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JAXA’s Venus Climate Orbiter (PLANET-C) overview
Launch: Jun 2010Arrival: Dec 2010Mission life: 2 years
Venus and Earth
• They have almost the same size and mass.• Surface environments are completely different.
(Venus’ environment: CO2 atmosphere, no ocean, 92bar, 740K, H2SO4 cloud ..)
• What differentiated these planets? How does the climate system work under different conditions?
Science goals
• Atmospheric dynamics– Mechanism of super-rotation– Meridional circulation– Meso-scale processes– Lightning– Cloud physics
• Detection of active volcanism• Inhomogeneity of surface material• Zodiacal light
Planetary wave
Baroclinic instability Tropical cyclones
Cloud crusterInertio gravity wave
Cumulus convectionGravity wave
Boundary layer
Boundary layer turbulence
Climate change
Wave breaking
Hierarchy of Earth’s meteorology
Interaction
1sec 10min 1hr 6hr 2d 20d 1yr 10yr
Macro
Meso
Micro
104 km
103 km
102 km
10 km
1 km
100 m
10 m
Hierarchy of Venus’ meteorology1sec 10min 1hr 6hr 2d 20d 1yr 10yr
Macro
Meso
Micro
104 km
103 km
102 km
10 km
1 km
100 m
10 m
?Super-rotation
???????Upscale cascade to super-rotation?
Forbes (2002)
Concept of meteorological satellite
• Monitoring global structure Wide field of view (12o)
• Covering wide-range of time scalesContinuous, systematic sampling
(every 2 hours)• Local time coverage
Equatorial orbit• Meso-scales / Wind vectors
High spatial resolution (~10 km)
SpacecraftMass 480 kg
(including fuel)Science payload 34 kgAttitude control
Pointing accuracy 0.1o
Stability 0.01o
OribitPeriapsis 300km
Apoapsis 13 RvPeriod 30 hours
12o FOV
Science instruments (1)1-μm camera (IR1) by Tokyo U.
λ= 1.01 μm (near-IR window)Pixels: 1024x1024, Detector: Si-CSD/CCD
Cloud (day/night)Active volcanism / surface emissivity (night)
2-μm camera (IR2) by Kumamoto U. λ= 1.73, 2.26, 2.32 μm (near-IR window), 2.02 μm (CO2 absorption), 1.65 μm (zodiacal light) Pixels: 1024x1024, Detector: PtSi
Cloud / Particle size Carbon monooxide (night) Cloud top height (day) Zodiacal light (cruising) Galileo (2.3μm)
Science instruments (2)UV imager (UVI) by Hokkaido U.
λ= 283, 365 nm Pixels: 1024x1024, Detector: SiCCD SO2 / Unknown UV absorber (day)Longwave IR camera (LIR) by Inst. of Polar Res. λ= 8-12 μm Pixels: 240x320, Detector: uncooled bolometer Cloud top temperature (day/night)Lightning and Airglow camera (LAC) by Tohoku U. λ= 777, 551, 553, 558, 630 nm Pixels: 8x8, Detector: APD (50kHz sampling) Lightning (night) O2 /O airglow (night)
Spacecraft motion
To the earth
Atmosphere
X-band beacon
Science instruments (3)Sensor Digital Electronics unit (DE) by JAXA
Controlling observation sequence of camerasOnboard calibrationJPEG2000 data compression
Ultra-stable oscillator (Radio science) by JAXA~10-13, provided by Timetech Co.
Temperature profilesH2SO4 vapor profileIonosphere
Usuda deep space center
1-μm camera
2-μm camera
Longwave IR camera
Lightning and airglow camera
Ultraviolet imager
0 50 100velocity (m s-1)
(km)100
80
60
40
20
0
Cloud layer
Sounding regionR
adio occultation
CO
(Near-IR
)Low
er cloud (Near-IR
)
Airglow
(Visible)
SO
/Unknow
n absorber (UV
)
Cloud top tem
perature (IR)
2
CO
absorption (Near-IR
) 2
Lightning
Surface (N
ear-IR)
Unknown momentum transport
Altitude coverage
Observation sequence in each revolution300km x 13 RVenusPeriod: 30 hoursInclination: 172 deg Global images of
atmosphere and ground surface (~24 hours)
Close-up images / Lightning / Airglow (~3 hours x 2)
Limb images (~1 hour)
Resolution: 10-20 km
Resolution: 1-10 kmResolution: 0.2-1 km
Temperature/H2SO4vapor by radio occultation
Orbital motion roughly synchronized with the super-rotational flow near the cloud base
60 m/s westward flow near the cloud base
Spacecraft
100-300 km
Movement with time
Derivation of cloud motion vectors every 2 hours
Cloud tracked winds on the Earth
Accurate derivation of eddy motions embedded in the background super-rotation
0 km
50 km
35-50 km
100 km
65 km
NightsideDayside
SO2 / Unknown absorber (UVI)
Cloud top temperature(LIR)
Lower clouds (IR1) Carbon monooxide
(IR2)
TemperatureH2SO4 vapor (RS)
Cloud motion vectors
Airglow (LAC)
Lightning (LAC)Active volcanism / Surface material (IR1)
Cloud top height (IR2)
3-D global meteorological data
Lower clouds (IR1/IR2)
• Search for hot lava by taking global pictures at 1.01μm several times per orbit
• Emissivity distribution of the ground surface
• Cloud feature is distinguished from surface feature by taking motion pictures and using 1.7μm and 2.3μm images which reflect cloud feature but not the surface feature.
Optical sounding of ground surface
Schedule2004 Proto Model (Phase-B) start2006 Flight Model design/manufacturing start2009 Final integration test2010 Launch / Arrival at Venus
IR2 test modelM-V rocket of JAXA