A bold satellite rescue mission came together in record time, but will it work?
A bold satellite rescue mission came together in record time, but will it work?
一项大胆的卫星救援任务在创纪录的时间内完成，但它能成功吗？
WALLOPS ISLAND, Virginia—Just 10 months ago, NASA asked three companies if they could do something nobody had done before. Could they build and launch a satellite to save a $500 million astronomy mission at risk of crashing back to Earth? What’s more, could they do it in less than a year on a tight budget? 弗吉尼亚州瓦勒普斯岛——就在10个月前，美国国家航空航天局（NASA）询问了三家公司，看他们是否能完成一项前所未有的任务。他们能否建造并发射一颗卫星，以拯救一项价值5亿美元、面临坠回地球风险的天文任务？更重要的是，他们能否在不到一年的时间内，在预算紧张的情况下完成这项任务？
Katalyst Space Technologies, a startup founded in 2020, presented the most compelling solution. “They came back with a response that was technically and programmatically plausible, and then we were like, ‘Yeah, let’s do it,’” said Shawn Domagal-Goldman, director of NASA’s astrophysics division. That was in August of last year. In September, NASA awarded Katalyst a $30 million contract to build, test, and launch a small satellite to chase down Swift and latch onto it with three robotic arms. Then, Katalyst’s Link servicing spacecraft will boost Swift’s orbit back to a safe operating altitude, allowing it to resume scientific observations. Easier said than done. 成立于2020年的初创公司Katalyst Space Technologies提出了最具说服力的方案。NASA天体物理学部主任肖恩·多马加尔-戈德曼（Shawn Domagal-Goldman）表示：“他们给出的回应在技术和项目规划上都是可行的，当时我们就想，‘好，就这么干。’”那是去年8月的事。9月，NASA授予Katalyst一份价值3000万美元的合同，要求其建造、测试并发射一颗小型卫星，去追赶“雨燕”（Swift）卫星，并利用三只机械臂将其抓住。随后，Katalyst的“链路”（Link）服务航天器将把“雨燕”的轨道提升回安全运行高度，使其能够恢复科学观测。说起来容易做起来难。
Reaching the finish line
冲向终点线
The Swift observatory is flying in low-Earth orbit, where the outermost layers of the atmosphere still exert some aerodynamic influence on satellites. The spacecraft launched in November 2004 on a mission to detect gamma-ray bursts, the most powerful explosions in the known Universe. Despite its age, astrophysicists still rely on Swift’s multi-wavelength instruments to identify and locate gamma-ray bursts for follow-up observations by other observatories. But there’s a hitch. Swift lacks any thrusters to maintain its orbit, so aerodynamic drag has gradually caused its altitude to decay. “雨燕”天文台目前在近地轨道飞行，大气层的最外层仍会对卫星产生一定的空气动力学影响。该航天器于2004年11月发射，任务是探测伽马射线暴——这是已知宇宙中最强大的爆炸。尽管“雨燕”已服役多年，但天体物理学家仍依赖其多波段仪器来识别和定位伽马射线暴，以便其他天文台进行后续观测。但问题在于，“雨燕”缺乏维持轨道的推进器，因此空气阻力已导致其高度逐渐下降。
The observatory launched into an orbit roughly 363 miles (585 km) above the Earth. As of Thursday, Swift was flying at 225 miles (363 km). The decay rate will increase as the spacecraft dips into denser layers of the atmosphere until Swift finally burns up during reentry. Swift is losing altitude faster than anticipated due to a period of extraordinary solar activity in recent years. An active Sun puffs up Earth’s atmosphere, creating higher drag for satellites in low-Earth orbit. 该天文台发射时的轨道高度约为363英里（585公里）。截至周四，“雨燕”的飞行高度已降至225英里（363公里）。随着航天器进入大气层更稠密的区域，其轨道衰减速度将加快，直到最终在重返大气层时烧毁。由于近年来太阳活动异常活跃，“雨燕”的高度下降速度比预期的要快。活跃的太阳会使地球大气层膨胀，从而对近地轨道上的卫星产生更大的阻力。
Satellites and space debris routinely reenter the atmosphere, and most of Swift is likely to burn up before it falls to Earth’s surface. “But this was not just any spacecraft,” Domagal-Goldman said. “This is an observatory with unique capabilities for astrophysics, similar to what its name would imply. It is a swift observatory that can quickly pivot across the night sky to find things that go boom in the night … So we decided, yeah, we want to go save this one, this time, because of how special it is. But then we had a different challenge of time was running out.” 卫星和太空碎片经常重返大气层，“雨燕”的大部分结构很可能在坠落到地球表面之前就会烧毁。多马加尔-戈德曼说：“但这不仅仅是普通的航天器。这是一个在天体物理学方面具有独特能力的天文台，正如其名（Swift意为‘雨燕’或‘迅速的’）。它是一个能够迅速转向夜空，寻找夜间爆炸现象的敏捷天文台……所以我们决定，是的，这次我们要去拯救它，因为它太特别了。但随后我们面临了另一个挑战：时间不多了。”
