# INSPIRE-SAT 7, a Second CubeSat to Measure the Earth's Energy Budget and to Probe the Ionosphere
## 3 Description of the INSPIRE-SAT 7 Mission and Mission Operations
### The Space Segment--The INSPIRE-SAT 7 CubeSat Platform  
INSPIRE-SAT 7 is a nanosatellite project based on CubeSat standard [14; 15]. INSPIRE-SAT 7 is a two-unit (2U) CubeSat designed to provide \(11.5\,\mathrm{cm}\ \times 11.5\,\mathrm{cm}\ \times 22.7\,\mathrm{cm}\) useful volume, which represents the allowable physical envelope of the stowed satellite. LATMOS is prime contractor of the 2U CubeSat with the support of ONERA, French industrial partners, radio amateurs, and a manufacturer (ISIS) to build a dedicated satellite platform. Main characteristics of the INSPIRE-SAT 7 CubeSat are given in Table 2. The INSPIRE-SAT 7 platform (Figure 1) is mainly based on the same subsystems and functions as those used in UVSQ-SAT [1]. The INSPIRE-SAT 7 CubeSat is made of several subsystems such as the mechanical structure, the power supply subsystem, the attitude determination and control subsystem (ADCS), the telemetry/tracking and command and data handling subsystem (CDHS), and the communication subsystem. INSPIRE-SAT 7 also has many payloads (Earth Radiative Sensors (ERS), Total Solar Irradiance Sensors (TSIS), Ultra-Violet Sensors (UVS), IONOSpheric payload (CUIONOI) with its antenna, Li-Fi payload, amateur radio SPINO payload, amateur radio audio transponder, 3-axis accelerometer/gyroscope/compass LATMOS inertial measurement unit (IMU)) to meet the requirements of the mission.  
The INSPIRE-SAT 7 power supply subsystem is different from that used in UVSQ-SAT [1]. It is based on an Electric Power Supply (iEPS) that includes a 4-cell battery pack with 45 Whr capacity. INSPIRE-SAT 7 consists of 6 solar panels with 20 Azurspace solar cells at high efficiency (30% for beginning of life). The solar cells could generate between 3.5 W to 3.8 W (orbit average power (OAP) in LEO). The following assumptions are taken into account when calculating the CubeSat generated power:  
* The satellite is spinning at 2\({}^{\circ}\) s\({}^{-1}\) rate around each axis,
* The efficiency of the solar cells is set to 29.11% that takes into account mechanical and assembly losses, and aging of the solar cells (1 year),
* Solar cells temperature is taken to be 20 \({}^{\circ}\)C,
* The solar flux is assumed to be 1362 Wm\({}^{-2}\)[12].  
The INSPIRE-SAT 7 ADCS subsystem is identical from that used in UVSQ-SAT [1]. It is mainly based on a magnetorquer board (iMTQ) and 6 coarse photodiodes to estimate the Sun's direction. INSPIRE-SAT 7 does not have an active pointing system like UVSQ-SAT. To solve this issue, we developed new methods (Tri-Axial Attitude Determination (TRIAD), Multiplicative Extended Kalman Filter (MEKF)) to have a knowledge of the satellite attitude. These methods were validated with UVSQ-SAT data in orbit [16], and represent an important issue for the INSPIRE-SAT 7 scientific analysis.  
The INSPIRE-SAT 7 CDHS subsystem is close to that used in UVSQ-SAT [1]. It is based on an onboard computer (OBC) with a LATMOS motherboard (iOBC) and a daughterboard (DB) used for interfacing with the platform sensors (6 temperature sensors and 6 coarse photodiodes). It is also used for interfacing with the payload electronic board. OBC communicates with the LATMOS payload electronic board (8 general purpose input/output (GPIO) pins, serial peripheral interface (SPI) data line), which manages the payload sensors. It is mainly based on an enhanced flash micro-controller (PIC18F4685), a voltage reference, a variable gain setting, a polarization voltage, an analog multiplexer, and an analog-to-digital converter (ADC).  
The communication subsystem is based on a VHF/UHF transceiver (TRXVU) and a deployable antenna system (two antennas with 60 cm in length for VHF, two antennas with 20 cm in length for UHF). The satellite will communicate in the amateur band (UHF selection of 437.410 MHz and VHF of 145.970 MHz), which requires a validation from International Amateur Radio Union (IARU).