An extensive-air-shower-like event registered with the TUS orbital detector

TUS (Tracking Ultraviolet Set-up) is the world's first orbital detector of ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on 28th April 2016 as a part of the scientific payload of the Lomonosov satellite. The main aim of the mission was to test the technique of measuring the ultraviolet fluorescence and Cherenkov radiation of extensive air showers generated by primary cosmic rays with energies above ~100 EeV in the Earth atmosphere from space. During its operation for 1.5 years, TUS registered almost 80,000 events with a few of them satisfying conditions anticipated for extensive air showers (EASs) initiated by UHECRs. Here we discuss an event registered on 3rd October 2016. The event was measured in perfect observation conditions as an ultraviolet track in the nocturnal atmosphere of the Earth, with the kinematics and the light curve similar to those expected from an EAS. A reconstruction of parameters of a primary particle gave the zenith angle around 44$^\circ$ but an extreme energy not compatible with the cosmic ray energy spectrum obtained with ground-based experiments. We discuss in details all conditions of registering the event, explain the reconstruction procedure and its limitations and comment on possible sources of the signal, both of anthropogenic and astrophysical origin. We believe this detection represents a significant milestone in the space-based observation of UHECRs because it proves the capability of an orbital telescope to detect light signals with the apparent motion and light shape similar to what are expected from EASs. This is important for the on-going development of the future missions KLYPVE-EUSO and POEMMA, aimed for studying UHECRs from space.Comment: 24 pages; v2: important changes to address comments by the anonymous referee; main conclusions unchange

Payload characterization for CubeSat demonstration of MEMS deformable mirrors

Coronagraphic space telescopes require wavefront control systems for high-contrast imaging applications such as exoplanet direct imaging. High-actuator-count MEMS deformable mirrors (DM) are a key element of these wavefront control systems yet have not been flown in space long enough to characterize their on-orbit performance. The MEMS Deformable Mirror CubeSat Testbed is a conceptual nanosatellite demonstration of MEMS DM and wavefront sensing technology. The testbed platform is a 3U CubeSat bus. Of the 10 x 10 x 34.05 cm (3U) available volume, a 10 x 10 x 15 cm space is reserved for the optical payload. The main purpose of the payload is to characterize and calibrate the onorbit performance of a MEMS deformable mirror over an extended period of time (months). Its design incorporates both a Shack Hartmann wavefront sensor (internal laser illumination), and a focal plane sensor (used with an external aperture to image bright stars). We baseline a 32-actuator Boston Micromachines Mini deformable mirror for this mission, though the design is flexible and can be applied to mirrors from other vendors. We present the mission design and payload architecture and discuss experiment design, requirements, and performance simulations.United States. National Aeronautics and Space Administration (Space Technology Research Fellowship

The Pierre Auger Observatory: Contributions to the 34th International Cosmic Ray Conference (ICRC 2015)

Contributions of the Pierre Auger Collaboration to the 34th International Cosmic Ray Conference, 30 July - 6 August 2015, The Hague, The NetherlandsComment: 24 proceedings, the 34th International Cosmic Ray Conference, 30 July - 6 August 2015, The Hague, The Netherlands; will appear in PoS(ICRC2015

A lunar far-side very low frequency array

Papers were presented to consider very low frequency (VLF) radio astronomical observations from the moon. In part 1, the environment in which a lunar VLF radio array would function is described. Part 2 is a review of previous and proposed low-frequency observatories. The science that could be conducted with a lunar VLF array is described in part 3. The design of a lunar VLF array and site selection criteria are considered, respectively, in parts 4 and 5. Part 6 is a proposal for precursor lunar VLF observations. Finally, part 7 is a summary and statement of conclusions, with suggestions for future science and engineering studies. The workshop concluded with a general consensus on the scientific goals and preliminary design for a lunar VLF array