The Roman telescope has enough gas for 22 years, double NASA’s expectations

罗曼太空望远镜燃料足以维持22年，是NASA预期的两倍

NASA’s Nancy Grace Roman Space Telescope is gliding toward its distant observation post on a pinpoint trajectory so precise that engineers estimate the spacecraft’s fuel load will last twice as long as their initial expectations, the space agency confirmed Monday. 美国国家航空航天局（NASA）周一证实，南希·格雷斯·罗曼太空望远镜（Nancy Grace Roman Space Telescope）正以极其精准的轨道向其遥远的观测点滑行。工程师估计，该航天器的燃料储备将比最初预期多出一倍。

The $4.3 billion observatory’s designers originally planned to load enough propellant into Roman’s four fuel tanks for a minimum lifetime of five years, plus a potential five-year mission extension. That was a conservative estimate. NASA officials knew an on-target launch and perfect execution of the observatory’s first post-launch course correction maneuver would leave Roman with a hearty fuel reserve. 这座耗资43亿美元的天文台，其设计者最初计划在罗曼望远镜的四个燃料箱中装载足够的推进剂，以支持至少5年的任务寿命，外加5年的潜在任务延长期。这是一个保守的估计。NASA官员深知，如果发射精准且发射后的首次轨道修正机动执行完美，罗曼望远镜将留有充足的燃料储备。

“As a result of exquisite planning by our orbital dynamics team, brilliant execution by the operations team, and a precise launch from SpaceX, Roman has fuel for at least 22 years of potential science operations,” Jamie Dunn, center director at NASA’s Goddard Space Flight Center, said in a press release. “得益于我们轨道动力学团队的精心规划、运营团队的出色执行，以及SpaceX的精准发射，罗曼望远镜目前拥有的燃料足以支持至少22年的潜在科学运行，”NASA戈达德太空飞行中心主任杰米·邓恩（Jamie Dunn）在新闻稿中表示。

The James Webb Space Telescope received a similar lifetime boost after a picture-perfect launch on a European Ariane 5 rocket in 2021. The Roman telescope launched August 30 from NASA’s Kennedy Space Center in Florida aboard a SpaceX Falcon Heavy rocket, kicking off a mission to widen our view of the Universe. 詹姆斯·韦伯太空望远镜在2021年搭乘欧洲阿丽亚娜5号火箭完美发射后，也获得了类似的寿命延长。罗曼望远镜于8月30日搭乘SpaceX的猎鹰重型火箭，从佛罗里达州的NASA肯尼迪航天中心发射升空，开启了旨在拓宽人类宇宙视野的任务。

Roman’s telescope and scientific instruments will provide astronomers with images of the sky at the same resolution as NASA’s Hubble Space Telescope, but with 100 times the field of view. It would take Hubble a century to observe what Roman will see in a month. Astronomers hope Roman’s broad vision will reveal insights into the largest structures in the Universe. 罗曼望远镜及其科学仪器将为天文学家提供与哈勃太空望远镜分辨率相当的天空图像，但其视场却是后者的100倍。哈勃望远镜需要一个世纪才能完成的观测任务，罗曼望远镜只需一个月即可完成。天文学家希望罗曼广阔的视野能揭示关于宇宙最大结构的深刻见解。

Roman’s Wide Field Instrument, fitted with 18 near-infrared detectors, will produce images equivalent to those of a 300-megapixel camera. Its wide viewing area will allow Roman to map galactic clusters, along with the filaments of matter and dark matter that string through the cosmos. Mapping so much of the sky could help astronomers study the nature of dark energy, scientists’ name for the elusive force driving the acceleration of the Universe. 罗曼望远镜的广角仪器配备了18个近红外探测器，将产生相当于3000万像素相机的图像。其广阔的观测区域将使罗曼能够绘制星系团，以及贯穿宇宙的物质和暗物质丝状结构。绘制如此大范围的天空图，有助于天文学家研究暗能量的本质——这是科学家对驱动宇宙加速膨胀的那种难以捉摸的力量的称呼。

Right on the money

精准到位

The Falcon Heavy released Roman on a trajectory that will take it a million miles from Earth, where the spacecraft will loop into a “quasi-halo” orbit around the Sun-Earth L2 Lagrange point, a point of balance between the gravitational pull of Earth and the Sun. It will take Roman about three months to reach L2. 猎鹰重型火箭将罗曼望远镜送入了一条通往距离地球100万英里处的轨道。在那里，航天器将进入围绕日地拉格朗日L2点的“准晕”轨道，这是一个地球和太阳引力之间的平衡点。罗曼望远镜大约需要三个月的时间才能到达L2点。

