Satellites, rocket shards and collision debris are creating major traffic risks in orbit around the planet. Researchers are working to reduce these threats

卫星、火箭碎片和碰撞碎片正在地球周围的轨道上造成重大的交通风险。研究人员正在努力减少这些威胁

A  Last year, commercial companies, military and civil departments and amateurs sent more than 400 satellites into orbit, over four times the yearly average in the previous decade. Numbers could rise even more sharply if leading space companies follow through on plans to deploy hundreds to thousands of large constellations of satellites to space in the next few years.

A  去年，商业公司、军事和民用部门以及业余爱好者将 400 多颗卫星送入轨道，是前十年年平均水平的四倍多。如果主要的太空公司在未来几年内落实向太空部署成百上千颗大型卫星群的计划，那么这一数字还会有更大幅度的增长。

All that traffic can lead to disaster. Ten years ago, a US commercial Iridium satellite smashed into an inactive Russian communications satellite called Cosmos-2251, creating thousands of new pieces of space shrapnel that now threaten other satellites in low Earth orbit – the zone stretching up to 2,000 kilometres in altitude. Altogether, there are roughly 20,000 human-made objects in orbit, from working satellites to small rocket pieces. And satellite operators can't steer away from every potential crash, because each move consumes time and fuel that could otherwise be used for the spacecraft's main job.

所有这些流量都可能导致灾难。十年前，一颗美国铱星商业卫星撞上了一颗名为宇宙-2251 的俄罗斯非活动通信卫星，产生了数以千计的新太空弹片，这些弹片现在威胁着低地球轨道上的其他卫星。轨道上总共有大约 2 万个人造物体，从工作卫星到小型火箭碎片。卫星操作员不可能避开每一次潜在的坠毁，因为每一次移动都会消耗时间和燃料，而这些时间和燃料本可以用于航天器的主要工作。

B  Concern about space junk goes back to the beginning of the satellite era, but the number of objects in orbit is rising so rapidly that researchers are investigating new ways of attacking the problem. Several teams are trying to improve methods for assessing what is in orbit, so that satellite operators can work more efficiently in ever-more-crowded space. Some researchers are now starting to compile a massive data set that includes the best possible information on where everything is in orbit. Others are developing taxonomies of space debris – working on measuring properties such as the shape and size of an object, so that satellite operators know how much to worry about what's coming their way.

B  对太空垃圾的担忧可以追溯到卫星时代的初期，但轨道上的物体数量正在迅速增加，研究人员正在研究解决这一问题的新方法。一些研究小组正试图改进评估轨道上物体的方法，以便卫星运营商能够在日益拥挤的太空中更有效地工作。一些研究人员正在着手编制一个庞大的数据集，其中包括有关轨道上所有物体位置的最佳信息。还有一些研究人员正在制定空间碎片分类法--致力于测量物体的形状和大小等属性，以便卫星运营商知道对即将到来的物体该有多担心。

The alternative, many say, is unthinkable. Just a few uncontrolled space crashes could generate enough debris to set off a runaway cascade of fragments, rendering near-Earth space unusable. 'If we go on like this, we will reach a point of no return,' says Carolin Frueh, an astrodynamical researcher at Purdue University in West Lafayette, Indiana.

许多人说，另一种情况是不可想象的。只要发生几次失控的太空撞击，就会产生足够多的碎片，引发一连串失控的碎片，导致近地空间无法使用。印第安纳州西拉法耶特普渡大学的天体动力学研究员卡罗琳-弗鲁赫（Carolin Frueh）说："如果我们继续这样下去，我们将到达一个不归点。

C  Even as our ability to monitor space objects increases, so too does the total number of items in orbit. That means companies, governments and other players in space are collaborating in new ways to avoid a shared threat. International groups such as the Inter-Agency Space Debris Coordination Committee have developed guidelines on space sustainability. Those include inactivating satellites at the end of their useful life by venting pressurised materials or leftover fuel that might lead to explosions. The intergovernmental groups also advise lowering satellites deep enough into the atmosphere that they will burn up or disintegrate within 25 years. But so far, only about half of all missions have abided by this 25-year goal, says Holger Krag, head of the European Space Agency's space-debris office in Darmstadt, Germany. Operators of the planned large constellations of satellites say they will be responsible stewards in their enterprises in space, but Krag worries that problems could increase, despite their best intentions. 'What happens to those that fail or go bankrupt?' he asks. 'They are probably not going to spend money to remove their satellites from space.'

