[PPS08-P09] Development of subsurface radar for future Mars, the Moon, and asteroid explorations
Keywords:Ground penetrating radar (GPR) installed on the rover, Subsurface radar sounder installed on the orbiter, Lunar polar ice exploration, Mars Aqueous-environment and space Climate Orbiter (MACO)
For MACO mission, we are proposing a radar sounder installed on the orbiter transmitting chirp pulse in a frequency range of 50-150 MHz with a peak power of 10 W in order to detect ice within a depth of several 100 meters at a vertical resolution of 1.5 m. For JAXA's lunar ice prospector mission, we are proposing a ground penetrating radar installed on the rover transmitting chirp pulse in a frequency range of 0.5-3 GHz with a peak power of 15 dBm in order to detect ice within a depth of several meters at a vertical resolution of 6 cm. For exploration of asteroid internal structures, the radar sounder for MACO will be applicable also. If we can plan bistatic radar sounding by using radar, transponder, and reflector installed on another orbiter or lander in addition, we can determine not only the subsurface structure of permittivity contrast but also the absolute value of permittivity for discussion of porosity and composition of the internal rock lumps.
In design of the radars for space missions, we can not select parts freely. We have to use limited rad-hard semiconductor parts. In 50-150 MHz, there are selectable D/A converter (DAC) and A/D converter (ADC). So we can select the method using DAC and ADC: Transmitting and reference signals are generated by DAC, and receiver output is sampled by ADC. On the other hand, in 0.5-3 GHz, there are not selectable DAC and ADC. So, we are planning to use VCO for generation of transmitting and reference signals. We are now developing BBM of transmitter and receiver considering parts selection and design for space-born instruments. In late 2020, we are planning performance tests with BBM by measuring soil simulant.
Acknowledgment: This study was supported by JSPS KAKENHI Grant Number 19K21891.