Transcript Spacecraft Instruments

Spacecraft
Instruments
Spacecraft Instruments
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Spacecraft instrument selection begins with the
mission description and the selected primary and
secondary mission objectives
 Available instruments and detectors may have minor influence
on the mission objectives
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Budget and resources (communications, launcher,
etc.) often have a dramatic impact on the mission
objectives
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Power limitations may also impact the instrument
selection
Spacecraft Instruments
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Data types, data processing, data communications, and data
analysis can also influence criteria used for instrument selection
Spacecraft Instruments
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A list of a typical set of instruments and systems is not
an accurate representation of any exploration
spacecraft since every space exploration mission is
unique
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Nevertheless, a list can help illustrate the selection
process
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A more useful exercise begins with identifying the
mission type before compiling a list of “typical”
instruments and systems
Spacecraft Instruments
Spacecraft mission types
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1. Planetary/solar system exploration examples
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Flyby (examples include Mariner series, Voyager, Pioneer series)
Orbiter (Explorer series, Magellan, Galileo)
Lander (Surveyor, Viking, Venera series)
Rover (Apollo, Luna series, Mars Pathfinder)
Atmospheric probe (Venera series, Galileo, Cassini)
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2. Astronomical observation (COBE, HST, IRAS)
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3. Communications (INTELSAT, TDRSS, INMARSAT)
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4. Survey & remote sensing
 Earth observation (LANDSAT series, SPOT)
 Meteorological (GOES series, MEOSAT)
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5. Reconnaissance (DoD satellites)
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6. Technology advancement (ASAT)
Spacecraft Instruments
Mission – Planetary/Moon Orbiter
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A spacecraft designed for travel to a distant planet and orbital
operations must include a substantial propulsive capability for
orbit insertion and orbit operations
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Orbital missions will expose the spacecraft to solar
occultations (planet or moon shadows the spacecraft)
 Interruption of solar panels' production of electrical power
 Subjects the vehicle to extreme thermal variation
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Orbital missions will also produce Earth occultations
 Interrupts uplink and downlink communications with Earth
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Orbital missions are used to follow up initial reconnaissance
mission(s) with in-depth study of the planet/moon
Spacecraft Instruments - Orbiter Mission
Spacecraft systems
Structures - similar or the same as other mission types
► Electrical Power Systems
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 Must have a secondary power supply system if inside 2 AU
 Must be a nuclear thermal (or reactor) system beyond 2 AU
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Propulsion
 Orbit insertion
 Orbital operations
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Telecommunications – Deep Space Network (DSN ) link
Thermal Control
 Extreme temperature environments in space are even more extreme
beyond Mars and inside to orbit of Venus
 Additional heating/cooling system considerations in these environments
Guidance, Navigation & Control - similar or the same as other
mission types
► Computer & Data Handling Systems - similar or the same as other
mission types
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Spacecraft Instruments - Orbiter Mission
Experiments and instruments
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Imaging
 Visible – geological features
 IR imaging spectrometers
► Heat
flow and composition
 Microwave
► Synthetic aperture radar (SAR)
► Used to penetrate thick atmospheres
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for surface imaging
Spectral analysis
 IR spectrometer
► Surface
composition and heat flow
 IR imaging spectrometers
► Heat
flow and composition
 UV spectrometers
► Surface
and atmospheric composition
Spacecraft Instruments - Orbiter Mission
Experiments and instruments
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Spectral analysis
 IR radiometer/bolometer
► Measures
net heat flow over a broad frequency range and
usually over a large area
 X-ray spectrometer
► Used
for mapping surface element distributions such as ice, iron,
etc.
 Gamma-ray spectrometer
► Also
used for mapping surface element distributions
 Neutron spectrometer
► Requires
low orbit altitude
► Used recently for mapping hydrogen (Lunar Prospector)
Spacecraft Instruments - Orbiter Mission
Experiments and instruments
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Radio Science
 Uses communications link between the spacecraft and the
DSN to measure Doppler shift acceleration, atmospheric
gases, and plasma interference
 Mass and density measurements
► Doppler
shift anomalies in spacecraft signal and celestial
mechanics used to measure mass distributions in planets/moons
 Occultations
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to measure ring systems, atmospheres (even trace gases) ,
and planet/moon diameters
 Gravity fields
• Doppler shift anomalies in spacecraft signal and celestial
mechanics used to measure and map gravity fields of
planets/moons
Spacecraft Instruments - Orbiter Mission
Experiments and instruments
► Magnetic
fields
 Magnetic field measurements are used to determine
internal activity of the planet/moon and the
differences in ancient and current fields
 Measurements made using sensitive
magnetometers
 Triaxial fluxgate magnetometer
► Most
common type used for planetary exploration
 Proton precession magnetometer
• Uses hydrogen/proton nuclear resonance to couple with
magnetic field
Spacecraft Instruments - Orbiter Mission
Experiments and instruments
► Particle
detectors
 Particle detectors are employed in the analysis of
low-energy and high-energy particles coming from
the Sun, and trapped in the magnetic fields
associates with the target planet/moon
 High-energy particle detectors
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to measure the energy spectra of trapped energetic
electrons, and the energy and composition of atomic nuclei
 Low-energy particle detectors
• Used to characterize the composition, energies, and
angular distributions of charged particles in interplanetary
space and within planetary systems
Spacecraft Instruments - Orbiter Mission
Experiments and instruments
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Particle detectors
 Dust detectors
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to measure the number, velocity, mass, charge, and
flight direction of dust particles striking the instrument
► Used to measure the energy spectra of trapped energetic
electrons, and the energy and composition of atomic nuclei
 Plasma detectors
► Designed for analyzing the lowest particle energies
► Used to measure the density, composition, temperature,
velocity and three-dimensional distribution of plasmas in
interplanetary regions and within planetary magnetospheres
► Plasma detectors are sensitive to solar and planetary plasmas
► Used to measure the solar wind and its interaction with a
planetary system