人类登月60周年：回顾首次登月时的重大险情

荷马·阿尔并未登上过月球。

但是阿尔和他在IBM的几千名同事，以及美国国家航空航天局（NASA）的地勤人员们，却以另一种特殊的方式，在人类的登月史上留下了印记。他们是一群默默无闻的计算机专家，然而没有他们，阿波罗11号飞船上的宇航员们就不可能在1969年7月20日成功登月，之后活着返回地球。没有这些与美国政府签约的工程师、技师、分析师和程序员，就不可能成就载人航天这一壮举。

现任IBM研究部门执行副总裁的约翰·凯利表示：“NASA把一切都押在了我们身上，我们也把一切都押在了他们身上。”他还记得自己十几岁时，在电视上看到登月成功的画面的场景。“如果当时出了什么问题，如果计算机出了故障，那天肯定不会是开心的一天。”

实际上，那天的确出了一些问题，好在它并未严重到毁掉人类历史上的这次壮举。

《财富》杂志近日采访了前IBM公司数学家、软件程序员阿尔。在阿波罗11号载人登月任务期间，他就在NASA位于休斯顿的约翰逊航天中心工作。阿尔今年73岁，已经退休了。采访中，他向《财富》杂志批露了这次登月任务中发生的一个几乎葬送了整个任务的重大险情。

起步

阿尔于1968年加入了IBM，也就是阿波罗11号任务的前一年，那年他才21岁。作为一名少年老成的工程师和一名刚毕业的大学生，他毅然拒绝了为得克萨斯州的一家大型建筑公司写软件的工作，决定到NASA去实现自己的抱负。而IBM公司刚好满足了他的三大标准：工作有挑战性、能报效国家、工作地点在得州。

同年12月，阿尔完成了他在NASA的第一个大项目——为阿波罗8号编写飞控软件。阿波罗8号也是人类第一艘实现了载人绕月飞行并返回的飞船。飞船的操作有相当一部分是在他的帮助下完成的。他回忆道：“我可能是控制台里最年轻的人了——甚至可能是整个休斯顿飞行系统部门里最年轻的一个。”

在经过了7个月和4次发射任务后，NASA终于做好了登月的准备——阿尔也是一样。他负责向IBM的电脑里输入指令，这些指令最终会被传输到阿波罗11号飞船上，由飞船上的宇航员执行。

阿尔说道：“肯尼迪的想法是把一个人送上月球，然后把他安全地带回家，但是后半部分被很多人忘掉了。不过我向你保证，那些为任务控制中心编写软件的人，和那些在任务控制中心里工作的人，无时无刻都在想着这件事的重要性。”

奔月

NASA征用了IBM在纽约州奥韦戈的联邦业务部门，用于制造和运行登月任务的指挥控制仪器以及计算器。这些仪器主要用于收集火箭遥测数据，确定飞行路径，并且为美国航天项目的“水星计划”、“双子星计划”和“土星计划”改进轨道。到1966年，IBM已经应用了现在十分著名的System/360 Model 75系列计算机。正是该系列计算机的成功，开启了IBM电脑的黄金时代。

“这些新计算机的性能是‘双子星计划’所使用的计算机的三倍（NASA在“双子星”计划时使用的是前一代的IBM 7094 II型计算机），计算能力是‘水星计划’所使用的计算机系统的50多倍。”当年的一份IBM公司的档案如是说。

这种技术水平在当时虽然很了不起，但跟现在我们习以为常的技术相比，却相形见绌。比如光是一部苹果iPhone的计算能力，就比安装在阿波罗飞船的控制舱和登月舱上的制导计算机还要强大几百万倍。

就在阿波罗11号开始向月面降落，即将迈出“人类的一大步”的关键时刻，危机陡然发生了。阿尔回忆道：“飞船里响起了警报声，场面非常混乱，在你耳朵里响个不停。”

阿尔先是在耳机里听到了警报声。很快，任务控制中心里警灯闪烁，警报声大作——出大事了！

大家起初并不清楚是什么触发了警报。不过阿尔的团队已经排练过类似场景很多次了。他回忆到，他的团队当时每周要演练3天，每天进行12次预案模拟，连续演练了3个月，总共进行了400多次测试。很多试验故意设置了一些难题，比如在推进器失灵的情况下应该怎么办——当然，90%的情况下都只有放弃任务这一条路。

回忆起当时IBM的计算机大楼里压抑的气氛，阿尔说道： “那一瞬间，我感觉整个30号楼里的空气都被抽干了，因为任务在不应该的情况下被要求终止了。你绝对不希望发生这种事。”

