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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
5 Min Read Making Mars’ Moons: Supercomputers Offer ‘Disruptive’ New Explanation
A NASA study using a series of supercomputer simulations reveals a potential new solution to a longstanding Martian mystery: How did Mars get its moons? The first step, the findings say, may have involved the destruction of an asteroid.
The research team, led by Jacob Kegerreis, a postdoctoral research scientist at NASA’s Ames Research Center in California’s Silicon Valley, found that an asteroid passing near Mars could have been disrupted – a nice way of saying “ripped apart” – by the Red Planet’s strong gravitational pull.
The team’s simulations show the resulting rocky fragments being strewn into a variety of orbits around Mars. More than half the fragments would have escaped the Mars system, but others would’ve stayed in orbit. Tugged by the gravity of both Mars and the Sun, in the simulations some of the remaining asteroid pieces are set on paths to collide with one another, every encounter further grinding them down and spreading more debris.
Many collisions later, smaller chunks and debris from the former asteroid could have settled into a disk encircling the planet. Over time, some of this material is likely to have clumped together, possibly forming Mars’ two small moons, Phobos and Deimos.
To assess whether this was a realistic chain of events, the research team explored hundreds of different close encounter simulations, varying the asteroid’s size, spin, speed, and distance at its closest approach to the planet. The team used their high-performance, open-source computing code, called SWIFT, and the advanced computing systems at Durham University in the United Kingdom to study in detail both the initial disruption and, using another code, the subsequent orbits of the debris.
In a paper published Nov. 20 in the journal Icarus, the researchers report that, in many of the scenarios, enough asteroid fragments survive and collide in orbit to serve as raw material to form the moons.
“It’s exciting to explore a new option for the making of Phobos and Deimos – the only moons in our solar system that orbit a rocky planet besides Earth’s,” said Kegerreis. “Furthermore, this new model makes different predictions about the moons’ properties that can be tested against the standard ideas for this key event in Mars’ history.”
Two hypotheses for the formation of the Martian moons have led the pack. One proposes that passing asteroids were captured whole by Mars’ gravity, which could explain the moons’ somewhat asteroid-like appearance. The other says that a giant impact on the planet blasted out enough material – a mix of Mars and impactor debris – to form a disk and, ultimately, the moons. Scientists believe a similar process formed Earth’s Moon.
The latter explanation better accounts for the paths the moons travel today – in near-circular orbits that closely align with Mars’ equator. However, a giant impact ejects material into a disk that, mostly, stays close to the planet. And Mars’ moons, especially Deimos, sit quite far away from the planet and probably formed out there, too.
“Our idea allows for a more efficient distribution of moon-making material to the outer regions of the disk,” said Jack Lissauer, a research scientist at Ames and co-author on the paper. “That means a much smaller ‘parent’ asteroid could still deliver enough material to send the moons’ building blocks to the right place.”
It’s exciting to explore a new option for the making of Phobos and Deimos – the only moons in our solar system that orbit a rocky planet besides Earth’s.
Jacob Kegerreis
Postdoctoral research scientist at NASA’s Ames Research Center
Testing different ideas for the formation of Mars’ moons is the primary goal of the upcoming Martian Moons eXploration (MMX) sample return mission led by JAXA (Japan Aerospace Exploration Agency). The spacecraft will survey both moons to determine their origin and collect samples of Phobos to bring to Earth for study. A NASA instrument on board, called MEGANE – short for Mars-moon Exploration with GAmma rays and Neutrons – will identify the chemical elements Phobos is made of and help select sites for the sample collection. Some of the samples will be collected by a pneumatic sampler also provided by NASA as a technology demonstration contribution to the mission. Understanding what the moons are made of is one clue that could help distinguish between the moons having an asteroid origin or a planet-plus-impactor source.
Before scientists can get their hands on a piece of Phobos to analyze, Kegerreis and his team will pick up where they left off demonstrating the formation of a disk that has enough material to make Phobos and Deimos.
