Review of Scientific Aspects of the NASA Triana Mission Letter Report (2000) / Chapter Skim
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Review of Scientific Aspects of the NASA Triana Mission
Review of Scientific Aspects of the NASA Triana Mission
Pages 4-22
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From page 4... ...
Prior to this meeting, it held two teleconferences to discuss the charge to the task group and plans for the meeting, and it also reviewed all relevant NRC reports, relevant government reports, and background materials.4 On the fIrst day of the meeting, the task group received presentations from NASA 's Triana s<:ience team, among others.5These presentationsdiscussedthe technical aspectsof the mission, including the science goals and objectives, data products, and instrument specifications and included a variety of opinions regarding the mission. One presenter made a number of recommendationsto improve the sciencereturn from the mission, includin~~significant redesign of the mission, as well as changesin the science team and data analysis efforts.
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From page 5... ...
In addition to Earth-viewing instruments, Triana includes an instrument package designed to meaS1JIe solar wind and the interplanetary magnetic field at L 1. Based on these observations Triana, during its limited lifetime, could provide early warning (about 1 hour)
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From page 6... ...
The size of the array, 2048 by 2048 pixels, coupled with the Cassegrain telescope of 30.5-cm aperture and 282-cm focal length (f9.38) ,8rovides a nominal spatial resolution of about 8 bl8 km for pixels viewed at nadir, yielding a groundprojected pixel area of 64 km .When observationsapproach the edge of the Earth disk, the effective pixel :;ize grows and the pixel changesshapeas Earth's surface tilts away from the instrument.
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From page 7... ...
Stabilities are unknown, but NIST reported that it has made efforts in the design ofNISTAR to minimize drift and to monitor in-flight the I3 An active cavity radiometer makes accurate measurementsof optical power by comparing it with equivalent electrical power at constant temperature when a shutter successively exposes and blocks the source of radiation. The active cavities respond to the electromagnetic spectrum from 0.2 to 100 ~, and thus to solar radiation Ihat Earth reflects and to longer wavelength radiation that Earth emits.
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From page 8... ...
Whipple, and A Korth, "Hydra -A 3.Dimensional Electron and Ion Hot Plasma Instrument for the Polar Spacecraft of the GGS Mission," Space Science Reviews 71(1/4)
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From page 9... ...
The orbit also changesshapeon a 4-year cycle such that the initial 4° divergence of view point expclndsto 15° through the cycle. Thus, Triana's EPIC and NISTAR instruments will view Earth from a direction that diverges from th~ direction of the Sun's illumination by an angle of 4 to 15°.19 The near-coincidence of view and illumination direction hcLS important implications for thlealgorithms that transform EPIC radiancesand NISTAR irradiances into geophysical data products.
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From page 10... ...
Data Processing and Distribution Triana's primary data products, as reported by the Triana scienceteam, are shown in Table 2. Some of the data products will require both Triana data and ancillary data from other sources,such as ground-basedinstruments or other satellites.
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From page 11... ...
Seethe key below for corresponding full references. One of the ways the task group addressedthe issue of whether the Triana mission and goals are consonant with published science strategies was to compare Triana's primary data products as defined by the science team ~,ith priorities in relevant NRC and government reports.
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From page 12... ...
The goals and objectives of the Triana mission fall within two general categories: (1) to launch a modest exploratory mission to demonstratethe value of remote sensing observations from Ll for Earth scienceand (2)
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From page 13... ...
Thl~task group concluded that it would be difficult, if not impossible, to establish more refmecl estimatesof priorities among these reports. Therefore, for the primary data products listed in Table 2, the task group has noted which earlier reports have indicated that the data were desirable, but it has not attempted to establish relative priorities.
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From page 14... ...
. However, if the ACE spacecraft is lost or its plasma or magnetometer instrument fails, then Triana as the only upstream monitor of solar wind and interplanetary magnetic fields could be critical to the Space Environment Center's mission.
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From page 15... ...
EPIC The EPIC camera relies on largely proven technology, and its fabrication is not apparently a significaJlt technological challenge. According to the Triana science team, EPIC's basic CCD array techIlology has been applied in other spacebomeimagers (namely the Michelson Doppler Imager on the Solar and Heliospheric Observatory [SOHO]
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From page 16... ...
-om the NISTAR radiation measurements.Since the sunlit disk albedo measurementsplanned by NIST AR are new observables,and the derived geophysical parameters from NISTAR and EF'IC are new data products, all of which lack algorithm heritage, it is not possible yet to assess effort required to deducereliable geophysical data from these .the observations. Howeve:r, experience with similar data sets (e.g., ERBE)
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From page 17... ...
29Valero, Francisco P.J., Jay Herman, Patrick Minnis, William D Collins, Robert Sadourny, Warren Wiscombe, Dan Lubin, and Keith Ogilvie, Triana- a Deep Space Earth and Solar Observatory, NASA background report, December 1999.
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From page 18... ...
31Valero, Francisco P.J., J;ly Herman, Patrick Minnis, William D Collins, Robert Sadourny, Warren Wiscombe, Dan Lubin, and Keith Ogilvie, Triana- a Deep Space Earth and Solar Observatory, NASA background report, December 1999.
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From page 19... ...
Operational algorithms can take a long time to implement and fully test. The scientific successof the Triana mission will be judged, in large part, on the quality of the initial data delivered to the scientific community .The task group 32The instrument will observe from space the polarization, and the directional and spectral characteristics, of solar light reflected by the Eartll-atmosphere system.
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will improve EPIC data, especially aerosols, and add new imormation about cloud 33Valero, Francisco P.J., Jay Herman, Patrick Minnis, William D Collins, Robert Sadourny, Warren Wiscombe, Dan Lubin, and Keith OgiJlvie, Triana- a Deep Space Earth and Solar Observatory, NASA background report, December 1999.
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From page 21... ...
More specificlllly, the task group found that the scientific objectives and deliverable data products of the Triana mission as described by NASA's Triana science team are consonant with SCieIllCe strategies and priorities proposed by various NRC and government reports, as summarized in Table 2 of this report. The task group notes that Triana's primary focus is technique and technology development at Ll, as the Pathways report recommended for future Earth Science ~;ystemPathfinder missions, rather than anyone specific scientific problem.
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From page 22... ...
mission that explore~:a new Earth observing perspective and provides unique data; (2) since a significant fr~Lction of the Triana funds (according to NASA and the Triana principal investigatolr, 50 percent of total funding and 90 percent of instrument development money)
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