Only two free articles this week because my “Axion Space, Inc. The Commercialization of Space” article was so lengthy and time-consuming to write. 15 pages and 2,700+ words. You could try the “7 Day Trial” to see whether that article and future space-industry company articles are worth it for you.
Nonetheless, the two articles below are well worth the read, both fascinating items.
NASA’s Artemis missions to the Moon comprise 3 stages. The first stage, planned for this year, 2022, is to send an unmanned SLS rocket and Orion capsule around the Moon. The second stage will send a manned SLS rocket and Orion capsule around the Moon. The third stage will put astronauts on the Moon’s surface at the South Pole.
The South Pole of the Moon poses interest because there may be substantial ice water in that area under the surface. The problem is it also is in a permanent shadow due to its angle to the Sun. That makes navigation a problem. There is no GPS on the Moon.
For that reason, NASA is testing a new type of lidar technology. Lidar stands for “Light Detection and Ranging” which uses pulsing lasers to measure distances. The new lidar tech is called “Frequency Modulated Continuous Wave” (FMCW), and combined with an orbiting GPS system in the proposed “Gateway” station, a real-time navigation system accurate to the centimetre can be mapped.
These tests fall under a program called “Kinematic Navigation and Cartography Knapsack” (KNaCK). A specialized backpack was developed by Torch Technologies Inc. which carries the FMCW lidar tech from Aeva Inc.
Tests conducted in the Potrillo volcanic field in New Mexico in late 2021 have proved successful. New tests are planned for April 2022. The goal is to further reduce the size of the equipment, currently weighing 40 lbs., and to ensure the hardware can withstand solar radiation.
An interesting video using the FMCW tech from a drone is embedded in this NASA article.
In joint, virtually identical press releases on April 13, 2022, NASA and the ESA disclosed that the Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope has reached its operating temperature of below 7 kelvins (-447 degrees Fahrenheit, or -266 degrees Celsius).
That’s cold. Absolute Zero, the temperature at which energy is almost eliminated (enthalpy and entropy) from even atoms, is 0 kelvins (-459.67 degrees Fahrenheit, or -273.15 degrees Celsius).
But why does MIRI need to be so cold, and how did it get down to that temperature?
Distant galaxies and stars emit infrared light, so it is important to be able to detect those. The problem is that warm instruments also emit infrared waves, even the instruments on the JWST! So, those locally-produced infrared waves would interfere with the instrument’s ability to detect distant infrared waves. Thus, by cooling the instruments themselves, interference can be eliminated.
All four of Webb’s instruments detect infrared waves, but MIRI can detect the longest waves, so it must be colder than the others.
A secondary reason for cooling the instruments to such a low temperature is that of “dark current”. Atoms vibrate, another factor that could throw off the effectiveness of the JWST instruments. By cooling the instruments, that vibration is also significantly reduced.
But to get the instruments down to such a low temperature, in particular the MIRI, required more than just letting them “cool” in the frigidity of open space (although the JWST has huge sun shields to assist in that). MIRI itself used a special electrically powered cryocooler (developed by Northrop Grumman).
MIRI now requires a few more calibration tests, and it will be good to go!
About Northrop Grumman’s cryocooler …