该计划中的任务是从欧洲科学界成员向欧空局提交的提案中竞选评出[20]，在每次竞选中，欧空局都会概述提案需要满足的各类任务评审标准[21]，它们分别是“L”级大型任务、“M”级中型任务、“S”级小型任务和“F”级快速任务，每类任务都有不同的预算上限和实施时间表[5][21]。参选提案随后由天文学工作组、太阳系与探索工作组、欧空局工程师和所有相关的特设工作组进行审查，作为“第 0 阶段”可行性研究的一部分[22][23]。对需要开发新技术的任务，会在研发期间由欧洲空间研究与技术中心的并行测试部门进行审查[24]。研究结束后，在“A 阶段”最多选出三项入围提案，并为每项候选任务制定初步设计[23][25]。然后，科学计划委员会就哪项提案进入“B”到“F”阶段作出最终决定，包括任务中所用航天器的开发、建造、发射和处置[26][27][28]。在 A 阶段，每项候选任务会分配两个相互竞争的承建商来建造航天器，并在 B 阶段选择获选任务的承建商[25][27]。
Equator was a planned mission by NASA to explore Earth's magnetosphere from an equatorial orbit. It was NASA's contribution to a joint mission with the STSP known as the International Solar-Terrestrial Physics (ISTP) programme.[87][88]
资料来源
Bonnet, Roger-Maurice; Bleeker, Johan; Olthof, Henk. Longdon, Norman , 编. Space Science – Horizon 2000. Esa's Report to the ... Cospar Meeting (Noordwijk, Netherlands: ESA Scientific & Technical Publications Branch). 1984 [9 July 2019]. ISSN 0379-6566. （原始内容存档于9 July 2019）.
Bonnet, Roger-Maurice. European Space Science - In Retrospect and in Prospect. Battrick, Bruce; Guyenne, Duc; Mattok, Clare (编). ESA Bulletin No. 81. Noordwijk, Netherlands: ESA Publications Division. 1995: 6–17 [7 July 2019]. ISSN 0376-4265. （原始内容存档于2021-06-04）. |journal=被忽略 (帮助)
Wilson, Andrew. ESA Achievements(PDF) 3rd. Noordwijk, Netherlands: ESA Publications Division. 2005 [10 July 2019]. ISBN 9290924934. （原始内容存档(PDF)于10 July 2019）.
ESA science programme planning cycles. ESA Science. 4 March 2019 [7 July 2019]. （原始内容存档于7 July 2019）. The Science Programme of the European Space Agency (ESA) relies on long-term planning of its scientific priorities.
ESA 2015，"The Science Programme within the Directorate of Science has two main objectives [...] The Science Programme has a long and successful history..."
ESA Media Relations Office. ESA Science Programme's new small satellite will study super-Earths. European Space Agency. 12 October 2012 [6 July 2019]. （原始内容存档于6 July 2019）. Studying planets around other stars will be the focus of the new small Science Programme mission, Cheops, ESA announced today. [...] The mission was selected from 26 proposals submitted in response to the Call for Small Missions in March [...] Possible future small missions in the Science Programme should be low cost and rapidly developed, in order to offer greater flexibility in response to new ideas from the scientific community.
ESA 1995，"ESA's Science Programme has three primary features that single it out among the Agency's activities [...] ESA's Science Programme has consistently focussed on missions with a strong innovative content."
Call for a Fast (F) mission opportunity in ESA's Science Programme. ESA Science. 16 July 2018 [7 July 2019]. （原始内容存档于7 July 2019）. This Call for a Fast mission aims at defining a mission of modest size (wet mass less than 1000 kg) to be launched towards the Earth-Sun L2 Lagrange point as a co-passenger to the ARIEL M mission, or possibly the PLATO M mission.
ESF and NRC 1998，page 36, "The fundamental rule of ESRO, and subsequently ESA, has been that ESA exists to serve scientists and that its science policy must be driven by the scientific community, not vice versa [...] [This] explains the determining influence that ESA's advisory structure has on the definition and evolution of the scientific program."
European Space Agency. Astronomy Working Group. ESA Cosmos Portal. 2011 [6 July 2019]. （原始内容存档于6 July 2019）. The Astronomy Working Group (AWG) provides scientific advice mainly to the Space Science Advisory Committee (SSAC). [...] The chair of the working group is also a member of the SSAC.
