With PRIMA, NASA will try to build a billion-dollar space telescope in record time
With PRIMA, NASA will try to build a billion-dollar space telescope in record time
NASA 将尝试以创纪录的时间建造价值十亿美元的 PRIMA 太空望远镜
The first in a new class of space telescopes is on track to reach the launch pad in the early 2030s, NASA announced this week. The PRIMA mission will be the first of NASA’s Probe Explorers, a new line of observatories intended to do more science for less money. NASA 本周宣布，新一代太空望远镜中的首个项目有望在 2030 年代初进入发射台。PRIMA 任务将是 NASA“探测器探索者”（Probe Explorers）系列的首个项目，该系列旨在以更低的成本实现更多的科学产出。
The agency’s space telescopes typically fall into lower-cost “Explorer-class” missions, with cost caps in the range of a few hundred million dollars, or flagship observatories like the recently launched Nancy Grace Roman Space Telescope, which came with a price tag of some $4.3 billion. With the Probe Explorers, NASA officials seek to find a better balance between the smaller Explorer missions and multibillion-dollar flagships. NASA 的太空望远镜通常分为成本较低的“探索者级”（Explorer-class）任务（成本上限在数亿美元左右），或是像最近发射的南希·格蕾丝·罗曼太空望远镜（Nancy Grace Roman Space Telescope）那样的旗舰级天文台，后者的造价约为 43 亿美元。通过“探测器探索者”项目，NASA 官员旨在小型探索者任务与数十亿美元的旗舰任务之间找到更好的平衡点。
NASA has studied potential Probe Explorer mission concepts for several years after an independent panel of scientists recommended the new mission category. But it wasn’t clear until recently whether NASA’s science budget, which is under pressure from the Trump administration, would be sufficient to actually start developing one. 在独立科学家小组建议设立这一新的任务类别后，NASA 已经对潜在的“探测器探索者”任务概念进行了数年的研究。但直到最近，人们还不清楚在特朗普政府的预算压力下，NASA 的科学预算是否足以真正启动此类项目的开发。
NASA announced Wednesday it will move forward with PRIMA, short for the Probe far-Infrared Mission for Astrophysics. PRIMA was the sole finalist for the first Probe Explorer mission after NASA disqualified a competing mission, an X-ray observatory known as AXIS, earlier this year. NASA said a concept study for AXIS indicated it would not meet the agency’s schedule and budget constraints. NASA 周三宣布将推进 PRIMA 项目，即“天体物理学远红外探测任务”（Probe far-Infrared Mission for Astrophysics）的缩写。在 NASA 今年早些时候取消了竞争对手——名为 AXIS 的 X 射线天文台后，PRIMA 成为了首个“探测器探索者”任务的唯一入围者。NASA 表示，AXIS 的概念研究显示其无法满足该机构的时间表和预算限制。
The scientist leading the AXIS concept study blamed disruptions and mismanagement at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, the NASA location charged with leading the AXIS mission if it moved forward into development. PRIMA will be led by NASA’s Jet Propulsion Laboratory in Pasadena, California, which has also found itself in an institutional crisis, with few missions in development and a series of layoffs. 负责 AXIS 概念研究的科学家将原因归咎于马里兰州格林贝尔特的 NASA 戈达德太空飞行中心（Goddard Space Flight Center）的混乱和管理不善，该中心本应负责领导 AXIS 任务的后续开发。PRIMA 将由位于加利福尼亚州帕萨迪纳的 NASA 喷气推进实验室（JPL）领导，该实验室目前也陷入了机构危机，在研任务寥寥无几，并经历了一系列裁员。
Flagship missions can take decades to design, build, and test before they make it to the launch pad. The Roman Space Telescope was the exception. It took 10 years from NASA’s approval to proceed into development until Roman’s launch last month on the way to an observation post a million miles from Earth. 旗舰任务从设计、建造到测试，往往需要数十年才能最终进入发射台。罗曼太空望远镜是个例外，从 NASA 批准开发到上个月发射前往距离地球一百万英里的观测点，仅用了 10 年时间。
Leftovers from Webb
来自韦伯的“遗产”
PRIMA, which has a cost cap of $1.2 billion excluding launch costs, will not be as big and complex as Roman, so it’s natural to assume a shorter development cycle. NASA wants to launch PRIMA seven years from now, in 2033. The telescope will observe the Universe in faint, far-infrared light in a range of wavelengths between 24 and 235 micrometers, requiring its primary optics to be cooled to 4.5 Kelvin, or minus 451° Fahrenheit. PRIMA 的成本上限为 12 亿美元（不含发射成本），其规模和复杂程度不及罗曼望远镜，因此开发周期更短是理所当然的。NASA 希望在七年后的 2033 年发射 PRIMA。该望远镜将观测 24 到 235 微米波长范围内的微弱远红外光，这要求其主光学系统冷却至 4.5 开尔文（即华氏零下 451 度）。
