Through industry-academia collaboration, seeking to solve problems of customers involved in space exploration activities
Hitachi, through separate collaborations with the Japan Aerospace Exploration Agency (JAXA) and The University of Tokyo, has proposed and verified the principle of basic technology for observation of radio waves from all directions and localization of their sources. By applying this technology to artificial satellites, the aim will be to improve the precision of space situational awareness (SSA)*1 and solve problems faced by customers involved in space exploration activities, such as preventing collisions with other satellites.
SSA needs are growing with the increasing number of satellite launches in recent years. However, as it is not easy to get a three-dimensional and comprehensive picture of the constantly changing space situation in orbits at various altitudes, there are concerns about such problems as ensuring the safety of space exploration activities.In this industry-academia collaboration, a rotational radio interferometry method was developed for three-dimensional visualization*2 of radio source directions. For this purpose, a three-dimensional array antenna (Fig. 1) was designed, adopting a tensegrity structure*3 with outstanding structural stability, light in weight and deployable, for mounting in an artificial satellite.The ability of this method to localize signal sources in three dimensions was confirmed by computer simulation and also by principle verification test using acoustic waves*4 (Fig. 2).It is hoped that deploying this technology in collaboration with customers involved in space exploration activities will further advance SSA and help solve problems faced by customers.
The results of this development project are scheduled to be announced in part at the Small Satellite Conference 2024,*5 an international conference planned for August 3 to 8, 2024 in Utah, USA.
Fig. 1. Three-dimensional array antenna adopting tensegrity structure (illustrative image)
Fig. 2. Principle verification of a rotational radio interferometry method for localizing signal sources in three dimensions*4
*1 Space situational awareness (SSA): Keeping track of the orbits of artificial satellites and other space objects.
*2 A method of visualizing radio sources in all directions around a three-dimensional antenna by representing the detected radio waves as an overlay of multiple spherical harmonics.
*3 Tensegrity structure: A structure in stable self-equilibrium based on the balance of compression and tension forces between compression and tension members.
*4 2.0 kHz acoustic waves were used for evaluation of 1.8 GHz radio source localization, based on the electromagnetic-acoustic similarity rule (relational expression for conducting interferometry experiments with acoustic waves similar to those for radio waves). Hitachi's basic technology for three-dimensional acoustic analysis, built up over many years, was applied.
*5 38th Annual Small Satellite Conference; https://smallsat.org/
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