ITF-1 (en)

ITF-1 was launched from Tanegashima Space Center on Feb, 28, 2014. It reentered the atmosphere on Jun, 29, 2014.

ITF-1 Flight Model

Missions

1. The construction of "YUI" network

We construct the network to interact with people who have experience receiving the signal from ITF-1.

2. The demonstration of ultra small antenna

We develop a new antenna without deployment mechanism and demonstrate in space.

3. The demonstration of new microcomputer

We monitor FRAM microcomputer which has high radiation resistance, and others which have a good track performance in space.

Overview

Name

ITF-1(Imagine The Future-1)

Nickname

YUI("結")

Size

1U(110.5*108.0*111.5 mm)

Weight

1.24 kg

Frequency band

430MHz band/Morse (uplink)

430MHz, 144MHz band/F2D(DTMF) (downlink)

Height

400 km

Characteristic

Attitude control system

ITF-1 adopted the passive magnetic control method by earth magnetism. ITF-1 used a permanent magnet and a hysteresis damper.

Attitude control components

1. Permanent magnet

For a magnetic material in a magnetic field, it is worked magnetic torque along direction which a magnetic moment in a magnetic material and magnetic field are parallel. A magnetic moment of permanent magnet loaded on ITF-1 interferes with earth magnetism, and ITF-1 will be able to control attitude direction.

Overview of permanent magnet

Size

9.0 x 4.5 x 30.0 mm

Material

neodymium

Magnetization direction

30.0 mm direction

Surface fabricaion

Ni plating

Surface magnetic flux density

5070 G

Adsorption power

2.09 kg

Grade

N35

Limit temperature

150 deg C

2. Hysteresis damper

ITF-1 will receive rotation kinetic energy from orbital deployer when it will be released. The rotation kinetic energy will constitute an obstacle to attitude control and ITF-1 needs to disperse it. However, since the atmosphere around ITF-1 is very dilute, a rotation kinetic energy dissipation rate is low and it takes a long time to stabilize attitude control. Therefore, ITF-1 uses the magnetic friction effect of hysteresis damper to disperse rotation kinetic energy and reduce the time to stabilize attitude control. We load two histerisis dampers on ITF-1.

Overview of hysterisis damper

Size

1.0 x 1.0 x 70.0 mm (prism)

material

PC permalloy (themally treate

Structure system

Structure team mainly handles the design and assembling of ITF-1.

Appearance of ITF-1

Material of ITF-1

Material

A6061P-T651, A7075-T7351

Assembly of ITF-1 FM (1)

Assembly of ITF-1 FM (2)

Thermal control system

Thermal control team handles thermal analysis of ITF-1. We must prevent the temperature of all devices from exceeding limit temperature showed in following table. Thus, we analyze by method of panel point under high temperature worst condition and low temperature worst condition.

Range of limit temperature of devices in ITF-1

Name

Range[deg C]

Solar cell

-100~100

Battery

0~40

Radio module

-10~60

Main board

-20~60

Power supply board

-20~60

The result of analysis under high temperature worst condition and low temperature worst condition shows following figures. Thus, thermal design of ITF-1 covers the range of limit temperature of devices.

Result under high temperature worst condition

Result under low temperature worst condition

Power supply system

Power supply system consists of solar cells to generate electric power, battery, regulator to stabilize power supply part and power CPU to check discharge and charge. Satellite power supply bus adopts non-stabilized power supply system, in which solar cells or battery provide electric power and regulators stabilize voltage.

ITF-1 provides electric power generated by solar cells to devices and charging battery during sunshine. During shade, battery provides electric power to each devices instead.

Power supply system block diagram

Solar cell

ITF-1 has solar panels on four faces. In order to secure enough electric power, ITF-1 adopts Triple Junction GaAs solar cells which have sufficiently high efficiency of electric power generation.

Overview of Solar cell

Average efficiency

29.1%

Voltage at Pmax

2379 mV

Current at Pmax

505 mA

Maximum power(Pmax)

1.2 W

Size

40 x 80 mm

ITF-1 solar cells

Battery

ITF-1 adopts Li-ion battery. Solar cells generate electric power and charge battery during sunshine, and battery provides electric power to each devices only during shade.

ITF-1 has one Li-ion battery and stores it in battery box made of polyacetal resin to keep temperature. We design thermal condition to prevent the temperature of battery from exceeding 40 deg C and control the temperature by a heater to prevent it from falling below 0 deg C.

Power CPU

Power CPU adopts PIC16F877A. The works of Power CPU is followng below.

1. After ITF-1 will be released from orbital deployer, kill switch will be open and ITF-1 will stand ready to transmit signal for 200 seconds.
2. Power CPU monitor with Main CPU mutually. If Main CPU works abnormally, Power CPU reset Main CPU. If Abnormal works of Main CPU happen, such as no transmittion from Main CPU at regular time intervals and abnormal data from Main CPU, Power CPU sets FET in Main CPU to OFF and resets it. In addition, Power CPU checks the current consumed in Main CPU.
3. If the current flowing to Main CPU increases due to latch-up, Power CPU resets Main CPU.
4. When ITF-1 receives signal from the ground station by monopole antenna and ultra small antenna, Power CPU orders to downlink morse code and passes the current to a resistance in order to cut a gut that keeps monopole antenna from deploying.

Power consumption

Power consumption of each devices

Device

Power consumption[W]

Radio module(transmit)

0.78

Radio module(receive)

0.24

Radio module(standby)

0.07

Power CPU(PIC16F877A)

0.1

Main CPU(ATmega128)

0.14

Communication CPU(PIC16F877A)(normal)

0.035

Communication CPU(PIC16F877A)(sleep)

0.000025

Communication CPU(ATmega128)(normal)

0.15

Communication CPU(ATmega128)(sleep)

0.0

Communication CPU(MSP430FR5739)

0.003

Battery heater

0.8

Communication system

Communication system block diagram

Communication microcomputer

Name

Microcomputer

Main CPU

ATmega128

PIC

PIC16F877A

AVR

ATmega128

FRAM

MSP430FR5739

Radio module / Antenna

ITF-1 has three radio module, DJ-C7 made by ALINCO, and two radio modules for 430 MHz band and one radio module for 144 MHz band. Antennas are 430 MHz monopole antenna, 430 MHz ultra small antenna, and 144 MHz ultra small antenna.

ultra small antenna