毅力号：七分钟的火星之旅

2021年02月16日

Perseverance: Seven Minutes to Mars
Video Credit: NASA, JPL

Explanation: How hard is it to land safely on Mars? So hard that many more attempts have failed than succeeded. The next attempt will be on Thursday. The main problem is that the Martian atmosphere is too thick to ignore — or it will melt your spacecraft. On the other hand, the atmosphere is too thin to rely on parachutes — or your spacecraft will crash land. Therefore, as outlined in the featured video, the Perseverance lander will lose much of its high speed by deploying a huge parachute, but then switch to rockets, and finally, assuming everything goes right, culminate with a hovering Sky Crane that will slowly lower the car-sized Perseverance rover to the surface with ropes. It may sound crazy, but the Curiosity rover was placed on Mars using a similar method in 2012. From atmospheric entry to surface touch-down takes about seven minutes, all coordinated by an onboard computer because Mars is too far away for rapid interactive communication. During this time, humans on Earth will simply wait to hear if the landing was successful. Last week, UAE’s Hope spacecraft successfully began orbiting Mars, followed a day later by the Chinese Tianwen-1 mission, which will likely schedule a landing of its own rover sometime in the next few months.

News: NASA Perseverance Coverage

Tomorrow’s picture: light pillar with flare

毅力号：七分钟的火星之旅
影片提供: NASA, JPL

说明: 要安全着陆火星有多难？非常困难，所以失败的远多于成功的案例，而最近的一次尝试将在这个星期四。主要的难题是火星的大气太浓密，不管不顾的话，太空船会镕化在其内。另一个面向是火星的大气太稀薄，不能光靠降落伞减速，否则太空船会坠毁。因此，就如这部主题影片所示，毅力号降落器会布署庞大的降落伞，把速度大幅降低，然后再倚靠火箭减速。如果一切顺利，最后会出动悬空的天空起重机，使用绳索把房车大小的毅力号火星车轻轻放到火星表面。这些步骤听来有些难以置信，不过2012年的好奇号火星车，就是用类似的方法登陆火星。从切入火星大气到着陆约历时7分钟，整个过程全靠机载电脑协调与执行，因为火星太远，无法进行即时互动操控。所以在降落的期间，地球上的人们只能旁观，静待着陆是否成功。在上星期，阿联的希望号太空船成功入轨并开始绕行火星。稍晚一天，中国的天问一号探测船也抵达火星，在接下来的数个月里，可能也会进行火星车布署。

新闻：NASA毅力号着陆实况

明日的图片: light pillar with flare