European Space Agency. Solar System and Exploration Working Group (SSEWG). ESA Cosmos Portal. 2011 [6 July 2019]. （原始内容存档于6 July 2019）. The Solar System and Exploration Working Group (SSEWG) provide scientific advice mainly to the Space Science Advisory Committee (SSAC). [...] The chair of the working group is also a member of the SSAC.
ESA 2015，"The Science Programme within the Directorate of Science has two main objectives; To provide the scientific community with the best tools possible to maintain Europe's competence in space; To contribute to the sustainability of European space capabilities and associated infrastructures by fostering technological innovation in industry and science communities, and maintaining launch services and spacecraft operations."
Cogen 2016，page 221, "All member states must participate in the mandatory programmes [...] Today, ESA's mandatory programmes are carried out under the General Budget, the Technology Research Programme, the Science Programme and ESA's technical and operational infrastructure."
ESA 1995，"...it is the only mandatory programme [...] In 1975, when ESRO and ELDO were merged to form ESA, it was immediately decided that the Agency's Science Programme should be mandatory."
ESA 2015，"All Member States contribute pro-rata to their Net National Product (NNP) providing budget stability and allowing long-term planning of its scientific goals. For this reason, the Science Programme is called 'mandatory'.
ESA 2015，"Long-term science planning and mission calls are established through bottom-up processes. This relies on broad participation, with input and peer reviews of the space science community. The ESA Science Programme is foremost science-driven."
ESF and NRC 1998，page 36, "They advise the director general and the director of the scientific program on all scientific matters, and their recommendations are independently reported to the SPC."
European Space Agency. Space Science Advisory Committee (SSAC). ESA Cosmos Portal. 2011 [6 July 2019]. （原始内容存档于6 July 2019）. The Space Science Advisory Committee (SSAC) is the senior advisory body to the Director of Science (D/SCI) on all matters concerning space science included in the mandatory science programme of ESA.
Cogen 2016，page 219, "The Council is responsible for the establishment of a Science Programme Committee which deals with any matter relating to the mandatory scientific programme."
ESA 2013，"These projects are identified and selected using the mechanism of the open call. Whenever appropriate, and compatible with the programme goals and constraints, ESA issues a call for proposals for new science missions."
ESA 2013，"The call includes descriptions of the scientific goals, size, cost of the mission, together with programmatic and implementation details. [...] Missions fall into three categories: small (S-class), medium (M-class) and large (L-class), their size reflecting the scientific goals addressed and eventually the cost and development time required."
ESA 2013，"ESA's various scientific advisory committees of experts assess the submissions. [...] ESA’s engineers also make an initial assessment of the feasibility of the missions. [...] Phase 0; Mission analysis and identification..."
Bonnet 2004，page 203, "Following a normal cycle of selection, through the Working Group, ESA undertook a feasibility study in 1984-1985, followed by the selection for Phase A in 1986."
ESA 2013，"This identifies any new technology that will need to be developed to make the mission possible. The majority of these studies are conducted internally at ESA's Concurrent Design Facility (CDF)."
ESA 2013，"The committees then make recommendations about which missions should proceed to 'Phase A'. [...] Usually two or three missions are downselected for the phase A study, for which two competitive industrial contracts are placed for each mission. Phase A results in a preliminary design for the mission."
ESA 2013，"Results are presented, again in Paris to the various committees, and a final decision on which proposal will be selected for each mission is made. [...] They will eventually lead to the 'adoption' of the mission and to the selection of one of the two industrial contractors to become the responsible for the whole implementation phase..."
Bonnet 2004，page 203–204, "The Titan Probe was eventually selected by ESA's SCP in Nov. 1988 as the first 'blue' mission of Horizon 2000, against four other missions: VESTA, LYMAN, QUASAT, and GRASP."
Krige et al. 2000，page 34, "The Convention establishing the European Space Agency was signed by ten European states on 30 May 1975 [...] At the same time the Conference of Plenipotentiaries adopted a Final Act including ten resolutions. These made allowance for the transition from ESRO and ELDO to ESA..."
Cogen 2016，page 217, "ESA is created in its current form in 1975, merging ELDO with ESRO, by the Convention for the Establishment of a European Space Agency of 30 May 1975."
Parks, Clinton. May 31, 1975: European Space Unites Under the ESA Banner. SpaceNews. 27 May 2008 [8 July 2019]. Established May 31, 1975, ESA formed from the merger of the European Space Research Organisation (ESRO) and the European Launcher Development Organisation (ELDO).
