SMILES

情報通信研究機構

Superconducting Submillimeter-waveLimb-emission Sounder

Mission Objectives
Space demonstration of asubmillimeter sensor technology
based on a superconductive
mixer and 4-Kelvin mechanicalcoolerExperiments of submillimeter limbemission sounding of theatmosphere
Global observation of trace gases inthe stratosphere andcontribution to the atmosphericsciences

Specifications
Observation Band:

640GHzBand

Target Gases:

O3, HCl, ClO, HO2, H2O2,

Altitude Range:

HOCl, BrO, HNO3, SO2,etc.
10 – 60 km

Latitude Range:
65N – 38S
Instruments:
Offset Cassegrain Antenna
SIS Mixer Receiver
4-Kelvin Mechanical Cooler
Acousto-optical Spectrometer
Frequency Resolution:
Sensitivity:

1.8 MHz

1 K(rms) in a single scan

Submillimeter-Wave Sensor Operated
at 4K in the shielded cryostat
SMILES instruments are protected against the ISS environmental electric field by
payload panels designed as an electric shield (shielding of 14 dB). Cryo-electronics unit,
which deals with signal at lowest power levels, are shielded more by the cryostat(shielding of 40 dB).

SIS: Superconductor-Insulator-Superconductor
hf/kReceiver Noise Temp. [K]10000SIS[4K]

SMILES 640GHz SIS Recieverin the shielded cryostat

SBD[300K]

1000

1001010200400600
Frequency [GHz]800

Superconductive SIS mixer receivers
have some 20 times higher sensitivity(lower noise) than conventional
Schottky-barrier-diode (SBD) mixer
receivers for frequencies less than 700
GHz. Sensitivity will be limited by thequantum limited noise (hf/k).

1000

Cooler & Cryostat (PFM)
Mixer & HEMT (EM)Stirling: 60-80 W (AC 15 Hz)
J-T Cooler:

30-37 W (AC 30 Hz)

High-Quality AtmosphericSpectroscopy
Band-A

Acousto-Optical
Spectrometer (AOS)

Band-B
SMILES is equipped with two units ofAOS, each has 1,500 channels over 1,200
MHz. This enables detection of more than
20 species involved in the atmosphericspectra.

Band-C

Molecular emissions in three
RF bands of SMILES
Emission intensity is dependent on thealtitude of the line-of-sight. This is shownwith spectra of different colors fordifferent altitudes. Species attributing eachpeak can be found by a dot in the lower
panel and its associated number.

Input Frequency :1.55 – 2.75 GHz
Frequency Resolution: 1.8 MHz (FWHM)
Channel Spacing:
0.8 MHz / channel
Unit Averaging Period: 0.47 sec

Principle of AOS: Radio signal, which
carries the atmospheric spectra, isconverted to acoustic waves in the Bragg
cell. It will deflect the incident light withangles depending on the input radio
frequency. The radio spectra are thus
converted to a linear image on a CCD.

Global Data of Trace Gases
with High Resolution
Global Coverage

The Arctic Region
Sampled in 24 Hours

Covered Latitudes
68N – 35S (ISS Yaw: +15 deg)
65N – 38S (ISS Yaw: 0 deg)
61N – 42S (ISS Yaw: −15 deg)

Trajectory for 24 Hours
Blue: ISS-SMILES Orbit
Red Dots: Sampled AreaMajor Species of SMILES
Expected altitude profile of the volume-mixing-ratio is shownfor nine major SMILES species according to a typical midlatitude model atmosphere (45N).
VMR
canSe
glSin

Averaged

Expected Resolution of SMILES Data
Upper Right: For a single scan data available in each 53 seconds
Lower Right: For a zonal averaged data available in each day

Resolution in VMR