Document Title: Jet Propulsion Laboratory, “Project Plan for International Solar Polar 1983 Mission," November 1978. Source: NASA Historical Reference Collection, History Office, NASA Headquarters, Washington, D.C. The next planned solar research mission after the Solar Maximum Mission was to be a joint effort with the European Space Agency (ESA). Such a mission had been under study for several years. This project plan represents the results of those studies, and it was the basis for project approval. NASA and ESA were to launch identical spacecraft that would transit the Sun's polar regions and would provide stereoscopic images of solar phenomena. The United States in 1981 cancelled its spacecraft contribution. (See Volume II, Chapter 1.) [cover sheet] Project Plan For International Solar Polar 1983 Mission Jet Propulsion Laboratory California Institute of Technology November 1978 [1-1] SECTION I A. IDENTIFICATION International Solar Polar Mission (ISPM) is the Project title (UPN 836) designated by the NASA Office of Space Science in its request for a plan under the NASA Physics and Astronomy Program. The Program Project Approval Document (PAD) (Ref. 1-1) [no references included] notes that the Program comprises Astrophysics Programs, Solar Terrestrial Programs, and Upper Atmospheric Research. The ISPM Project is an element of the NASA Solar Terrestrial Program. B. SCIENTIFIC BACKGROUND Studies of the Sun and heliosphere have a central role in the space program, as this area of science is one with vast practical benefits to man. The Sun provides the controlling influence on Earth's weather and climate. Since changes in solar conditions have the potential for causing variations in weather and climate, increased human knowledge of the Sun can allow increased understanding of these variations and their implications. The Sun is a star, and is the only star close enough that we can resolve its surface structure. The heliosphere is the only large-scale astrophysical plasma that we can observe in situ. Then by analogy, observations of the Sun and the heliosphere serve as a basis for deciding what is possible in other astrophysical settings. Numerous space missions have been flown to study the Sun and the heliosphere. Each of these missions has been limited in one major respect. To date no spacecraft has ventured off the solar equatorial plane by more than about 15° in heliographic latitude. This limitation is a serious one. As can be seen in the eclipse photograph shown in Figure 1-1 [figures not included] or in the X-ray photograph of the solar corona shown in Figure 1-2, the solar atmosphere exhibits [1-3] pronounced variations with latitude which should result in commensurate variations in the heliosphere. To date, then, we have studied only a non-representative sample of the solar wind. Similarly, our observations of the Sun are limited by projection effects because we have observed the Sun only from a narrow range of view angles. Recent advances have now made it possible to explore the heliosphere and view the Sun over the full range of heliographic latitudes. The major advances of note are: (1) Planetary payload injection capability, from the Titan/Centaur launch vehicle system of the 1970's to the Space Shuttle/Inertial Upper Stage combination of the 1980's. (2) Precision space navigation and trajectory correction maneuver capabilities, such as made possible the multiple flybys of the planet Mercury by the MVM Spacecraft and the swingbys of the planet Jupiter by Pioneers 10 and 11. A science rationale is provided in Section III-A [not included]. C. PROGRAMMATIC BACKGROUND Out-of-ecliptic missions have been considered by NASA almost from its formation as an agency (Ref. 1-2, 1959). In its early years, NASA also sponsored scientific meetings, of relevance to such missions, that collected and disseminated the results of space research, such as the plasma space science symposium held at the Catholic University of America, Washington, D.C., on 11-14 June 1963 (Ref. 1-3), and the conference on the solar wind held at the California Institute of Technology, Pasadena, California, on 1-4 April 1964 (Ref. 1-4). Various studies that lead to an out-of-ecliptic mission were published between 1963 and 1974, wherein the early studies are technology-oriented and the later studies focus on projects and system designs. Minovitch described in his now-classic report (Ref. 1-5, 1963) the use of gravity-assisted trajectories [1-4] to obtain multiple-body flybys. Biermann (Ref. 1-6, 1965) reviewed aspects of the physics of interplanetary space, such as the interplanetary plasma, magnetic fields and dust, and cosmic rays. Minovitch (Ref. 1-7, 1965) next