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太空直播体验与人造流星雨

更新时间:2019/1/30 20:14:40 来源:纽约时报中文网 作者:佚名

The plan to make artificial meteor showers
太空直播体验与人造流星雨

If you ever find yourself sitting back in wonder as super-bright artificial meteors flash across the sky, you will be able to thank the credit crunch – at least in part. After the crisis of 2008 that Lena Okajima decided to leave her job at a financial company for a radical new venture: a firm that aimed to put satellites in orbit capable of launching artificial meteor showers.

你惊奇地坐观天空,划过苍穹的“人工流星雨”灿烂夺目,此时此刻便会觉得信贷紧缩何尝不是一件幸事——至少在某种程度上如此。2008年的经济危机后,冈岛礼奈(Lena Okajima)决定辞去在金融机构的工作,创立一家新的风险企业。她的公司业务是将卫星发射升空,在进入预定轨道后,再发射人造流星雨。

“I had to change my job because the financial situation was very bad at the time,” she explains now, nearly 10 years later.

过了10年后的今天她解释说:“我不得不换工作,因为当时的金融形势非常糟糕。”

It was even earlier, way back in 2001, while watching the natural Leonid meteor shower that she first had the idea of trying to recreate such a display artificially.

早在那以前的2001年,她看到狮子座流星雨的自然现象,便萌生此意,想人为制造流星雨。

“These meteor showers occurred from very small particles from outer space so we thought we could recreate the same situation using little satellites,” Okajima says.

冈岛说:“流星雨是由外太空非常微小的颗粒闯入地球形成的,因此我们认为发射小型卫星,可以人为制造流星雨。”

Now her company, Astro Live Experiences (ALE), is on track to launch its first satellite and begin experiments in space for the first time. If successful, ALE could be on its way to creating meteor shows at special events for crowds of thousands. And other forms of artificial celestial entertainment may follow. But will Okajima’s plan really work?

如今,冈岛创办的公司“太空直播体验”(ALE)计划将发射首颗制造流星雨的人造卫星,已开始在太空进行实验。如果实验成功,该公司就能够在特殊场合为成千上万观众制作流星雨,也许还会推出其他形式的太空娱乐表演。但冈岛打造“人工流星雨”的计划真的可行吗?

Her ambition is certainly great. The idea is to load each satellite with 400 pellets, each one 2cm (less than an inch) in diameter. A few of them would be released at a time to allow for a meteor shower three to 10 seconds long. A full show could last several minutes, says Okajima.

她当然雄心勃勃。这项人造流星雨技术为每颗卫星装载400粒金属小球,每粒直径约为2厘米(不足1英寸)。人造卫星将在指定的时间发射其中的一些小球,以让流星雨能持续3至10秒。冈岛说,“人造流星雨的全场表演可达几分钟。”

One of ALE’s promotional videos shows spherical pellets fired from the back of an orbiting satellite. They whizz down through Earth’s atmosphere and as they are heated they begin to glow, creating fabulous meteor effects over cities and – why not – Mount Fuji.

该公司的一则宣传影像资料显示,卫星进入轨道后,其尾部发射出一些特殊小球。小球穿过大气层,飞速下降,在发热燃烧过程中开始发光,在城市上空,当然还有富士山的夜空,形成美丽的流星雨效果。

It’s the same thing that happens to natural meteors, tiny grains of space dust or small rocks that meet the Earth’s path as our planet orbits the Sun. Some of the dust burns up in the atmosphere, causing meteor showers.

这项技术效仿自然界流星的运行机制,地球行星绕太阳公转时,宇宙尘埃或小陨石的细微颗粒物飞过地球绕日轨道,有一部分会闯入地球大气层,因受摩擦而燃烧发光,从而形成流星雨。

ALE’s promotional video makes the process of doing this artificially seem effortless. In reality, it will be anything but easy. Okajima’s colleague Adrien Lemal, an aerothermodynamics engineer, explains that the pellets need to be fired out of the satellite with great accuracy and at a high speed. Otherwise they might not re-enter the Earth’s atmosphere as planned.