“Next, we hope to build on this proof-of-concept project to simulate and study in greater detail the full timeline of formation,” said Vincent Eke, associate professor at the Institute for Computational Cosmology at Durham University and a co-author on the paper. “This will allow us to examine the structure of the disk itself and make more detailed predictions for what the MMX mission could find.”
For Kegerreis, this work is exciting because it also expands our understanding of how moons might be born – even if it turns out that Mars’ own formed by a different route. The simulations offer a fascinating exploration, he says, of the possible outcomes of encounters between objects like asteroids and planets. These events were common in the early solar system, and simulations could help researchers reconstruct the story of how our cosmic backyard evolved.
This research is a collaborative effort between Ames and Durham University, supported by the Institute for Computational Cosmology’s Planetary Giant Impact Research group. The simulations used were run using the open-source SWIFT code, carried out on the DiRAC (Distributed Research Utilizing Advanced Computing) Memory Intensive service (“COSMA”), hosted by Durham University on behalf of the DiRAC High-Performance Computing facility.
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Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.
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Last Updated Nov 20, 2024 Related Terms
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By NASA
Imagine designing technology that can survive on the Moon for up to a decade, providing a continuous energy supply. NASA selected three companies to develop such systems, aimed at providing a power source at the Moon’s South Pole for Artemis missions.
Three companies were awarded contracts in 2022 with plans to test their self-sustaining solar arrays at the Johnson Space Center’s Space Environment Simulation Laboratory (SESL) in Houston, specifically in Chamber A in building 32. The prototypes tested to date have undergone rigorous evaluations to ensure the technology can withstand the harsh lunar environment and deploy the solar array effectively on the lunar surface.
The Honeybee Robotics prototype during lunar VSAT (Vertical Solar Array Technology) testing inside Chamber A at NASA’s Johnson Space Center in Houston.NASA/David DeHoyos The Astrobotic Technology prototype during lunar VSAT testing inside Chamber A at Johnson Space Center. NASA/James Blair In the summer of 2024, both Honeybee Robotics, a Blue Origin company from Altadena, California and Astrobotic Technology from Pittsburgh, Pennsylvania put their solar array concepts to the test in Chamber A.
Each company has engineered a unique solution to design the arrays to withstand the harsh lunar environment and extreme temperature swings. The data collected in the SESL will support refinement of requirements and the designs for future technological advancements with the goal to deploy at least one of the systems near the Moon’s South Pole.
The contracts for this initiative are part of NASA’s VSAT (Vertical Solar Array Technology) project, aiming to support the agency’s long-term lunar surface operations. VSAT is under the Space Technology Mission Directorate Game Changing Development program and led by the Langley Research Center in Hampton, Virginia, in collaboration with Glenn Research Center in Cleveland.
“We foresee the Moon as a hub for manufacturing satellites and hardware, leveraging the energy required to launch from the lunar surface,” said Jim Burgess, VSAT lead systems engineer. “This vision could revolutionize space exploration and industry.”
Built in 1965, the SESL initially supported the Gemini and Apollo programs but was adapted to conduct testing for other missions like the Space Shuttle Program and Mars rovers, as well as validate the design of the James Webb Space Telescope. Today, it continues to evolve to support future Artemis exploration.
Johnson’s Front Door initiative aims to solve the challenges of space exploration by opening opportunities to the public and bringing together bold and innovative ideas to explore new destinations.
“The SESL is just one of the hundreds of unique capabilities that we have here at Johnson,” said Molly Bannon, Johnson’s Innovation and Strategy specialist. “The Front Door provides a clear understanding of all our capabilities and services, the ways in which our partners can access them, and how to contact us. We know that we can go further together with all our partners across the entire space ecosystem if we bring everyone together as the hub of human spaceflight.”
Chamber A remains as one of the largest thermal vacuum chambers of its kind, with the unique capability to provide extreme deep space temperature conditions down to as low as 20 Kelvin. This allows engineers to gather essential data on how technologies react to the Moon’s severe conditions, particularly during the frigid lunar night where the systems may need to survive for 96 hours in darkness.
