Status Report

NASA Hubble Space Telescope Daily Report # 3422

By SpaceRef Editor
August 10, 2003
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HUBBLE SPACE TELESCOPE

DAILY REPORT # 3422

PERIOD COVERED: DOY 219

OBSERVATIONS SCHEDULED

STIS/MA1 8658

Atmospheric Escape and the D/H Ratio in Mars’ Atmosphere

The highly extended upper atmosphere and the UV airglow of Mars have
not been studied by any in situ spacecraft since Mariner 9 in 1972. At
the same time, one of the main elements of NASA’s space science
program today is the study of Mars and how it has evolved over time to
a hostile environment, compared with the favorable conditions on the
Earth. The availability of long aperture spatially resolved UV spectra
with STIS makes it possible to obtain unique information on the
extended upper atmosphere of Mars by mapping the H and O dayglow
emissions with altitude above the limb. We propose to make these
observations just before Mars opposition near the end of HST cycle 9.
Initial modeling indicates that we will have sufficient angular
resolution and sensitivity to measure the scale heights of the
suprathermal atom populations of H and O atoms. We also propose to
determine accurate values for the D and H columns, and the D/H ratio,
in the upper atmosphere of Mars. The present-day D/H ratio gives vital
information leading to understanding the evolution of Mars’
atmosphere, the historic escape of water into space, and potentially
the remaining water abundance on Mars.

WFPC2 9458

Probing the Formation & Evolution of M31’s Outer Disk and Halo

The fossil record of galaxy formation and evolution is imprinted on
the spatial distribution, ages and metallicities of galactic stellar
populations. The observations proposed here build significantly upon
our extensive ground-based and archival WFPC2 programs and aim to
constrain the formation and evolution of our nearest large neighbor,
M31. We propose deep imaging of 8 fields in the outer disk and halo,
several of which have been identified from our panoramic ground-based
CCD survey {covering ~ 26 square degrees} to possess significant
stellar density and/or potential metallicity variations. Deep
colour-magnitude diagrams reaching ~2-3 magnitudes below the
horizontal branch will be constructed, allowing detailed
characterization of the luminous evolved stellar populations via the
red giant metallicity distribution, the luminous asymptotic giant
branch, the horizontal branch morphology and the red clump, as well as
the detection of a main-sequence that may be present from any younger
component. Our primary goals are to: {i} quantify the stellar
population variations associated with M31 halo substructure, including
the newly- discovered giant stellar stream, and {ii} derive stringent
constraints on the age and metallicity of stars in the far outer disk.
These observations will directly address two key predictions of cold
dark matter hierarchical galaxy formation models.

WFPC2 9595

WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt3/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot
pixels.

STIS 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9608

CCD Bias Monitor – Part 2

Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1,
and 1×1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.

STIS 9633

STIS parallel archive proposal – Nearby Galaxies – Imaging and
Spectroscopy

Using parallel opportunities with STIS which were not allocated by the
TAC, we propose to obtain deep STIS imagery with both the Clear
{50CCD} and Long-Pass {F28X50LP} filters in order to make
color-magnitude diagrams and luminosity functions for nearby galaxies.
For local group galaxies, we also include G750L slitless spectroscopy
to search for e.g., Carbon stars, late M giants and S-type stars. This
survey will be useful to study the star formation histories, chemical
evolution, and distances to these galaxies. These data will be placed
immediately into the Hubble Data Archive.

ACS 9675

CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS.

STIS 9708

STIS Pure Parallel Imaging Program: Cycle 11

This is the default archival pure parallel program for STIS during
cycle 11.

WFPC2 9709

POMS Test Proposal: WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure Parallel
program. The program will be used to take parallel images of random
areas of the sky, following the recommendations of the 2002 Parallels
Working Group.

WFPC2 9775

Tracking the Homunculus and Outer Ejecta of Eta Carinae

We request WFPC2 images of Eta Carinae in order to complete our WFPC2
database to track the expansion of high-velocity material ejected
during one or more giant outbursts of the central supermassive star.
These images will increase the time baseline to 8 years of
high-resolution Planetary Camera data for measuring proper motions and
monitoring photometric changes in the debris field. Assuming a
distance to Eta of 2300 pc, we will be able to trace transverse
motions of the debris to better than 15 km/s precision and should be
able to discern deviations from linear motions that are predicted in
some models for the Giant Eruption. PC1 images in red and blue
continuum filters will be used to track the expansion of the dusty
bipolar lobes of Eta’s ”Homunculus” and equatorial skirt of ejecta.
WF3 emission-line images will be used to trace motions of the outer
debris field 10” – 40” from the central star. We can uniquely
address issues of hydrodynamic expansion and wind-wind interactions
through a time series of exposures of this textbook bipolar system.
Because many groups around the world who are working on different
facets of Eta Carinae will be interested in these images, we waive the
proprietary rights to the dataset in order to maximize its usage. The
science goals and exposures requested here are NOT covered in the
Cycle 11 Treasury program to monitor the Eta Carinae ”event” in May
2003.

