NASA researchers created a new sensor called CASALS. It helps make full maps of Earth's surface. The team works at Goddard Space Flight Center. John Yorks leads this project. He is a physical research scientist there.
The device uses light to scan the ground. It has a laser that changes color many times. This laser works at 1040 nanometers. It cycles through 256 different wavelengths. A special grating directs the light beams. This method removes moving parts. So, the machine is smaller and lighter. It also needs less power. This makes it better for space use.
The detector captures weak signals well. It works with 80 percent efficiency. This helps see dark areas or thick trees. On November 12, 2024, they tested a prototype. They flew it over the Great Cypress Swamp in Delaware. The plane was five kilometers high. The map resolution was 22 centimeters. John Yorks said his team did a good job.
NASA plans another flight in summer 2027.
beamn.光束a line of light that comes from a lamp
lasern.激光a tool that makes a strong, thin line of light
projectn.项目；工程a planned piece of work that needs time and effort
resolutionn.分辨率how clear a picture or map is
capturev.捕捉；记录to take a picture or record something
cyclev.循环；变换to go through steps again and again
devicen.装置；设备a tool or machine made for a special job
efficiencyn.效率how well you do work without wasting time or power
percentn.百分之……one part in every hundred parts
removev.去除；消除to take something away
1. What is the main benefit of removing moving parts from the sensor?
Researchers at NASA’s Goddard Space Flight Center have developed a new sensor called CASALS. This instrument is designed to create continuous three-dimensional maps of the Earth's surface. Traditional laser scanning systems often leave gaps between their lines of data. CASALS aims to fill these voids by using an optical grating instead of mechanical mirrors to direct the light beam.
The system works by cycling through 256 distinct wavelengths during operation. It uses a seed laser with a center frequency of 1040 nanometers. Diffraction physics allows the device to send each pulse to a different location along the flight path based on its wavelength. By removing moving parts, the hardware becomes smaller and more reliable for use in space conditions.
The detector array has a quantum efficiency rating of 80 percent. This high efficiency helps the instrument capture weak signals from dark surfaces or dense foliage. On November 12, 2024, an airborne prototype was tested over the Great Cypress Swamp in Delaware. The aircraft flew at an altitude of approximately five kilometers. During this test, the instrument achieved a horizontal resolution of 22 centimeters.
John Yorks, a physical research scientist at the center and the principal investigator for the project, said that team members Guang Yang and Jeffrey Chen performed well during the initial flights. According to Yorks, funding is being used to optimize performance and prepare technologies for a future version that can operate in space.
Looking ahead, the organization plans to conduct another flight as part of the ASCENT campaign in summer 2027. Future development steps include expanding the measurement width and adding software to process data directly on the aircraft before creating a space-ready model.
aircraftnoun飞机；航空器a vehicle that can fly, such as a plane.
altitudenoun海拔高度；飞行高度the height of something above sea level or the ground.
beamnoun光束a line of light that comes from a source like a lamp.
campaignnoun活动；战役（此处指有组织的系列行动）a planned series of activities for achieving a goal.
datanoun数据information collected for study or use.
denseadjective茂密的；浓密的having many things close together; thick.
hardwarenoun硬件；设备the physical parts of a computer or machine system.
lasernoun激光a device that produces a strong, narrow line of light.
projectnoun项目；工程a planned piece of work that has a specific purpose.
pulsenoun脉冲；短促的光束a single short burst of light or sound.
continuousadjective连续的；不间断的happening without stopping.
reliableadjective可靠的；稳定的able to be trusted to do what is needed consistently.
1. What technology does CASALS use to direct the light beam instead of mechanical mirrors?
Researchers at NASA’s Goddard Space Flight Center have developed a new lidar instrument called CASALS, designed to create continuous three-dimensional maps of the Earth's surface. The project aims to address data gaps that occur between traditional laser scanning lines, which often leave unmeasured spaces in terrain models. John Yorks, who serves as the principal investigator for the initiative, leads the effort from his position as a physical research scientist at the center.
The core innovation of CASALS lies in its method of steering the laser beam. Instead of relying on mechanical mirrors, which are prone to wear and require significant power, the system uses an optical grating. This approach allows the device to generate uninterrupted terrain renderings by directing light pulses based on their wavelength. By removing moving components, the team has significantly lowered the size, weight, and power demands of the hardware, thereby enhancing reliability for future space applications.
Technically, the device employs a seed laser operating at a center frequency of 1040 nanometers. During operation, this laser cycles through 256 distinct wavelengths. Diffraction physics enables the transmission grating to direct each pulse into a separate location along the flight trajectory. This wavelength-based steering mechanism is crucial for achieving dense coverage without mechanical movement. Furthermore, the detector array achieves a quantum efficiency rating of 80 percent. This high sensitivity allows the instrument to capture weak return signals even from dark surfaces or dense foliage, which can be challenging for standard sensors.
To test these capabilities, an airborne prototype was flown on Nov. 12, 2024. The experiment took place aboard a B200 King Air aircraft over the Great Cypress Swamp in Delaware. During this campaign, the instrument operated at an altitude of approximately five kilometers and achieved a horizontal resolution of 22 centimeters. These results demonstrated the potential of the technology to produce detailed topographical data in complex environments.
Yorks stated that team members Guang Yang and Jeffrey Chen performed well during these initial campaign flights. According to Yorks, funding is currently being utilized to optimize performance and prepare technologies for a future spaceborne version. Looking ahead, the organization plans to conduct another flight as part of the ASCENT campaign scheduled for summer 2027. Future development steps include expanding the measurement swath width and integrating onboard software for data processing before creating a model ready for space deployment.
lidarn.激光雷达A technology that uses light to measure distances and create maps of the Earth's surface.
terrainn.地形；地势The physical features of an area of land, such as hills, valleys, or flat ground.
principal investigatorn. phr.首席研究员The main scientist who is responsible for leading a research project.
optical gratingn. phr.光栅A device with many fine lines that splits or directs light beams.
wavelengthn.波长The distance between two peaks of a wave, used here to describe different colors of light.
trajectoryn.轨迹；路径The path that an object follows through space.
quantum efficiencyn. phr.量子效率A measure of how well a sensor converts incoming light into an electrical signal.
foliagen.叶子；枝叶The leaves of plants, especially when they are thick and green.
airborneadj.空中的；机载的Carried by or happening in the air, usually involving an aircraft.
topographicaladj.地形的；地貌学的Relating to the detailed description of the shape and features of land surfaces.
spaceborneadj.太空中的；航天器上的Designed to operate while carried by a spacecraft in space.
1. What is the primary advantage of using an optical grating instead of mechanical mirrors in the CASALS system?
If I learn the truth in the morning, I can feel happy even if I die that evening.”
—— WenXi，化用《论语·里仁》「朝闻道，夕死可矣」
This old sentence does not mean we want to die.
It tells us: we should love learning very much.
For our English study, the “truth” means new language skills.
When you read an English text or understand an English talk, you find this joy.