“Testing these prototypes will help ensure more safe and reliable space mission technologies,” said Chuck Taylor, VSAT project manager. “The goal is to create a self-sustaining system that can support lunar exploration and beyond, making our presence on the Moon not just feasible but sustainable.”
The power generation systems must be self-aware to manage outages and ensure survival on the lunar surface. These systems will need to communicate with habitats and rovers and provide continuous power and recharging as needed. They must also deploy on a curved surface, extend 32 feet high to reach sunlight, and retract for possible relocation.
“Generating power on the Moon involves numerous lessons and constant learning,” said Taylor. “While this might seem like a technical challenge, it’s an exciting frontier that combines known technologies with innovative solutions to navigate lunar conditions and build a dynamic and robust energy network on the Moon.”
Watch the video below to explore the capabilities and scientific work enabled by the thermal testing conducted in Johnson’s Chamber A facility.
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By NASA
4 min read
Final Venus Flyby for NASA’s Parker Solar Probe Queues Closest Sun Pass
On Wednesday, Nov. 6, 2024, NASA’s Parker Solar Probe will complete its final Venus gravity assist maneuver, passing within 233 miles (376 km) of Venus’ surface. The flyby will adjust Parker’s trajectory into its final orbital configuration, bringing the spacecraft to within an unprecedented 3.86 million miles of the solar surface on Dec. 24, 2024. It will be the closest any human made object has been to the Sun.
Parker’s Venus flybys have become boons for new Venus science thanks to a chance discovery from its Wide-Field Imager for Parker Solar Probe, or WISPR. The instrument peers out from Parker and away from the Sun to see fine details in the solar wind. But on July 11, 2020, during Parker’s third Venus flyby, scientists turned WISPR toward Venus in hopes of tracking changes in the planet’s thick cloud cover. The images revealed a surprise: A portion of WISPR’s data, which captures visible and near infrared light, seemed to see all the way through the clouds to the Venusian surface below.
“The WISPR cameras can see through the clouds to the surface of Venus, which glows in the near-infrared because it’s so hot,” said Noam Izenberg, a space scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
Venus, sizzling at approximately 869 degrees Fahrenheit (about 465 C), was radiating through the clouds.
The WISPR images from the 2020 flyby, as well as the next flyby in 2021, revealed Venus’ surface in a new light. But they also raised puzzling questions, and scientists have devised the Nov. 6 flyby to help answer them.
Left: A series of WISPR images of the nightside of Venus from Parker Solar Probe’s fourth flyby showing near infrared emissions from the surface. In these images, lighter shades represent warmer temperatures and darker shades represent cooler. Right: A combined mosaic of radar images of Venus’ surface from NASA’s Magellan mission, where the brightness indicates radar properties from smooth (dark) to rough (light), and the colors indicate elevation from low (blue) to high (red). The Venus images correspond well with data from the Magellan spacecraft, showing dark and light patterns that line up with surface regions Magellan captured when it mapped Venus’ surface using radar from 1990 to 1994. Yet some parts of the WISPR images appear brighter than expected, hinting at extra information captured by WISPR’s data. Is WISPR picking up on chemical differences on the surface, where the ground is made of different material? Perhaps it’s seeing variations in age, where more recent lava flows added a fresh coat to the Venusian surface.
“Because it flies over a number of similar and different landforms than the previous Venus flybys, the Nov. 6 flyby will give us more context to evaluate whether WISPR can help us distinguish physical or even chemical properties of Venus’ surface,” Izenberg said.
After the Nov. 6 flyby, Parker will be on course to swoop within 3.8 million miles of the solar surface, the final objective of the historic mission first conceived over 65 years ago. No human-made object has ever passed this close to a star, so Parker’s data will be charting as-yet uncharted territory. In this hyper-close regime, Parker will cut through plumes of plasma still connected to the Sun. It is close enough to pass inside a solar eruption, like a surfer diving under a crashing ocean wave.