在该公司的宣传片中,实现人造流星雨的过程看起来轻而易举。但事实上绝不简单。冈岛的同事勒马尔(Adrien Lemal)是空气热力学工程师。他解释道,人造卫星释放出金属小球,必须做到相当精确,且保持高速运转,否则小球可能无法按计划回落至地球大气层。

To do it, Lemal and his team have come up with a pressure-driven system of gas tanks that shoot the pellets out at 8 km/s.

为了完成目标,勒马尔团队设计了以负压为驱动的气缸系统,可以8千米/秒的速度将小球发射出去。

“It’s something that has never been developed here on Earth and we need to make sure it works in space,” says Lemal.

勒马尔说:“这是人类在地球上前所未有的发明,我们必须确保卫星升空后顺利发射小球。”

But the really crucial part, perhaps, is what those pellets – the artificial meteors themselves – are actually made of. On that point, both Lemal and Okajima are more reserved.

不过,真正关键的地方也许是,那些用作人造流星的金属小球到底是用什么制成的。对此问题,勒马尔和冈岛都闭口不谈。

“We cannot disclose anything about the composition of the metal ore,” says Lemal, stiffly.

勒马尔言辞坚决:“对于金属小球的构成,我们拒绝透露任何信息。”

He is, however, happy to explain that the special materials the team has chosen mean the artificial meteors could be brighter than natural ones. Plus, they can be designed to burn up in different colours.

然而,他乐意向我们解释,团队所选用的材料经过特殊处理,使人造流星比自然界流星更为绚烂。此外,他们可以通过调整小球的组成成分,使其燃烧时发出不同颜色的光芒。

In the lab, it’s possible to heat the material, causing it to emit plasma – hot ionised gas – and produce light at specific wavelengths. ALE has successfully tested a number of colours including blue, green and orange. Red has been trickier to obtain as it is at the less vibrant end of the spectrum, explains Okajima, but the material has since been “optimised” for this hue. Again, the pair won’t say how.

研究人员利用实验室的设备,对这种材料进行热处理,使其产生等离子体(热电离气体),发出特定波长的光。该公司已经成功测试了几种颜色,如蓝色、绿色和橙色。冈岛解释称,红色位于光谱的一端,没有那么活跃,因此要显现红色比较麻烦,为了显示红色,科研人员已经对小球的成分采取“优化处理”。两位依旧不肯透露具体的做法。

This research has been going on for years. But within the next few months, ALE hopes to launch its very first satellite on a low-cost rocket supplied by Jaxa, the Japanese Space Agency.

团队对人造流星雨技术已研究了好几年。但再过几个月,公司有望通过小型固体燃料火箭,将首颗人造流星卫星发射升空,日本宇宙航空研究开发机构(Jaxa)负责火箭的发射工作。

“The launch window is December [2018] to March [2019] next year,” says Okajima, who adds that she is feeling both “excited” and “anxious” about it all.

冈岛说:“发射窗口时限是从(2018年)12月到明年(2019年)3月。”她继续补充道,对于此次卫星发射,她既“激动不已”,也“感到焦虑”。

Historic displays

具历史意义的人造天文现象

The plan to use pellets made from special materials is in principle a good one, says Robert Massey at the Royal Astronomical Society. “With meteors they’re not much bigger than a grain of sand,” he explains. “If you had something the size of a bullet, that would be a lot brighter – those would be very visible.”

英国皇家天文学会(Royal Astronomical Society)的梅西(Robert Massey)表示,原则上,采用特殊材料制成的金属小球是不错的做法。他解释说:“流星的大小不过如沙粒一般,如果人造流星是子弹那么大,效果将明亮很多,在夜空中会非常明显。”

Humans have intentionally brought defunct spacecraft back down to Earth before, creating spectacular displays as the satellites or vehicles blaze up in the atmosphere. While it’s less commonly known, we also have recreated natural celestial phenomena before, if not meteors. In the 1980s, the Active Magnetospheric Particle Tracer Explorer (AMPTE) mission sought to recreate comets by releasing vapours into the magnetosphere.

以前,人类特意将不再使用的宇宙飞船收回地球,当这些废弃的卫星或太空船进入地球大气层燃烧时,也曾形成非常壮观的场面。即使不是流星,我们也曾人为地制造过天文现象,不过没有引起多大的关注。上世纪80年代,科学家通过地球磁层粒子示踪探测器向地球磁层释放云雾状的金属,试图产生类似彗星的天体现象。

Although the effects could just about be seen from the ground with a small telescope for example, the objective wasn’t principally entertainment. The scientists behind the mission wanted to find out more about how charged particles flung across space by the Sun, known as solar wind, interact with Earth’s atmosphere.

举例来说,虽然研究人员通过小型望远镜,才能观测到人造彗星效果,但研究目标并非是为了娱乐地球大众。探测任务幕后的科学团队希望通过这项研究深入了解太阳风这个电磁现象如何影响地球的天气。太阳大气最外层射出大量电子流,形成太阳风,对地球有影响。

A satellite was loaded with canisters of lithium or barium vapour. When the contents of these canisters were exploded, the vapour would fly into the solar wind and become ionised (charged) by it. As a result, a visible effect – having the appearance of a comet with head and tail – was generated. Instruments were able to measure the energy signature of the ions as they passed through Earth’s atmosphere.

人造彗星卫星载有金属锂或金属钡的烟雾罐。这些金属烟雾罐在近地太空引爆时,释放出云雾状的金属,金属烟雾飞进太阳风后形成等离子体(带电粒子)。结果地球上观测到一枚有头有尾的小彗星的出现。这个带电粒子彗星穿过地球大气层时,研究人员利用仪器测得其能量参量。

But the excitement of scientists involved in AMPTE was not just limited to the gathering of new data on Earth’s magnetosphere. It was just a pretty cool thing to do, too. Andrew Coates at UCL’s Mullard Space Science Laboratory was project manager for the ion experiment on AMPTE. “Scientifically it was useful, but also it did engage people [who tried to] see these things. Comets have that type of attraction for people,” he says. He remembers peering through his own set of binoculars and feeling “almost sure” he could see the artificial comet himself.

但是,让探测任务科研团队倍感振奋的地方不仅在于地球磁层的数据采集。人造彗星本身也是一项很酷的事。伦敦大学学院(UCL)穆兰德空间科学实验室(Mullard Space Science Laboratory)的科茨(Andrew Coates)是这项探测任务的项目经理,负责等离子体的研究工作。他说:“从科学的角度来说,这是很有帮助的研究,而且也让研究人员(有志于此)观测到很酷的结果,这的确是相当吸引人的工作。”他回忆起自己透过望远镜望向天空,当时的感受是“几乎肯定”他亲眼见到了这枚人造彗星。

Coates points out that humans have also been successful in generating artificial aurora borealis in the past. One such experiment that achieved this took place back in 1969. A rocket carried an electron accelerator into the atmosphere and pulses of electrons were fired, in bursts one second long at a time, down towards Earth. “The idea of being able to paint Earth’s magnetic environment a bit is an attractive idea,” admits Coates.

科茨指出,在人造北极光方面,人类也曾取得佳绩。早在1969年,研究人员进行相关实验,实现了人造北极光。电子加速器搭载火箭,冲进地球大气层,引爆电子脉冲,单次的爆炸时长为一秒,以此频率返回地球。科茨坦言:“实验的目标是利用地球磁场,产生五彩缤纷的奇景,这个想法很吸引人。”

Sky canvas

以天为幕的灯光秀

Okajima is clearly thinking along these lines. “We want to use the sky as canvas and create very beautiful things,” she says.

显然,冈岛的想法与之类似。她说:“我们希望以天为幕,营造出美轮美奂的效果。”

But is there a downside to artificially turning our atmosphere into a charged particle light show?

但是,人为地将地球大气层变为带电粒子的灯光秀,这么做有没有害处呢?

Hugh Lewis at the University of Southampton is an expert in space debris and space junk – the old satellites and bits of spacecraft orbiting Earth that pose a genuine danger to other satellites and astronauts on the International Space Station (ISS).