然而演习跟真正的战斗终归不是一回事。“在真正的任务中发生这种事，总是会更加混乱，更加有压力，更令人不安。”他补充道。

登陆

即便是对于这些在当时看来全新的技术，最终的发言权也依然在人类手中。

阿波罗任务的首席飞控总监吉恩·克兰兹曾经要求NASA的计算机与航电专家杰克·加尔曼写下飞船所有可能的故障情形和应对预案（加尔曼也曾经在IBM的电脑上训练过）。加尔曼拿出了那张预案表格研究了一会儿，最终决定任务应该继续。

阿尔回忆道：“警报第一次响了10到15秒钟后，他才说道：‘继续执行。’然后警报一次次地再度响起。”警报每响起一次，阿波罗任务的登月舱朝月球表面的下降速度就加快一分。不过加尔曼仍然向上级表示应该继续执行任务。

最后，大家终于明白发生了什么——飞船上的计算机超载了。由于某些故障，计算机试图处理的数据，超出了自身所能处理的极限。计算机无法完成所有要求它们完成的任务，便触发了警报。（《探索》杂志对此做了很好的科学解释。）

“从轨道的角度看，除了继续前进，没有别的选择。”阿尔说：“登月舱降落得很成功，如果我们取消了任务，那将是一场悲剧。”

人类的一大步

当他回忆起50年的事时，他好几次强行抑制住自己的情绪。他说，回想起这段往事，他的感觉就像二战老兵回忆起诺曼底登陆一样。在收看上个月的诺曼底登陆纪念活动时，一种想法击中了他。“我的眼睛湿润了，哽咽了起来。这种感觉跟我谈论起飞船的着陆、降落、海上降落这些事时的感觉是一样的。”

“我觉得7月20日就是我们的‘诺曼底登陆日’。”他激动地说：“这一天，我们将人类从地球上解放了出来，人类实现了在另一个天体上行走。我们将人类从地球的束缚中解放了出来。”

今天的科学家则希望把火炬传递得更远。IBM研究部门执行副总裁约翰·凯利表示，阿波罗11号登月任务“是一项惊人的成就。这个国家所冒的风险，NASA所冒的风险，IBM所冒的风险——这些宇航空将自己绑在一个火箭上，飞跃25万英里，到一块冰冷的石头上——都是惊人的。”

凯利也赞扬了IBM和NASA这种公立部门和私营企业间的合作关系。“作为企业，作为国家，我们需要多一点这样的合作。不仅仅是渐进性的合作，而是要做一些真正的反省。我们承担足够的风险了吗？我们准备好去登月了吗？我们准备好真的去攻克癌症了吗？我们准备好去解决环境问题了吗？我们有勇气和必要的手段去解决这些问题吗？”

“人类可以做到几乎任何事。”凯利补充道：“只要他们下定决心。”（财富中文网）

译者：朴成奎

Homer Ahr never stepped foot on the Moon.

But Ahr (pronounced “are”) along with thousands of his International Business Machines colleagues and on-the-ground partners in NASA, made their mark on history another way. They were the unsung computer whizzes responsible, on July 20, 1969, for helping Apollo 11’s astronauts touch down on the lunar surface—and return home to Earth, alive. Without these government contracted engineers, technicians, analysts, and coders, that miracle of a manned moonshot surely would have failed.

NASA “bet everything on us and we bet everything on them,” says John Kelly, now executive vice president of IBM’s research division, who remembers watching a televised broadcast of the lunar landing as a teenager. “If something had gone wrong, if those computers had failed, it would not have been a happy day.”

In fact, something did go wrong. But not wrong enough to ruin one of the greatest achievements in human history.

Fortune spoke to Ahr, a former IBM mathematician and software programmer who worked at NASA’s Johnson Space Center in Houston during the Apollo 11 mission, about his experience. (From a perch near his self-described “mancave” in Texas, he introduces himself over the phone as Homer, “like a homerun.”) Ahr, now 73-years-old and retired, described for Fortune an unsettling incident that almost derailed that momentous occasion.

The first steps

Ahr joined IBM in 1968 at age 21, a year before the Apollo 11 flight. A precocious engineer and recent college graduate, he had turned down a lucrative gig writing software for one of Texas’s biggest construction companies to work for NASA. A job with Big Blue met his criteria: Do something challenging; do something for the country; and do it in Texas.

Ahr made his first mark in December of that year writing code for the Apollo 8 flight, the first crewed mission to orbit the Moon and return. His instructions helped the spacecraft maneuver. “I was probably the youngest person on the console—maybe the youngest person in FSD [flight systems division] Houston,” Ahr says.

Seven months and four missions later, NASA was ready for its moonshot—and so was Ahr. He was responsible for inputting commands into IBM’s computers that ultimately would be transmitted to the Apollo 11 spacecraft to be executed by the astronauts on board.

