National Academies Press: OpenBook
Suggested Citation:"Letter." National Research Council. 2000. Review of Scientific Aspects of the NASA Triana Mission: Letter Report. Washington, DC: The National Academies Press. doi: 10.17226/9789.
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Suggested Citation:"Letter." National Research Council. 2000. Review of Scientific Aspects of the NASA Triana Mission: Letter Report. Washington, DC: The National Academies Press. doi: 10.17226/9789.
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Suggested Citation:"Letter." National Research Council. 2000. Review of Scientific Aspects of the NASA Triana Mission: Letter Report. Washington, DC: The National Academies Press. doi: 10.17226/9789.
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I I. "C I\dvlsers to t/ie Natlo/1 0/1 S(le/1(e, E"glneeri/1g, a/Id Medl(i/1e NationalAcademy Sciences of NationalAcademyof Engineering Instituteof Medicine Space Studies Board NationalResearch Council C<rnrTission on Physical saences, Mathematics and Applications March 3, 2000 Dr. GhassemR. A~irar Associate Administrator for Earth Science Code y NASA Headquarters Washington, D.C. :20546 Dear Dr. Asrar: At your request the National ResearchCouncil established a task group to evaluate the scienti.fic aspectsof the Triana mission. The charge to the Task Group on the Review of Scientific Aspects of the NASA Triana Mission was to review (I) the extent to which the mission's goals and objectives are consonantwith published science strategies and priorities, (2) the likelihood that the planned measurementscan contribute to achieving the state.dgoals and objectives, and (3) the extent to which the mission can enhanceor complement other missions now in operation or in development. Triana is a mission designedto be deployed into a stable orbit, at roughly a million miles from Earth in the direction of the Sun. An orbit at this location, known as Lagrangian point I (LI), is stable in the sensethat the satellite remains on the Sun-Earth line and views the full sunlit disk of Earth continuously. From L I Triana will observe Earth with two insltrurnents,and a third will monitor the spaceenvironment in the direction of the Sun. Observed data are expectedto be delivered in near real time to ground stations. As proposed, Triana is an exploratory mission to investigate the scientific and technical advantagesofLI for Earth observations. The continuous view of the full sunlit disk of Earth will (~omplementand extend observations from low Earth orbit (LEO) or geostationary EartJllorbit (GEO) satellites. Triana will provide a global synoptic view (a continuous, from sunrise to sunset,simultaneous view of the sunlit side) of Earth in a range of wavelengths including ultraviolet, visible, and infrared to observe variations in ozone, aerosols, clouds, and surface ultraviolet radiation and vegetation. Triana is a flight opportunity to ext(~ndand improve observation of the solar wind and spaceweather at a most meaningful site, supplementing the data from the Advanced Composition Explorer satellite. A detailed analysis of instrumentation, data collection and reduction, systems operation, and maJ1agement beyond the scope of the task group. s effort and was was precluded by the time and budgetary constraints placed on the preparation of this report Nevertheless, the task group agreed on a number of general issuesrelated to the likely scientific successof the mission basedon its review of relevant documents and reports and briefings by N-ASA's Triana science team. In its evaluation, the task group relied heavily on presentations from NASA and members of the Triana science team, and on detailed questioning of the presenters. 2101Constitution A~enue, Washington, 20418 Telephone NW, DC (202)3343477 Fax(202)3343701 Office Alfdress:MiltonHarris Building, Room584,2001 Wisconsin Avenue, N.W.. Washington, 20007 DC

2 In the attached more detailed technical assessment, task group relates Triana's the scientific objectivt~sand deliverable data products to the researchstrategiesand priorities proposed in earlier National ResearchCouncil and government reports. The task group found that the scientific goals and objectives of the Triana mission are consonant with published science strategies and priorities for collection of climate data sets and the need for development of new technologies. However, as an exploratory mission, Triana's focus is tJle development of new observing techniques, rather than a specific scientific investigation. The apparent spaceflight heritage of some of the Triana technology and tht~applicable legacy of the data reduction algorithms should contribute to the achievement of the mission's objectives. The task group concluded that the planned measurements, if successfully implemented, will likely contribute to Triana's stated g.()alsand objectives. It did not attempt to evaluate the applicability of this heritage for a mission at Ll. The task g:roup also found that the Triana mission will complement and enhance data froJIDother missions because of the unique character of the measurements olJltainable at the Ll point in space, which allows continuous imaging of the full sunlit disk of Earth and monitoring of the space environment upstream from Earth. FurtllemlOre, the full-disk Earth observations provide a unique perspective from which to develop new databases and validate and augment existing and planned global databases.l\S an exploratory mission, Triana may well open up the use of deep- spaceobservation points such as Ll for Earth science.The task group believes that the potential impact is sufficiently valuable to Earth sciencethat such a mission might have been viewed as an earlier NASA priority had adequatetechnology been available at reasonable cost. The task group is concerned, however, that because of the compressed schedule there may not be adequate time for instrument testing and calibration prior to launch. The task gJ.oup also concernedthat significant development, testing, and is validation of the operational algorithms are needed,and it recommendsthat this work start immediately. The scientific successof the Triana mission will be judged, in large part, on the qualit)r of the initial data delivered to the scientific community .The task group therefore recommends that NASA seriously consider increasing the level of effort invested in development and testing of data reduction algorithms for the core Earth data prOd1Jlcts soon as possible. In addition, it is concerned that there may as be insufficient fuJ[lding for scientific analysis of the data. If Triana lasts longer than its nominal 2 years, i1:will be important for NASA to support the data processing activities for the mission's useful duration. The task gJ.OUp lacked the proper expertise, resources,and time to conduct a credible cost or cost-benefit analysis (such an effort might take many months and much detailed analysis) or an analysis of the mission goals and objectives within the context of a limited NASA budget or relative to other Earth Science Enterprise missions. However, based on the available infomlation, the task group found that (1) the cost of Triana is not out of line for a relatively small mission that explores a new Earth observing perspective and provides unique data; (2) since a significant fraction of the Triana funds (according to NASA and the Triana principal investigator, 50 percent of total funding and 90 percent of instrument development money) have already been expended, weighing cost issues would lead to only limited opportunities to save or transfer funds to other projects. In addition, the task group endorsesthe statementby

3 Congressthat the delay in the mission mandatedto produce this report may mean additional costs. The task gt.oup emphasizesthat the attacheddiscussion of the ability of Triana to achieve the mission's stated goals and objectives is predicated on the assumption that the instruments and sa,tellitehave been, and will continue to be, subject to all necessaryand appropriate exploratory-mission technical and quality control reviews. Under no circumstances should this report or the statementscontained in it be used as a replacementfor these technical evaluations. Sincerely, Mark Abbott Acting Chair, Space Studies Board v Eric~J. Barron Raymond Jeanloz Chilir, Board on Atmospheric Chair, Board on Earth Sci,~nces and Climate Sciences and Resources

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