This would usually require a brand-new build of a sophisticated cryocooler. PRIMA will instead use a spare leftover from the development of the James Webb Space Telescope, modified to use helium-3 instead of helium-4 as the cooling fluid. The focal planes of PRIMA’s kinetic inductance detectors will be chilled even lower to 100 milliKelvin, putting the mission’s optics in contention for the coldest ever sent into space. 这通常需要全新制造一台复杂的低温冷却器。但 PRIMA 将使用詹姆斯·韦伯太空望远镜（JWST）开发时留下的备件，并进行改装，改用氦-3 而非氦-4 作为冷却流体。PRIMA 动感应探测器的焦平面将被进一步冷却至 100 毫开尔文，这使得该任务的光学系统有望成为有史以来送入太空的最冷设备。
Its far-infrared sensitivity will give PRIMA visibility into the origins of planets and their atmospheres, the coevolution of galaxies and black holes, and changes in the properties of dust and metals over cosmic time, according to the scientists heading the mission. PRIMA, with a 5.9-foot-diameter (1.8-meter) primary mirror, will set up shop in an orbit around the Sun-Earth L2 Lagrange point a million miles from Earth. 据任务负责人介绍，PRIMA 的远红外灵敏度将使其能够洞察行星及其大气的起源、星系与黑洞的共同演化，以及宇宙时间尺度下尘埃和金属属性的变化。PRIMA 配备了 5.9 英尺（1.8 米）直径的主镜，将部署在距离地球一百万英里的日地拉格朗日 L2 点轨道上。
The mission will peer deeper into the infrared bands than any of NASA’s past or current infrared observatories, such as Spitzer and Webb, and will build on discoveries made by Europe’s Herschel space telescope, which gave astronomers new insights into the formation of cosmic filaments and the role of water in the formation of stars and planets. 该任务对红外波段的观测深度将超过 NASA 过去和现在的任何红外天文台（如斯皮策和韦伯），并将基于欧洲赫歇尔太空望远镜的发现进行研究，后者曾为天文学家提供了关于宇宙丝状结构形成以及水在恒星和行星形成中作用的新见解。
“The PRIMA mission is humanity’s next window into the deep Universe,” said Nicky Fox, associate administrator for NASA’s Science Mission Directorate, in a statement. “It will unveil the obscure across cosmic time to better understand the formation of planets, stars, black holes, and even how water on Earth came to be.” “PRIMA 任务是人类通往深空的下一扇窗口，”NASA 科学任务理事会副局长尼基·福克斯（Nicky Fox）在一份声明中表示。“它将揭开宇宙时间长河中那些隐秘的事物，帮助我们更好地理解行星、恒星、黑洞的形成，甚至地球上的水是如何产生的。”
NASA’s announcement this week gave the green light to move into Phase B of development, working toward a preliminary design review before a confirmation review at NASA Headquarters at a few years from now that will mark final approval to proceed into integration of flight hardware. The complete observatory is expected to weigh less than 3.4 metric tons (7,500 pounds) at launch. NASA 本周的公告为进入开发 B 阶段开了绿灯，目标是在几年后于 NASA 总部进行确认审查之前完成初步设计审查，这将标志着最终批准进入飞行硬件集成阶段。整个天文台在发射时的重量预计将低于 3.4 公吨（7,500 磅）。
“A single mission alone can’t probe all the Universe’s mysteries. But by extending the survey capabilities of our fleet into far-infrared wavelengths with PRIMA, we’re enabling an incredibly comprehensive look at the cosmos,” said Shawn Domagal-Goldman, director of NASA’s Astrophysics Division. “With our Webb and Roman space telescopes, we set a cadence of launching premier-class missions in both halves of the decade. We’re going to keep that up and kick off the next decade with PRIMA, as part of a pipeline that will consistently have missions of this caliber ready to go.” “单靠一项任务无法探究宇宙的所有奥秘。但通过 PRIMA 将我们探测器的观测能力扩展到远红外波长，我们正在实现对宇宙极其全面的观察，”NASA 天体物理学部主任肖恩·多马加尔-戈德曼（Shawn Domagal-Goldman）表示。“通过韦伯和罗曼太空望远镜，我们在十年内保持了发射顶级任务的节奏。我们将保持这一势头，并以 PRIMA 开启下一个十年，作为我们持续推出此类高质量任务计划的一部分。”
Flagships are still hard
旗舰任务依然艰难
Meanwhile, NASA continues preliminary architecture studies and technology development for its next big flagship space telescope, the Habitable Worlds Observatory, planned for launch in the 2040s. It is expected to be at least as large as the James Webb Space Telescope, with the potential for an even bigger primary mirror if NASA can take advantage of new super-heavy-lift launch vehicles, such as SpaceX’s Starship. 与此同时，NASA 正在为其下一个大型旗舰太空望远镜——“宜居世界天文台”（Habitable Worlds Observatory）进行初步架构研究和技术开发，计划于 2040 年代发射。预计其规模至少与詹姆斯·韦伯太空望远镜相当，如果 NASA 能利用 SpaceX 的“星舰”（Starship）等新型超重型运载火箭，其主镜甚至可能更大。