An experimental Japan Aerospace Exploration Agency solar sail vehicle launched by an H-IIA rocket on 21 May 2010 (JST) from the Tanegashima Space Centre. It is world’s first interplanetary space mission ever to be propelled by sunlight and the smallest interplanetary craft sent into space. The spacecraft is a 310 kg cylinder measuring 1.6 x 0.8 metres, with a 20-metre-diagonal 0.0075-millimetre-thick polymide sail embedded with a thin-film solar array. IKAROS rode piggyback aboard the Akatsuki spacecraft before unfurling its solar sail on 10 June, after which it relied on the pressure of photons streaming from the Sun for acceleration. On 8 December the craft passed about 80 800 km from Venus, completing all planned experiments and making a record discovery with its Gamma-Ray Burst Polarimeter. JAXA extended the mission to March 2011, after which IKAROS moved into solar orbit where it remains today, intermittently going in and out of planned hibernations without any known ill effects.