ACS/WFC 9891

A snapshot survey of rich stellar clusters in the Large and Small
Magellanic Clouds

Rich stellar clusters are vital to a wide variety of astrophysical
research, from stellar evolution studies to the formation and
evolution of galaxies. In this context, it is important to understand
how rich star clusters form and evolve. The cluster systems in the LMC
and SMC are particularly important in achieving this, because they are
the only systems which contain clusters at all stages of evolution
while being close enough to be studied as fully resolved stellar
populations – although in general this requires the capabilities of
HST. We have recently investigated the structural evolution of LMC and
SMC clusters using archival WFPC2 data, and demonstrated a dramatic
trend in the sizes of these clusters with age. We have shown that this
trend likely represents genuine structural evolution in these
clusters, although it is not clear whether we are observing a
dynamical process or the signature of changing formation conditions.
This result has implications for all astronomical research involving
massive stellar clusters. To develop this work further requires the
extension of our two samples, so that they are statistically
quantifiable. This will allow a number of key questions regarding the
structural evolution trend to be answered. We propose a two-colour
ACS/WFC SNAP survey of rich Magellanic Cloud clusters to achieve this
aim. The unique resolution and sensitivity of ACS/WFC is required for
success, because of the crowded nature of the targets. The SNAP data
will have a large number of additional applications, both to globular
cluster and Magellanic Cloud research.

ACS 9984

Cosmic Shear With ACS Pure Parallels

Small distortions in the shapes of background galaxies by foreground
mass provide a powerful method of directly measuring the amount and
distribution of dark matter. Several groups have recently detected
this weak lensing by large-scale structure, also called cosmic shear.
The high resolution and sensitivity of HST/ACS provide a unique
opportunity to measure cosmic shear accurately on small scales. Using
260 parallel orbits in Sloan textiti {F775W} we will measure for the
first time: beginlistosetlength sep0cm setlengthemsep0cm setlength
opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em the
skewness of the shear distribution, and em the magnification effect.
endlist Our measurements will determine the amplitude of the mass
power spectrum sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20,
and the mass density Omega_m with s/n=4. They will be done at small
angular scales where non-linear effects dominate the power spectrum,
providing a test of the gravitational instability paradigm for
structure formation. Measurements on these scales are not possible
from the ground, because of the systematic effects induced by PSF
smearing from seeing. Having many independent lines of sight reduces
the uncertainty due to cosmic variance, making parallel observations
ideal.

ACS/HRC 9989

Starburst Galaxies and Their Population of Super Star Clusters

Starbursts are ideally suited to study the evolution of high mass
stars, the physics of star formation, and the chemical enrichment of
the intergalactic medium {IGM}. Starbursts efficiently form Super Star
Clusters {SSC} which may be young protoglobular clusters. High
resolution imaging will address two important outstanding issues: 1}
how long starbursts last and 2} whether SSCs are indeed young globular
clusters. The duration of starbursts is important because: {1} it
determines how efficiently a starburst can heat and enrich the IGM;
{2} the duration combined with estimates of the fraction of galaxies
which host starbursts yields the total number of starbursts a galaxy
can suffer. Finally, since local starbursts are analogs to high-z
galaxies, the results have implications on the initial formation
timescale of galaxies. Starburst duration will be determined from HRC
imaging of two face-on starburst galaxies rich in SSCs. The UV to
optical colors of the SSCs, which represent single burst chronometers,
will yield their reddening and ages. The range of ages gives the
starburst duration. The nature of SSCs will be investigated by imaging
four of the nearest starbursts in 3 bands. By comparing the sizes of
their SSCs at different wavelengths we will address the issue of
whether SSCs suffer from early mass segregation. Without some mass
segregation the velocity dispersions of SSCs suggest that they are
deficient in low mass stars, and hence may not represent true
proto-globular clusters.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.) None

COMPLETED OPS REQs:

  • 16624-0 – Reset NCS Min/Max Buffer (Generic OR) @ 219/1301z
  • 17023-1 – Start Circulator and Compressor @ 219/1715z

OPS NOTES EXECUTED: None

                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq              6                          6
FGS REacq              10                        10
FHST Update            12                        12
LOSS of LOCK

SIGNIFICANT EVENTS:

Successfully restarted the NCC Circulator @ 219/13:00:33Z at a nominal
commanded Voltage of 6.17 Volts and telemetry Voltage of 6.06 Volts.
The frequency and speed were also nominal at 1200 Hz and 1200 rps,
respectively (OR 17023-1).

Successfully restarted the NCC Compressor @ 219/13:06:15Z at the
nominal frequency of 5000 Hz (OR 17023-1).

Successfully ramped the NCC Compressor to 6000 Hz @ 219/14:32:58Z (OR
17023-1). Full control authority was then given to the PID control
law software @ 219/14:35:24Z. The software will continue to
transition the Compressor speed up to its surge-limited value of 7043
rps. The NCS CPL was commanded to its nominal set point of -12 ?C @
219/14:37:15Z. Reservoir temperatures were running at -5.5 ?C and
decreasing, as expected. Once the Turbo alternator Inlet temperature
reaches 82 ?K, the Compressor speed limit will be raised to its full
value of 7330 rps and cooling will continue to the specified control
point temperature of 72.38 ?K.

SpaceRef staff editor.