15095( 9) - 06-Feb-2019 20:10:59 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15095 Version: 9 Check-in Time: 06-Feb-2019 20:10:59 STScI Edit Number: 1 Title Constraining the Surface Composition of Europa with Spatially Resolved Mid-UV Spectra ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Tracy M Becker Southwest Research Institute Y CoI: Dr. Kurt David Retherford Southwest Research Institute N CoI: Dr. Amanda R. Hendrix Planetary Science Institute N CoI: Dr. Lorenz Roth Royal Institute of Technology N CoI: Dr. Pippa Molyneux Southwest Research Institute N CoI: Mr. Juan Alday Royal Institute of Technology N ------------------------------------------------------------------------------------ Abstract We propose to observe Jupiter's icy moon, Europa, to obtain spatially resolved UV spectra of its leading, trailing, sub-Jovian and anti-Jovian hemispheres that include diagnostic mid-UV wavelengths that have not previously been analyzed. Current published observations of Europa include near-UV observations from 210 nm - 320 nm, and far-UV observations from ~110 nm - 170 nm; however, the data in the mid-UV (170 nm - 210 nm) is lacking. Although Europa's surface consists mostly of water ice, the characteristic sharp absorption edge observed at ~165 nm in lab spectra and on the icy moons of Saturn has not been detected on Europa. Observations in the mid-UV could reveal the absorption edge at longer wavelengths, suggestive of larger ice grains on the surface. Conversely, the mid-UV spectrum could verify that the water ice absorption edge is not present on Europa. The reflectance of Europa's hemispheres drops significantly between the near- and far-UV. The spectral shape in the mid-UV will be used to constrain the surface composition across the satellite. Mid-UV observations with STIS will span the previous near- and far-UV data sets, providing a seamless UV spectrum. These observations will provide the first spatially resolved spectra of each of Europa's hemispheres in the mid-UV. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will use the STIS G230L mode with the 52 x 0.2 slit centered at 237.6 nm. We will use a pattern to shift the slit one time on Europa to cover the central ~0.4 arcseconds of the ~1" sized satellite and still obtain useful SNR at the shortest wavelengths. The observations will be scheduled such that we observe the sub-Jovian, leading, anti-Jovian, and trailing hemispheres (0 deg, 90 deg, 180 deg, and 270 deg orbital longitudes). Depening on the exact timing of the visits, the observations will need to be offset slightly from 0 or 180 deg to avoid observing Europa while in transit of Jupiter, or in eclipse by Jupiter, respectively. We request to observe Europa when the Jovian system is within 5 weeks of opposition, which occurs on May 9, 2018, to maximize Europa's size, increase its brightness (and SNR), and reduce background from terrestrial UV airglow from ~10-15 kilorad (kR) to ~2.4 - 4 kR. We assume a 5 minute acquisition time 15095( 9) - 06-Feb-2019 20:10:59 - [ 2] for the target, followed by a 2400 s observation period, consisting of two exposures for each visit. The first exposure will be offset from the center of Europa by -0.1" and the second will be offset by +0.1" perpendicular to the slit, such that the 0.2" wide slit covers 0.4" of the central part of Europa's surface. The spectral range covered by this instrument (157 - 318 nm) will provide a spectrum covering the mid-UV wavelengths not previously studied. This spectral range will confirm the lack of a water-ice absorption edge in the UV spectra on all hemispheres of Europa and will be used to constrain the composition of Europa's surface. ------------------------------------------------------------------------------------ 15095( 9) - 06-Feb-2019 20:10:59 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: EUROPA-EAST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Europa at Eastern Elongation ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS OLG OF EUROPA-EAST FROM EARTH BETWEEN 75 105, SEP OF EUROPA-EAST CALLISTO FROM EARTH GT 10", SEP OF EUROPA-EAST IO FROM EARTH GT 10", SEP OF EUROPA-EAST GANYMEDE FROM EARTH GT 10" ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.29 +/- 0.5 Ephemeris Center: EARTH Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 TARGET NAME: EUROPA-WEST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Europa at Western Elongation ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF EUROPA-WEST CALLISTO FROM EARTH GT 10", SEP OF EUROPA-WEST IO FROM EARTH GT 10", SEP OF EUROPA-WEST GANYMEDE FROM EARTH GT 10", OLG OF EUROPA-WEST FROM EARTH BETWEEN 255 285 ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.29 +/- 0.5 Ephemeris Center: EARTH Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 15095( 9) - 06-Feb-2019 20:10:59 - [ 4] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 TARGET NAME: EUROPA-SUBJUP ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Europa at near 0 deg orb longitude ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF EUROPA-SUBJUP CALLISTO FROM EARTH GT 10", SEP OF EUROPA-SUBJUP IO FROM EARTH GT 10", SEP OF EUROPA-SUBJUP GANYMEDE FROM EARTH GT 10", OLG OF EUROPA-SUBJUP FROM EARTH BETWEEN 340 20 ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.29 +/- 0.5 Ephemeris Center: EARTH Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 TARGET NAME: EUROPA-ANTIJUP ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Europa near 180 deg orbital longitude ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF EUROPA-ANTIJUP CALLISTO FROM EARTH GT 10", SEP OF EUROPA-ANTIJUP IO FROM EARTH GT 10", SEP OF EUROPA-ANTIJUP GANYMEDE FROM EARTH GT 10", OLG OF EUROPA-ANTIJUP FROM EARTH BETWEEN 160 200 ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.29 +/- 0.5 Ephemeris Center: EARTH Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 15095( 9) - 06-Feb-2019 20:10:59 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type STIS-PERP-TO-SLIT Pattern_Purpose MOSAIC Number_Of_Points 2 Point_Spacing 0.2 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 0.0 Angle_Between_Sides Center_Pattern YES Pattern_Comments: If the center of Europa is (x, y) = (0, 0) and 'x' is perpendicular to the slit, then the first point in the pattern should be (-0.1", 0"), the second point should be (+0.1", 0"). ------------------------------------------------------------------------------------------------------------------------------------ 15095( 9) - 06-Feb-2019 20:10:59 - [ 6] Visit: 01 (Leading) Visit Requirements: BETWEEN 04-APR-2018:00:00:00 AND 13-JUN-2018:00:00:00 On Hold Comments: Additional Comments: The leading hemisphere of Europa can be observed when Europa is at an orbital longitude of 90 degrees. This is when Europa is at eastern elongation. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA-EAST STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=21, 1 0.1 S (0.1 DIFFUSE-CENTER=GEOMETRIC-CENTE S) R ------------------------------------------------------------------------------------------------------------------------------------ 2 EUROPA-EAST STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=99 1 1200 S PATTERN 2 2 -MAMA G see below (1974 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA-EAST 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A EUROPA-EAST 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 1 none none none 1 987.0 S -MAMA G EUROPA-EAST 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 2 none none none 1 987.0 S -MAMA G 15095( 9) - 06-Feb-2019 20:10:59 - [ 7] Visit: 02 (Trailing) Visit Requirements: BETWEEN 04-APR-2018:00:00:00 AND 13-JUN-2018:00:00:00 On Hold Comments: Additional Comments: The trailing hemisphere of Europa can be observed when Europa is at an orbital longitude of 270 degrees. This is when Europa is at western elongation. