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Experiment/Payload Overview

Information provided courtesy of the Japan Aerospace and Exploration Agency (JAXA).
Brief Summary

SMILES is aimed at global mappings of stratospheric trace gases by means of the most sensitive submillimeter receiver. Although SMILES has stopped atmospheric observation due to instrumental failures since April 2010, high sensitive data obtained for a half year will provide accurate global datasets of atmospheric minor constituents related to ozone chemistry. SMILES is still continuing operations for instrumental calibration and cooling of mechanical cooler, as well as brush-up of retrieval algorithms for atmospheric constituents.

Principal Investigator

Masato Shiotani, , Kyoto University, Kyoto, , Japan

Co-Investigator(s)/Collaborator(s)

Masahiro Takayanagi, , , , , Japan

Payload Developer

Japan Aerospace Exploration Agency, Tsukuba, Ibaraki, Japan

Sponsoring Space Agency

Japan Aerospace Exploration Agency (JAXA)

Sponsoring Organization:

Information Pending

ISS Expedition Duration:

March 2009 - October 2013

Expeditions Assigned

19/20, 21/22, 23/24, 25/26, 27/28, 29/30, 31/32, 33/34, 35/36

Previous ISS Missions

UARS/MLS(1991) is the first satellite mission for Microwave Limb Emission. Odin/SMR(2001) is the first Sub-millimeter-wave Radiometer. SMILES is the first super-conductive sensor.

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Experiment/Payload Description

Research Summary

• The main scientific target of the SMILES mission is to evaluate quantitatively the recovery and stability of the stratospheric ozone layer. There are still considerable uncertainties in factors affecting ozone levels. There is a need for a detailed understanding of ozone chemistry based on a high sensitive observation.



• SMILES will demonstrate its high potential to observe atmospheric minor constituents which contribute the ozone destraction in the middle atmosphere.



• The unprecedented high sensitive observation by SMILES will provide accurate global datasets of ozone-depletion gas concentrations. It will provide important insights into the ozone trend. Especially, chroline and bromine compounds related to ozone chemistry will be determined quantitatively.

Description

SMILES (Superconducting Submillimeter-Wave Limb-Emission Sounder) is a sensitive submillimeter-wave sounder. The objective of SMILES is to monitor global distributions of the stratshperic trace gases which contribute ozone depletion. SMILES is the first to use a superconductive low-noise receiver with a mechanical 4-K refrigerator in space to realize a high sensitive observation.

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Applications

Space Applications

The technologies of the cryogenic system used in SMILES will be taken over by future space science programs.

Earth Applications

The high sensitive observations of SMILES will gain a better understanding of processes controlling the stratospheric ozone chemistry and those related to climate change.

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Operations

Operational Requirements

SMILES will perform cooling operation and instrumental calibration operaion. For the cooling operation, low-rate downlink will be used, and will be performed four times in 2011, each of the operations will take a few weeks. For the instrumental calibration operation, both low- and medium-rate downlink will be used.

Operational Protocols

For the cooling operation, two mechanical cryocoolers are operated. The operation procedures will be adjusted aiming to achieve a cryogenic temperature of about 4 Kelvin. For the instrumental calibration operation, subsystems related to a signal chain are powered on. The internal calibration signals are generated to investigate the response of the subsystems.

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Results/More Information

SMILES has performed atmospheric observation for a half year, from October 2009 to April 2010. After the cryocooler failure occurred at June 2010, 14-times cooling operations have been performed. Although the analysis of the atmospheric data is still continuing, we have derived some preliminary results to date. The profiles and horizontal distributions of ozone and HCl are reasonable. Even for those species with weak signals, such as BrO and HO2, we can get promising results, even for a single scan. Averaging, such as daily zonal means, will produce scientifically useful signal-to-noise ratios for these species. We have shown the capability of obtaining high-quality scientific data that will be important to addressing scientific issues such as the ozone trend problem, middle atmosphere chemistry with a special focus on the diurnal cycle, and the transport process of minor species. These outcomes from SMILES will demonstrate the high potential to observe atmospheric minor constituents in the middle atmosphere. And the knowledges obtained through the cooling operations will provide useful informations for future cryogenic missions

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Related Web Sites

JEM SMILES

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Publications

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Ground Based Results Publications

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ISS Patent Publications

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Related Publications

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Images

SMILES. Image courtesy of JAXA.

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On January 23, 2010, SMILES observed destruction of the ozone layer at an altitude of 22 kilometers. Utilizing its high sensitivity, SMILES not only observes ozone depletion (shown in fi gure 1) but also captures changes in chlorine compound levels over a single day (the increase shown in fi gure 2 and the decrease shown in figure 3).

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