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 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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