From orbit, today’s space-based laser instruments measure Earth’s forests and terrain one narrow line at a time. Between those lines are enormous gaps that include millions of acres of land scientists never directly measure. NASA’s CASALS instrument will blend machine learning with an ultra-compact lidar instrument to adaptively ‘sweep’ large swaths of Earth’s surface. This new capability for space-based remote sensors allows CASALS to create truly three-dimensional (3D) topographical renderings.
当今的天基激光仪器在轨道上一次只能测量一条窄线，即地球的森林和地形。这些界限之间存在着巨大的差距，其中包括科学家从未直接测量过的数百万英亩土地。 NASA 的 CASALS 仪器将机器学习与超紧凑型激光雷达仪器相结合，自适应地“扫描”地球表面的大片区域。这种天基遥感器的新功能使 CASALS 能够创建真正的三维 (3D) 地形渲染。
A team of researchers at NASA’s Goddard Space Flight Center (GSFC) has developed a new instrument designed to eliminate blind spots between lines of lidar data on the Earth’s surface. Built with support from NASA’s Earth Science Technology Office (ESTO), the Concurrent Artificially-intelligent Spectrometry Lidar System (CASALS) could help researchers map the features of Earth’s surface with unprecedented detail. Rather than mechanically steering a laser with moving mirrors, CASALS steers light using wavelength itself, generating a continuous, 3D swath of the ground below.
美国宇航局戈达德太空飞行中心（GSFC）的一组研究人员开发了一种新仪器，旨在消除地球表面激光雷达数据线之间的盲点。在 NASA 地球科学技术办公室 (ESTO) 的支持下构建的并行人工智能光谱测量激光雷达系统 (CASALS) 可以帮助研究人员以前所未有的细节绘制地球表面的特征图。 CASALS 不是使用移动镜子机械地控制激光，而是使用波长本身来控制光，从而生成下方连续的 3D 地面带。
John Yorks, a physical research scientist at GSFC and Principal Investigator for CASALS, explained that the instrument features a novel transmitter and optical grating system that manipulates laser pulses without heavy, failure-prone motorized mirrors.
GSFC 的物理研究科学家兼 CASALS 的首席研究员约翰·约克斯 (John Yorks) 解释说，该仪器具有新颖的发射器和光栅系统，可以操纵激光脉冲，而无需笨重且容易出现故障的电动镜子。
Instead, CASALS uses a fast-pulsing, tunable “seed” laser centered at 1040 nanometers, rapidly cycling through 256 unique wavelengths as it pulses through an optical component with a microscopic pattern of ridges called a transmission grating.
相反，CASALS 使用以 1040 纳米为中心的快速脉冲、可调谐“种子”激光器，当它脉冲通过具有微观脊状图案（称为透射光栅）的光学组件时，会快速循环通过 256 个独特的波长。
At this point, the physics of diffraction takes over. Because light bends at slightly different angles depending on its exact wavelength, the grating naturally “steers” each of the 256 pulses into a distinct position across the flight path.
此时，衍射物理学占据了主导地位。由于光根据其具体波长以略微不同的角度弯曲，因此光栅自然地将 256 个脉冲中的每一个“引导”到飞行路径上的不同位置。
This non-mechanical approach paints a continuous 3D swath of the ground. Not only does this eliminate the large unmapped gaps left between the isolated tracks of legacy spaceborne lidars, but stripping away moving parts drastically reduces the instrument’s size, weight, and power (SWaP) requirements. This makes it more reliable for the harsh environment of space.
这种非机械方法绘制了连续的 3D 地面带。这不仅消除了传统星载激光雷达隔离轨道之间留下的大的未映射间隙，而且去掉了移动部件，大大降低了仪器的尺寸、重量和功率 (SWaP) 要求。这使得它对于恶劣的太空环境更加可靠。
Another key innovation within CASALS is its detector array. This component features a uniquely high Quantum Efficiency (QE), a variable that describes how effectively a detector converts incoming light (photons) into an electrical signal. CASALS operates at 80% QE. This means CASALS wastes almost none of the light that makes it back to the sensor.
CASALS 的另一个关键创新是其探测器阵列。该组件具有独特的高量子效率 (QE)，该变量描述了探测器将入射光（光子）转换为电信号的效率。 CASALS 的量化宽松率为 80%。这意味着 CASALS 几乎不会浪费任何返回传感器的光线。
With QE that high, CASALS can detect much weaker return signals, allowing it to collect useful measurements from darker surfaces or through denser vegetation.
