Typical Spacecraft Contents

Appendix A: Typical Spacecraft This appendix contains descriptions and images of a dozen spacecraft selected from the many that are currently operating in interplanetary space or have successfully completed their missions, plus one that is now preparing for launch. Included is at least one representative of each of the eight spacecraft classifications described in Chapter 7 (see page 243). The scheme of limiting coverage of each spacecraft to a two-page spread in this appendix allows the reader to easily compare the various craft, their specifications, their missions, and their classifications, but it does not allow room to list all of a spacecraft’s activities, discoveries and questions raised; indeed entire books can and have been written on each. Complete profiles of these and other spacecraft are, how- ever, readily available at a single web site: http://nssdc.gsfc.nasa.gov/planetary. Contents: Spacecraft Classification Page Voyager Flyby 294 New Horizons Flyby 296 Spitzer Observatory 298 Chandra Observatory 300 Galileo Orbiter 302 Cassini Orbiter 304 Messenger Orbiter 306 Huygens Atmospheric 308 Phoenix Lander 310 Mars Science Laboratory Rover (launch: 2009) 312 Deep Impact Penetrator 314 Deep Space 1 Engineering 316 294 Appendix A: Typical Spacecraft The Voyager Spacecraft Fig. A.1. Each Voyager spacecraft measures about 8.5 meters from the end of the science boom across the spacecraft to the end of the RTG boom. The magnetometer boom is 13 meters long. Courtesy NASA/JPL. Classification: Flyby spacecraft Mission: Encounter giant outer planets and explore heliosphere Named: For their journeys Summary: The two similar spacecraft flew by Jupiter and Saturn. Voyager 2 continued on to encounter Uranus and Neptune. Both are on solar-system escape trajectories, and have penetrated the solar-wind termination shock. In 1998, Voyager 1 became the most distant human-made object. Payload: Imaging science wide-angle and narrow-angle cameras, UV spectrometer, IR spectrometer-radiometer, photopolarimeter, on scan platform. Low-energy charged particle detector, plasma spectrometer, cosmic ray detector, magnetometers (4), plasma wave detector, planetary radio astronomy receiver, audio and video messages from Earth en- coded on gold record. Nation(s): USA Mass at Launch: 800 kg Radio Link: S- and X-band Stabilization: 3-Axis, thrusters Propulsion: Hydrazine Electrical power: RTG Launch date: 1977 Launch vehicle: Titan-IIIE/Centaur The Voyager Spacecraft 295 Fig. A.2. One of the Voyager spacecraft during vibration testing at JPL on March 25 1977. Mission module is attached atop the injection propulsion unit (IPU) which was later jettisoned. Science boom (right) and radioisotope thermoelectric generator (RTG) boom (left) are folded down in launch configuration. The 13-meter long magnetometer boom is stowed within canister above middle left. White cylinders are RTG mass simulators; actual RTGs were installed just prior to launch. Thermal control louvers were placed differently prior to flight; the golden record of messages from Earth was placed on the bay seen near the center of the image. Courtesy NASA/JPL-Caltech. 296 Appendix A: Typical Spacecraft The New Horizons Spacecraft Fig. A.3. The New Horizons Spacecraft measures about 3 meters overall at its widest dimension. Courtesy NASA/JPL. Classification: Flyby spacecraft Mission: Encounter Pluto and Charon then explore Kuiper Belt Named: For its journey Summary: New Horizons took a gravity-assist from Jupiter in 2007 and will fly by dwarf planet Pluto and its moon Charon in 2015. It is expected to encounter one or more additional objects in the Kuiper Belt. Image courtesy Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI). Payload: Seven instruments: Ralph, a 6-centimeter aperture telescope to feed its Mul- tispectral Visible Imaging Camera and Linear Etalon Imaging Spectral Array. Alice, an ultraviolet imaging spectrometer. LORRI, the Long Range Reconnaissance Imager, which consists of a 20.8-centimeter aperture telescope with a CCD imager. SWAP, the Solar Wind Analyzer around Pluto, which measures charged particles from the solar wind. PEPSSI, the Pluto Energetic Particle Spectrometer Investigation, which characterizes neutral atoms. SDC, the Student Dust Counter. REX, the Radio Science Experiment, which functions as a microwave radiometer. It also records the received spectrum of the DSN’s uplink during occultation experiments. Nation(s): USA Mass at Launch: 478 kg Radio Link: X-band Stabilization: 3-Axis thrusters or spin Propulsion: Hydrazine Electrical power: RTG Launch date: January 19, 2006 Launch vehicle: Atlas-V/Centaur The New Horizons Spacecraft 297 Fig. A.4. Artist’s conception of the New Horizons spacecraft encountering a Kuiper Belt object. The Sun, about 45 AU away, appears in the glow of the zodiacal dust. The many objects in the Kuiper Belt, normally not visible because they are so far apart, are shown here to give an impression of the large number of icy worlds beyond Neptune. Image courtesy Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI). 