南安普顿大学(University of Southampton)的刘易斯(Hugh Lewis)是太空碎片和太空废弃物方面的专家。这些废弃过时的人造卫星和太空船部件形成的太空垃圾,至今还在绕地运行,确实对其他仍在使用的卫星和国际空间站(ISS)上的宇航员造成威胁。

“Given the fact that we’re trying to encourage good behaviour in the space environment and so on, just to throw things up there because they look pretty is a bit problematic,” he says.

刘易斯说:“既然我们极力倡导在太空环境中要文明良好,为何要将一些东西发射到太空而只图其视觉效果,这么做是很有问题的。”

He notes that at the lower altitude ALE intends to use for its meteor shows, any potential debris left by pellets that fail to burn up would likely not threaten most satellites, or the ISS. And they may well re-enter after a short time anyway. But in the future, more satellites will likely use this region of space and so leftover artificial meteors could be a problem.

刘易斯提到,冈岛公司计划在近地球较低的太空制造流星雨,即使金属小球未能充分燃烧,产生碎片垃圾,也不会对大多数卫星和国际空间站造成威胁。没过多久,碎片终究能落入大气层,回到地球。但是,今后还会有别的人造卫星在此空间展开工作,因此人造流星的残留物可能会带来问题。

Lemal says extensive simulations suggest that the chances of meteors failing to burn up are very low. “We are confident that we don’t create pollution, we don’t create debris,” he says. He adds that the material used in the pellets is “non-toxic”. However, no-one has ever tried anything quite like this before, so ALE is working with space debris committees to ensure that they are compliant with existing regulations.

勒马尔说,他们做的大量的模拟实验显示,人造流星不充分燃烧的概率极低。他说:“我们的实验不会造成环境污染,不会产生碎片垃圾,对此我们很有把握。”他继续说道,小球的化学成分是“无毒”的。然而,这是前所未有的科学探索,因此该公司正在配合太空碎片委员会的工作,以确保人造流星雨的做法符合现有规定。

Lewis has other reservations, though. He’s not convinced that it will be possible to create meteor showers in the exact bit of sky requested by ALE’s future clients. This is because it’s extremely difficult to predict how a satellite’s orbit will evolve over time. Releasing the particles early to compensate for a slightly off-course orbit might add even more uncertainty as to when and where the “meteors” will re-enter.

不过,刘易斯还有别的疑问。冈岛的公司将按照今后客户的要求,在指定的地点营造一场流星雨,对此他不太相信。因为人造卫星的运行轨道如何随时间而变化是极难预先设定的。如果卫星的轨迹稍有偏离,为了弥补偏差,提前释放流星颗粒,那只会使设定工作更为困难,“人工流星”将于何时何地上演,难以把握。

ALE says its meteor shows will be visible within an area of 200 sq km – and apparently has simulations that suggest it can achieve the necessary accuracy –  but Lewis is sceptical that this will be possible. “You could miss by an entire continent,” he says. Only time and real-world experimentation will tell.

冈岛公司声称其人造流星雨表演,在方圆200平方公里内的人们都能观赏到,据说也进行了模拟实验,表明能够在指定的时间和地点制造一场流星雨。但刘易斯抱有怀疑态度。他说:“可能到时看到的流星雨是在另一个洲。”但到底如何,只有时间和真实的实验才会给出答案。

Even if it does work, there will certainly be some who prefer the authenticity of the real thing.

即使人造流星雨真的能实现,肯定有一些人更喜欢自然实景。

“I think there’s always something quite fascinating about a thing we don’t actually control but which is nonetheless beautiful,” says Massey. “That has a romantic and soulful quality that perhaps an artificial shower doesn’t.”

梅西说:“我认为,我们无从主宰但却非常美丽的自然现象永远令人着迷不已,能够引发浪漫多情而哀伤的情绪,这是人造流星雨做不到的。”

Okajima would undoubtedly disagree – she has been dreaming of putting on her artificial meteor shows for nearly twenty years now. Despite the naysayers, the many challenges and potential pitfalls, she is clearly determined to see it through.

毫无疑问,冈岛对此不同意。过去的20年里,打造“人工流星雨”一直是她的夙愿。尽管曾遭人否定,经历了重重挑战,遇到很多可能出现的困难,但她坚持到底的决心毫不动摇。

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