“This is a major engineering accomplishment,” said Adam Szabo, project scientist for Parker Solar Probe at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The closest approach to the Sun, or perihelion, will occur on Dec. 24, 2024, during which mission control will be out of contact with the spacecraft. Parker will send a beacon tone on Dec. 27, 2024, to confirm its success and the spacecraft’s health. Parker will remain in this orbit for the remainder of its mission, completing two more perihelia at the same distance.
Parker Solar Probe is part of NASA’s Living with a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The Living with a Star program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, manages the Parker Solar Probe mission for NASA and designed, built, and operates the spacecraft.
By Miles Hatfield
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Nov 04, 2024 Related Terms
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA’s Perseverance rover captured the silhouette of the Martian moon Phobos as it passed in front of the Sun on Sept. 30, 2024. The video shows the transit speeded up by four times, followed by the eclipse in real time. NASA/JPL-Caltech/ASU/MSSS/SSI The tiny, potato-shaped moon Phobos, one of two Martian moons, cast a silhouette as it passed in front of the Sun, creating an eye in Mars’ sky.
From its perch on the western wall of Mars’ Jezero Crater, NASA’s Perseverance rover recently spied a “googly eye” peering down from space. The pupil in this celestial gaze is the Martian moon Phobos, and the iris is our Sun.
Captured by the rover’s Mastcam-Z on Sept. 30, the 1,285th Martian day of Perseverance’s mission, the event took place when the potato-shaped moon passed directly between the Sun and a point on the surface of Mars, obscuring a large part of the Sun’s disc. At the same time that Phobos appeared as a large black disc rapidly moving across the face of the Sun, its shadow, or antumbra, moved across the planet’s surface.
Astronomer Asaph Hall named the potato-shaped moon in 1877, after the god of fear and panic in Greek mythology; the word “phobia” comes from Phobos. (And the word for fear of potatoes, and perhaps potato-shaped moons, is potnonomicaphobia.) He named Mars’ other moon Deimos, after Phobos’ mythological twin brother.
Roughly 157 times smaller in diameter than Earth’s Moon, Phobos is only about 17 miles (27 kilometers) at its widest point. Deimos is even smaller.
Rapid Transit
Because Phobos’ orbit is almost perfectly in line with the Martian equator and relatively close to the planet’s surface, transits of the moon occur on most days of the Martian year. Due to its quick orbit (about 7.6 hours to do a full loop around Mars), a transit of Phobos usually lasts only 30 seconds or so.
This is not the first time that a NASA rover has witnessed Phobos blocking the Sun’s rays. Perseverance has captured several Phobos transits since landing at Mars’ Jezero Crater in February 2021. Curiosity captured a video in 2019. And Opportunity captured an image in 2004.
By comparing the various images, scientists can refine their understanding of the moon’s orbit to learn how it’s changing. Phobos is getting closer to Mars and is predicted to collide with it in about 50 million years.
More About Perseverance
Arizona State University leads the operations of the Mastcam-Z instrument, working in collaboration with Malin Space Science Systems in San Diego, on the design, fabrication, testing, and operation of the cameras, and in collaboration with the Niels Bohr Institute of the University of Copenhagen on the design, fabrication, and testing of the calibration targets.
A key objective for Perseverance’s mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and cache Martian rock and regolith (broken rock and dust).
Subsequent NASA missions, in cooperation with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis.
The Mars 2020 Perseverance mission is part of NASA’s Moon to Mars exploration approach, which includes Artemis missions to the Moon that will help prepare for human exploration of the Red Planet.
NASA’s Jet Propulsion Laboratory, which is managed for the agency by Caltech in Pasadena, California, built and manages operations of the Perseverance rover.
Space Science Institute produced this video.
For more about Perseverance:
https://mars.nasa.gov/mars2020
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agle@jpl.nasa.gov
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Last Updated Oct 30, 2024 Related Terms
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