Astronomical observations during the transit phase, in orbit about Mars, and from the surface present important scientific objectives. Primary astronomical objectives are being summarized by J. Burns (University of New Mexico). Additional or alternative options will be introduced here, together with their strengths, weaknesses, viability, and value. It is important to note at the outset that not all possible options are necessarily important or viable

Suess, S. T.

English

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ABSTRACT
Astronomical
Mars, and from
][ANNI_ItaJ_ WISSION
ASTRONOMY OPTIONS
S. T. Suess
Marshall Space Flight Center
Marshall Space Flight Center, AL
N87-17765
observations during the transit phase, in orbit about
the surface present important scientific objectives.
Primary astronomical objectives are being summarized by J. Burns (Univ.
of New Mexico). Additional or alternative options will be introduced
here, together with their strengths, weaknesses, viability, and value. It
is important to note at the outset that not all possible options are
necessarily important or viable 1.
Options
Potential experiments are limited only by imagination. Several op-
tions are listed in Table 1 and discussed individually below. Ultimately,
in addition to weight, power, and volume limitations, the selection of
experiments will be based on research interest and the value of antici-
pated scientific return.
Radio Astronomy
Prime radio astronomy experiments and observations that can be made
from the manned Mars mission are those that require the radio quiet
conditions found far from the neighborhood of the Earth. Some frequencies
of interest here are quite low so that dipole arrays, in addition to
parabolic dish antennas, would be used.
In addition, there are several active and passive radio measurements
that can be made of the Martian in situ plasma wave detector. Many of
these would make use of the same equipment used for the radio astronomy
experiments. The plasma wave detector would be on the free-flying space-
craft in low Martian orbit.
Finally, the radio telescopes may be used for further monitoring of
solar activity from the surface of Mars.
Solar Astronomy
Solar optical observations show the photospheric structure of the
Sun and, with simple filters, map the large scale magnetic field struc-
ture, sunspots, filaments, and flares. During a large part of the transit
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TABLE I
OPTIONS
Experiment
Radio telescope
Met wave dipole array radio
telescope
Solar astronomy
Optlcal observations of
cataclysmic variables
UV all-sky mapping
Lyman-alpha all-sky mapping
Cosmic ray detectors/telescope
Gamma ray telescope
Translt/In Orblt/Surface
(X:yes, -:no)
x/-/-
X/-/-
X/X/X
X/X/X
Hydrogen-alpha telescope
Weight
Power
TABLE 2
SOLAR INSTRUMENTATION
25- 40-cm optics
Birefrlngent filter
1000 x 1000 CCD detector
Digitally stored images
Digital display
50 kg including multl-use display termlnal
< 1 kw
Whole-disk x-ray monitor
Weight
Power
< 10 kg
< 0.1 kw
0.5- 8 Angstrom sensitivity
1 second time resolution
544
and while at Mars, the side of the Sun exposed to the spacecraft will be
invisible from the Earth. Observations of the Sun in the Hydrogen-alpha
spectral line will therefore be necessary for solar flare/erupting fila-
ment prediction and warning. These observations would have to be made
during all three phases of the mission, but would be done from orbit
during the surface excursions. More information on this Is given in the
white paper on Solar Physics: Solar Activity Monitoring and Prediction.
A minimum instrument package is outlined in Table 2.
Additional solar observations are possible with more complex instru-
ments - including magnetic field and velocity measurements. However, it
Is probable that these observations would be more efficiently and
accurately made from Earth orbiting spacecraft.
The solar telescope will be used for other observations 2 wlth
supporting equipment such as special filters. Planets will be observed
to determine their albedo in the UV and visible ranges, and the same UV
filters will be used for an all-sky UV survey. Opportunities will occur
for the observation of stellar occultation by the outer planets, and the
ephemertdes should be developed for these observations. Other opportuni-
ties may occur for the observation of cataclysmic variables 2.
Planetary Astronomy
Optical observations of the planets and asteroids are possible
during all three phases of the mission. The main advantage of doing these
from the manned Mars mission is that during the transit phase the space-
craft will approach significantly closer to the main asteroid belt than
is ever done by the Earth and will have uninterrupted viewing during the
transit phases. However, It is llkely that Space Telescope observations
would supersede any information that would be gained from the size and
quality of a telescope that could be carried to Mars, except for those
types of observations noted above in the solar astronomy section. There-
fore, It is suggested that the solar telescope w111 be sufficient for
planetary astronomy in visible, ultraviolet, and Infrared wavelengths.
These low spatial and spectral resolution, uninterrupted measure-
