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际空间站(International Space Station)每90分钟绕地球一圈，是有史以来在太空中组装的最昂贵项目。再过几天，国际空间站就只能靠一条造价不菲的线维系了，而这根线将掌握在美国在航天领域的历史劲敌俄罗斯手中。
Reuters
亚特兰蒂斯号航天飞机准备进行最后一次飞行。
最后一架美国航天飞机定于周五升空。之后，美国等国将依靠俄罗斯的“老爷”宇宙飞船向造价1,000亿美元的国际空间站运送宇航员。俄罗斯将独霸载人航天领域，而紧张局面已经在不断加剧。在俄罗斯人将用“联盟号”(Soyuz)宇宙飞船向国际空间站运送宇航员的价格提高近两倍的过程中，其他国家除支付更高的价格外，别无选择。
欧洲航天局(European Space Agency)局长多丹(Jean-Jacques Dordain)说，我们处境不妙，这还算是委婉的说法，我们犯了一个集体性错误。欧洲航天局是联合管理国际空间站的五个国际机构之一。
“联盟号”代表了低成本人类太空探索的成功。这种俄罗斯宇宙飞船使用一次性大型火箭进行发射，将宇航员像制导加农炮弹一样运送到绕地轨道上，或从轨道上运回地球。相反，美国则围绕著有史以来最复杂的飞行器──可重复使用的航天飞机──建立了自己的航天计划。自航天飞机诞生以来，美国已经在上面花费了2,091亿美元，而整个俄罗斯航天计划目前每年仅花费20亿美元。
俄罗斯航天局Roskosmos新任局长波波夫金(Vladimir Popovkin)上个月对一家俄罗斯报纸说，今天，可重复使用的航天飞机是一种非常昂贵的享受，在经济上实际不可行。俄罗斯航天局官员没有就本文所说话题发表评论。
俄罗斯在载人航天中的独霸地位不会永远保持下去。如果一切如美国国家航空及太空总署(NASA)的计划，俄罗斯的霸主地位将于2016年结束，NASA希望届时能够从数种新的商业载人航天器中选择一种使用，目前这些航天器仍在设计之中。NASA正在寻找一种商业航天出租车服务──所用航天器由私营部门设计、制造和运营，在降低成本的同时加快发展速度。
NASA航天业务副主管William Gerstenmaier说，我们正竭力获得自己的人员运送能力。他还兼任负责管理国际空间站的国际委员会的主席。
自2004年小布什(George W. Bush)总统宣布航天飞机计划结束以来，俄罗斯航天局已经八次提高运送美国宇航员去国际空间站的价格。据NASA一项新的审计报告说，根据最新的合约，到2016年时，“联盟号”上的每个座位将花费NASA 6,300万美元，较2005年上涨175%。
最大幅度的一次涨价将于今年夏季晚些时候生效，届时最后一次航天飞机任务将结束。这就意味着，今年晚些时候，每位美国宇航员乘坐“联盟号”将花费4,340万美元，较上半年涨了57%。
数位美国航天专家说，俄罗斯政府不太可能将目前在向国际空间站运送宇航员的独霸地位作为一种外交施压手段，不过，它肯定会获取商业利益。
俄罗斯人并没有对航天飞机的终结幸灾乐祸。俄罗斯航天局载人计划负责人克拉斯诺夫(Alexei Krasnov)上个月对一家俄罗斯报纸说，就算美国将付钱给我们以使用我们的“联盟号”，放弃航天飞机对俄罗斯来说也没有好处。俄罗斯是国际空间站的一大支持国，他指出，假如没有航天飞机，国际空间站的修建是不可能的。他说，假如航天飞机继续飞行，对我们会更好，即使是每年只有一次。
国际空间站的设计初衷是作为一个向其他星球发送航天器的平台。不过，这一使命转变成了一个绕地球运行的实验室，对人类和其他生物体在失重环境下的表现进行试验。希望藉此对基本生命功能有更多的了解、发现新的医疗方法和疫苗。在很多试验中，需要由人类进行或参与。
NASA
1963年，时任美国总统肯尼迪（右）在卡纳维拉尔角视察。
目前为止，NASA已经买下了2016年底前的46个“联盟号”座位，并希望买更多。NASA官员将涨价归因于通货膨胀和生产更多“联盟号”宇宙飞船所需增加的成本。俄罗斯人建造“联盟号”已经有近40年历史。俄罗斯人一直在不断改进“联盟号”，今年将推出一个新的版本。
今年4月份，NASA向美国五家航天公司总计拨款2.693亿美元，用于开发将人类送往国际空间站的系统。
专家说，其中一家位于加利福尼亚州霍桑市的“空间探索科技公司”(Space Exploration Technologies Corp.)似乎进展地最为深入。该公司承诺建造一个可以重复使用的系统，该系统能以每人最低2,000万美元的成本将七名宇航员送入轨道。这一报价只是大多数未来人员运送预估成本的一小部分。
