An Operations Overview of the Hubble Space Telescope Servicing Mission 4

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An Operations Overview of the Hubble Space
Telescope Servicing Mission 4

• Keith Walyus
• Michael Prior
• Lisa Mazzuca

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Topics

• Observatory Health
• Servicing Mission 4 (SM4) Overview
• SM4 Manifest

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HST Spacecraft Health
High gain antenna

• Equipment Section
• Degraded MLI Install NOBLs on Bays 5, 7, 8 in
  SM4
• NOBLs 1, 6, 9, and 10 already installed

Secondary mirror
Aperture door
Primary mirror

• Fine Guidance Sensors
• FGS2R degrading servo LED
• FGS3 degrading bearings
• replace one FGS on SM4

Aft Shroud

• Solar Arrays
• SA3 installed in SM3B

• Axial Scientific Instruments
• NICMOS restored installed NCS in SM3B
• STIS, failed 8/04

• Batteries
• Charge capacity trending downward replace all 6
  batteries on SM4

• Rate Sensor Units
• Gyros 3 and 5 failed replace all 6 gyros on SM4

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HST's Science and Life Limitations

• Availability of gyros drives HST science life
• Has no impact on ability to service Hubble
• Switched to Two-Gyro Science operations August
  29, 2005
• Previously used three gyros for all science
  operation
• Predictions indicate 2-gyro science likely until
  late 2008
• Work initiated on One-Gyro Science Mode
• Declining observatory battery system charge
  capacity drives HST life on-orbit
• Determines Hubble availability to be serviced
• Batteries capacity will be sufficient to allow
  HST to be serviced by the Shuttle
• Life extension activities in the area of battery
  charge management indicate positive results
• Degraded MLI (multi-layer insulation)on Bays 5
  and 8 potentially accelerates aging of critical
  avionics
• Bay 5 and Bay 8 approach thermal red limits every
  hot season (winter when earth is closer to the
  sun)
• Accelerated MLI degradation expected due to solar
  minimum
• Installation of NOBLs (new outer blanket layers)
  on Bays 5 8 a priority for SM4
• Installation of NOBL on Bay 7 is highly desired

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Degraded MLI on Bays 5, 7, 8
Bay 5
Radiators
(SM3B Survey)
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Avionics System

• Hubble is not dying
• Hubble contains known wear-out items that need to
  be replaced from time to time
• The rate of random failures in other Hubble
  systems (avionics) has decreased dramatically
  since the first 5 years of Hubbles Mission
• Hubble is well past infant mortality, and as
  repair and maintenance needs have arisen they
  have been addressed in the prior four Servicing
  Missions
• Hubble is probably more reliable and robust as a
  spacecraft than a newly launched observatory
  could be because (as shown below) all of the
  infant mortality anomalies have already occurred
• The avionics failure rate during the last 5 years
  of HST operations is 73 lower than the failure
  rate averaged over the entire 14.6-year mission
  (through 2004), and 86 lower than during the
  first 5 years of operation

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Assumptions for SM4

• Program planning for SM4 assume the following
• Launch Readiness Date (LRD) is December 6, 2007
• Shuttle mission cargo manifest includes
• HST life extension hardware
• Rate Sensing Units (3 RSUs, 6 gyros total)
• Batteries (2 modules 6 batteries total)
• Fine Guidance Sensor (FGS)
• New Outer Blanket Layers (NOBLs, for Bays 5, 7,
  and 8)
• HST science upgrades
• Wide Field Camera 3 (WFC3) (replace WFPC2)
• Cosmic Origins Spectrograph (COS) (replace
  COSTAR)
• Science restoration
• Space Telescope Imaging Spectrograph (STIS)
  repair is on a best efforts basis and possibly
  install hardware to help cool STIS
• Soft Capture and Rendezvous System
• 5 EVAs in a 11 day mission with rendezvous at 304
  n. mi.

