Conceptual design of a wide-field near UV transient survey in a 6U CubeSat

A conceptual design of a wide-field near UV transient survey in a 6U CubeSat is presented. Ultraviolet is one of the frontier in the transient astronomy. To open up the discovery region, we are developing a 6U CubeSat for transient exploration. The possible targets will be supernova shock-breakouts, tidal disruption events, and the blue emission from NS-NS mergers in very early phase. If we only focused on nearby/bright sources, the required detection limit is around 20 mag (AB). To avoid the background and optical light, we chose a waveband of 230-280 nm. As an imaging detector, we employ a delta-doped back-illuminated CMOS. In addition to delta doping, the multi-layer coating directly deposited on the detector enables both a high in-band UV QE and the ultra-low optical rejection ratio. Taking into account these specifications, even an 8 cm telescope can achieve the detection limit of 20 magAB. The expected FoV is larger than 60 deg^2

PETREL: Platform for Extra and Terrestrial Remote Examination with LCTF

A small satellite ”PETREL” for UV astronomy and remote sensing with ”tunable” multi-spectral cameras conducted by an academia-industrial collaboration is presented. This project was originally proposed by an astronomer who desired a satellite for exploration of explosive objects in ultraviolet. To avoid the earthshine the astronomical observations are scheduled only in the nighttime. To utilize the daytime more electively we conceived a plan of ”satellite sharing” with the industrial collaborators, that can also reduce the developing cost drastically. The daytime mission is spectroscopy that is one of the potential fields in terms of data business, because that can provide chemical and biological information on the surface of the earth. We employ multi-spectral cameras making use of liquid crystal tunable filters (LCTFs) that enable adaptive observations at the optimized wave-bands for each targets. In 2020, this remote-sensing project and ultraviolet astronomy mission were accepted as a small satellite project of JAXA’s Innovative Satellite Technology Demonstration program and as an ISAS/JAXA’s small-scale program, respectively. This satellit

Extensible Boom-Based Optical System for Nano-Scale Remote Sensing Satellite PRISM

Intelligent Space Systems Laboratory (ISSL), the University of Tokyo is now developing the nano-scale remote sensing satellite named as PRISM. This satellite aims at obtaining high resolution Earth images with 30m of ground resolution. Conventional remote sensing satellites have adopted reflective optical system using multiple mirrors to realize long focal length and large aperture. However, such system requires very high stiffness, machining accuracy and thermal management in order to maintain the designed light path. Thus we concluded that common reflective optical system cannot be applied to our nano-satellite, and adopted a totally different concept. PRISM deploys an extensible boom up to 800mm in space. The boom has a lens on its end, which realizes the desired long focal length. In other words, the boom works as a structure of telescope. Of course additional technological issues occur if we employ this methodology, such as how to keep focusing at the focal plane, and how to avoid the stray light coming into the optics. We are developing a kind of auto-focus system suitable for our nano-sized satellite, and light shade to be implemented on the extensible boom. PRISM is now at the engineering model phase, intending to be launched in 2006