Bonnet 2004，page 201, "At their long term planning meeting in 1970, the LPAC decided not to plan any planetary missions because they were considered at the time too expensive and beyond the financial capabilities of ESRO. Cooperation with NASA or the USSR was the only option for Europe to participate in the exploration of the Solar System."
Bonnet 2004，page 201–202, "The first change from that policy was the proposal of the ESA Science Director, Ernst Trendelenburg, followed by the positive decision of ESA's SPC in 1980, to launch a fast fly-by mission to Halley's comet on the occasion of its return to the vicinity of the Sun in March 1986."
Bonnet 1995，page 9, "These two events together explain the series of decisions taken between 1980 and 1983. Giotto and Hipparcos were selected by the SPC in 1980 (again with great difficulties in deciding between astronomy and solar-system missions) and ISO in March 1983."
Bonnet 1995，page 9, "The crisis came in the same period as the arrival of Ariane, which was successfully launched for the first time on Christmas Eve 1979, giving Europe full autonomy in accessing space. [...] All three missions were to use the Ariane launcher and were originally European-only missions."
Bonnet 2004，page 202, "Giotto (the name given to that mission) was the first purely European mission to explore the Solar System with its own launcher: Ariane 1, launched on July 2 1985."
Bonnet 1995，page 9, "The ISPM crisis then opened their eyes as they realised for the first time the fragility of agreements signed by their trans- Atlantic counterparts. The Memorandum of Understanding, the official document establishing the basis for the cooperation, which had a binding significance on the European side, had a different interpretation for the Americans, with NASA's budget submitted to yearly discussion at the White House and in Congress."
Bonnet 1995，page 10, "In 1983, it became clear that ESA could no longer continue with its existing method of selecting project after project, without a long-term perspective and some kind of commitment that would allow the scientific community to prepare itself better for the future. ESA too needed a long-term programme in space science."
Krige et al. 2000，page 39, "The DG replaced the LPAC with the SAC (Science Advisory Committee) reporting directly to him on all scientific matters [...] A Life Sciences Working Group (LSWG) and Materials Sciences Working Group (MSWG) were also added to the AWG and SSWG, with all working groups reporting to the DG."
Krige et al. 2000，page 43, "The SAC, which had previously advised the Director General on all scientific matters, was now transformed into the SSAC (Space Science Advisory Committee). Its role became to advise the Director of Scientific Programmes on activities covered by the AWG and the SSWG."
Krige et al. 2000，page 43, "The spirited and controversial figure of Ernst Trendelenburg, who had spent almost twenty years in ESRO and then ESA, was replaced as Director of Scientific Programmes on 1 May 1983 by the French space scientist Roger Bonnet, former chairman of the SAC from 1978 to 1980."
Bleeker et al. 1984，page 3, "Over the past 25 years, space science has progressed from the pioneering and exploratory stage to a firmly established mature branch of fundamental science. The time has come to identify what the main thrusts of European space science should be for the coming decades to consolidate Europe's position in the forefront of scientific development"
Bleeker et al. 1984，page V, "The study, which led to the long term plan proposed in this document, was initiated by the Director of the Scientific Programme in September 1983 and was coordinated by a Survey Committee composed of scientists from different areas of fundamental science."
Krige et al. 2000，page 43, "Bonnet presented his idea to a meeting of the SPC in October 1983. The scientific community would be asked to suggest mission concepts which would be assessed by expert teams covering various disciplines in astronomy and the solar system sciences."
Bonnet 1995，page 10, "Following a Call for Mission Concepts issued in Autumn 1983, to which the European scientific community responded with some 68 proposals (Table 2)..."
ESF and NRC 1998，page 36, "The SSAC formed the core of the survey committee. The membership of the survey committee, in addition to the SSAC [...] the European Science Foundation, Centre d'Études et de Recherches Nucléaires (CERN), the European Southern Observatory (ESO), and the International Astronomical Union (IAU)."
Harvey 2003，page 210, "The Agency adopted a team of scientists under Johan Bleeker and made a call for mission concepts: one that was widely supported (70 were received)..."
Krige et al. 2000，page 43, "Their proposals would be evaluated by a Survey Committee which would draw up a global model programme for the years 1985 - 2004."
