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