ments will supplement the extremely high spatial and spectral resolution
observations that will be made in the near future from Earth orbit.
545
One opportunity ls that stereo observations of the planets or
asteroids would be possible using Earth and mission based telescopes.
However, there has been no stated need for such experiments.
Backscattered Solar Lyman-alpha
An opportunity exists to make high spatial resolution observations
of Lyman-alpha solar emission that is backscattered from interstellar
neutral gas that is entering the solar system. Low resolution observa-
tions have been made from unmanned spacecraft and have provided important
information of solar spectral emission variability and the properties of
the local interstellar medium. These observations are best made far from
the Earth because of contamination by the Earth's hydrogen geocorona.
Optical t Infrared r Ultravtolet_ and X-ra_
Extra-Solar System Astronomy
Observations of stars, the Mllky Way, nebulae, pulsars, extra-
galactic objects, etc. will be receiving particular emphasis wlth Earth-
orbiting spacecraft. The Space Telescope and AXAF are only the first of a
variety of missions planned by NASA and ESA. It Is extremely unlikely
that a large variety of useful information would be gained from manned
Mars mission observations. However, there are a few narrowly selected
specific observations that suggest potential benefits from being made on
the manned Mars mission.
Galactic and Solar Cosmic Rays
Cosmic ray detectors and telescopes wlll be used for monitoring
solar energetic particles. In addition, the data from these instruments
will show galactic cosmic ray intensities and their variation wlth solar
activity and the solar cycle. The modulation mechanism of cosmic rays in
the solar system is not understood and data on variations at Mars, wlth
correlative data from solar observations, wlll help solve thls problem.
The observations can be made from the surface of Mars, as well as from
orbit and during transit phases.
Gamma Rays
Gamma rays are emitted impulsively during very short astronomlcal
events. The location of these events Is determined through timing of the
detection of the gamma ray pulse at wldely spaced spacecraft. Placing a
gamma ray event detector on Nars would help wlth these calculations by
making It easier to do the timing calculations.
546
Summary
All types of astronomical observations are technically possible from
the manned Mars mission, and it is desirable to go Into space for many
of these observations. However, the advantages of going into space are
equalled or even exceeded by placing many of the instruments in low Earth
orbit (LEO), rather than sending them to Mars. The reason for this is
that the main purpose for going to space Is usually to avoid atmospheric
interference and the day/nlght cycle. These goals are best achieved from
LEO or, to avoid the day/nlght cycle, from a polar orbit or near-Earth
stable position.
A more distant observing position is required by four types of
observations. The first is any measurement which might be obstructed by
the Earth's hydrogen geocorona - which extends out to many Earth radii.
The second is any radio observation of low magnitude objects which might
be obstructed by artificial radio sources on and near the Earth. This
second source of pollution also extends to several Earth radii at some
wavelengths and has led to suggestions for observatories on the opposite
side of the Moon I. The third is a cosmic ray observatory/detector on the
Mars orbiter and on the surface, to monitor solar cosmic rays and provide
a more global view of how solar disturbances and evolution modulate
galactic cosmic rays. The fourth is a gamma ray detector to give a long
baseline for gamma ray event timing and triangulation. A minimal
instrument package to meet these goals is outlined in Table 3.
Also, it will be essential to conduct solar observations from the
manned Mars mission for the purpose of activity monitoring and predic-
tion, complimented by solar whole-dlsk x-ray detectors and energetic
particle monitors.
547
TABLE3
OTHERINSTRUMENTATION
Backscatter Solar LymanAlpha
Utilizes solar telescope
Special filter
Weight
Power
uv All Skz Map
Utilizes solar telescope
Special filter
Weight
Power
Radio Astronomy
Dish antenna
Weight
Power
< 100 kg
< 1 kw
< I0 kw
Dipole array
Weight
Power
< I00 kg
< 1 kw
Ionosonde
Weight
Power
<100 kg
< 1 kw
< 10 kw
Cosmic R_ Detectors/Telescope
Weight < I0 kg
Power < 1 kw
Gamma Ray Detector
Weight < 20 kg
Power < 1 kw
< 5 kg
No additional
< 5 kg
No additional
receiving
transmitting
receiving
receiving
transmitting
548
REFERENCES
1. Astronomy and Astrophysics for the 1980's, Volume 1:
Re_sport of the Astronomy Survex Committee, Astronomy
Survey Coxlttee, Assembly of Mathematical and Physi-
cal Sciences, National Research Council, National
Academy Press, 2101 Constitution Ave., N.W.,
Washington, D.C. 20418, 1982.
2. Scientific Experiments for a Manned Mars Mission,
NASA TM X-2127, March 1971, by H. Dudley, J. Harri-
son, J. Ballance, N. Page, J. Dabbs, J. Power, K
Hudson, and M. Powell, Marshall Space Flight Center.
549


Manned Mars mission astronomy options

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