Krige et al. 2000，page 44, "The philosophy of Horizon 2000 was to divide projects into three classes: cornerstones, costing two annual budgets, and having long lead times; medium size projects, costing one annual budget, and of the class of then current missions like Giotto, Hipparcos and Ulysses; and low-cost projects, costing 0.5 annual budgets, typically participation in international programmes."
Harvey 2003，page 210, "In the end, the committee produced a report called Space Science Horizon 2000, often referred to as Horizon 2000. This adopted the principle of 'cornerstone' missions, projects that will advance space science substantially in distinct areas over a period of many years."
Krige et al. 2000，page 44, "The overall budget for the programme was set at 200 MAU annually (1983 prices) as from 1991, this level to be achieved by an annual 7% increase over the 1984 budget (about 130 MAU)."
Bonnet 2004，page 203, "In addition, Horizon 2000 offered the possibility of introducing at any stage in the selection process, medium-size or 'blue' missions, so-called because they were represented as blue boxes in the original diagram of the plan, whose cost would not be larger than half the value of the yearly budget."
Bleeker 1984，page 6, "Having established the major missions as the 'cornerstones' of the programme, provisions are to be made within the overall long term programme for a number of typical but as yet unidentified medium and small size missions [...] Detailed identification and selection of these smaller missions will be made at the appropriate time and follow the established competitive procedure." harvnb模板錯誤: 無指向目標: CITEREFBleeker1984 (幫助)
Bonnet 1995，page 10, "In addition, the plan also included both small and medium size projects [...] but with no i priori （原文如此） exclusion of disciplines, so that a community not 'served' directly by the Cornerstones could still find a place in responding to the regularly released 'Calls for Ideas'."
Krige et al. 2000，page 44, "The astronomers selected an X-ray spectroscopy mission intended to build a third generation of observatory-class satellites for high-energy astrophysics. Their second cornerstone was in the field of submillimetre heterodyne spectroscopy [...] As for the solar system scientists, one of their cornerstones built on the achievements of Giotto, involving a mission to primordial bodies (comets and asteroids) with a return of pristine materials."
Bleeker et al. 1984，page 10–11, "The four cornerstones are: The Solar Terrestrial Programme (STP) [...] A Mission to Primordial Bodies including Return of Pristine Materials [...] A High Throughput X-Ray Mission for Spectroscopic Studies between 0.1- 20 keY [...] A High Throughput Heterodyne Spectroscopy Mission..."
Bonnet 1995，page 10, "so-called 'Cornerstones' were approved in four domains: solar-terrestrial physics (STSP), comet science (CNSR, now called Rosetta), X-ray (XMM), and submillimetre astronomy (FIRST)."
Bleeker et al. 1984，page 11, "As a follow-up to these four elements it is already possible to identify beyond the horizon 2004 other major thrusts: these are the Solar Probe and the Heliosynchronous Out of Ecliptic Mission in solar terrestrial physics, the Mars Rover in the planetary area, and, in astronomy, two-dimensional interferometry for high spatial resolution in the visible, infrared (IR) and millimetre (mm) wavelength region. These thrusts are beyond the present programme, for technological and financial reasons..."
Krige et al. 2000，page 44, "After the expert teams had prepared their reports an historic meeting of leading members of the European space science community on the San Giorgio Island in Venice from 30 May to 1 June 1984 consolidated the choices between them and produced a long-term plan which received the name Horizon 2000."
Bonnet 1995，page 10, "...a survey committee and several Topical Teams were formed to [...] formulate recommendations to ESA's then Director General Erik Quistgaard, for him to present to the Council of Ministers in January 1985 in Rome."
ESA 1995，"The programme objectives are to: contribute to the advancement of fundamental scientific knowledge; establish Europe as a major participant in the worldwide development of space science; offer a balanced distribution of opportunities for frontline research to the European scientific community; provide major technological challenges for innovative industrial developments."
ESF and NRC 1998，page 52, "At the final meeting of the survey committee in May 1984 in Venice, Italy, only three cornerstones were originally foreseen. It was therefore a surprise when a fourth, consisting of the SOHO and Cluster missions, was introduced by the chairman of the Solar System Working Group. [...] This cornerstone was called the Solar-Terrestrial Science Program (STSP)..."
Krige et al. 2000，page 44, "The second, not foreseen in the original outline, sneaked in at the Venice meeting and covered the fields of solar and plasma physics. It involved combining two existing proposals, SOHO and Cluster."
