新型聚变晶体燃料可使飞船三个月抵达火星

人类开启航天时代已经超过半个世纪了，然而我们目前在太空中仍然不能以很高的速度飞行。著名的美国天文学家卡尔·萨根曾经这样说道：“地球的表面是宇宙之海的海滨，就在最近，我们开始尝试向外走出去一点距离，海水大约漫到了我们的脚踝。”萨根说这些话的时候是在1980年，但是遗憾的是在那之后我们也没有再向前迈出一步。

造成这种情况的主要原因很简单，那就是宇宙实在太大了，大的让人绝望。美国宇航局在1970年代发射的旅行者-1号探测器是迄今人类制造的飞行器中飞行速度最快的，其速度达到了每秒10.5英里(约合16.9公里)，这一速度值跟光速相比简直可以忽略不计。即便是抵达火星，使用传统火箭发动机推动，我们也需要花费6～8个月的时间。而诸如曲率驱动之类的技术还仍然停留在科幻的程度上，在我们的有生之年都不太可能成为现实。然而如果使用一种聚变燃料，我们或许可以将前往火星的飞行时间缩减为3个月，这就是“二锂晶体”——是的！就像《星际迷航》里那样。

不过当然了，后者毕竟是科幻电影，两者之间还是存在着差别。在电影中，这种晶体是一种罕见的物质，飞船的乘员们花费很长的时间找到这种物质晶体，而他们的飞船发动机可以使用这种物质达到超光速飞行。而在现实中，美国亚拉巴马州亨茨维尔大学的一个科学家小组正和来自美国波音公司，美国宇航局以及橡树岭国家实验室的研究人员一起研发一款新型推进技术，其可以实现相当于现有技术两倍的推进速度。

根据通用电气公司的在线科技杂志“Txchnologist”的说法，这种核聚变引擎将使用几吨的氘(一种氢的同位素)和锂-6(这是一种锂的稳定分子)构成的晶体形态，也就是所谓的“二锂”晶体。从技术上说，二锂应当是两个锂原子相互结合而成的，而锂-6则有6个锂原子组成，但是对于这一点就让我们忽略它吧，毕竟只是作为一个比喻。

当在高压环境下将氘和锂-6相互混合时，它们两者将会发生聚变反应并释放能量。尽管目前看来聚变还无法作为一种成熟的产能技术，但是在不久的将来我们或许就可以拥有这种技术。

这种引擎被称作“充电-1号脉冲能量发动机”，按照设计它将和飞船的其它部分一起在太空中进行组装，以便避开在各种精密的核聚变装置配件在穿越大气层时需要应对的技术困难，这种采用蚂蚁搬家方式在外太空组装的方式非常适合大型设备的组装，国际空间站就是对此最好的例证。一旦准备就绪，人们就可以启动反应堆。

飞船的理论最高速度可以达到10万公里每小时。这几乎已经和地球围绕太阳运行的速度相当。

然而，正如《经济参考》杂志指出的那样，预计这种技术，不管是用于商业还是科学目的，只有当美国军方允许时才可能被使用，事实上，开展这些研究所使用的设备也都来自此前军方的相关研究项目。当然，这一计划的实现也有赖于开发出一种产能大于耗能的核聚变技术。

'Dilithium crystals' could cut Mars travel time to three months

Humanity has been in space for a while, but we really haven't managed to go very far.Carl Sagan once said that "the surface of the Earth is the shore of the cosmic ocean, and recently we've waded a litile way out, maybe ankle deep" -- that was in 1980, and we haven't risked testing the water any deeper since then.

One of the main reasons for that, though, is that space is so frustratingly massive.Voyager 1 is the fastest manmade thing ever, but 17 kilometres per second is a piffling fraction of the speed of light.Even getting to one of our nearest neighbours, Mars, would take six to eight months using conventional spaceship engines.Ideas like warp drives are still theoretical, and unlikely to be seen within our lifetimes.However, it might be possible to cut that trip to Mars down to as few as three months using a form of fusion fuel -- "dilithium crystals".Yep, just like Star Trek.

It's not quite the same, of course.In the sci-fi series, the crystals are a rare substance that the crew spend an inordinate amount of time searching for, and their engines can use it to travel faster than the speed of light.This engine, currently under development at the University of Hunstville by a team working in collaboration with Boeing, Nasa and the Oak Ridge National Laboratory, would by comparison be about twice as fast as the best current technology.

According to Txchnologist, General Electric's online tech magazine, this fusion reactor would be fuelled by "a few tonnes" of deuterium (a heavy isotope of hydrogen) and lithium-6 (a stable molecule of lithium) in a crystalline structure -- hence the "dilithium crystal" claim.Technically, dilithium is a molecule with two covalently bonded lithium atoms, while lithium-6 features six bonded atoms, but we can forgive them for the temptation of using a litile poetic license.When the deuterium and the lithium-6 are forced together under high pressure they undergo a fusion reaction -- a process which they're still trying to turn into a net producer of energy.While fusion isn't yet a viable fuel source, recent developments in the fi eld seem to indicate that we can't be far away.

The engine, dubbed the "Charger-1 Pulsed Power Generator", would be constructed in space along with the rest of the spaceship to avoid the tricky engineering difficulties of getting all that delicate fusion equipment up through the atmosphere -- just like the International Space Station.Once ready, the reactor would be engaged, and millions of amps are passed through super-thin lithium wires in 100 nanosecond pulses -- this could generate up to three terrawatts of power.Those wires vaporise into plasma, which is collapsed onto the core of deuterium and lithium-6, inducing a fusion reaction.