新的“决策地图”可以帮助我们选择保护地球免受小行星撞击的最佳任务

新的“决策地图”可以帮助我们选择保护地球免受小行星撞击的最佳任务

Near-Earth asteroids are a serious risk for humanity as we still know little about these objects and their properties. Strategies and tabletop exercises have been employed over the last few years to make us more prepared, and researchers have now produced an interesting tool that could be used as well.

近地小行星对人类来说是一个严重的威胁，因为我们对这些天体及其特性知之甚少。在过去的几年里，我们一直在使用一些策略和桌面练习来让我们做更多的准备，研究人员现在已经开发出一种有趣的工具，也可以使用。

Alfredo Carpineti

Soon to be reported in Acta Astronautica, engineers from the Massachusetts Institute of Technology (MIT) have created a decision map tool to help us decide what’s the best mission to employ when dealing with potentially risky asteroids. The idea particularly focuses on ensuring asteroids avoid gravitational keyholes, small regions of space where a planet’s gravity can turn a risky asteroid into a planet-killer.

不久将在《宇航学报》上报道，来自麻省理工学院(MIT)的工程师们创建了一个决策地图工具，帮助我们决定在处理有潜在风险的小行星时采用的最佳任务是什么。这个想法特别关注于确保小行星避开重力锁孔，即一个行星的重力可以将一个危险的小行星变成行星杀手的小空间区域。

“People have mostly considered strategies of last-minute deflection, when the asteroid has already passed through a keyhole and is heading toward a collision with Earth,” lead author Sung Wook Paek, a former graduate student in MIT’s Department of Aeronautics and Astronautics, said in a statement. “I’m interested in preventing keyhole passage well before Earth impact. It’s like a preemptive strike, with less mess.”

该研究的主要作者、前麻省理工学院航空航天系研究生Sung Wook Paek在一份声明中说:“当小行星已经穿过一个钥匙孔，正朝着与地球相撞的方向前进时，人们通常会考虑最后一刻偏离轨道的策略。”“我对在地球撞击之前防止钥匙孔通过很感兴趣。这就像先发制人，减少了混乱。”

Acting in advance could be crucial and that’s where the framework kicks in. Missions to deflect an asteroid will have to deal with a lot of uncertainties regarding their target. The asteroid’s mass, composition, and momentum all need to be known if we are to shift its orbit away from Earth. But this might not be possible and the missions might have to be launched with significant unknowns, some of which could lead to failure and have deadly consequences.

提前行动可能是至关重要的，这就是框架发挥作用的地方。使小行星偏离轨道的任务将不得不处理有关其目标的许多不确定性。如果我们要把小行星的轨道从地球移开，就必须知道它的质量、组成和动量。但这可能是不可能的，而且发射任务可能会有重大的未知因素，其中一些可能会导致失败和致命的后果。

“Does it matter if the probability of success of a mission is 99.9 percent or only 90 percent? When it comes to deflecting a potential planet-killer, you bet it does,” co-author Professor Oliver de Weck of MIT added. “Therefore we have to be smarter when we design missions as a function of the level of uncertainty. No one has looked at the problem this way before.”

“任务成功的概率是99.9%还是只有90%，这有关系吗?”麻省理工学院的奥利弗·德·韦克教授补充道。“因此，当我们根据不确定性水平设计任务时，我们必须更聪明。以前从来没有人这样看待这个问题。”

The team considered three scenarios for potential missions. The first involves sending a kinetic impactor probe, a spacecraft that will crash into the asteroid to push it off its course. The second sends a scout mission to measure the asteroid followed by a kinetic impactor. The third has two scouts, one to measure the asteroid and one to push the asteroid slightly off course, followed by the major kinetic impactor.

该小组考虑了可能的任务的三种情况。第一种方法是发射一个动能撞击探测器，即一艘宇宙飞船撞击小行星，使其偏离轨道。第二次发射了一个侦察任务来测量小行星，随后是一个动力冲击器。第三个探测器有两个，一个用来测量小行星，另一个用来把小行星稍微推离轨道，接着是主要的动能冲击器。

The team plugged properties of real asteroids into their simulations, such as 99942 Apophis, which will fly very close to Earth in 2029 and then again in 2036. In their framework, they saw that if Apophis were going to pass near a gravitational keyhole in five years or so, there would be enough time to send the two scouts followed by the impactor. If this were to happen just two to five years in the future, the second scenario is preferable. Any sooner than that and things get very troubling. The kinetic impactor alone might not be enough to push the asteroid away.

研究小组将真实小行星的特性加入到他们的模拟中，比如阿波菲斯99942，它将在2029年飞离地球很近，然后在2036年再次飞离地球。在他们的研究框架中，他们发现，如果阿波菲斯在5年左右的时间内通过一个引力锁眼附近，就有足够的时间让两个侦察兵跟着这个撞击者。如果这种情况只在两到五年后发生，那么第二种情况会更好。如果早于此，事情就会变得非常麻烦。单靠动能冲击器可能不足以把小行星推开。

The work is very interesting but assumes that we will be aware of asteroids well in advance and that we are ready to launch a mission at the drop of a hat. This might not be the case in real life.

这项工作非常有趣，但前提是我们要提前知道小行星的存在，并随时准备执行任务。在现实生活中可能不是这样。