空间探索公司首席执行长马斯克(Elon Musk)是贝宝（PayPal）和Tesla Motors公司的联合创始人。他说，项目必须要以纳税人愿意支付的价格完成。这意味着NASA能够输送数量多得多的宇航员，其对国际空间站的使用也会更加充分。
Aerospace Corp.进行的一次由NASA赞助的分析则没有那么乐观。Aerospace预测，每一座位的未来运输成本在9,000万美元至1.5亿美元之间。Aerospace Corp.是NASA最有影响力的外部咨询机构之一。
空间探索公司已经和NASA签署了一份总值16亿美元的合同。从明年开始，前者将利用其名为“龙”的试验宇宙飞船和“隼”号(Falcon)火箭为国际空间站运送补给物资。今年4月份，NASA再次给该公司拨款7,500万美元，以便为“龙”号宇宙飞船研发一个弹射逃生系统。这一系统对于“龙”号宇宙飞船正式变成载人运输工具非常重要。
但俄罗斯联邦航天署的官员今年4月警告说，短时间内他们不会允许“龙”号无人宇宙飞船接近国际空间站，也不会允许其在空间站上停靠──直到他们认为飞船安全为止。1997年，因为受到一个货运舱的撞击，俄罗斯和平号(Mir)空间站曾严重受损。
事实上，NASA检察总长上周就警告说，私人公司开发出安全的商用载人系统的时间可能过长，这可能会危及美国对国际空间站的使用。
乔治华盛顿大学(George Washington University)空间政策分析家劳德斯登(John Logsdon)说，如果你押注这些公司中一家或多家能够开发出一种成本可负担、可持续使用的载人系统，那么打赌失败的风险仍然很高；目前来看，美国宇航员只能搭乘俄罗斯的飞船。
事实上，NASA已经行动起来，在俄罗斯载人飞船上为美国宇航员购买了更多座位，以防商业开发继续落后于计划的风险。目前，NASA已经购买的俄罗斯“联盟”号(Soyuz)飞船的座位只能够用到2016年，而且这样做还要求国会解除对俄技术贸易的法律限制。要购买更多的“联盟”号座位，NASA还要获得国会的进一步批准。对此NASA正在申请。
虽然票价越来越高，但和NASA的航天飞机的运行成本相比，“联盟
”号飞船的票价相对较低。这主要是因为两种飞行器采用的载人航天的工程法存在根本不同。“联盟”号在很多方面与美国在上世纪60年代使用的“阿波罗”号(Apollo)登月飞船和“土星”号(Saturn)火箭类似。
相比之下，航天飞机就是由宇航员驾驶的可以重复使用的、加了机翼的宇宙飞船，宇航员可以像驾驶滑翔机那样操纵航天飞机脱离轨道着陆。每一架航天飞机含有250多万个零部件，使用的线缆总长达230英里（约合370公里），并可以在极速、极热、极冷、失重和真空环境下飞行。
上世纪70年代，NASA的航天飞机设计师承诺民用载人宇宙飞行能实现廉价、安全、常规三大目标，以成为人类向其它星球航行的起点。按他们的计划，航天飞机每年最多发射50次。
在30年的飞行中，这些航天飞机把50多颗卫星送进了轨道，将超过300万磅（约合1360吨）的货物和来自16个国家的355名人员送入太空。并发射了行星际探测器和包括哈勃太空望远镜(Hubble Space Telescope)在内的一些重要轨道观测仪。
但在实践中，航天飞机项目从未实现常规、可靠或廉价的目标。航天飞机每次发射成本高达15亿美元，而1972年项目启动时，NASA官员承诺的是每次发射成本1,050万美元，总计发射100次。且NASA也从未接近于实现其设计者曾经预测的发射频率。
没有了可以依赖的航天飞机，NASA管理层匆匆改变了他们运营国际空间站的方式。这些人修改了此前计划的维修方式以及未来10年开展研究的方法。他们计划利用最后几次航天飞机的飞行建设大型备用零部件的存储站，目前给国际空间站运送物资的俄罗斯、欧洲和日本的无人补给飞船无法装下这些大型备用零部件。
最后，美国不得不思考一个颇具讽刺意味的问题：它成功研发出航天飞机，赢得了技术竞赛，但却输掉了这场战争。杜克大学(Duke University)空间历史学家罗兰德(Alex Roland)说，可以这么说，尽管俄罗斯的宇宙飞船离不开又大又笨的助推火箭，但其发展轨道始终是正确的。
Shuttle's Last Flight Leaves Russia With Space Monopoly
Circling the Earth every 90 minutes, the International Space Station is the most expensive project ever assembled in space. Within days, it will hang by a single, costly thread. And Russia, the U.S.'s historic rival in space, is holding it.