provided details in his sequel to Ref. 1-5 of out-of-ecliptic trajectories which used Jupiter to perturb the spacecraft to achieve trajectories as described in Section IV-A [not included] herein. Hrach (Ref. 1-8, 1968) described an out-of-ecliptic probe mission which used electric propulsion. Simpson and others (Ref. 1-9, 1969) reviewed the potential of an out-of-ecliptic mission for fields and particles astronomy. Hrach and Strack (Ref. 1-10, 1970) described an early application of solar electric propulsion to a 1 AU outof-ecliptic mission. The NASA Ames Research Center (ARC) accomplished an in-house study during FY 1971 of a Pioneer Spacecraft out-of-ecliptic mission, with supporting tasks performed by the TRW Systems Group, and thus provided the first comprehensive report (Ref. 1-11, 1971) on the use of the Jupiter swingby mode. This mission was discussed in the context of an FY 1973 New Start with launch in May 1974. NASA assigned lead Center responsibility for out-of-ecliptic missions to the ARC in the early 1970's. JPL accomplished an in-house study during FY 1971 of a 3-axis stabilized, solar electric (propulsion) multimission spacecraft (SEMMS) capable of the following baseline missions: (1) Out-of-ecliptic at 1 AU or less. (2) Mercury orbiter. (3) Outer planet orbiter. (4) Comet and asteroid rendezvous. (5) Close solar probe. (6) Direct and swingby outer planet flyby. A project plan (Ref. 1-12, 1971) was submitted for Phase B and for planning Phase C/D as an FY 1973 New Start with earliest launch in July 1975. The final report is in three volumes (see Ref. 1-13, 1971). [1-5] European scientists had also realized the desirability of designing an out-of-ecliptic mission. During 1971 and 1972, a preliminary study of an independent out-of-ecliptic probe was carried out by a European Space Research Organization (ESRO) group composed of three scientists and five staff members (Ref. 1-14, 1972). Wilcox (Ref. 1-15, 1973) considered specific aspects of space exploration with an outof-ecliptic spacecraft and gave particular attention to the solar latitude interval from about 35° to about 65°, an area where projection effects begin to hamper earth-based observations, and to the polar regions above 65°. Wilcox used the ARC-prepared description of the trajectory of a single spacecraft. ARC continued discussions with NASA Headquarters on the use of Pioneer H (a refurbished Pioneer 10/11 prototype spacecraft with refurbished experiments) for an out-of-ecliptic mission and a project plan (Ref. 1-16, 1973) was submitted for an FY 1975 New Start with launch in July or August 1976. The ESRO Solar System Working Group, having discussed the scientific priorities for the 1980's, recommended to the ESRO Launch Program Advisory Committee (LPAC) a solar-interplanetary mission aimed at investigating the heliographic latitude dependance [sic] of solar wind properties and at performing a stereoscopic study of solar activity (Ref. 1-17, 1973). Shortly afterwards, when defining the guidelines for ESRO scientific mission studies (Ref. 1-18, 1974), the LPAC identified two candidate projects: (1) A solar stereoscopic mission, requiring a space probe reaching an angular distance from the Sun-Earth line of at least 40°. This mission, according to the LPAC, could probably be carried out most cheaply in the case of a dedicated solar mission by a spacecraft in the ecliptic plane. However, the LPAC recognized that if an out-of-ecliptic interplanetary mission was planned, a stereoscopic view could be obtained using the separation in solar latitude thus achieved. [1-6](2) An out-of-ecliptic mission, reaching at least 37° of heliographic latitude (direct injection), but preferably getting to higher latitudes. The two candidate projects above were considered during the NASA/ESRO Science Program Review held at the European Space Research and Technology Centre (ESTEC) on February 11, 1974, when the following conclusions were agreed: (1) Solar Maximum Mission (SMM); NASA would continue independently to study the SMM, since it seemed quite possible to use the SMM as one half of a stereoscopic mission. ESRO would continue independently its studies on a spacecraft which would constitute the other half of a stereoscopic mission. (2) Out-of-the-Ecliptic Probe; it was proposed that NASA and ESRO jointly study mission concepts which can achieve a higher heliographic latitude via the direct injection mode. The one possibility noted was to incorporate a solar electric propulsion (SEP) module in the spacecraft. NASA would use this mission as a test flight for SEP in preparation for a 1981 Encke rendezvous mission, therefore the out-of-ecliptic mission would be launched in 1979/1980. The