凤凰号的红色星球自拍
NASA’s Mars Phoenix Lander gathered images of itself for this selfie from June 5 through July 12, 2008, with its Surface Stereo Imager (SSI). This mosaic is made up of more than 100 different SSI pointings, with images taken through three different filters at each pointing. 15 years ago in August 2008, Phoenix completed its three-month mission studying Martian ice, soil, and atmosphere.
The goals of the Phoenix Mars Lander were to study the history of water in the Martian arctic, search for evidence of a habitable zone, and assess the biological potential of the ice-soil boundary. More broadly, the lander was designed to determine whether life ever existed on Mars, characterize the climate and geology of the Red Planet, and to help prepare for future human exploration of its surface. Phoenix sampled Martian dirt for ice, and two months later, scientists confirmed that there is water on Mars. In addition, study of another soil sample suggested that the soil was composed of salts and other chemicals such as perchlorate, sodium, magnesium, chloride, and potassium.
The lander went into safe mode on Oct. 28, 2008, due to insufficient sunlight and poor weather conditions; Martian winter had come. During safe mode, activities that weren’t critical were suspended while the spacecraft awaited instructions from mission control. There was daily communication with the lander from Oct. 30 to Nov. 2 but no signals were received after Nov. 2, 2008, and the mission ended.
Image Credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University
2008年6月5日至7月12日，NASA的凤凰号火星着陆器用其表面立体成像仪（SSI）收集了自己的照片。这个拼接图由100多个不同的SSI点组成，每个点的图像都通过三个不同的滤镜拍摄。15年前的2008年8月，凤凰号完成了为期三个月的火星冰、土壤和大气层研究任务。
凤凰号火星着陆器的目标是研究火星极地的水历史，寻找宜居带的证据，并评估冰土边界的生物潜力。更广泛地说，着陆器的设计目的是确定火星上是否存在生命，描述这颗红色星球的气候和地质特征，并帮助为未来人类探索火星表面做准备。凤凰号从火星泥土中取样寻找冰，两个月后，科学家们证实火星上有水。此外，对另一个土壤样本的研究表明，土壤由盐和其他化学物质组成，如高氯酸盐、钠、镁、氯化物和钾。
2008年10月28日，由于日照不足和恶劣的天气条件，火星的冬天也已来临，着陆器进入了安全模式。在安全模式下，不重要的活动暂停，航天器等待任务控制中心的指令。从10月30日到11月2日，任务控制中心与着陆器每天都有通信，但在2008年11月2日之后，任务控制中心没有收到任何信号，任务结束。
影像来源：NASA/JPL-Caltech/University of Arizona/Texas A&M University