Krige et al. 2000，page 44, "..as a result of which those present agreed to increase the level of the mandatory programme by 5% annually in real terms over the period 1985 - 1989."
ESA 1995，"Carrying out Horizon 2000 required a special financial effort from the Member States, amounting to a progressive budgetary increase of 7% per year from 1985 to a steady state in 1992. The Council meeting at Ministerial Level in Rome authorised a slower progression of 5% a year until 1989, thus affording about 50% of the requested increase."
ESA 1995，"The realisation of the entire Horizon 2000 plan became dependent on such a progression of 5% a year being maintained until 1994. This progression was granted by the ESA Council in December 1990, thereby opening the way to full implementation of Horizon 2000."
Bonnet 1995，page 10, "...the ESA science budget was granted an annual increase of 5% above inflation [...] an increment that was to be implemented over ten years."
Krige et al. 2000，page 44, "This was subsequently extended at the Ministerial Meeting in The Hague to enable the programme to reach a level of almost 217 MAU in 1992 (in 1985 prices)."
Lumb et al. 2012，page 1, "...culminating in a mission presentation at an ESA workshop held in Lyngby, Denmark in June 1985. In the papers presented at this conference the mission design contained 12 low-energy and 7 high-energy telescopes..."
Lumb et al. 2012，page 1, "When the report of the telescope working group was delivered in 1987, the consideration of practical constraints had reduced the number of telescopes to a more modest total of 7."
Lumb et al. 2012，pages 1, 4, "The mission was approved into implementation phase in 1994, and an improved observing efficiency achieved with a highly eccentric orbit allowed the number of telescopes to be reduced. [...] Effective area (1keV); 1500 cm2"
European Space Agency. XMM-Newton Overview. ESA Science. 4 June 2013 [9 July 2019]. （原始内容存档于9 July 2019）. Following the experience with Exosat, which demonstrated the value of a highly eccentric orbit for long uninterrupted observations of X-ray sources, XMM was to be placed in a 48-hour period orbit using the Ariane 4 launcher.
Wilson 2005，page 206, "The heart of the mission is the X-ray telescope. It consists of three large mirror modules and associated focalplane instruments held together by the telescope's central tube"
Krige et al. 2000，page 217, "To this, Bonnet replied that the Executive would offer the SPC the choice between implementing the STSP as a wholeor selecting one of the three projects in competition (SOHO, Cluster and Kepler), but stressed that "if the Executive could implement the STSP Cornerstone within 400 MAU, it would do so unless the SSAC expressed a strong negative opinion on this approach"."
Krige et al. 2000，page 217, "The supporters of Kepler had a good card in their hands, however, i.e. the high cost of the twin SOHO/Cluster mission, well above the 400 MAU ceiling."
Krige et al. 2000，page 217, "The decision was not however taken without some conflict. One of the new SSAC members, M. Ackerman, did not like the "inferiority situation" in which Kepler had found itself as aconsequence of the introduction of the STSP Cornerstone and insisted that the Mars mission should be maintained in the selection cycle."
Krige et al. 2000，page 219, "The SPC met on 6 February 1986, in the aftermath of the dramatic accident which had destroyed the Challenger Shuttle, killing its crew (28 January). This event threw a new shadow on the STSP programme: firstly, because SOHO was assumed to be eventually launched on the Space Shuttle..."
Krige et al. 2000，page 217, "After a dramatic discussion on the various options, the SSAC agreed that an STSP mission consisting of a descoped SOHO and a three-spacecraft Cluster should eventually be pursued..."
Krige et al. 2000，page 218–219, "The SSWG unanimously agreed to recommend the STSP programme [...] The SSAC, for their part, fully endorsed the SSWG recommendation [...] all SPC delegations finally approved the adoption of the STSP double mission into ESA's Scientific Programme..."
Krige et al. 2000，page 219, "ESA would also develop the SOHO spacecraft (including payload integration) for which NASA would provide testing, launch services and operations. European and US experiments would be included in SOHO and the first Cluster spacecraft."
Krige et al. 2000，page 219, "In the event, a tentative agreement was reached with NASA in October that year, by which ESA would develop four identical Cluster spacecraft, one of which would be launched by NASA in 1993 into an equatorial orbit, thereby replacing NASA's "Equator" ISTP satellite now cancelled, and the three others would be launched in 1994 (free of charge) on an Ariane-5 demonstration flight."
