Hayabusa LIDAR

LIDAR in HAYABUSA Mission

Takahide MizunoInstitute of Space and Astronautical Science JAXA

Katsuhiko Tsuno, Eisuke OkumuraNEC Toshiba Space Systems Ltd.

Michio NakayamaToshiba Corporation

•Outline of HAYABUSA Mission•How to use LIDAR?•LIDAR System & components•Lessons Learned•Ranging Data at Touchdown•Conclusion

Agenda

Hayabusa LIDAR

HAYABUSA Objectives

Hayabusa LIDAR

HAYABUSA is Spacecraft to demonstrate following technologyand to observe small asteroid Itokawa.

- Operation of Ion Engines for more than - Earth Gravity Assist with Ion Engines- Rendezvous with Itokawa with Autonomous Navigation- Scientific Observation of Itokawa- Touch-down and Sample Collection- Return and Recovery of Capsule

HAYABUSA Today

Hayabusa LIDAR

LaunchedMay 9, 2003

Earth SwingbyMay 19, 2004

Arrival at ItokawaSeptember 12, 2005

First touchdownNovember 19, 2005

Second TouchdownNovember 25, 2005

Preparation to return voyageNow

Spacecraft Trajectory

GP (Gate Position) AcquisitionGlobal Mapping, Remote SensingGravity and Solar radiation Estimation,

HP(Home Position) Keeping Remote SensingDetailed Global Mapping,

Earth Direction

Approach by RCS

～7km

～20km

X

Rendezvous and Landing Sequence

50km

50m

50,000km

R&RR

R&RR + ONC + LIDAR

R&RR + ONC

R&RR + ONC + LRF

Δ=2000km

Δ=2～3 km

Δ=～6 mSignal Level60dB

Hayabusa LIDAR

Telescopic Camera (ONC-T)

ISAS Robot Lander MINERVA

Sample Collector Horn

Laser Range Finder

Solar Array Panel Target MarkerX-ray FluorescentSpectrometer

Wide-angle Camera (ONC-W1)

Fan Beam Sensor (one of four)

Near Infrared Spectrometer

LIDAR

Medium Gain Antenna

Start Tracker (STT)Sample Recovery Capsule

Bottom Panel View of HAYABUSA

Hayabusa LIDAR

240mm×228mm×250mmRadiator: 240mm×300mm

Size

17.0W (+LD Heater max5W) Power

3.7kgInclude: DC/DC, Radiator

Weight

Q-SW, Nd:Cr:YAG1064 nm8 mJ14 nsecφ1.7 mrad（1/e2）

φ1 mradCasegren φ126 mm、SiC

LaserWave lengthOutput PowerPulse WidthTX Beam WidthRX FOVRX Optics

50m～50km±1m(@50m) 1Hz

RangeAccuracyRepetition Rate

Specification Items

HAYABUSA LIDAR

Hayabusa LIDAR

Laser Transmitter

BandpassFilter

APD

Gain Control

Pre-Amplifier

ReceiverElectronics

Receiver Optics

Primary Optics(Receiving Optics)Primary Optics

(Receiving Optics)

Diode Pumped Nd:YAG Laser

Power SupplyTransmitterElectronics

Laser Beam

Detector and Digital Controller

APDPre-Amplifier

Transmitting OpticsTransmitting Optics

Block Diagram of LIDAR

Digital CounterCLK: 75MHz

DigitalController

Resolution 1m

Hayabusa LIDAR

OUTPUT DATA (to AOCU)RANGE and STATUS (Valid/Invalid)SIGNAL LEVEL (TX/RX Level Monitor)STATUS (MODE, GAIN, etc)

AOCURS422

RX Casegren Telescope

Main Reflector Truss Sub Reflector

Surface Irregularity 0.18μmP-V

FOV: 1mradSiC: Small Thermal Expansion

Hayabusa LIDAR

YAG Laser Resonator

Pumping PeriodQ Switch Open

LiNbO3

Nd:Cr:YAG Rod

Laser Beam

Trapezoid Prism Output Mirror

PolarizerLaser Diode

Porro Prism

Wedge Plate Wave Plate

Hayabusa LIDAR

- Single Mode Q-Switched Diode Pumped Nd:YAG- LD is thermally controlled between 30 and 35 degrees by thermostat

to tune LD wave length to the absorption line.-Some protective windows are installed to avoid radiation damagedue to contaminations.

- Pockels Cell is driven by 2.7kV high voltage driver. - Output Laser is expanded by expander with magnification of 3.

Lessons Learned

•Deterioration of LD•Damaged by contamination•LiNbO3•Thermal Vacuum test

Hayabusa LIDAR

Stability of On Board Counter- Range Error of LIDAR 1-

-5

-4

-3

-2

-1

0

1

2

3

4

5

10 100 1000 10000 100000

Range of Delay Pulse Generator [m]

Err

or

[m]

Accuracy 300ps

50m 50km

Hayabusa LIDAR

Signal Level Dependency- Range Error of LIDAR 2 -

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7 8 9 10

RX Level (0～255)

Range (

m)

42m

Fixed Length Optical Fiber

Hayabusa LIDAR

From Tracking Radar to 20m Antenna

Field Experiment with PM at UchinouraOct. 2001

1.93323Edge of Sub Reflector

1.53313Edge of Main Reflector

σ (m)Measured Range (m)Target

20mΦ Antenna

Tracking Radar Site

Laser Light from LIDAR

Hayabusa LIDAR

LIDAR First Light

0

10000

20000

30000

40000

50000

60000

70000

09/10 00:00:00 09/10 12:00:00 09/11 00:00:00 09/11 12:00:00 09/12 00:00:00 09/12 12:00:00

Date and Time(UST)

Ran

ge (

m)

0

5

10

15

20

25

30

35

40

RX

LEV

EL (

count)

TX level

9/10 4:26:2648602m

9/10 5:55:1847182m

9/10 6:07:5146970m

Gate Position

48.6km

GP

RX Signal Level

30cm/sec

Hayabusa LIDAR

Ranging Result at First Landing R

ange

(m)

Universal Time

19 Nov. 2005

RX

Lev

el

Hayabusa LIDAR

LIDAR Operation History

0

10000

20000

30000

40000

50000

60000

7000009/05

09/15

09/25

10/05

10/15

10/25

11/04

11/14

11/24

12/04

TIME

RA

NG

E(m

)

-12.5

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

RETU

RN

SIG

NA

L(V

)

RANGERETURN SIGNAL

1st Touch down

2st Touch down

1st Approach

2nd and 3rd ApproachArrival

Hayabusa LIDAR

188.6188.5

42.943.3

Calculation from shadow (m)

38.539.9

LIDAR Range (m)

Good agreement!

Calibration with shadow of HAYABUSA

No Range Bias.

Hayabusa LIDAR

Measurement of ITOKAWA Surface

Hayabusa LIDAR

-Tukuba boulder with 3-4m heightwas identified

-A possible rock fissure was also identified

- Rough Terrain: Surface roughnessnear Tsukuba Boulder: 2.2m

- Smooth Terrain: Surface roughness in the Muses Sea: 0.6m

Gravity (Mass) Estimation of ITOKAWA=> Science June 2 2006

Conclusion

-Three month LIDAR operation is successfully performedwith 4.1 million laser shot.

- No Laser power degradation was observed.-HAYABUSA had successfully rendezvoused with ITOKAWA

by LIDAR data.-HAYABUSA had successfully touchdown based on its navigation sensor including LIDAR.

-LIDAR detected the range from 50km to 30m.-LIDAR data will provide important surface information of ITOKAWA

Hayabusa LIDAR