The launch was so accurate that the first big burn with Roman’s control thrusters, executed one day into the mission, consumed just 40 pounds (18 kilograms) of hydrazine fuel, down from the preflight allocation of 441 pounds (200 kilograms), NASA said. NASA表示，此次发射非常精准，任务执行第一天进行的罗曼控制推进器首次大推力点火，仅消耗了40磅（18公斤）肼燃料，远低于飞行前预留的441磅（200公斤）。

“I do thank SpaceX for putting us down the middle. It’s going to help us in terms of long-duration performance, how long we can stay at L2, as well as our positioning capability,” said Amit Kshatriya, NASA’s associate administrator, during a talk Tuesday at the American Astronautical Society’s Glenn Space Technology Symposium. “我非常感谢SpaceX将我们精准送入轨道。这将在长期性能、我们在L2点的停留时间以及我们的定位能力方面为我们提供巨大帮助，”NASA副局长阿米特·克沙特里亚（Amit Kshatriya）周二在美国宇航学会格伦空间技术研讨会上说道。

Roman launched nine months ahead of the schedule set by NASA during the mission’s confirmation review in 2020. It also launched lighter than planned. Both are rather unusual in the annals of NASA science missions. The observatory’s actual weight at completion was 17,760 pounds (8,056 kilograms), approximately two tons less than its maximum allowable weight. 罗曼望远镜的发射时间比NASA在2020年任务确认审查时设定的时间提前了九个月。此外，它的发射重量也比计划更轻。这两点在NASA科学任务史上都相当罕见。该天文台完工后的实际重量为17,760磅（8,056公斤），比其最大允许重量轻了约两吨。

This allowed ground crews at Kennedy Space Center to load 290 gallons of hydrazine into Roman’s fuel tanks, more than engineers anticipated early in the mission’s design phase. The hydrazine feeds 24 thrusters scattered around the outside of the observatory. At launch, the fully fueled Roman observatory weighed 20,224 pounds (9,173.5 kilograms), still a half-ton below its weight limit, a NASA spokesperson told Ars. 这使得肯尼迪航天中心的地面人员能够向罗曼的燃料箱中注入290加仑的肼，这比工程师在任务设计初期预期的要多。这些肼燃料供应给分布在天文台外部的24个推进器。一位NASA发言人告诉Ars，发射时，加满燃料的罗曼天文台重20,224磅（9,173.5公斤），仍比其重量限制低了半吨。

In addition to the extra fuel, Roman’s lower mass meant its thrusters did not have to fire as long for the course correction maneuver the day after launch. 除了额外的燃料外，罗曼较低的质量意味着其推进器在发射后第二天的轨道修正机动中无需点火太久。

“A spacecraft’s mass changes throughout the design and build process, so we base the propellant budget on a set maximum value so we won’t come up short,” said Alison Rao, the Roman propulsion lead at NASA Goddard. “We track the propellant needed based on actual mass throughout integration and testing as well, to make sure we have wiggle room. Since Roman’s was lower than we budgeted for, we were able to fill the propellant tanks to their capacity rather than only filling them as much as we needed to for the 10-year requirement.” “航天器的质量在设计和建造过程中会发生变化，因此我们将推进剂预算设定在一个最大值，以确保不会出现燃料不足的情况，”NASA戈达德中心的罗曼推进负责人艾莉森·拉奥（Alison Rao）表示。“我们也会在整个集成和测试过程中根据实际质量跟踪所需的推进剂，以确保有回旋余地。由于罗曼的实际质量低于我们的预算，我们能够将推进剂箱加满，而不是仅仅加注满足10年任务需求所需的量。”

A second course correction planned for later this month will give Roman the last tiny boost to get into position for another maneuver in early December to slip into its final orbit at L2. “According to current projections, both maneuvers will use less fuel than planned, potentially saving even more for future science,” NASA said. 计划于本月晚些时候进行的第二次轨道修正将为罗曼提供最后一点推力，使其进入预定位置，以便在12月初进行另一次机动，从而进入L2点的最终轨道。“根据目前的预测，这两次机动消耗的燃料都将少于计划，这可能会为未来的科学任务节省更多燃料，”NASA表示。

Roman’s thrusters will perform additional station-keeping burns roughly every 28 days. The observatory will also use its propulsion system to periodically unload momentum from its six reaction wheels, which normally control Roman’s pointing. 罗曼的推进器大约每28天会进行一次额外的轨道保持点火。该天文台还将利用其推进系统定期卸载其六个反作用轮的动量，这些反作用轮通常用于控制罗曼的指向。

Refueling deferred

延后加油

The mission’s exceptional fuel savings lower the likelihood of NASA having to send a refueling mission to Roman anytime soon. The observatory’s life-limiting resource will likely be propellant, and NASA set a requirement early on in Roman’s development that the space… 此次任务节省的巨额燃料降低了NASA在短期内向罗曼发送加油任务的可能性。该天文台限制寿命的资源很可能就是推进剂，而NASA在罗曼开发初期就设定了一项要求，即该航天器……