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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The mystery of why life uses molecules with specific orientations has deepened with a NASA-funded discovery that RNA — a key molecule thought to have potentially held the instructions for life before DNA emerged — can favor making the building blocks of proteins in either the left-hand or the right-hand orientation. Resolving this mystery could provide clues to the origin of life. The findings appear in research recently published in Nature Communications.
Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes (catalysts that speed up or regulate chemical reactions). Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acid building blocks in a huge variety of arrangements to make millions of different proteins. Some amino acid molecules can be built in two ways, such that mirror-image versions exist, like your hands, and life uses the left-handed variety of these amino acids. Although life based on right-handed amino acids would presumably work fine, the two mirror images are rarely mixed in biology, a characteristic of life called homochirality. It is a mystery to scientists why life chose the left-handed variety over the right-handed one.
A diagram of left-handed and right-handed versions of the amino acid isovaline, found in the Murchison meteorite.NASA DNA (deoxyribonucleic acid) is the molecule that holds the instructions for building and running a living organism. However, DNA is complex and specialized; it “subcontracts” the work of reading the instructions to RNA (ribonucleic acid) molecules and building proteins to ribosome molecules. DNA’s specialization and complexity lead scientists to think that something simpler should have preceded it billions of years ago during the early evolution of life. A leading candidate for this is RNA, which can both store genetic information and build proteins. The hypothesis that RNA may have preceded DNA is called the “RNA world” hypothesis.
If the RNA world proposition is correct, then perhaps something about RNA caused it to favor building left-handed proteins over right-handed ones. However, the new work did not support this idea, deepening the mystery of why life went with left-handed proteins.
The experiment tested RNA molecules that act like enzymes to build proteins, called ribozymes. “The experiment demonstrated that ribozymes can favor either left- or right-handed amino acids, indicating that RNA worlds, in general, would not necessarily have a strong bias for the form of amino acids we observe in biology now,” said Irene Chen, of the University of California, Los Angeles (UCLA) Samueli School of Engineering, corresponding author of the Nature Communications paper.
In the experiment, the researchers simulated what could have been early-Earth conditions of the RNA world. They incubated a solution containing ribozymes and amino acid precursors to see the relative percentages of the right-handed and left-handed amino acid, phenylalanine, that it would help produce. They tested 15 different ribozyme combinations and found that ribozymes can favor either left-handed or right-handed amino acids. This suggested that RNA did not initially have a predisposed chemical bias for one form of amino acids. This lack of preference challenges the notion that early life was predisposed to select left-handed-amino acids, which dominate in modern proteins.
“The findings suggest that life’s eventual homochirality might not be a result of chemical determinism but could have emerged through later evolutionary pressures,” said co-author Alberto Vázquez-Salazar, a UCLA postdoctoral scholar and member of Chen’s research group.
Earth’s prebiotic history lies beyond the oldest part of the fossil record, which has been erased by plate tectonics, the slow churning of Earth’s crust. During that time, the planet was likely bombarded by asteroids, which may have delivered some of life’s building blocks, such as amino acids. In parallel to chemical experiments, other origin-of-life researchers have been looking at molecular evidence from meteorites and asteroids.
“Understanding the chemical properties of life helps us know what to look for in our search for life across the solar system,” said co-author Jason Dworkin, senior scientist for astrobiology at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and director of Goddard’s Astrobiology Analytical Laboratory.
Dworkin is the project scientist on NASA’s OSIRIS-REx mission, which extracted samples from the asteroid Bennu and delivered them to Earth last year for further study.
“We are analyzing OSIRIS-REx samples for the chirality (handedness) of individual amino acids, and in the future, samples from Mars will also be tested in laboratories for evidence of life including ribozymes and proteins,” said Dworkin.
The research was supported by grants from NASA, the Simons Foundation Collaboration on the Origin of Life, and the National Science Foundation. Vázquez-Salazar acknowledges support through the NASA Postdoctoral Program, which is administered by Oak Ridge Associated Universities under contract with NASA.
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Last Updated Nov 21, 2024 EditorWilliam SteigerwaldContactNancy N. Jonesnancy.n.jones@nasa.govLocationGoddard Space Flight Center Related Terms
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By NASA
NASA and the military have shared strong connections since the agency’s early days. From the nation’s earliest aeronautic research and the recruitment of test pilot astronauts to modern-day technology development, satellite management, and planetary defense, NASA has built a longstanding partnership with the military.
This legacy of collaboration has created natural opportunities for former service members to join NASA’s ranks at the conclusion of their military careers.
Lewis Swain is one of the many veterans working at Johnson Space Center in Houston today. Swain was recruited by NASA contractor McDonnell Douglas after leaving the military in 1980. He commissioned as a second lieutenant and served in the Air Force for 12 years, flying nearly 200 combat missions during two tours in Vietnam.
“The shuttle program was starting, and they needed ex-military pilots to serve as simulation instructors,” he said. Swain specialized in control and propulsion systems instruction for several years before becoming the training team lead for shuttle missions. Following the Challenger accident in 1986, Swain transitioned to supporting the International Space Station Program and Return to Flight evaluations. He has been a civil servant since 1989 and a training facility manager since 2006.
L. Jerry Swain during his Air Force career (left) and as a facility manager at Johnson Space Center in Houston (right).Images courtesy of L. Jerry Swain NASA’s Pathways Internship Program has also provided a point of entry for former service members. John Smith was studying mechanical engineering at the University of Texas at El Paso when he made an impactful Johnson connection. “I met with a former flight director, Ms. Ginger Kerrick, at a career fair hosted by my university,” he said. “Pathways happened to be accepting applications at the time and she enthusiastically encouraged me to apply. I never expected to get a response, much less an offer. I couldn’t say yes fast enough when it came!”
