

Size of Earth’s Atmosphere

6400 km

600 km above surface

Size of Hubble’s Orbit

100 km above surface

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Some Hubble History

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• 1946 – Space telescope proposed

• 1962 – National Academy of Sciences recommends

Lyman Spitzer

• 1976 – NASA & ESA collaborate• 1977 – Congress funds project• 1985 – Construction complete• 1986 – Challenger accident

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• 1990 – Launch• 1993 – Servicing Mission 1• 1997 – Servicing Mission 2• 1997 – Mission extended

from 15 to 20 years• 1999 – Servicing Mission 3A• 2002 – Servicing Mission 3B• 2003 – Columbia accident• 2004 – No shuttle mission?• 2005 – Two gyro mode• 2006 – “One final house

call”• 2008 – Hardware delay

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What Makes Hubble So Great?

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• Clear View – located above blurring effects of atmosphere

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• Serviceable – new instruments every few years keeps it current

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• Public – Observers get only one year of exclusive access

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• Professional – STScI provides excellent support to scientists

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Houston, We Have a Problem

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Hubble Servicing Missions

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Servicing Mission 1 – December 1993

• COSTAR, WFPC2

• solar arrays, gyros

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Servicing Mission 2 – February 1997

• NICMOS, STIS

• fine guidance sensor, solid state recorder, reaction wheel assembly

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Servicing Mission 3A – December 1999

• gyroscope failure in November

• computer, data recorder, fine guidance sensor, electronics improvement, thermal protection

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Servicing Mission 3B – March 2002

• ACS

• solar arrays, NICMOS cooling system, reaction wheel assembly, power control unit

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Servicing Mission 4 – May 2009

• WFC3, COS

• ACS repair, STIS repair, gyros, batteries, fine guidance sensor, thermal blanket, de-orbit module

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Servicing Mission 4 – May 2009

• WFC3, COS

• ACS repair, STIS repair, gyros, batteries, fine guidance sensor, thermal blanket, de-orbit module

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1990

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1993

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1997

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2002

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2009

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Hubble, We Have an Anomaly

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SM4: An Ambitious Workload

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SM4: An Ambitious Workload

“This final mission will be, without doubt, the most complicated and challenging that NASA has ever mounted.”

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Major Goals for SM4

1 Enhance Hubble’s scientific capabilities with a new camera and new spectrograph• WFC3, a panchromatic camera, replacing WFPC2

• COS, a very efficient spectrograph, replacing COSTAR

2 Restore existing Hubble capability through in-situ repair• STIS: repair failed electronics

• ACS: repair failed electronics

3 Upgrade Hubble to last to beyond 2014• Install refurbished Fine Guidance Sensor

• Install 6 new gyros

• Install 6 new batteries

• Install thermal protection covers

• Install Capture Mechanism for de-orbit mission

If successful, HST will be at the height of its power,

with 6 working, complementary, science instruments

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NOTE: Now that SM4 is officially manifested and a crew has been assigned, the EVA timeline is controlled by the Space Shuttle Program.

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Wide Field Camera 3

– WFC3…

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Wide Field Camera 3

• WFC3 has two wide field cameras– near ultraviolet and optical imaging

(UVIS)– near infrared imaging camera (IR)

• First truly panchromatic camera• Improves on ACS & NICMOS

– UVIS >30x discovery power of ACS/WFPC2– IR 15-20x discovery power of NICMOS

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Camera Comparison

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Cosmic Origins Spectrograph

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Cosmic Origins Spectrograph

• COS optimized for ultraviolet observations• Far Ultraviolet Channel

– 1-reflection, aberration-corrected along dispersion– 2 side-by-side 16k by 1k pixel detector (FUSE design)– Records arrival time of every detected photon– 3 gratings; 300 or 800 (nm) spectral range– Resolving power ~3000, ~20,000 [115 to 205 nm]

• Near Ultraviolet Channel– Fully corrected optical design– 1k by 1k pixel detector (STIS design)– Records arrival time of every detected photon– 4 gratings– 10 to 80 nanometers spectral ranges– Resolving power ~2000, ~20,000 [170 to 320 nm]

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COS vs STIS

Limiting Flux for S/N=10 in 3600 sec (R~10,000 (0.15 Ǻ) binning)

-15.5

-15.0

-14.5

-14.0

-13.5

-13.0

-12.5

1100 1200 1300 1400 1500 1600 1700 1800

Wavelength (Ǻ)

log

Flu

x (

erg

cm

-2 s

ec-1

Ǻ-1)

STIS E140MR=45,000

STIS G140MR~11,000-17,000

COS G130MR~20,000-24,000

COS G160MR~20,000-24,000

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ACS Repair

• Advanced Camera for Surveys• ACS failure in January 2007• Cut through a grill• Similar to WFC3, but …

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STIS Repair

• Space Telescope Imaging Spectrograph

• STIS failure in August 2002• > 100 fasteners• Similar to COS, but …

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Gyros

• 3 gyros operating is nominal• 2 gyro mode since 2005• 3 failed, 2 operating, 1 spare

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Gyros installed in SM3A

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G1 G2 G3 G4 G5 G6

RR

RR

Solid blue = run tim e @ SM3BSlant blue = run tim e @ 9/17/07Red = run tim e @ pre-SM3B failureSlant red = run tim e @ pos t-SM3B failureRR = rotor res triction failure

Gyros in HST at completion of SM1

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1

2

3

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G1 G2 G3 G4 G5 G6

Ru

n-t

ime

in

Ye

ars

FL

FL

FL

FL

Solid blue = run tim e @ SM2Slant blue = run tim e @ SM3ARed = run tim e @ failureFL = flex lead failure

50% failure probability

75% failure probability

95% failure probability

ON

OFF

FL

ON

G1 G2 G3 G4 G5 G6 G1 G2 G3 G4 G5 G6

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Batteries

• Hubble can not point without batteries

• About 100,000 charge-discharge cycles

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Bay 8 Thermal Situation

BAY9

BAY8

SM3B Survey

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Bay 8 Thermal Situation•Patched during SM2, however expected to

be completely degraded

PATCHBAY 7 BAY 8

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Bay 8 Thermal Situation

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• Possible severe scheduling impacts

Possible Bay 8 Impacts

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SM4 Preparations

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HFMS Fit Check

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HFMS Fit Check

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ASIPE Fit Check

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HST equipment at KSC

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May 12, 2009

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