Miniature Gps Receiver

ISTS 2006-keynote-04v

OVERVIEW AND IN-ORBIT RESULTS OF SMALL SCIENTIFIC SATELLITE “INDEX”

Hirobumi Saito Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan e-mail Koubun@isas.jaxa.jp / [email protected] Takahide Mizuno, Koji Tanaka, Yoshitsugu Sone, Seisuke Fukuda, Shin-ichiro Sakai, Nobukatsu Okuizumi, Makoto Mita, Yosuke Fukushima, Masafumi Hirahara*, Kazushi Asamura, Takeshi Sakanoi**, Akira Miura, Toshinori Ikenaga, and Yasunari Masumoto Japan Aerospace Exploration Agency, Japan *Rikkyo University, Japan , **Tohoku University, Japan

1 SUMMRY & CONTENTS

1. DEVELOPMENT of INDEX (REIMEI) SAT 72kg, 3 AXIS CONTROL, $4M + our salary. 2. LAUNCH at 2005 Aug & FINE at Now 3. IN-ORBIT PERFORMANCE 0.05deg 3Axis Control, 160W, 131kbps Aurora Science 4． CONCLUSIONS

2 Outline of INDEX (REIMEI)

Size 72 x 62 x 62cm3 Mass 72 kg Power 160W (MAX) Engineering Technology Mission Validation Science Aurora Mission Observation

3 Outline of INDEX (REIMEI) Contd.

Attitude Control - Three-Axis Controlled w/ Bias-Momentum - Magnetic Control - Accuracy : 0.05deg Launch Vehicle Dnepr Rocket Launch Date 2005/8/24, from Baikonur Orbit Near Sun Synchronous (608 x 655 km) Mission Life One Year Passed Cost $ ４ million + our salary 4 Launch By DNEPR ROCKET at 2005 AUG

z Converted From ICBM “SS-18” z Launched From Under-Ground Silo

INDEX is installed under OICETS

Config. in Space Head Module

5 Operation / Ground Station

ISAS/JAXA Sagamihara Campus Station • The station has an antenna of 3 meter in diameter on the roof of the main building. • Downlink: 131kbps* / Uplink: 1kbps • Orbit determination is based on: – one-way doppler – TLE information – onboard GPS receiver (mission) • The REIMEI operation team consists of young researchers, engineers, and students. Most operation software and tools are developed by themselves and a venture software house. >> Flexible operation!!!

*The onboard S-band transmitter (STX) is in the high-power mode. The mode is limitedly used when the satellite face6s a critical situation. Aurora Observation

Multi-spectral Auroral Camera (MAC) Scientific Objectives - high time and high spatial resolutions, - at three different wavelengths.

Targets of Auroral Emissions + ※ -N2 1st Negative Band : 427.8nm（ Δ=2.5nm） - OI Green line : 557.7nm（Δ=1.6nm）

-N2 1st Positive Band : 670nm（Δ=38nm） ※Δfull width half maximum

Instrumental Parameters - Channel number : 3 - Objective Lenses : f = 50mm, F/1.5 - CCD : 1024×1024pixels, interline binning 16x16, 8x8, 2x2 pix. - Field-of-view : 7.6° - Weight : 4580 g 7 - Power : 11W(1ch), 13W(2ch), 15W(3ch) REIMEI TAKES MOVIE OF DYNAMIC AURORA

Case A. 2005/12/22

N2 Blue OI Green N2 Red 105km 120km 105km 130km

8 動画が再生しないときは画像をクリック AURORA ELECTRON MESUREMENT Descending Electrons Induce Dynamic Aurora

Auroral Intensities at footprint Dec. 22, 2005

N2+(428nm) O(558nm) N2(670nm)

100

) 60 kR (

y t i 40 ns e Int 20

0 UT 09:31:44-09:32:55 Tota31l. 6E66ner7 31.gy8333 Flu32x D32e.1c6.6 72322.,33 23300325.5 32.6667 32.8333 33 -20 UT min (09:31) Down )

3Estr +12 Electron x / u 2 l Downward E flux F m

2E+12 c

Perp y / g r c e

1Ese +12 / En

Up V e

( 0 9 09:31:3031.5 31. 7 31. 09:32:008 32 32.232.309:32:3032.532. 7 3 2. 809:33:033 0

UT ATTITUDE CONTROL SYSTEM

Actuators MW MPC Max. ang. Mom 1.0 [Nms] x 1 MTQ Zarm Linear dipole > 6.0 [Am2] x 3 Sensors FOV 30 x 40 [deg] STT NTS x 1 Random Noise < 3 [a-min] (3σ) Mass 140g (1 axis) Bias Stability 3 [deg/h] spec. x 3 0.1[deg/h] temp. cntl FOG JAE 3/2 σu 6.4E-4 [a-sec/s ] σ 2.5 [a-sec/s1/2] v x 1 Type Consumer products NSAS NTS Accuracy < 0.05 [deg] x 1

SSAS MEC Accuracy < 0.3 [deg] x 101 GAS MEDA Range +/- 1000 [mG] x 1 FIBER OPTICAL GYRO with TEMPERATURE CONTROL • Commercial FOG 140 g x 3 • Temperature Control Enhances Bias Rate Stability to 0.06deg/h(1h).

