AKATSUKI RETURNS TO VENUS

MASATO NAKAMURA

VENUS AS THE MORNING STARJANUARY 1, 2016

Akatsuki is now orbiting this planet …

PLANET-C the Venus Climate Orbiter

Near IR camera 1 λ=0.9, 0.97, 1.01µm

Near IR camera 2 λ=1.65, 1.73, 2.02, 2.26, 2.32µm

Longwave IR camera λ=8-12µm

UV camera λ=283, 365nm

Lightning and Airglow cameraλ=777, 551, 558nm

Science goal : Atmospheric dynamicsLightning, Cloud physics, Active Volcano, Geological SurveyLaunch : Summer 2010Arrival : December, 2010 -> 2015

3-D meteorological observation by multi-wavelength cameras

Near-IR UV

LaunchMay 21st 2010 6:58:22JST

7:25Spacecraft separation

Start of Occultation 08:50:43JST

End of Occultation09:12:03JSTNo telemetry

2010/12/7Nominal case： 9:01:00JST OME stop Actually 8:51:38JST

OME start2010/12/7. 08:49JST

Orbit Plan

10:26JST Spacecraft was discovered

5

Failure of VOI on December 7th, 2010

Venus

Broken OME（500N)

RCS (23N x８)thrust

Reaction Control System should be used for orbital maneuver instead of broken OME

7

ORBITAL MANEUVER（2011-2015）

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

Venus

Earth

Akatsuki

AkatsukiEvents

EarthEvents

VenusEvents

AkatsukidV

EarthdV

VenusdV

J2000Eclipticcoordinate

x108km

太陽

あかつき

金星

地球

2015/12月2015/1/1

2015/2月

2015/5月 2015/7月

2015/8月2015/1/1DV4(2015/7月)

近日点(2015/2月,8月)

遠日点(2015/5月,12月)VOI-R(2015/12月)

2015/1/1

2015/2月

2015/5月

2015/8月

2015/7月

DV42015/07 ΔV 89m/s

Last perihelion 2015/8/30

• Orbital maneuver （DV1-3）was done in 2011 to meet VENUS on 22 November, 2015• Orbit analysis revealed that the spacecraft would crash with Venus very shortly• July 2015 additional maneuvers (DV4-1,2,3) was done to correct the orbit to meet

Venus on 7 December, 2015

3

VOI-R1Geometry(Suncenter)

0.55�����

Venus

Akatsuki

EarthdV

AkatsukidV

VenusdV

Venus1daystep

Akatsuki1daystep

J2000Eclipticcoordinate

x108km

-2

-1

0

1

2

�� �� � � �

Earth

Akatsuki

Venus

EarthdV

AkatsukidV

VenusdV

J2000Eclipticcoordinate

x108km

Sun

EarthNov9,2015

Planet-C

Venus

Dec7,2015

Nov9,2015

Dec7,2015VOI-R1

Dec7,2015VOI-R1

Dec1,2015

[Suncentered]

Dec6,2015

AttitudechangeforVOI-R1

Red:Venus,Green:Planet-CTicks:everyoneday

VOI-R1 ON 7 DECEMBER, 2015

Doppler monitor

10

First light

SUMMARY

11AKATSUKI returns to Venus，Nakamura et al., submitted to Earth, Planets and Space, 2016

• Akatsuki becomes the 1st Japanese probe orbiting other planet 15 years after the proposal to ISAS.

• All the sub systems are working almost perfectly.

• Akatsuki will send data over two years to us, and it means that Japan’s exploration enters the new era when Japan deliver the continuously changing planet’s data to the world.