ESRO Scientific Program Board, during its meeting on April 30, 1974, decided that a mission definition study should immediately be undertaken in connection with NASA, to study the scientific objectives and technical feasibility of a combined Out-ofEcliptic/Solar Stereoscopic mission. NASA agreed, and a Joint Mission Definition Group was established in May 1974 with 3 European scientists and 4 U.S. scientists. Program guidance was provided by ESRO Headquarters and NASA Headquarters. Technical and programmatic support were supplied by ESRO, ARC and JPL. A symposium on "The Sun and Solar System in Three Dimensions", organized by ESRO, was held at the European Space Research Institute (ESRIN), Frascati, Italy, in July 1974. Written versions of the talks were made available to the Mission Definition Group. The Group met at JPL in August 1974 [1-7] when ARC first proposed the dual spacecraft concept. The report (Ref. 1-19) of the Mission Definition Group was published in December 1974, and it is noted that the dual spacecraft concept proposed by ARC is first described therein. The report described the use of both the SEP and Jupiter swing by options. The NASA/ESRO Science Program Review was next held 4-5 February 1975. NASA and ESRO agreed: (1) To accept the dual spacecraft mission as primary with a single spacecraft option. (2) To pursue preliminary spacecraft and mission definition studies. (ESRO and the European Launcher Development Organization (ELDO) merged about this time to form the European Space Agency (ESA).) A workshop on mechanisms for solar Type III radio bursts was held at the University of California, Berkeley, California, on 8-9 May 1975. Baumbach and others (Ref. 1-20) reported the use of plasma wave experiments on satellites to determine three-dimensional trajectories of such bursts. NASA and ESA sponsored a symposium on the study of the Sun and interplanetary medium in three dimensions at the NASA Goddard Space Flight Center (GSFC) on 15-16 May 1975 (Ref. 1-21). Over 200 European and U.S. scientists attended to review the outof-ecliptic mission and all aspects of related science. To carry out the studies agreed upon, ESA contracted with the British Aircraft Corporation (BAC) for a detailed spacecraft definition study to start September 1975. ARC and JPL performed in-house studies, and ARC contracted with TRW and Martin Marietta for additional support. Joint ground-rules were: [1-8] (1) Use Space Shuttle with 4-stage IUS. (2) Dual spacecraft concept. (3) Backup option no. 1: a single spacecraft; and Space Shuttle with 2-stage IUS plus spinning injection stage (TEM-364-4). (4) Backup option no. 2: a single spacecraft; and Atlas/Centaur launch vehicle plus spinning injection stage (TEM-364-4). The BAC 4-volume final report was published in April 1976 and provided a complete technical description of the ESA spacecraft and all of its interfaces, a system specification, system analysis and definition, subsystem analysis and definition, development plans and cost estimates (see Ref. 1-22). The ARC final report was also published in April 1976 (Ref. 1-23). ESA published its own final report in May 1976 (Ref. 1-24). NASA assigned overall project management responsibility for continuing the out-ofecliptic mission studies to the JPL on 1 July 1976. NASA and JPL formed an Out-of-Ecliptic Science Working Group (SWG) in August 1976 to provide science guidance to JPL inhouse studies during FY 1977. (The SWG report is found in Ref. 1-25, and the JPL final reports are found in Refs. 1-26 and 1-27.) ESA contracted with BAC for additional studies. The JPL and ESA/BAC study groundrules were: (1) Use Space Shuttle with 4-stage IUS (no change). (2) Dual spacecraft concept (no change). (3) No backup options. (4) Two modes of NASA/ESA cooperation: (a) Each to provide one spacecraft. (b) NASA to provide selected subsystems and ESA to provide both spacecraft. (This mode was eliminated from further consideration in January 1977.) The NASA Cost Review was held at JPL in May and July 1977. Subsequently the Project was submitted to the Congress as a (proposed) New Start for FY 1979. ESA plans to contract competitive studies for the period January through July 1979, followed by study by a single contractor from September through [1-9] December 1979. The ESA contract for development of the ESA Spacecraft is planned to be signed in January 1980. The details of the planned JPL contract-ing effort for the NASA Spacecraft are provided in Table 6-2 [not included] herein. D. SCOPE OF PROJECT PLAN This Plan defines the Joint NASA/ESA International Solar Polar 1983 Mission. Two spacecraft will be launched from Cape Canaveral, Florida, by a single NASA Space |