HR: 13:40h
AN: P12C-01 INVITED     [PDF]
TI: Hubble Space Telescope Imaging and Spectroscopy of Mars During the Extremely Close Approach of 2003
AU: * Bell, J F
EM: jfb8@cornell.edu
AF: Cornell Univ., Dept. of Astronomy, Ithaca, NY 14853 United States
AU: Wolff, M J
EM: wolff@colorado.edu
AF: SSI, 3100 Marine St., Boulder, CO 80303 United States
AU: Noll, K
EM: noll@stsci.edu
AF: STScI, 3700 San Martin Dr., Baltimore, MD 21218 United States
AU: Lubenow, A
EM: lubenow@stsci.edu
AF: STScI, 3700 San Martin Dr., Baltimore, MD 21218 United States
AU: Noe-Dobrea, E
EM: ezn1@cornell.edu
AF: Cornell Univ., Dept. of Astronomy, Ithaca, NY 14853 United States
AU: Hubbard, M Y
EM: min@twcny.rr.com
AF: Cornell Univ., Dept. of Astronomy, Ithaca, NY 14853 United States
AU: Morris, R V
EM: richard.v.morris@nasa.gov
AF: NASA/JSC, Code SR, Houston, TX 77058 United States
AU: Videen, G
EM: gvideen@arl.army.mil
AF: SSI, 3100 Marine St., Boulder, CO 80303 United States
AU: Shkuratov, Y
EM: shkuratov@vk.kh.ua
AF: Kharkov State Univ., Astron. Obs., Kharkov, 310022 Ukraine
AB: We observed Mars using HST during Aug. and Sept. 2003. These observations took advantage of the closest Earth-Mars encounter in nearly 60,000 years as Mars passed within 0.372 AU of Earth and subtended an apparent angular diameter of 25.1"; this is the closest the planet will come to Earth until the year 2287. We used four instruments on HST to take advantage of this unprecedented spatial resolution as well as the telescope's unique UV and near-IR capabilities. The observations were also designed to provide scientific and calibration data that are complementary to observations being obtained from Mars orbit by the NASA Mars Global Surveyor and Mars Odyssey spacecraft. Our observing program consisted of: (1) Multispectral images using the WFPC2 CCD camera at six rotational aspects and using 10 to 12 filters spanning 255 nm to 1042 nm. These observations have a spatial resolution of 13 km/pixel near the sub-Earth point on the planet. The filters were chosen to detect atmospheric ozone in the UV, weak crystalline $Fe^{3+}$ absorptions in the UV and visible/near-IR in altered surface or airborne dust materials, and $Fe^{2+}$ absorptions in the near-IR from relatively less-altered volcanic materials, and to extend the long-term coverage at these wavelengths from WFPC2 programs in 1997, 1999, and 2001; (2) Multispectral images using the NICMOS near-IR camera at four rotational aspects and using 15 filters covering 970 to 2370 nm. These observations have a resolution of 13 to 26 km/pixel near the sub-Earth point. The NICMOS filters were chosen to detect $CO_{2}$ and water vapor/clouds as well as surface OH-bearing minerals; (3) Multispectral and multi-polarization images using the ACS/HRC CCD camera imaging a single hemisphere of the planet over 5 phase angles from 6$^{o}$ to 16$^{o}$. These observations have a resolution of 7 km/pixel near the sub-Earth point--the highest spatial resolution observations of Mars ever made from the Earth. The ACS filters, three 120$^{o}$ polarizers, and phase angles were all selected to characterize the nature of the Mars phase curve, which can reveal information about the physical and compositional properties of the materials; and (4) Imaging spectroscopic observations using the STIS CCD spectrograph at four rotational aspects and from 270 to 590 nm at a spectral resolution of 0.275 nm/channel. The 0.2x50" STIS slit was "pushbroomed" to generate hyperspectral image cubes of the surface south of about 40$^{o}$N and at approximately 13x52 km/spectrum. These data are being analyzed for evidence of absorption features diagnostic of specific $Fe^{3+}$ mineral phases on Mars as well as information on the physical and radiative properties of airborne dust. All of the planned observations have been successfully acquired and highlights will be shown here. The martian atmosphere was relatively free of both dust and water ice clouds during this southern Mars summer/perihelion observation period ($L_{s}$=250$^{o}$). These observations can be directly compared to our similar 2001 HST measurements that were taken during conditions of high atmospheric dust opacity, providing an excellent opportunity to derive new information on dust compositional and physical properties from the comparison of dusty and dust-free observations from the same instruments and at comparable spatial scales.
UR: http://hubblesite.org/newscenter/2003/22/
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting