The mission operational plans are determined jointly by the TES Science Team and the Flight Operations Team. At the initial phase of the mission (launch + 9 months), the plan is flexible, allowing evaluations of instrument performance and validations of the data.

TES has two basic science operating modes: Global Surveys and Special Observations. Global surveys are the routine observations that TES conducts approximately every two days, which produce "standard products." Special (Research) Observations include all other measurements, including those of validation and such events as volcano eruptions and biomass burning.

A detailed schedule will soon be made available at the Mission Schedule page. These two documents provide more details: TES Mission Plan and TES Mission Planning Requirements.

Global Surveys:

Global Surveys consist of 16 orbits of routine observations in both the nadir and limb modes, repeated about every other day. This is the source of Standard Products.

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Global Surveys are made on roughly a "one day on, one day off" cycle. The "off" periods are available for Special Observations. If no Special Observations are needed, TES rests to avoid wear and tear on the mechanical components and extend the life of the instrument. The Aura orbit repeats every 16 days (every 233 orbits), which can be divided into eight TES cycles, each of which takes about 2 days. Each cycle consists of the following measurements:

• 2 orbits of global survey pre-calibration
• 16 orbits of global survey
• 2 orbits of global survey post-calibration
• 9 orbits of special observation opportunities (except the 8th cycle, which has 10 orbits of special observations)

Except for emergencies, Global Surveys are never interrupted (e.g., by Special Operations). If a pre-planned event (e.g., a spacecraft maneuver or orbit adjustment) would interrupt a Global Survey, the survey is skipped in its entirety.

For more on TES Global Surveys, click here.

Special Observations:

Special Observations are conducted in any of 4 modes:

• Stare: In nadir mode, point at a specific latitude & longitude for up to about 4 minutes.
• Transect: In nadir mode, point at a set of contiguous areas to cover about 850 km.
• Step-&-Stare: Point at nadir for 4 seconds (5.2 seconds with necessary reset). During that time, Aura moves 39 km in its orbit, and its nadir point on Earth's surface moves 35 km. Point at nadir again. Repeat indefinitely.
• Limb only: Set of continuous trailing limb scans.

The mode used -- targeted, transect, step-and stare, or limb -- depends on the science requirement. Volcanoes, for example, would usually be targeted with the stare mode (point at the caldera and hold the view there for as long as possible). Biomass burning, on the other hand, could use any of the 4 modes depending on whether we wish to measure the fire itself or look for specific gases in the plume coming from the fire. Limb Special Observations would normally be used for intercomparison with the other AURA instruments.

For more on TES Special Observations, click here.