The Landolt mission

The Landolt mission is a timely and low-cost (~$13 million) 12U CubeSat mission currently proposed to the NASA Pioneers program that will provide significant improvement in the accuracy of photometric measurements of stellar fluxes. This will be accomplished with a high accuracy National Institute of Standards and Technology (NIST) calibrated suite of laser beacons which will be observable from selected ground-based observatory stations. Landolt will improve the photometric accuracy to <0.5% at visible (VIS) and near-infrared (NIR) wavelengths for >60 target stars – improving upon the half-century old techniques that use ground-based blackbodies and calibrated lamps along with with model stellar atmospheres. The Landolt mission will allow us to re-calibrate the brightnesses of millions of stars. Such measurements can only be achieved by a space-based orbiting artificial star, where the physical photon flux is accurately known. Consequently, Landolt will enable the refinement of dark energy parameters, improve our ability to assess the habitability of terrestrial worlds, and advance fundamental constraints on stellar evolution. Accuracy of absolute flux zero points is now the limiting error budget term in the characterization of stars, be they standard stars or exoplanet hosts. Similarly, the accuracy of the ratio of the VIS/NIR absolute flux calibration zero point is the limiting error budget term in the Supernovae (SNe) Ia cosmological constraints on dark energy, a key science goal of the Nancy Grace Roman Space Telescope (Roman) and Vera C. Rubin Observatory (Rubin). The spacecraft bus will be provided by a private space company, and the payload will build on the mission heritage of a previous cubesat mission. We will use a rideshare to achieve a baseline Geosynchronous Orbit (GEO), with a lower altitude orbit for our threshold mission. The payload consists of two sets of two VIS and two NIR single mode fiber lasers, to create an artificial star for which we know the photon rate transmitted to the telescope aperture and detectors to the required flux uncertainty of <0.5%. By modulating the lasers on and off, recording the emitted flux via NIST-calibrated onboard photodiodes, pre-launch beam profile characterization, monitoring the power and temperature of the lasers, and with precision pointing knowledge, we will be able to reconstruct the absolute flux knowledge of the artificial star. During passes of the spacecraft in its one year primary mission, we will be able to precisely calibrate the absolute flux of nearby celestial targets to a level not yet achieved.