“Kennedy’s vision was to land a man on the Moon—and bring him home safely. That latter part gets forgotten by a lot of people,” Ahr says. “But I guarantee you the people writing software for Mission Control Center and the people in Mission Control Center lived every day of our lives knowing just how important that was.”

Big Blue moon

NASA tapped IBM’s federal business, based in Owego, N.Y., to build and run the command-and-control machines and calculators needed to collect rocket telemetry, determine flight paths, and redirect trajectories for the space program’s Mercury, Gemini, and Saturn series of missions. By 1966, IBM had installed its now-famous System/360 Model 75 computers, the super-popular mainframe that kicked off and defined the company’s golden era.

“These new computers are three times more powerful than the Gemini installation”—which used IBM 7094 II computers, a predecessor—“and more than 50 times the power of the computing system which supported the Mercury program,” a contemporary document from IBM’s archives says.

While the technology was cutting edge for the time, the systems were far less capable than the technology we’re familiar with today. An Apple iPhone, for instance, is millions of times more powerful than the guidance computers installed on the Apollo mission’s command and lunar modules.

But as the Apollo 11 mission neared the moment of truth, beginning its descent toward the lunar surface, crisis struck. “Audible alarms went off in the spacecraft,” Ahr recalls. “It was very chaotic. It was going off in your ears.”

Ahr first heard the sirens through his hands-free headset. Soon, alarms and flashing lights began to go off inside Mission Control Center. Something had gone wrong.

It wasn’t immediately clear what tripped the buzzers. But Ahr’s team had rehearsed similar scenarios—a lot. The group had run simulations 12 times a day, three times a week, for three months, summing to more than 400 test runs total, he says. The trials, many of which involved intentionally suboptimal circumstances, like what to do in the event that a thruster malfunctioned, ended in abortion as much as 90% of the time, Ahr estimates.

“We knew what it felt like for the air to be sucked out of building 30 because an abort had been called when it shouldn’t have,” Ahr says, referring to the instant onset of depression that befell workers inside the facility where IBM’s so-called real-time computer complex, the mechanical brains of the mission, was housed, when a test-run went awry. “Boy, you don’t want to do that.”

But practice is no match for game day. “It’s always more chaotic or emphatic or disconcerting when it happens during a real mission,” Ahr adds.

Go for moon landing

Even in the midst of all this then-new technology, humans had the final say.

Jack Garman, a NASA computer specialist and avionics expert trained on IBM’s computers, had been asked by Gene Kranz, the mission's chief flight director, to write down all possible error conditions to prepare for any contingency. Garman, who died in 2016, studied a table he had written down which described all the failure modes and what to do about them as the alarms blared. Looking over the alerts, he determined that the mission should proceed.

“It took 10-to-15 seconds the first time [the alarm] occurred for him to say ‘Keep going,’” Ahr remembers. “Then it happened again and again and again.” Each time an alarm triggered, as the Apollo mission’s lunar module descended faster toward the Moon’s surface, Garman told his superiors to continue the mission.

Eventually, people got a grip on what had happened: Onboard computers were overloaded. Due to some error, the machines were trying to process more data than they could handle. Because the computers couldn’t accomplish all the tasks asked of them, they sounded off. (Discover Magazine has a good technical explanation.)

“From a trajectory standpoint there was no other call but to keep going,” Ahr says. “It was a good descent. It would have been a travesty if we had aborted.”

One giant leap

As he recollects the events that transpired fifty years ago, Ahr has to stifle an upwelling of emotion. He compares his response to the reactions veterans might have when looking back on the invasion of Normandy during World War II. While watching a commemoration of the D-Day landing last month, a thought struck him. “I started getting teary-eyed and choked up the same way I do when I talk about landings, splashdowns, or descents,” he says.

“I got to thinking that July 20th was our D-Day,” Ahr continues, audibly moved. “It was the day we liberated mankind from just walking on the Earth. We walked on another celestial body. We liberated man from the bounds of the Earth—for good. ”

Today’s scientists hope to carry the torch further. The Apollo 11 mission “was an incredible accomplishment,” says IBM Research’s Kelly. “The risks that the country took, that NASA took, that IBM took—these astronauts strapped themselves onto a rocket to go a quarter million miles to a cold piece of rock—is just amazing.”

Kelly praises the gamble of a public-private partnership that IBM and NASA forged. “We as companies and countries need to do more of that. Not just the incremental—we need to do some real soul-searching,” he says. “Are we taking enough risks? Are we going for the Moon? Are we going to try to really cure cancer? Are we really going to try to understand what’s going on with the environment? And do we have the guts and wherewithal to do it?”

“Humans can do almost anything,” Kelly adds, “if they put their minds to it.”