C  即使我们监测太空物体的能力不断提高，在轨物体的总数也在增加。这意味着公司、政府和其他太空参与者正在以新的方式开展合作，以避免共同的威胁。机构间空间碎片协调委员会等国际组织已经制定了空间可持续性准则。其中包括在卫星使用寿命结束时，通过排放可能导致爆炸的加压材料或剩余燃料，使卫星失活。这些政府间组织还建议将卫星降到足够深的大气层，使其在 25 年内烧毁或解体。位于德国达姆施塔特的欧洲航天局太空碎片办公室负责人霍尔格-克拉格（Holger Krag）说，但迄今为止，只有大约一半的任务遵守了这一 25 年目标。计划中的大型卫星群的运营商表示，他们将成为太空企业中负责任的管理者，但克拉格担心，尽管他们有良好的意愿，但问题可能会越来越多。他问道："那些失败或破产的公司会怎么样？'他们可能不会花钱把卫星从太空中移走。

D  In theory, given the vastness of space, satellite operators should have plenty of room for all these missions to fly safely without ever nearing another object. So some scientists are tackling the problem of space junk by trying to find out where all the debris is to a high degree of precision. That would alleviate the need for many of the unnecessary manoeuvres that are carried out to avoid potential collisions. 'If you knew precisely where everything was, you would almost never have a problem,' says Marlon Sorge, a space-debris specialist at the Aerospace Corporation in El Segundo, California.

D  从理论上讲，由于太空浩瀚无垠，卫星运营商应该有足够的空间让所有这些任务安全飞行，而不会接近另一个物体。因此，一些科学家正在试图通过高精度地找出所有碎片的位置来解决太空垃圾问题。这将减少为避免潜在碰撞而进行的许多不必要的机动。位于加利福尼亚州埃尔塞贡多的航空航天公司的太空碎片专家马龙-索格（Marlon Sorge）说："如果你能精确地知道所有东西的位置，你几乎永远不会遇到问题。

E  The field is called space traffic management, because it's similar to managing traffic on the roads or in the air. Think about a busy day at an airport, says Moriba Jah, an astrodynamicist at the University of Texas at Austin: planes line up in the sky, landing and taking off close to one another in a carefully choreographed routine. Air-traffic controllers know the location of the planes down to one metre in accuracy. The same can't be said for space debris. Not all objects in orbit are known, and even those included in databases are not tracked consistently.

E  这一领域被称为太空交通管理，因为它类似于道路或空中的交通管理。德克萨斯大学奥斯汀分校的天体动力学家莫里巴-贾（Moriba Jah）说，想象一下机场繁忙的一天：飞机在空中排成一排，以精心编排的例行程序相互靠近降落和起飞。空中交通管制员对飞机的位置了如指掌，精确到一米。而太空碎片却不是这样。并非所有轨道上的物体都为人所知，即使是那些被纳入数据库的物体，也无法得到一致的跟踪。

F  An additional problem is that there is no authoritative catalogue that accurately lists the orbits of all known space debris. Jah illustrates this with a web-based database that he has developed. It draws on several sources, such as catalogues maintained by the US and Russian governments, to visualise where objects are in space. When he types in an identifier for a particular space object, the database draws a purple line to designate its orbit. Only this doesn't quite work for a number of objects, such as a Russian rocket body designated in the database as object number 32280. When Jah enters that number, the database draws two purple lines: the US and Russian sources contain two completely different orbits for the same object. Jah says that it is almost impossible to tell which is correct, unless a third source of information made it possible to cross-correlate. Jah describes himself as a space environmentalist: 'I want to make space a place that is safe to operate, that is free and useful for generations to come.' Until that happens, he argues, the space community will continue devolving into a tragedy in which all spaceflight operators are polluting a common resource.

F  另一个问题是，没有权威的目录可以准确地列出所有已知空间碎片的轨道。贾赫用他开发的网络数据库说明了这一点。该数据库借鉴了多个资料来源，如美国和俄罗斯政府维护的目录，以直观地显示物体在太空中的位置。当他输入一个特定太空物体的标识符时，数据库就会画出一条紫色的线来指定其轨道。不过，这对很多物体来说并不太管用，比如数据库中编号为 32280 的俄罗斯火箭体。当 Jah 输入这个编号时，数据库会画出两条紫线：美国和俄罗斯的资料中包含了同一个物体的两个完全不同的轨道。贾说，除非有第三种信息来源可以进行交叉比对，否则几乎不可能分辨出哪个是正确的。贾自称是一名太空环保主义者： 我想让太空成为一个可以安全运行、自由且对后代有用的地方。他认为，除非做到这一点，否则太空界将继续演变成一场悲剧，所有太空飞行操作者都在污染共同的资源。