11:15 AM - 11:30 AM
[PPS07-03] ASTERISC PROJECT: Nanosatellite mission for observation of cosmic dust with a new large film type dust sensor
Keywords:Cosmic dust, dust sensor, Nanosatellite, CubeSat
Dust particles are thought to be a ubiquitous constituent of planetary systems and have contributed to the origin and evolution of the planetary systems in various ways. In the early stage of our solar system, dust particles agglomerated into planetesimals, and planetesimals coalesced together to form planets. Afterward, dust would have been released from comets and asteroids which were remnants of planetesimals. The released dust particles have distributed in interplanetary space as interplanetary dust. In some cases, interplanetary dust would have accreted onto other planets. Actually, interplanetary dust is thought to have contributed significantly to the mass inventory of extraterrestrial matter on the earth.
Here, we focus on β-meteoroids. β-meteoroids are one of the main carriers that constantly transport planetary materials outward within the solar system and out of the solar system. To better understand the evolution of the interplanetary dust cloud, the material transport within the solar system, and furthermore, the supply of the materials into interstellar space, we need to know in detail the flux of β-meteoroids. However, its nature has not been fully resolved yet, due to some observational difficulties. First, the assumed β-meteoroid size is small (several micrometers or less). A high detection sensitivity is required to observe such a small size. Second, a small spatial density of β-meteoroids requires a sensor with a large sensitive area. Third, it is impossible for the existing dust analyzer to observe the direction of the sun from which β-meteoroids come (The impact ionization-based dust analyzer cannot work due to the photelectric effect caused by the sunlight).
In this study, we developed our second 3U CubeSat “ASTERISC” to monitor interplanetary dust using a new type of dust sensor system (∼ 0.1 m2 sensitive area for dust detection) which we have developed.
We have developed a new particle sensor system, a thin-film dust sensor system. The sensor is a thin polyimide film attached with small piezoelectric sensors to pick up elastic waves induced by dust impacts (Fig. 1). Specifically, (i) elastic wave generated by a collision of a dust particle onto a polyimide film are converted into electric signals by a group of piezoelectric sensors arranged on the film surface, (ii) the signals are fed by cables to an electronics circuit and (iii) the signal waveforms are sampled by A/D converter. By simultaneously measuring with multiple piezoelectric sensors placed evenly spaced apart on the film, the true signal is distinguished from noise with reference to the arrival time, amplitude, and FTT spectrum of the signal acquired by each piezoelectric sensor.
Since the entire film operates as a dust sensor, a large area sensor can be easily realized by increasing the area of the film. The film dust sensor can be folded during the launch and deployed to use after launch. Because the system detects only solid particles impacting onto the film and are not affected by the sunlight, it can turn the sensor to the direction of the sun, which is a requisite for observation of β-meteoroids.
Because the sensor can observe dust particles in real-time, it is possible to know when and where the particles collided, resulting in obtaining a spatial distribution of the particles in orbit. Rough orbit of the particles is also estimated from the orientation of the dust sensor at the time of particle detection. Furthermore, the sensor is a momentum sensor, in which the transferred momentum from the collided dust particle to the film is proportional to signal strength. So, the momentum of dust particles colliding onto the film can be measured.
The ASTERISC was launched in November 2021 by the JAXA Epsilon rocket and is in the initial operational phase. The sensor has been deployed by a command from our ground station, and we have already succeeded in observing particles in orbit. The satellite is ready to start nominal observation phase.
Here, we focus on β-meteoroids. β-meteoroids are one of the main carriers that constantly transport planetary materials outward within the solar system and out of the solar system. To better understand the evolution of the interplanetary dust cloud, the material transport within the solar system, and furthermore, the supply of the materials into interstellar space, we need to know in detail the flux of β-meteoroids. However, its nature has not been fully resolved yet, due to some observational difficulties. First, the assumed β-meteoroid size is small (several micrometers or less). A high detection sensitivity is required to observe such a small size. Second, a small spatial density of β-meteoroids requires a sensor with a large sensitive area. Third, it is impossible for the existing dust analyzer to observe the direction of the sun from which β-meteoroids come (The impact ionization-based dust analyzer cannot work due to the photelectric effect caused by the sunlight).
In this study, we developed our second 3U CubeSat “ASTERISC” to monitor interplanetary dust using a new type of dust sensor system (∼ 0.1 m2 sensitive area for dust detection) which we have developed.
We have developed a new particle sensor system, a thin-film dust sensor system. The sensor is a thin polyimide film attached with small piezoelectric sensors to pick up elastic waves induced by dust impacts (Fig. 1). Specifically, (i) elastic wave generated by a collision of a dust particle onto a polyimide film are converted into electric signals by a group of piezoelectric sensors arranged on the film surface, (ii) the signals are fed by cables to an electronics circuit and (iii) the signal waveforms are sampled by A/D converter. By simultaneously measuring with multiple piezoelectric sensors placed evenly spaced apart on the film, the true signal is distinguished from noise with reference to the arrival time, amplitude, and FTT spectrum of the signal acquired by each piezoelectric sensor.
Since the entire film operates as a dust sensor, a large area sensor can be easily realized by increasing the area of the film. The film dust sensor can be folded during the launch and deployed to use after launch. Because the system detects only solid particles impacting onto the film and are not affected by the sunlight, it can turn the sensor to the direction of the sun, which is a requisite for observation of β-meteoroids.
Because the sensor can observe dust particles in real-time, it is possible to know when and where the particles collided, resulting in obtaining a spatial distribution of the particles in orbit. Rough orbit of the particles is also estimated from the orientation of the dust sensor at the time of particle detection. Furthermore, the sensor is a momentum sensor, in which the transferred momentum from the collided dust particle to the film is proportional to signal strength. So, the momentum of dust particles colliding onto the film can be measured.
The ASTERISC was launched in November 2021 by the JAXA Epsilon rocket and is in the initial operational phase. The sensor has been deployed by a command from our ground station, and we have already succeeded in observing particles in orbit. The satellite is ready to start nominal observation phase.