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Preliminary - For HST Program Planning Purposes
OnlySM-4 EVA Scenario
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HST Servicing Mission 4 (SM4) Configuration
(Preliminary)
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Batteries

• On-orbit HST Batteries are original batteries
  from launch
• Operating for over 16 years!
• Capacity has degraded over the years
• HST has six batteries grouped into two separate
  modules and located in two separate bays
• Current plan is to change out the batteries on
  two separate days

HST Battery Module
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Gyros

• HST has six gyros on board
• Gyros were last replaced in 1999.
• Two have failed
• One is in a degraded state although still usable
• Originally, HST always used three gyros with one
  kept on as a hot spare
• HST operationally now uses two gyros
• A new guidance algorithm was developed to use
  only two gyros
• Only a small loss of science capability
• By keeping the gyros in an off state, the gyros
  will last longer
• Analysis on-going to develop a one gyro guidance
  algorithm

Rate Sensing Unit, which contains 2 gyros
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Cosmic Origins Spectrograph

• The Cosmic Origins Spectrograph (COS) is a
  third-generation instrument to be installed on
  the Hubble Space Telescope (HST) during Servicing
  Mission 4.
• COS is designed to perform high sensitivity,
  medium- and low-resolution spectroscopy of
  astronomical objects in the 1150-3200Å wavelength
  range.
• COS is not meant to be a replacement for the
  Space Telescope Imaging Spectrograph (STIS),
  which will remain in HST after the servicing
  mission and will be available to the community
  after its successful repair.

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Wide Field Camera 3

• WFC3 is designed to ensure that HST maintains its
  unique imaging capabilities until the end of its
  mission, while at the same time advancing its
  survey and discovery capability due to its
  combination of wavelength coverage, field of
  view, and sensitivity. WFC3 will also provide a
  good degree of redundancy for ACS and NICMOS.
• The optical design of WFC3 features two
  independent channels, one sensitive at
  ultraviolet (UV) and optical wavelengths,
  approximately 200 to 1000 nm (the UVIS channel),
  and the other sensitive at near infrared (IR)
  wavelengths, approximately 850 to 1700 nm (the IR
  channel).

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Wide Field Camera 3
Near-IR

• Capabilities
• Imaging from 2000 Å to 1.7 ?m
• Slitless spectroscopy
• Huge improvement in near-UV, near-IR imaging

Ultraviolet
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STIS Repair

• Objective is to regain full ultraviolet and
  visible spectroscopy capabilities of HST Space
  Telescope Imaging Spectrograph instrument
• Spectroscopy is a fundamental tool of astronomy
• STIS is a powerful general-purpose spectrograph
  suitable for investigating the full range of
  astronomical phenomena
• STIS has had a great track record of scientific
  productivity
• If returned to service, STIS will continue to
  provide that high scientific return for the
  astronomical community into the future

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STIS
V3 Side
MEB-2
Flight STIS Instrument
V2 Side
MEB-1
STIS Closeup
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STIS Main Electronics Box (MEB)
MEB-1 Cover Removed
LVPS-2 Board (Engineering Unit)
MEB Structure (non-flight)
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FGS Change-out Decision

• Both FGS2R and FGS3 exhibit life limiting
  degradation modes
• One flight spare unit is available
• Decision of which unit to change out will be made
  before the Cargo Integration Review (L- 10
  months)
• FGS3 baselined for planning purposes since it is
  the more difficult for EVA

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SCRS Overview

• The Soft Capture Rendezvous System (SCRS) shall
  enable/assist the safe end-of-life deorbit of the
  HST Observatory.
• Soft Capture Mechanism system (SCM)
• The SCM is a compact device which attaches to the
  HST Aft Bulkhead
• It is designed to make HST a friendly and
  cooperative passive target for future rendezvous
  and capture operations.
• Additional optical targets will be mounted.

RMS End Effector Compatible Grapple Fixture
HST Attachment Mechanism (3x)
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Summary

• After the next Servicing Mission, HST will be at
  the peak of its scientific and engineering
  capability
• Launch is officially scheduled for December 06
• Dependent on Shuttle schedules
• Tune-in for an incredibly exciting Servicing
  Mission!!!