The last U.S. space shuttle is scheduled to blast off Friday. After that, the U.S. and other nations will rely on vintage Russian spacecraft to ferry their astronauts to the $100 billion station. Russia will hold a monopoly over manned spaceflight, and tensions already are rising. The Russians are in the process of nearly tripling the cost of using their Soyuz crew capsules for transport to the orbiting base, and other countries have little choice but to pay up.
'We are not in a very comfortable situation, and when I say uncomfortable, that is a euphemism,' said Jean-Jacques Dordain, director general of the European Space Agency, one of five international agencies that jointly manage the orbiting laboratory. 'We made a collective mistake.'
The Soyuz represents the triumph of a low-cost approach to human space exploration. The Russian capsules are launched on massive expendable rockets, carrying astronauts in a kind of guided cannonball to and from orbit. By contrast, the U.S. built its space program around the most complex flying machine ever, the reusable space shuttle. While the U.S. has spent $209.1 billion on the space shuttle since its inception, the entire Russian space program currently costs just $2 billion a year.
'Today, reusable ships are a very expensive pleasure, and economically they're not really justified,' Vladimir Popovkin, the newly appointed head of Roskosmos, the Russian space agency, told a Russian newspaper last month. Officials at Roskosmos didn't provide comment for this article.
The Russian monopoly on manned spaceflight won't last forever. If all goes as NASA plans, the Russian monopoly will end in 2016 when the agency hopes to take its pick of several new commercial crew transports currently on the drawing board. NASA is now seeking a commercial space-taxi service─designed, built and operated by the private sector─to cut costs while speeding the pace of development.
'We are working aggressively to get our own crew capability,' said William Gerstenmaier, NASA's associate administrator for space operations, the chairman of the international board that oversees the space station.
Since President George W. Bush announced the end of the space-shuttle program in 2004, the Russian space agency has increased the price of taking U.S. astronauts to the space station eight times. By terms of the latest contract, each seat on a Soyuz crew capsule will cost NASA $63 million by 2016─a 175% price increase since 2005, according to a new agency audit.
The largest single price increase takes effect later this summer, coinciding with the conclusion of the last space-shuttle mission. It will cost U.S. astronauts $43.4 million apiece to fly aboard the Soyuz later this year, a 57% increase from the first-half cost.
The Russian government is unlikely to use its current monopoly over access to the space station as a diplomatic pressure point, but it would certainly take commercial advantage, several U.S. space experts said.
The Russians haven't crowed over the demise of the space shuttle. Alexei Krasnov, head of manned programs at Roskosmos, told a Russian newspaper last month, 'Even though the U.S. will be paying us to use our Soyuzes, giving up the shuttles isn't good for Russia.' His country is a big backer of the International Space Station, and he noted that it would have been impossible to build the station without space shuttles. 'It would be better for us if the shuttles continued to fly, even just once a year,' he said.
The space station was originally conceived as a platform for sending spacecraft to other planets. But its mission has changed into an orbiting laboratory to conduct experiments on how humans and other organisms fare in a low-gravity environment. The hope is to understand more about basic life function and to discover new medical treatments and vaccines. And humans are needed to conduct, or be participants in, many of these experiments.