Goddard Space Flight Center. Equator-S. Space Science Data Coordinated Archive. [15 July 2019]. （原始内容存档于15 July 2019）. Equator-S is different from NASA's ISTP/EQUATOR spacecraft, which was dropped when the ISTP mission was re-scoped in late 1989.
Bonnet 2004，page 203, "In response to a call for ideas for new missions released by ESA in 1982, a group of European and US scientists proposed adding a Titan Probe as an element of the US Cassini mission."
Harvey 2003，page 211, "Also in the melting pot for consideration were an ultraviolet observatory (Lyman), a very long baseline interferometry mission (Quasat)..."
Krige et al. 2000，page 220, "All three missions under consideration were recommended by the Working Groups for Phase-A study, the Titan probe for the Cassini mission by the SSWG and Lyman and Quasat by the AWG."
Bonnet 2004，page 203–204, "The Titan Probe was eventually selected by ESA's SPC in Nov. 1998 （原文如此） as the first 'blue' mission of Horizon 2000, against four other missions: VESTA, LYMAN, QUASAT, and GRASP."
Bonnet 1988，page 87, "Vesta is a trilateral (USSR, CNES, and ESA) mission to the small bodies of the Solar System [...] Each spacecraft will fly-by a minimum of three asteroids [...] A cometary fly-by will also be included."
Krige et al. 2000，page 220, "Later on, however, NASA informed ESA that because of budgets cuts, in the wake of the Challenger accident, they could no longer consider the Lyman and Quasat projects for the present."
Bonnet 2004，page 204, "At the end of the SPC meeting the Director of the Science Programme reminded delegations that the Saturn moon Titan had been discovered in 1655 by the Dutch astronomer Huygens. In response to the Swiss request, he therefore proposed that the European contribution to the American Cassini project henceforth by known as 'Huygens'."
ESF and NRC 1998，page 54, "The early definition of INTEGRAL attempted to combine the best features of the two earlier gamma-ray missions studied on both sides of the Atlantic [...] In June 1989, in response to the ESA call for new mission proposals, INTEGRAL was proposed jointly [...] on behalf of a consortium of institutes and laboratories in Europe and the United States."
ESF and NRC 1998，page 54, "The renewed discussions of INTEGRAL in Europe following the rejection of GRASP stemmed in part from the NASA Explorer competition of 1989 in which a U.S. gamma-ray spectroscopy mission, the Nuclear Astrophysics Explorer (NAE), had been selected for a Phase A study but then was not selected for flight."
ESF and NRC 1998，page 54, "In December 1991, the Russian Academy of Sciences offered to provide a Proton launcher, free of charge, as a contribution in exchange for a share of the observing time."
ESF and NRC 1998，page 55, "Moreover, NASA had no previously identified INTEGRAL in its overall mission planning. Given this uncertainty, NASA was unable to make a firm commitment. [...] A suspicion arose within the U.S. space science community that funding the spectrometer would require funds be derived from the Explorer line."
ESF and NRC 1998，page 55, "At ESA's June 1993 meeting, the SPC approved INTEGRAL as ESA's M2 mission, based on an international cooperation in which Russia would provide the Proton launcher and NASA the spectrometer instrument, as well as a contribution to the ground segment."
Wilson 2005，page 236, "Integral was selected by the Agency's Science Programme Committee in 1993 as the M2 medium-size scientific mission. It was conceived as an observatory, with contributions from Russia (launch) and NASA (Deep Space Network ground stations)."
ESF and NRC 1998，page 55, "The INTEGRAL mission had still not garnered broad U.S. support or a vocal constituency in the NASA space science advisory process for several reasons [...] the perception that INTEGRAL had never passed the required peer review in the Explorer competition..."
ESF and NRC 1998，page 55, "...early concerns of some astrophysists that the lack of detection of bright descrete sources of line emission [...] implied that the spectrometer planned for INTEGRAL might not be sensitive enough."
ESF and NRC 1998，page 55, "...it became increasingly clear that NASA could not support INTEGRAL at the $70 million level expected by U.S. PIs. [...] Finally in September 1994, a meeting between ESA and NASA led to the conclusion that NASA could not support the U.S. spectrometer PI."
ESF and NRC 1998，page 55, "The proposal was made possible because the Centre National d'Études Spatiales (CNES), the French national space agency, agreed to assume the financial burden resulting from NASA's withdrawal on the spectrometer..."
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