NASA engineers estimate Swift will fall below an altitude of 186 miles (300 km) this fall—perhaps around October. At that altitude, Swift will be too low for Katalyst to safely approach it due to the effects of increasing drag. NASA gave Katalyst less than a year to design and build the satellite. The Swift rescue mission had to launch before the end of June. NASA工程师估计，“雨燕”将在今年秋季（可能在10月左右）降至186英里（300公里）以下的高度。在该高度，由于阻力增加，Katalyst将无法安全接近它。NASA只给了Katalyst不到一年的时间来设计和制造这颗卫星。“雨燕”救援任务必须在6月底之前发射。
“To be honest, no one thought it was going to be possible. No one thought we would get as far as we’ve already gotten today,” Domagal-Goldman said. “And I have to be honest, there are still risks ahead of us, but I’m both deeply thankful and as optimistic as I can be that we’ll meet those challenges because of the people that have worked on it.” “老实说，没人认为这可能实现。没人想到我们今天能走到这一步，”多马加尔-戈德曼说。“我必须坦诚，前方仍有风险，但我深表感激，同时也尽可能保持乐观，因为参与这项工作的人员，我相信我们能够应对这些挑战。”
Katalyst’s Link servicing spacecraft is now complete and ready for launch, a prospect that wasn’t a given just a few months ago, when Ars visited the company’s factory in Colorado. At that time, engineers were racing to piece together the Link satellite from a mix of structural components, fuel tanks, solar arrays, thrusters, and robotic arms designed to grab onto Swift more than 200 miles above the planet. It all came together just in time. Katalyst的“链路”服务航天器现已完成并准备发射。就在几个月前，当Ars（媒体）访问该公司位于科罗拉多州的工厂时，这还不是板上钉钉的事。当时，工程师们正争分夺秒地将结构组件、燃料箱、太阳能电池阵列、推进器和旨在在地球上方200多英里处抓住“雨燕”的机械臂组装在一起。一切都在最后关头完成了。
Katalyst shipped the Link satellite from its Colorado factory to NASA’s Goddard Space Flight Center in Maryland for a battery of thermal vacuum and vibration tests this spring to simulate the environments it will see in space and during launch. Then the satellite shipped to NASA’s Wallops Flight Facility in Virginia for integration with its ride to space: Northrop Grumman’s Pegasus XL rocket. 今年春天，Katalyst将“链路”卫星从科罗拉多州的工厂运送到马里兰州的NASA戈达德太空飞行中心，进行了一系列热真空和振动测试，以模拟其在太空和发射过程中将面临的环境。随后，卫星被运往弗吉尼亚州的NASA瓦勒普斯飞行设施，与它的太空座驾——诺斯罗普·格鲁曼公司的“飞马座XL”（Pegasus XL）火箭进行集成。
The Pegasus XL is an air-launched vehicle. It releases from a modified commercial airliner at about 39,000 feet, then ignites a series of three solid-fueled rocket motors to climb and accelerate into orbit. After 45 missions since 1990, this is the final Pegasus rocket scheduled to fly. Katalyst selected the Pegasus XL largely for its mobility. Swift is in an unusual orbit that takes the observatory between 20 degrees north and south latitude on each trip around the Earth. That makes Swift hard to reach from a launch pad at Cape Canaveral, Florida, without a dedicated launch on an oversized, more expensive rocket. “飞马座XL”是一种空射运载火箭。它在约39,000英尺的高空从改装的商用客机上释放，随后点燃三级固体燃料火箭发动机，爬升并加速进入轨道。自1990年以来，该型号已执行了45次任务，这是最后一枚计划飞行的“飞马座”火箭。Katalyst选择“飞马座XL”主要是看中其机动性。“雨燕”处于一个不同寻常的轨道上，每次绕地球飞行时，其纬度都在北纬20度和南纬20度之间。这使得从佛罗里达州卡纳维拉尔角的发射台很难到达“雨燕”，除非使用超大型且更昂贵的火箭进行专门发射。
The Link spacecraft, weighing just under a half-ton at launch, fits snugly within the Pegasus rocket’s payload fairing. Northrop Grumman’s L-1011 carrier jet will transport the 58-foot-long (18-meter) Pegasus rocket with the Link servicing satellite to a location over the remote equatorial Pacific Ocean near Kwajalein Atoll in the Marshall Islands. The multi-day journey to Kwajalein from the Pegasus integration base in Virginia began Thursday with the L-1011’s departure from Wallops. Launch is scheduled for June 27. “链路”航天器发射时重量不到半吨，可以紧密地安装在“飞马座”火箭的有效载荷整流罩内。诺斯罗普·格鲁曼公司的L-1011载机将把这枚58英尺（18米）长的“飞马座”火箭连同“链路”服务卫星，运送到马绍尔群岛夸贾林环礁附近偏远的赤道太平洋上空。从弗吉尼亚州的“飞马座”集成基地前往夸贾林的多日旅程已于周四随着L-1011从瓦勒普斯起飞而开始。发射定于6月27日进行。
Doing the impossible
完成不可能的任务
It would normally take several years for a satellite of Link’s complexity to be designed, manufactured… 通常情况下，设计和制造像“链路”这样复杂的卫星需要数年时间……