在 QE 如此高的情况下，CASALS 可以检测到更弱的返回信号，使其能够从较暗的表面或通过较茂密的植被收集有用的测量结果。
This technology isn’t limited to a laboratory environment. In November 2024, an airborne CASALS prototype flew aboard NASA’s B200 King Air aircraft. The instrument produced science-quality datasets on its first campaign, exceeding the team’s expectations.
这项技术不仅限于实验室环境。 2024 年 11 月，一架 CASALS 原型机搭载在 NASA 的 B200 King Air 飞机上飞行。该仪器在第一次活动中生成了科学质量的数据集，超出了团队的预期。
“I’m very impressed with Guang Yang, Jeffrey Chen, and all our engineers, and how well CASALS performed. This worked really well from the first time we flew it, which is pretty impressive,” said Yorks.
“杨光、Jeffrey Chen 和我们所有的工程师以及 CASALS 的出色表现给我留下了深刻的印象。从我们第一次驾驶它起，它就表现得非常好，这令人印象深刻，”约克斯说。
Flying at an altitude of roughly five kilometers, CASALS can distinguish individual tree branches and subtle changes in ground elevation, thanks to its 22-centimeter horizontal resolution.
CASALS 在大约 5 公里的高度飞行，凭借 22 厘米的水平分辨率，可以区分单个树枝和地面海拔的细微变化。
“We’re able to see really fine details of vegetation structure and changes in the topography of the surface,” Yorks said.
“我们能够看到植被结构和地表地形变化的非常精细的细节，”约克斯说。
The team aims to fly CASALS again as part of the Airborne Surface, Cryosphere, Ecosystem, and Nearshore Topography (ASCENT) campaign, scheduled for summer 2027.
该团队的目标是再次飞行 CASALS，作为定于 2027 年夏季进行的机载表面、冰冻圈、生态系统和近岸地形 (ASCENT) 活动的一部分。
But there’s more work to do to prepare the technology for space. The team plans to make several improvements to CASALS before creating a space-ready prototype. Specifically, they’re widening the instrument’s swath and adding onboard data processing software.
但要为太空技术做好准备还有更多工作要做。该团队计划在创建太空原型之前对 CASALS 进行多项改进。具体来说，他们正在扩大仪器的范围并添加机载数据处理软件。
Transitioning from a successful airborne prototype to a fully realized space mission is a challenge, but the CASALS team is up to the task.
从成功的机载原型机过渡到完全实现的太空任务是一项挑战，但 CASALS 团队能够胜任这项任务。
“The team’s really done a great job of sticking together and keeping on task and on schedule. We are being funded to optimize and improve the performance, and we’re also then looking at ways to take the technologies used in the airborne instrument and mature them and prepare them for a spaceborne version in the future,” said Yorks.
约克斯说：“该团队在团结一致、按时完成任务方面确实做得非常出色。我们正在获得资金来优化和提高性能，然后我们也在寻找方法，利用机载仪器中使用的技术并使它们成熟，并为未来的星载版本做好准备。”
If successful, CASALS could become the first spaceborne lidar capable of mapping Earth’s forests and terrain as continuous three-dimensional swaths rather than isolated profiles, giving scientists a dramatically more complete picture of our changing planet.
如果成功，CASALS 可能成为第一个能够将地球森林和地形绘制为连续的三维条带而不是孤立的轮廓的星载激光雷达，从而使科学家能够更加完整地了解我们不断变化的星球。
For additional details, see the entry for this project on NASA TechPort .
有关更多详细信息，请参阅 NASA TechPort 上该项目的条目。
Project Lead(s): John Yorks, NASA’s Goddard Space Flight Center
项目负责人：John Yorks，美国宇航局戈达德太空飞行中心
Sponsoring Organization(s): NASA’s Decadal Survey Incubation (DSI) program; NASA’s Instrument Incubation Program (IIP); NASA’s Goddard Space Flight Center; University of California, Santa Barbara; Virginia Polytechnic Institute and State University
赞助组织：NASA 十年调查孵化 (DSI) 计划； NASA 的仪器孵化计划 (IIP)；美国宇航局戈达德太空飞行中心；加州大学圣塔芭芭拉分校；弗吉尼亚理工学院暨州立大学