ASTERIA (spacecraft)

The Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) was a six-unit (6U) CubeSat space telescope deployed from the International Space Station (ISS) with the goal of testing new technologies for the detection of exoplanets using the transit method. The program was funded at JPL through the Phaeton Program for training early career employees. Its target mission lasted for 90days, after which it was extended until the loss of contact with the spacecraft. ASTERIA's capabilities enabled precision photometry to be performed on an opportunistic basis to study stellar activity, transiting exoplanets, and other astrophysical phenomena. The technological objectives of the mission were "to achieve arcsecond-level line of sight pointing error, and highly stable focal plane temperature control for precision photometry" as a way to detect transiting exoplanets, and characterize their host stars. The pointing stability was demonstrated over 20-minute observations. Pointing repeatability would be determined over a minimum of five observations over eight or more days, with the target star being returned to the same position on the focal plane by adjusting the spacecraft orientation and focal plane position. This mission may serve as a pathfinder for a fleet of low-cost space telescopes observing multiple targets at once to refine long-term mission goals by identifying new objects for other telescopes to observe. The miniaturization of a photometric detection system into a CubeSat could enable a constellation of multiple orbiting observatories for a continuous study of the brightest Sun-like stars which is not possible by conventional space observatories given their cost. Having one or more CubeSats pointed at a target star for extended duration could reveal long-transiting exoplanets. This mission also provided additional information in the design of future space telescopes. ==Launch==

ASTERIA was launched on board a SpaceX Falcon-9 rocket (mission SpaceX CRS-12) on and it was deployed to low Earth orbit from the International Space Station in . A crew member in the ISS transferred the satellite from the cargo vehicle to the Japanese Experiment Module (JEM) airlock for transfer outside the ISS. ==Design==

The ASTERIA concept was a follow-on to the proposed 3U CubeSat mission called ExoplanetSat that was designed in the early 2010s. The ASTERIA telescope is a 6U CubeSat measuring 10×20×30cm, and has a mass of . Power was supplied by deployable fixed solar panels and rechargeable batteries. over a period of 20minutes. The gain of each pixel was temperature sensitive, so the second objective of ASTERIA was to demonstrate milliKelvin-level (1mK=10K) temperature stability of the imaging detector. In , NASA's JPL reported that ASTERIA "has accomplished all of its primary mission objectives, demonstrating that the miniaturized technologies on board can operate in space as expected." ==References==