SPACE
TELESCOPE
SCIENCE
INSTITUTE
Operated for NASA by AURA
SMOV4 Requirements Review
Cosmic Origins Spectrograph
Scott D. Friedman
STScI
30 July 2003
L.10.4.2.1 Engineering Activities
L.10.4.2.1.1 Detector States
The ability of the COS detectors to operate in each of their
states shall be demonstrated.
NUV detector states:
HOLD, Low Voltage ON (LVON), High Voltage ON
(HVON), and High Voltage in SAA (HVSAA).
FUV detector states:
HOLD, BOOT, OPERATE, HV LOW, HV NOMINAL,
HV SEGMENT A, and HV SEGMENT B.
Slide 2 of 17
Engineering Activities (cont.)
L.10.4.2.1.2 Load and Dump On-board Memory
Demonstrate the ability to load and dump on-board COS
memory.
L.10.4.2.1.3 Science Data Buffer Check
Demonstrate the ability to read from and write to the
Science Data Buffer.
Slide 3 of 17
Engineering Activities (cont.)
L.10.4.2.1.4 MAMA Detector Turn-on and Anomalous
Recovery Test
Test the procedure used for initial turn-on of MAMA
detector. Test the procedure for recovery after anomalous
shutdown.
L.10.4.2.1.5 FUV Detector Turn-on and Anomalous
Recovery Test
Test the procedure used for initial turn-on of FUV detector.
Test the procedure for recovery after anomalous shutdown.
Slide 4 of 17
L.10.4.2.2 Contamination
Monitoring
COS operations shall be managed to minimize the risk of
contamination of its optical surfaces. The COS external
shutter shall provide protection against illumination by the
bright earth. A sensitivity monitoring program shall be
initiated as soon as possible after the servicing mission.
(Reference: COS CARD item 3.4.12.20.)
Slide 5 of 17
L.10.4.2.3 Conduct Science
Verification & Calibration
L.10.4.2.3.1 Upon release the COS instrument shall
undergo a period of depressurization and
decontamination.
Once the internal pressure of COS is = 10 micro-Torr, as
measured by the onboard pressure monitor or as predicted
by a model, the MAMA detector HV can be turned on, and
calibration and alignment of the NUV channel can begin.
The NUV channel shall be aligned first in order to provide
additional time for the pressure within COS to decrease
further. The FUV detector HV can be turned on when the
pressure is = 5 micro-Torr.
Slide 6 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.2 Internal NUV calibrations shall be
conducted to measure the post -launch alignment of the
optics.
This includes:
o a detector dark image.
o an internal wavelength calibration spectrum using each
NUV channel at a single central wavelength setting.
o a TA-1 image of the wavelength calibration lamp.
o intensity of each lamp in a single mode.
Slide 7 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.3 The relationship between the HST coordinate
system and the COS primary science aperture (PSA)
shall be measured. The NUV channel in the TA-1 mode
shall be used to locate the PSA in HST V2, V3
coordinates. This is accomplished by raster scanning in a
4x4 grid, monitoring the count rate in the NUV detector,
and calculating the location of the HST OTA point spread
function with respect to the PSA. The calculating is done
on the ground after the observations are complete.
Slide 8 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.4 The locations of the spectra for each NUV
mode shall be measured. This is done by observing an
astronomical target and acquiring a spectrum using
G185M, G225M, G285M, and G230L channels, as well as
a TA-1 image.
Slide 9 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.5 The NUV channel shall be focused. Conduct a
focus scan of the NUV channel using the TA-1 mode while
observing an astronomical target.
L.10.4.2.3.6 The target acquisition algorithms for NUV
operations shall be tested and verified.
L.10.4.2.3.6.1 TA-1 target acquisition shall be tested.
L.10.4.2.3.6.2 NUV dispersed light target acquisition shall be
tested.
Slide 10 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.7 The NUV channel performance shall be
calibrated.
L.10.4.2.3.7.1 The zero point offsets in the dispersion
relations for the NUV spectroscopic modes for each central
wavelength setting shall be measured.
L.10.4.2.3.7.2 The spectral resolution of the NUV
spectroscopic modes shall be measured.
L.10.4.2.3.7.3 The spatial resolution of the NUV
spectroscopic modes shall be measured.
Slide 11 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.7.4 The flat-field response of the G185M grating
shall be measured.
L.10.4.2.3.7.5 The sensitivity of each NUV channel for each
central wavelength setting shall be measured.
L.10.4.2.3.7.6 The stability of a single mode of the NUV
channel shall be characterized to determine if there are
signatures of structural or thermal distortions in the data.
Slide 12 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.8 Internal FUV calibrations shall be
conducted to measure the post -launch alignments of the
optics.
This includes:
o a detector dark image.
o an internal wavelength calibration spectrum using each
FUV channel at a single setting.
o intensity of each lamp in a single mode.
Slide 13 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.9 The locations of the spectra for each FUV
mode shall be measured. This is done by observing an
astronomical target and acquiring a spectrum using
G130M, G160M, and G140L channels.
L.10.4.2.3.10 The FUV channel shall be focused. Conduct
a focus scan of each of the FUV channel while observing
an astronomical target.
Slide 14 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.11 The target acquisition algorithms for FUV
operations shall be tested and verified.
L.10.4.2.3.11.1 FUV dispersed light target acquisition shall
be tested.
Slide 15 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.12 The FUV channel performance shall be
calibrated.
L.10.4.2.3.12.1 The zero point offsets in the dispersion
relations for the FUV spectroscopic modes for each central
wavelength setting shall be measured.
L.10.4.2.3.12.2 The spectral resolution of the FUV
spectroscopic modes shall be measured.
L.10.4.2.3.12.3 The spatial resolution of the FUV
spectroscopic modes shall be measured.
Slide 16 of 17
Science Verification
& Calibration (cont.)
L.10.4.2.3.12.4 The flat-field response of the G130M and
G160M gratings shall be measured.
L.10.4.2.3.12.5 The sensitivity of each FUV channel for each
central wavelength setting shall be measured.
L.10.4.2.3.12.6 The stability of a single mode of the FUV
channel shall be characterized to determine if there are
signatures of structural or thermal distortions in the data.
Slide 17 of 17