page_title: ASTERIA (spacecraft)
section_title: Design
hierarchical_section_title: ASTERIA (spacecraft) / Design
caption_attribution_description: English: ASTERIA CubeSAt lens alignment
context_page_description: ASTERIA was a miniaturized space telescope technology demonstration and opportunistic science mission to conduct astrophysical measurements using a CubeSat. It was designed in collaboration between the Massachusetts Institute of Technology and NASA's Jet Propulsion Laboratory. ASTERIA was the first JPL-built CubeSat to have been successfully operated in space. Originally envisioned as a project for training early career scientists and engineers, ASTERIA's technical goal was to achieve arcsecond-level line-of-sight pointing error and highly stable focal plane temperature control. These technologies are important for precision photometry, i.e., the measurement of stellar brightness over time. Precision photometry, in turn, provides a way to study stellar activity, transiting exoplanets, and other astrophysical phenomena.
  ASTERIA was launched on 14 August 2017 and deployed into low Earth orbit from the International Space Station on 20 November 2017. The primary mission lasted 90 days, but the satellite continued operations for 745 days through three extended missions until last successful communications were made on December 5, 2019. The satellite decayed 24 April 2020.
context_section_description: 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 × 30 cm, and has a mass of 12 kg (26 lb). Power was supplied by deployable fixed solar panels and rechargeable batteries.
  Commercial reaction wheels provided coarse orientation (attitude control), while fine pointing control was achieved by tracking a set of guide stars on the active pixel sensor (CMOS) and moving the piezoelectric positioning stage to compensate for residual pointing errors. The goal was to maintain the target star image to within a fraction of a detector pixel over long durations, with a pointing accuracy better than 60 arcsecond, and optimally as precise as 5 arcsecond over a period of 20 minutes. The gain of each pixel was temperature sensitive, so the second objective of ASTERIA was to demonstrate milliKelvin-level temperature stability of the imaging detector.
  ASTERIA demonstrated the ability to collect photometric data, and process photometric light curves from a CubeSat. Secondary applications included measuring stellar rotation periods, characterizing stellar activity of exoplanet hosts, and supporting ground-based radial velocity measurements with simultaneous photometry. After the success of its 90 day planned mission, ASTERIA's extended mission targeted bright stars (luminosity Vmag < 8) with known low-mass planets discovered by the radial velocity method, that are not yet known to transit.
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