For others, the NASA SkillBridge Program has been instrumental in transitioning from the military to civilian careers. The program connects individuals in their final months of military service with a NASA office or organization. SkillBridge fellows work anywhere from 90 to 180 days, contributing their unique skillsets to the agency while building their network and knowledge. Since fellows’ pay and benefits are provided by their military branch, their support comes at no additional cost to NASA.
Johnson hosted the agency’s first-ever SkillBridge fellow in spring 2019, paving the way for many others to follow. Albert Meza, an Air Force space professional, was among this first wave of service members at NASA.
Approaching retirement from the Air Force in November 2019, Meza planned to move his family back to Houston that summer, then join them in the fall once his military service ended. A colleague encouraged him to apply for SkillBridge because it would let Meza move with his family. Meza was skeptical, noting the military is not typically flexible on moves or timelines, but after a quick meeting with his commanding officer and finding a Johnson team to work with, he was on his way to Houston. “It was unbelievable,” he said. “It kind of fell into my lap.”
Albert Meza visits Johnson Space Center’s Space Vehicle Mockup Facility while serving in the Air Force (left) and receives an award from NASA astronaut Rex J. Walheim during his retirement ceremony at Space Center Houston (right). Images courtesy of Albert Meza Today Meza is a payload integration manager for NASA’s CLPS (Commercial Lunar Payload Services) program, working within the Exploration Architecture, Integration, and Science Directorate at Johnson. In this role, he acts as a liaison between payload teams and the vendor developing a lander to help ensure flight requirements are understood and met.
Meza is also one of SkillBridge’s on-site coordinators. He said that when he first arrived at Johnson, he realized the program was relatively unknown. “I thought, I need to take the responsibility for waving the flag for SkillBridge at NASA.” Meza works tirelessly to educate service members, military leaders, and NASA supervisors about the program’s benefits. He also emphasizes how easy it is for NASA supervisors to host a fellow. “You get someone for six months who is already disciplined, loyal, and has all of these highly trained credentials,” he said. “Any civil servant supervisor can host a SkillBridge fellow. The only real requirement is that the supervisor can provide IT assets and a work location.”
Johnson has hosted more than 25 SkillBridge fellows since the program’s inception. Many fellows have since accepted full-time positions with NASA, including Patricia “Trish” Elliston. Meza found her a SkillBridge position with the center’s Protective Services Division in spring 2023. Elliston relocated to Houston in 2020, a few years prior to her anticipated retirement from the U.S. Coast Guard. Living in Houston and interacting with numerous NASA employees, along with prior experience working with the agency in maritime safety, convinced Elliston that Johnson was the place for her.
Trish Elliston flies aboard an aircraft during a mission (left) and visits Johnson Space Center’s Space Vehicle Mockup Facility (right) while serving in the U.S. Coast Guard. Images courtesy of Trish Elliston “During my internship I networked as much as possible and made every effort to learn as much as I could so that I could be better prepared to start my civilian career,” Elliston said. “I worked hard and learned a lot, and when a job opportunity became available, I applied.” She now works as a cyber intelligence analyst within the Flight Operations Directorate.
Meza notes that SkillBridge is a transition program, not a hiring program, and that some fellows have not received a job offer or have decided to pursue other opportunities. What happens after a SkillBridge fellowship depends on each individual and whether they’ve demonstrated their potential and built relationships in a way that turns this ‘foot in the door’ into a full-time position.
Interested in becoming a SkillBridge fellow at NASA? Learn more about the program and submit your application here.
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By USH
Over the years, numerous mysterious events have been witnessed in the sky, defying explanation. Recently, yet another unusual sky phenomenon was observed over Southern Australia capturing attention and sparking curiosity.
Video footage reveals what appears to be a dome-shaped structure, with an even stranger detail: lightning seems to bounce off or perhaps even originate from within the dome.
The mysterious formation has led to numerous theories. Some viewers suggest it could be a unique (red) rainbow or a rare weather event like a haboob (sandstorm). Others speculate it might be the result of weather manipulation or even an energy field projected over the region.
Opinions also vary on the lightning, some say it’s bouncing off the dome, while others believe it could be emanating from within. Although it may just be an unusual natural phenomenon, the seemly strange interaction with the lightning remains unexplained.
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By USH
A strange image has been circulating across social media in Thailand, showing a large, dark pillar-like structure mysteriously appearing in the sky over Ubon Ratchathani. According to the photographer, the picture was taken on Sunday, October 20, 2024, while they were trying to capture the "beautiful, colorful sky.
This peculiar sighting isn't entirely unprecedented. Similar strange phenomena have been reported before. On October 7, 2015, a mysterious "floating city" with skyscrapers appeared in the clouds over Foshan, Guangdong province in China. Again, on March 18, 2016, ghostly buildings were seen above the sea along the port of Dalian, in Liaoning Province, China, lingering in the sky for several minutes.
Most recently, on September 11, 2020, an eerie image resembling the Hogwarts School from Harry Potter was spotted hovering over modern buildings in Jinan, Shandong Province. On July 14, 2022, a bizarre occurrence was also witnessed by residents in Haikou, Hainan, where a mysterious floating city appeared in the sky.
Scientists suggest that these events are most likely optical illusions, with mirages being the leading theory. Mirages occur when light rays bend, causing distant objects or parts of the sky to appear displaced. One specific type, known as a Fata Morgana, can create towering, distorted images of distant objects, contributing to these surreal sights.
Although the sightings between 2015 and 2022 were witnessed by many, the photographer in Thailand later realized that the mysterious pillar hadn't been visible to the naked eye at the time. This discovery has led some to speculate that the phenomenon might have been caused by a Project Blue Beam test, holographic technology, or even a temporary vortex connected to a parallel universe.
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