Triana - a Deep Space Earth and Solar Observatory

4.5 Data Characterization

The EPIC Level-2 data will consist of hourly frames of 4 million calibrated Earth-located radiances along with ancillary data related to the Triana orbit and Earth geometry. These ancillary data will be sufficient to derive the main science products and any additional science quantities related to the Earth‚s surface and atmosphere as well as the lunar surface. The main science products will also be available for each of the 4 million Earth radiance locations. The radiance data obtained every 15 minutes from the 443, 551, and 645 nm visible channels will also be available for science and Earth images. EPIC Level-3 data will consist of the main derived science products on a fixed latitude by longitude grid at a resolution of at least 0.5° along with false-color images suitable for animation. Each Level 2 main science-product or radiance-channel data will consist of approximately 4096*4096*12/8*24 = 0.6 Gbytes per day (~0.2 Terabytes per year per data product or radiance) plus ancillary data that could be of comparable size or larger. The data are expected to be in HDF (or other standard self-documenting format) that could add 10 to 20% overhead in size. Primary data distribution will be through a NASA DAAC and through the Scripps Science Operations Center.

Table 2 Comparison of NASA Solar Wind Missions to L-1

Triana	SOHO	ACE	WIND	Genesis
Launch in 2001	Launched 1995	Launched 1997	Launched 1994	Launch Jan. 2001
Mission:Provides real-time solar wind info. with much better time resolution than WIND or ACE*	Mission: Study the internal structure of the Sun, its extensive outer atmosphere, and the origin of the solar wind.	Mission: Determine and compare the isotopic and elemental composition of several distinct samples of matter, including the solar corona, the interplanetary medium, the local interstellar medium, and Galactic matter.	Mission: Use a changing orbit to provide complete plasma, energetic particle, and magnetic field input for magnetospheric and ionospheric studies. (No longer at L-1; operating at other orbits closer to Earth.)	Mission: Collect solar wind samples at L-1 and return to Earth.
Covers period of decreasing solar activity.	Does not measure magnetic field, which is essential for space weather and solar wind studies.	Provides real-time space weather info.**
Earth-viewing, with solar wind instrument positioned sunward to make continuous measurements	Continuous Sun-viewing	Continuous Sun-viewing	Intermittent Sun-viewing	Sun-viewing

*Triana assures the continuity of space weather data beyond the design lifetime of ACE.

** For the period that both Triana and ACE are operating, they will operate from opposite positions in the orbit around L-1, enabling comparisons and more detailed study of solar wind structure.

NISTAR data will consist of a total daylight-side Earth-radiance time series from each of the 4 channels along with ancillary data related to the viewing geometry. The one-second time resolution of the data translates as approximately 25 megabytes per day, or 9 Gbytes per year.

Plasma-Mag data will consist of time series for magnetic field, solar wind speed, and plasma energy along with ancillary data related to the spacecraft-Sun geometry. The data size is a few megabytes per day, or about 1 Gbyte per year.