Multispectral imagery and broadband radiometry from a deep space Lagrange-1 orbit (L-1) offer an exciting opportunity to look at the Earth in a bulk thermodynamic sense, particularly as an open system exchanging radiative energy with the Sun and space. "The Earth as a planet" astronomers would say, as opposed to the "pixelated" Earth. This is a fundamental scientific goal with very appealing prospects for Earth sciences. The location at L-1 is also ideal to monitor the Sun and study solar weather.
Triana will have a continuous (from sunrise to sunset) and simultaneous view of the sunlit face of the Earth as it rotates beneath the spacecraft. This ability alone gives the Triana observations a capability never available from any other spacecraft or Earth observing platform in the past. Additionally, Triana will always observe from the near retro-reflection position, a unique viewing geometry. Spectral images and radiometric measurements will be made to obtain important atmospheric environmental data (e.g., ozone, UV-irradiance at the Earth‚s surface, water vapor, aerosols, cloud height, etc.) and information related to the Earth's energy balance. Triana measurements will have the advantage of synoptic context, high temporal and spatial resolution, and accurate in-flight lunar calibrations. Except for the period immediately after launch, Triana will observe from near the retro-reflection position and gain a unique piece of the Earth's energy-balance data, along with having increased sensitivity to changes on the Earth's surface.
In this document we describe the questions that can be addressed by the Triana data. We also demonstrate the value of deep-space observatories for acquiring important data not available in other ways. A few key points emphasizing the unique features of the spacecraft's L-1 view of the Earth will be presented here.