Japan launches Venus orbiter and solar sail experiment

Physics Today : The Japan Aerospace Exploration Agency yesterday launched two scientific spacecraft aboard a single H-IIA rocket. The 640-kg Akatsuki (“daybreak”) is now on its way to a rendezvous with Venus in late December or early January. From its orbit around the planet, the spacecraft’s suite of instruments will study lightning, volcanism, and other active Venusian processes. The objective of the rocket’s other payload, the 300-kg IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), is to assess the feasibility of propelling spacecraft solely with solar energy. In a few weeks’ time, IKAROS (depicted at right) will unfurl a 14 × 14 m ² sail that will harvest the momentum of solar photons. Embedded in the sail are thin solar cells that will power the spacecraft’s electronics and drive a second means of locomotion and maneuver: an ion propulsion engine.