298 Appendix A: Typical Spacecraft The Spitzer Space Telescope Fig. A.5. The Spitzer Space Telescope measures about 5 meters in length overall. Tele- scope shell cut away to reveal cooled telescope assembly within. Adapted from images courtesy NASA/JPL-Caltech. Classification: Observatory spacecraft Mission: Observe objects deep in the universe, galaxy, and solar system Named: In honor of American astrophysicist Lyman Spitzer, Jr. (1914–1997). Originally Space Infrared Telescope Facility (SIRTF), renamed after launch. Summary: One of the four NASA Great Observatories including Hubble, Compton, and Chandra. Orbits the Sun in an Earth-trailing orbit at about 1 AU, keeping its solar panel facing the Sun to shield the entire spacecraft from infrared radiation. The telescope has an 85-centimeter diameter primary mirror cooled to 5.5 K by boiling off liquid helium from an onboard 50.4-kilogram supply. This cools the telescope’s optics via a vapor-cooled shell and also cools the instruments near the focal plane. Cooling permits Spitzer to observe deep into the infrared region of the spectrum without interference from warm optics. Upon exaustion of coolant in 2009, sunshade keeps telescope at 34 K (instruments 4 K cooler due to additional passive cooling). Payload: Spitzer’s Infrared Array Camera operates simultaneously at 3.6 μm, 4.5 μmm, 5.8 μmm and 8 μmm wavelengths. The Infrared Spectrograph observes from 5.3 μmto 37 μm. The Multiband Imaging Photometer works from 24 μm to 160 μm. Nation(s): USA Mass at Launch: 950 kg Radio Link: X-band Stabilization: 3-Axis reaction wheels Propulsion: Cold nitrogen Electrical power: Solar Launch date: August 25, 2003 Launch vehicle: Delta-II The Spitzer Space Telescope 299 Fig. A.6. Spitzer releases its aperture dust cover in this artist’s conception. Thermal blanketing on the warm spacecraft bus is not shown. The vapor-cooled shell which sur- rounds the whole telescope has an upper surface (facing the solar panel shield) of polished metal to reject heat. The lower half of the shell is painted black to best radiate heat (which can be better seen by searching online for image ID: sirtf0410 04). The parabolic high-gain antenna is affixed to the lower left end of the spacecraft bus and cannot be seen in this view. Image courtesy NASA/JPL-Caltech. 300 Appendix A: Typical Spacecraft The Chandra X-Ray Observatory Fig. A.7. The Chandra spacecraft measures 13.8 meters in length. Its solar arrays span a width of 19.5 meters end-to-end across the spacecraft. Courtesy NASA/CXC/SAO. Classification: Observatory spacecraft Mission: Capture images and spectra of high-energy events in the universe Named: In honor of Indian-American astrophysicist Subrahmanyan Chandrasekhar (1910–1995) (Not to be confused with lunar orbiter Chandra-yaan) Summary: One of the four NASA Great Observatories (including Hubble, Spitzer, and Compton). Its mirrors’ high angular resolution give Chandra one hundred times greater sensitivity than previous x-ray telescopes. Known as the Advanced X-ray Astrophysics Facility (AXAF) prior to launch. Operates in a 64.2-hour, 10,000-kilometer x 140,000- kilometer Earth orbit above the x-ray absorbing atmosphere. Data from Chandra has been greatly advancing the field of x-ray astronomy since August 1999. Payload: The Advanced CCD Imaging Spectrometer (0.2–10 keV) and the High Reso- lution Camera (0.1–10 keV), both within the Science Instrument Module. Either of two spectroscopic gratings may be swung into the optical path downstream of the mirrors: the High Energy Transmission Grating (0.4–10 keV) or the Low Energy Transmission Grating (0.09–3 keV). Nation(s): USA Mass at Launch: 4,620 kg Radio Link: S-band Stabilization: 3-Axis, reaction wheels Propulsion: Hydrazine Electrical power: Photovoltaic Launch date: July 23, 1999 Launch vehicle: STS Columbia/IUS The Chandra X-Ray Observatory 301 Fig. A.8. Artist’s conception of the Chandra spacecraft. Concentric rings below the open aperture cover are the leading-edge rims of the 1.2-meter and smaller diameter nested high-resolution modified-cylindrical mirrors of Chandra’s Wolter grazing-incidence (see page 197) 10-meter focal length telescope, which extends toward the science instrument module at right. Courtesy NASA/CXC/SAO. 302 Appendix A: Typical Spacecraft The Galileo Spacecraft Fig. A.9. Galileo spacecraft in flight configuration. Spacecraft height is 5.3 meters. Com- ponents below the Spin Bearing Assembly are de-spun to permit pointing while upper part spins. From image courtesy NASA/JPL. Classification: Orbiter spacecraft Mission: Explore Jupiter, its moons, and its magnetosphere Named: In honor of Galileo Galilei (1564–1642), who observed Jupiter and discovered its four largest moons in 1610 Summary: Observed Venus, Earth, and two asteroids en route; deployed Jupiter atmosphere probe; orbited Jupiter 1995–2003 and observed Jupiter and Galilean satellites at high resolution.

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