新华网华盛顿3月4日电美国白宫4日提交2015财年联邦政府预算报告。报告显示,美国不仅要继续探索火星、登陆小行星,还把目光投向了木星的卫星木卫二,这是太阳系中除地球外被认为最有可能存在生命的星球。白宫当天提交的预算报告首次提到了木卫二探索任务。据美国航天局介绍,预算中包括1500万美元的资金,为本世纪20年代中期向木卫二发射无人探测器做早期准确工作。木卫二表面温度低于零下100摄氏度,所以表面的水永久冻结。不过在它的表面冰层下却隐藏着一个巨大海洋,许多专家 Xinhua News Agency, Washington, March 4 The White House submitted its FY15 federal government budget report on the 4th. The report shows that not only must the United States continue to explore Mars and land an asteroid, but also look toward Jupiter’s satellite Europa, which is considered to be the most likely life-existent planet in the solar system. The budget report submitted by the White House for the first time mentions the exploration of Europa. According to NASA, the budget includes $ 15 million in funding for the early and accurate work of launching an unmanned detector to Europa for the mid-1920s. Europa surface temperature is below minus 100 degrees Celsius, so the surface of the water is frozen forever. However, in its surface ice is hidden a huge ocean, many experts