Observation principles

Submillimeter-wave limb-emission sounding

The International Space Station (ISS) orbits at an altitude of 350 to 400 km above the ground and completes a single earth orbit in about 90 minutes. It is a non-sunsynchronous orbit with an inclination angle of 51.6°. SMILES, that is installed on the Exposed Facility(EF) in the Japanese Experiment Module "KIBO", observes limb of the atmosphere about 2,000km ahead from ISS.

SMILES is a highly sensitive receiver with superconducting technology. SMILES detects thermal emission from the atmosphere in the submillimeter-wave region, and allows us to know the quantity of chemical substances contained in the atmosphere. The observation geometory is limb. Therefore, the instrument is called a "superconducting submillimeter-wave limb-emission sounder".

The antenna FOV is about 3 km in a vertical scale at tangent point. SMILES scans the antenna from -30 km to 120 km with a time period of 53 seconds, and obtains the emission signal from chemical substances at the several height in the atmosphere.

smiles-limb


SMILES observation coverage of Earth's atmospehre

SMILES observes about 1,630 observation points per day over the Earth, and produce a global map everyday for each compositions. The latitudinal range of the observation covers from 65 degree north to 38 degree south, which depends on the ISS altitude.

Latitude range


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