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA-WEST STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=21, 1 0.1 S (0.1 DIFFUSE-CENTER=GEOMETRIC-CENTE S) R ------------------------------------------------------------------------------------------------------------------------------------ 2 EUROPA-WEST STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=99 1 1200 S PATTERN 2 2 -MAMA G see below (1974 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA-WEST 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A EUROPA-WEST 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 1 none none none 1 987.0 S -MAMA G EUROPA-WEST 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 2 none none none 1 987.0 S -MAMA G 15095( 9) - 06-Feb-2019 20:10:59 - [ 8] Visit: 03 (Sub-Jovian) Visit Requirements: BETWEEN 04-APR-2018:00:00:00 AND 13-JUN-2018:00:00:00 On Hold Comments: Additional Comments: The sub_Jovian hemisphere of Europa can be observed when Europa is at an orbital longitude near 0 degrees. This is when Europa is near eclipse. We do not want Europa to be in eclipse for the observation, however Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA-SUBJ STIS/CCD ACQ F28X50LP MIRROR DIFFUSE-CENTER=GEOMETRIC-CENTE 1 0.1 S (0.1 UP R, S) ACQTYPE=DIFFUSE, CHECKBOX=21 ------------------------------------------------------------------------------------------------------------------------------------ 2 EUROPA-SUBJ STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=99 1 1200 S PATTERN 2 2 UP -MAMA G see below (1974 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA-SUBJUP 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A EUROPA-SUBJUP 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 1 none none none 1 987.0 S -MAMA G EUROPA-SUBJUP 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 2 none none none 1 987.0 S -MAMA G 15095( 9) - 06-Feb-2019 20:10:59 - [ 9] Visit: 04 (Anti-Jovian) Visit Requirements: BETWEEN 04-APR-2018:00:00:00 AND 13-JUN-2018:00:00:00 On Hold Comments: Additional Comments: The anti-Jovian hemisphere of Europa can be observed when Europa is at an orbital longitude of 180 degrees. We will observe Europa near this longitude, but do not want it to be transiting Jupiter during the observation. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA-ANTI STIS/CCD ACQ F28X50LP MIRROR DIFFUSE-CENTER=GEOMETRIC-CENTE 1 0.1 S (0.1 JUP R, S) CHECKBOX=21, ACQTYPE=DIFFUSE ------------------------------------------------------------------------------------------------------------------------------------ 2 EUROPA-ANTI STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=99 1 1200 S PATTERN 2 2 JUP -MAMA G see below (1974 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA-ANTIJUP 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A EUROPA-ANTIJUP 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 1 none none none 1 987.0 S -MAMA G EUROPA-ANTIJUP 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 2 none none none 1 987.0 S -MAMA G 15095( 9) - 06-Feb-2019 20:10:59 - [ 10] Visit: 51 (Leading) Visit Requirements: BETWEEN 24-MAY-2019:00:00:00 AND 28-JUN-2019:00:00:00 On Hold Comments: Additional Comments: The leading hemisphere of Europa can be observed when Europa is at an orbital longitude of 90 degrees. This is when Europa is at eastern elongation. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA-EAST STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=21, 1 0.1 S (0.1 GS ACQ SCENARIO BASE1BE DIFFUSE-CENTER=GEOMETRIC-CENTE S) R ------------------------------------------------------------------------------------------------------------------------------------ 2 EUROPA-EAST STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=99 1 1200 S PATTERN 2 2 -MAMA G see below (1854 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA-EAST 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A EUROPA-EAST 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 1 none none none 1 927.0 S -MAMA G EUROPA-EAST 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 2 none none none 1 927.0 S -MAMA G 15095( 9) - 06-Feb-2019 20:10:59 - [ 11] Summary Form for Proposal 15095 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.2, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=DIFFUSE, BUFFER-TIME=99, CHECKBOX=21, DIFFUSE-CENTER=GEOMETRIC-CENTER ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 04-APR-2018:00:00:00 AND 13-JUN-2018:00:00:00, BETWEEN 24-MAY-2019:00:00:00 AND 28-JUN-2019:00:00:00, GS ACQ SCENARIO BASE1BE, PATTERN 2 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names EUROPA-ANTIJUP, EUROPA-EAST, EUROPA-SUBJUP, EUROPA-WEST ------------------------------------------------------------------------------------------------------------------------------------