SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA SMOV4 Requirements Review Cosmic Origins Spectrograph Scott D. Friedman STScI 30 July 2003

Slide 2 of 17 L Engineering Activities L 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 3 of 17 Engineering Activities (cont.) L Load and Dump On-board Memory Demonstrate the ability to load and dump on-board COS memory. L Science Data Buffer Check Demonstrate the ability to read from and write to the Science Data Buffer.

Slide 4 of 17 Engineering Activities (cont.) L 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 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 5 of 17 L 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 )

Slide 6 of 17 L Conduct Science Verification & Calibration L 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 7 of 17 Science Verification & Calibration (cont.) L 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 8 of 17 Science Verification & Calibration (cont.) L 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 9 of 17 Science Verification & Calibration (cont.) L 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 10 of 17 Science Verification & Calibration (cont.) L 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 The target acquisition algorithms for NUV operations shall be tested and verified. L TA-1 target acquisition shall be tested. L NUV dispersed light target acquisition shall be tested.

Slide 11 of 17 Science Verification & Calibration (cont.) L The NUV channel performance shall be calibrated. L The zero point offsets in the dispersion relations for the NUV spectroscopic modes for each central wavelength setting shall be measured. L The spectral resolution of the NUV spectroscopic modes shall be measured. L The spatial resolution of the NUV spectroscopic modes shall be measured.

Slide 12 of 17 Science Verification & Calibration (cont.) L The flat-field response of the G185M grating shall be measured. L The sensitivity of each NUV channel for each central wavelength setting shall be measured. L 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 13 of 17 Science Verification & Calibration (cont.) L 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 14 of 17 Science Verification & Calibration (cont.) L 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 The FUV channel shall be focused. Conduct a focus scan of each of the FUV channel while observing an astronomical target.

Slide 15 of 17 Science Verification & Calibration (cont.) L The target acquisition algorithms for FUV operations shall be tested and verified. L FUV dispersed light target acquisition shall be tested.

Slide 16 of 17 Science Verification & Calibration (cont.) L The FUV channel performance shall be calibrated. L The zero point offsets in the dispersion relations for the FUV spectroscopic modes for each central wavelength setting shall be measured. L The spectral resolution of the FUV spectroscopic modes shall be measured. L The spatial resolution of the FUV spectroscopic modes shall be measured.

Slide 17 of 17 Science Verification & Calibration (cont.) L The flat-field response of the G130M and G160M gratings shall be measured. L The sensitivity of each FUV channel for each central wavelength setting shall be measured. L 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.