木星トロヤ群小惑星へランデブーし，子機を着陸させて，試料採取・その場分析などを行います． 「はやぶさ」で実証した小天体サンプルリターン技術を発展させ外惑星領域に拡張するもので，木星圏・土星圏での着陸・サンプルリターンを可能にします． 目標天体での直接探査のほか，目標天体に到達するまでの航行期間中にもクルージング環境を利用した観測を実施します． 特に，外惑星領域では赤外線での観測の妨げとなる黄道光の影響が内惑星領域に比べて極めて小さいため，史上初めて黄道光の影響を受けない環境下での宇宙赤外線背景放射の直接観測が期待されます．

It will rendezvous with Jupiter Trojan asteroids, deploy a small lander, and perform sample collection and in-situ analysis. By advancing the small-body sample-return technology demonstrated by Hayabusa and extending it to the outer solar system, it will enable landings and sample return in the Jovian and Saturnian systems. In addition to direct exploration at the target bodies, observations will also be carried out during cruise prior to arrival. In particular, because the influence of zodiacal light that hampers infrared observations is far smaller in the outer planetary region than in the inner planetary region, direct observations of the cosmic infrared background in an environment essentially free from zodiacal light are expected to be possible for the first time.