Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4518 Report Date: 18-Jul-95:16:51 Version: ********** Check-in Date: ********** 1.Proposal Title: HIGH RESOLUTION SPECTROSCOPY OF VENUS CLOUDS-CYC3 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID SOLAR SYSTEM GO Sub Category INNER PLANETS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Larry W Esposito U.COLORADO LASP USA ------------------------------------------------------------------------------------ 7. Abstract Observations of the Venus atmosphere are important to understand the cloud chemistry and dynamics. Sulfur dioxide is an indicator of surface geological activity and, thus, the geologic evolution of Venus. Ground based observers, Pioneer Venus, IUE and rockets have observed the Venus UV spectrum and found significant temporal changes over the past decade. The HST has the capability to extend these observations in the decade the 90s at higher spectral resolution than Pioneer Venus and spatial resolution than IUE. It is important that these observations continue the monitoring of SO2 (Pioneer Venus mission ended in 1992). At elongation, the Sun angle is more than 45 degrees making the observations of Venus possible while HST is in Earth shadow. We propose to observe Venus in Earth shadow using blind pointing in the wavelength regions centered on 2070A and 2160A to identify and measure SO2, SO and other absorbers. In addition, we plan to make an observation with the Echelle-B grating to study the saturation of SO2 bands which has a critical importance for the chemistry of Venus clouds. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0.08 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4518 PI: Larry W Esposito Proposal Title: HIGH RESOLUTION SPECTROSCOPY OF VENUS CLOUDS-CYC3 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Larry W Esposito U.COLORADO LASP USA Chan Y Na U.COLORADO LASP USA ------------------------------------------------------------------------------------ 2. Scientific Justification. Paper copy only. ------------------------------------------------------------------------------------ 3. Description of proposed observations. Because of the Sun constraint, HST will initially be pointed 50 degrees from the Sun, several degrees beyond Venus. After the Sun sets behind the Earth's limb, HST will slew on gyros to the center of Venus, and offset point to 5.9 seconds in the Sunward direction. The observations follow: GHRS G200M with LSA (1 minute), centered on 2070A; GHRS G200M with LSA (1 minute), centered on 2160A; GHRS Echelle-B centered on 2070A(2 minutes). After the exposures, slew to a safe position. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The observation of Venus in the middle UV is crucial to measure the abundance of SO2 on Venus. The Earth atmosphere is opaque at these wavelenghths. Pioneer Venus has now burned up in the Venus atmosphere. IUE sensitivity and pointing accuracy are too low. Continuing studies require HST monitoring. The GHRS echelle provides the best spectral resolution and can identify the level of band saturation. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Venus is most safely observed near its maximum elongation, when it is furthest from the Sun. A short slew will allow pointing to Venus while HST is in the Earth's shadow. Venus is more than 43 degrees from the Sun from 31 May 1993 to 12 July 1993. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. None. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. We will use the latest GHRS calibration and STSDAS to reduce the data. Further data analysis will occur at Colorado and SWRI. We use a multiple scattering RT model and consider vertically inhomgeneous distributions for absorbers and scatterers. This method has been exstensively used to analyze PV, IUE, and rocket observations. The results from HST will be directly compared to previous findings. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. ------------------------------------------------------------------------------------ 9. Description of previous HST work. None. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). PI academic year support. Computing facilities and costs. Undergrad students through the UROP Program. ------------------------------------------------------------------------------------ 11. Address Information Page 3 Name: Larry W Esposito Category: PI Institution: U.Colorado LASP Address: LASP Campus Box 392 City: Boulder State: CO Zip Code: 803090392 Country: USA Telephone: 303/492-7325 Telex (or e-mail): 910/940-3441 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4518 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 3 VENUS+5D I,606 RA = 235.1777384D +/- 2000 0.00001D, DEC = -15.5724451D +/- 0.00001D Comments: FIXED POINTING AT ELONG 51.88 DEG FROM SUN ON 1/9 AND GETTING FARTHER... ------------------------------------------------------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 4518 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: VENUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET VENUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = VENUS | TYPE = POS_ANGLE, | ANG = 0, | RAD = 5.9, | REF = SUN | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | VENUS ELONGATION | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |F(2070) = 10 +/- 5 E-10 | SUN REFERENCE MORE DIRECT THAN | | CELESTIAL REFERENCE SUGGESTED BY | | STORRS. | ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4518 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 0.5 VENUS+5D S/C DATA V1 1 1S CYCLE 4 / 0.5-3.5 PCS MODE F SEQ 0.5-3.5 NO GAP Comments: POINTING BEYOND 50 DEG SOLAR AVOIDANCE LIMIT. EACH LINE ITS OWN OBSET. ------------------------------------------------------------------------------------------------------------------------------------ 1 VENUS HRS ACCUM 2.0 G200M 2070 SPYBAL=NO 1 1M 25 1 1 GUID TOL 5" 1M DARK TIME PCS MODE C Comments: MAY ACQ SINGLE GS, THEN DROP TO GYRO TO OBSERVE. EACH LINE ITS OWN OBSET. ------------------------------------------------------------------------------------------------------------------------------------ 1.5 VENUS+5D S/C DATA V1 1 1S PCS MODE F Comments: POINTING BEYOND 50 DEG SOLAR AVOIDANCE LIMIT. EACH LINE ITS OWN OBSET. ------------------------------------------------------------------------------------------------------------------------------------ 2 VENUS HRS ACCUM 2.0 G200M 2160 SPYBAL=NO 1 1M 25 1 2 GUID TOL 5" 1M DARK TIME PCS MODE C Comments: MAY ACQ SINGLE GS, THEN DROP TO GYRO TO OBSERVE. EACH LINE ITS OWN OBSET. ------------------------------------------------------------------------------------------------------------------------------------ 2.5 VENUS+5D S/C DATA V1 1 1S PCS MODE F Comments: POINTING BEYOND 50 DEG SOLAR AVOIDANCE LIMIT. EACH LINE ITS OWN OBSET. ------------------------------------------------------------------------------------------------------------------------------------ 3 VENUS HRS ACCUM 2.0 ECH-B 2070 SPYBAL=NO 1 2M 25 1 3 GUID TOL 5" 2M DARK TIME PCS MODE C Comments: MAY ACQ SINGLE GS, THEN DROP TO GYRO TO OBSERVE. EACH LINE ITS OWN OBSET. ------------------------------------------------------------------------------------------------------------------------------------ 3.5 VENUS+5D S/C DATA V1 1 1S PCS MODE F Comments: POINTING BEYOND 50 DEG SOLAR AVOIDANCE LIMIT. EACH LINE ITS OWN OBSET. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4518 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations S/C HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes DATA ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SPYBAL=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 0.08 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category INNER PLANETS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4 / 0.5-3.5; PCS MODE F; SEQ 0.5-3.5 NO GAP; GUID TOL 5"; DARK TIME; PCS MODE C; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G200M ECH-B ------------------------------------------------------------------------------------------------------------------------------------ Target Names VENUS+5D VENUS ------------------------------------------------------------------------------------------------------------------------------------