(

)

Temperature Control of FOG Allan Deviation of FOG at Constant Temperature11 Fine 3 Axis Attitude Control with RWx1+3MTQ

– Pointing Accuracy ±0.05[deg] （3 arcmin)

MTQ axis

RW axis

12 Triple – Voting CPU

• SEU - Robust CPU System CPU

by Triple – Voting DataOUT RadH ard CPU VOTER

• Possible to Use CPU Cutting – Edged Commercial CPU • HITACHI SH – 3 Triple Voting CPU

13 Solar-Concentrated Paddle

Sunlight 84 W/kg Reflector 130℃

14 46 W/kg Solar Array 100℃ Solar Concentrator In-Orbit Solar Concentration Ratio = 1.2～1.25 Generating Power = 160W

Ground Test of Ⅰ-Ⅴ Curve In – Orbit Power Generation

4 6

without Reflector 5

with Reflector ) A (

3 t 4 n rre ]

A 3 [ Cu ent 2 SAP 2 r r u

C 1

1 0 -50 0 50 SUN ANGLE (deg)

0 Predicted Value (without Reflector) 0 10 20 30 40 50 Predicted Value (with Reflector) Volts Measured Value in Orbit(with Reflector)

15 Laminated Li-Ion Battery– Potting

Commercial Laminated Li-Ion Cell are Potted for Vaccum.

Unit Cell Potted Cells BBM Potted by Epoxy

Vacuum Cycle Test on Ground Verifies More Than One Year Life in Orbit.

16 MINIATURE GPS RECEIVER

• Modified from JRC Automobile Receiver • Search Frequency Expanded, ±17kHz → ±57kHz ( Doppler Freq.) • Very Small ( Receiver 10g , 232g including with Hybrid ) • Accuracy 3m without Ionospheric Effect • Cold Start within 25 min FM-GPS Receiver + RF Hybrid • 20krad Radiation Tolerance

• SEL Free ( 200MeV Proton ) Cu m u lat iv e pr o bab ili t y o f T TFF 16 14 測位誤差[m] 1. 2 12 PDOP 1 y

10 ilit b 0. 8 a b o 8 r P

e 0. 6 iv t a

6 l u m 0. 4 4 Cu C a lc u lat e d V al u e 2 0. 2 Si m u lat io n s 測位誤差[m] ＆ PDOP 0 0 00.511.52 1 3 5 7 9 11 1315 1719 212325 2729 3133 353739 41 Time[hour] TT FF [ m in ] 17 Position Error Cold Start Time RANDOM NOISE OF GPS IN ORBIT

SHORT TERM GPS ORBIT DETERMINATION – GPS POSITION = less than 1 m

1.2

g n i 1 on i t i s 0.8 po

S [m] 0.6 P G

of 0.4 on i 0.2 at i r a

V 0 4:06:20 4:06:30 4:06:40 4:06:50 4:07:00 4:07:10 4:07:20 4:07:30 UTC [hh:mm:ss]

Fig. 9 Difference between GPS Positioning and Orbit Determination based on One Minute GPS Data 18 GPS COLD START TIME < 25 minutes

IN ORBIT DATA SIMULATION DATA

Cumulative probability of TTFF

1.2

1 1 0.9 y it il 0.8 0.8 b a b o r

0.7y P

e 0.6 ilit v

0.6 i t b a l a 0.5 u b m u o 0.4 r 0.4 C

P Calculated Value 0.3 Simulations 0.2 0.2 0.1 0 0 1357911131517192123252729313335373941 0 5 10 15 20 25 30 TTFF[min] 19 TTFF（minute） Conclusion

・ REIMEI (72kg, ３Ａｘｉｓ，$4M) was developed & launched at 2005 Aug by Dnepr.

・ All REIMEI Instruments are Perfect in Orbit. – Aurora Science (to be submitted to “Nature”) – Attitude Control…0.05deg Accuracy – Miniature Instruments (Processor, GPS, FOG)