So far, NASA has purchased 46 seats for Soyuz flights through 2016, and it wants to buy more. NASA officials attribute the price hikes to inflation and the increased cost of making more Soyuz spacecraft, which the Russians have been manufacturing for almost 40 years. The Russians have continued to tweak the Soyuz, and have a new version coming out this year.
In April, NASA awarded a total of $269.3 million to five U.S. aerospace companies to develop systems for transporting humans to the space station.
One of them─-Space Exploration Technologies Corp., based in a Hawthorne, Calif.─-appears to be furthest along, experts said. It pledged to build a reusable system that could ferry seven astronauts into orbit for as little as $20 million each─a fraction of most forecasts of future crew-transport costs.
'It has to be done for an amount of money that taxpayers are willing to pay,' said Space Exploration Chief Executive Elon Musk, who co-founded PayPal and Tesla Motors. 'That should allow NASA to transport a much greater number of astronauts and to get much more use out of the space station.'
A NASA-sponsored analysis by Aerospace Corp., one of the agency's most influential outside advisers, is less sanguine. It forecast future transportation costs at $90 million to more than $150 million per seat.
Space Exploration already has a $1.6 billion NASA contract to ferry supplies to the space station using its experimental Dragon spacecraft and its Falcon rocket, beginning next year. In April, NASA awarded the company an additional $75 million to build a launch-escape system for the Dragon spacecraft─a key component in converting it into a crew transport.
Officials at Roscosmos, however, warned in April they wouldn't let the unmanned Dragon spacecraft fly near the space station or dock with it any time soon─not until they deem it safe. In 1997, Russia's Mir space station was badly damaged when a cargo module slammed into it.
Indeed, NASA's inspector general last week warned that private companies may take so long to develop safe commercial crew transportation that it could threaten U.S. access to the space station.
'It is still a very risky bet that one or more of these companies can come up with an affordable and sustainable way for crew transport,' said George Washington University space-policy analyst John Logsdon. 'For the time being, American astronauts will be taking Russian taxis.'
In fact, NASA is already moving to buy more seats for U.S. astronauts aboard Russian crew capsules in case commercial development continues to fall behind schedule. Currently, NASA has purchased seats on the Russian Soyuz only through 2016, and doing so required a congressional waiver of legal limits on technological trade with Russia. To purchase more Soyuz seats, the agency will need additional congressional approval, which it is seeking.
Despite its rising ticket price, the Soyuz capsule is a relative bargain compared to the cost of the NASA space shuttle, largely because the vehicles represent radically different engineering approaches to human spaceflight. In many ways, the Soyuz resembles the Apollo moon capsules and Saturn rockets used by the U.S. in the 1960s.
By contrast, the space shuttle is a reusable winged spacecraft piloted by astronauts who can land it from orbit like a glider. Each shuttle contains more than 2.5 million parts and 230 miles of wiring, operating at extremes of speed, heat, cold, gravity and vacuum.
Working in the 1970s, NASA's shuttle designers promised to make civilian manned spaceflight cheap, safe and routine─ a jumping-off point for human voyages to other planets. Shuttle missions would be launched up to 50 times a year.
In 30 years of flights, the crafts deployed more than 50 satellites into orbit. They carried more than three million pounds of cargo and 355 people from 16 countries into space. They launched interplanetary probes and major orbital observatories, including the Hubble Space Telescope.
In practice, however, the space-shuttle program was never routine, reliable or cheap. A shuttle launch cost $1.5 billion─100 times the $10.5 million dollars each that NASA officials promised at the start of the program in 1972. And the agency never came close to achieving the launch rates its designers had predicted.
Without the shuttle to rely on, NASA managers have scrambled to revamp the way they operate the space station. They revised the way they plan to repair it and conduct research there in the decade to come, using their last space-shuttle flights to build up orbiting caches of large spare parts that can't fit aboard unmanned Russian, European or Japanese supply craft that currently supply the station.
In the end, the U.S. is left to ponder an irony: It won the technological race to develop a space shuttle but lost the war. 'You can argue that the Russians were on the right trajectory all along, by flying big, dumb boosters,' said Duke University space historian Alex Roland.
Robert Lee Hotz
