Kennedy's Desert RATS
Every September, after the summer rain backs off but before the mornings get too cold, a pack of RATS descends on the desert near Flagstaff, Ariz., to spend two weeks testing technologies that will play a vital role in the future of space exploration.
Roughly 150 engineers and scientists participate in the NASA program, known as Desert Research and Technology Studies, or "Desert RATS." The 10-year-old program is part of the agency's Exploration Systems Mission Directorate and involves groups from several NASA centers and universities. During the annual trip out west, they take advantage of the variety of desert terrains to test new or improved equipment that astronauts may use during excursions on the surface of the moon. Projects in testing range from computer hardware and software to spacesuits, rovers and astronaut habitats.
Three teams from NASA's Kennedy Space Center in Florida make the trip out west each year: the communications/networking group, the cryogenics surface systems team and the surface physics group.
Marc Seibert, a communications and networking engineer from Kennedy, has been attending the desert outings for six years. Seibert is part of the KSC Telescience Laboratory, which is responsible for video, voice, data, wired and wireless networking, and network security for the desert test site each year. Since reliable communications are essential and everyone needs communications at the test site, Telescience lab team members are usually the first people on duty in the morning and the last to leave each night.
"Our role in Desert RATS is to make sure everything can communicate, and make sure people back in the mission control building at Johnson Space Center can connect and interact with the test site," Seibert explained.
One of the group's accomplishments during the September 2007 desert test was a fourth-generation digital signal processor and audio system that dramatically cleans up the quality of the audio from spacesuit helmets. Although today's astronauts use a head-mounted system with noise-cancelling microphones, the goal is to fix the microphones inside the suit helmet itself. But in this arrangement, the hiss of air flowing over the wearer's head and the resonance of the helmet can make it difficult to understand what an astronaut is saying. With the addition of the processor, the audio is vastly improved, with excess noise almost entirely removed.
Another helpful contribution from the Kennedy communications/networking group is a large semi trailer that is part habitat simulator and part control center. In the rear of the trailer, spacesuit stands allow crew members to practice suiting up and exiting a lunar habitat. In the front, a team of engineers can interact with the suited subjects and monitor and control the software on the suits and rovers.
For the 2007 test, the group provided aggregate wireless communications for the field team through nearby Mount Elden in Flagstaff. At future desert outings, the group plans to demonstrate a lunar delay simulator that allows team members to selectively insert a delay into network traffic between devices in the field and mission control. For example, they would mimic the delay between a lunar rover and mission controllers.
The cryogenics surface systems group debuted a new technology that will allow lunar explorers to recharge their liquid air packs with super-cold consumables without the interference of lunar dust. Known as the "dust-tolerant cryogenic quick disconnect," it uses a special bellows-like enclosure around the contacts to protect the seals from the damaging dust that blankets the moon's surface.
Lunar dust is clingy and as sharp as crushed glass, and can tear up the seals on ordinary quick disconnects, causing leaks. Internal contamination is also a concern, especially in oxygen systems. Since the soil at an area known as Meteor Crater near Flagstaff has properties similar to lunar dust, the annual desert outing was the perfect opportunity to test the dust-tolerant technology. The cryogenics team exposed the new device to the soil, then easily transferred liquid nitrogen from a tank into a small cooler.
"We proved the concept and it worked very well," said Rob Mueller, a surface systems lead engineer and member of the Desert RATS cryogenics group. "And since we now had very cold liquid nitrogen in the output storage vessel, we decided to make ice cream for the whole crew out of it."
Kennedy's cryogenics lab, run by NASA and ASRC Aerospace, and the NASA prototype shop assisted in developing and manufacturing the disconnect hardware. During the coming year, Mueller and his colleagues hope to create a second-generation version that incorporates lessons learned for this demonstration and is smaller in size.
The group has two more projects in development for the coming year. The lunar operations cryogenics umbilical system aims to scavenge and reuse the leftover propellants in lunar lander tanks for life support needs. A related project, the zero-boil-off cryogenic storage unit, will use a special cryo-cooler to prevent residual propellants from boiling away when they could be used at a lunar outpost.
Imagine how much easier life on the moon could be if surfaces could somehow repel that clingy lunar dust. At this year's desert outing, the electrostatics and surface physics laboratory demonstrated a technology designed to do just that. It starts with a voltage signal applied in a specific sequence to three sets of electrodes embedded in the surface. This creates a traveling electric field that moves like an invisible wave and forces dust particles off the surface.
"What we brought this year was an optically transparent dust screen," explained Dr. Jim Mantovani, a physicist. "This would have applications for solar cells, visors on astronaut helmets, windows -- any application where you have a transparent surface and you need to keep it dust-free."
According Dr. Carlos Calle, who leads the electrostatics and surface physics laboratory, current research efforts may allow the application of the dust screen technology to flexible surfaces, such as spacesuits. Additionally, the cryogenics group plans to incorporate it into the next generation of their quick-disconnect device.
The interactivity, cooperation and rehearsals between the Desert RATS teams at various NASA centers and universities continue throughout every year, culminating in the annual desert test. This ongoing process means problems are rooted out long before new flight hardware is made, helping to ensure these new technologies will be ready for the next giant leap in human space exploration.
"It's surreal to see the crew members walking around like they will on the moon again and someday on Mars, taking rock samples, reporting on what they're doing, etc." Seibert said. "It just feels like you're there."
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