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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
Artist’s concept of a young, newly discovered planet, exposed to observation by a warped debris disk. Credit: Robert Hurt, Caltech-IPAC. The discovery
A huge planet with a long name – IRAS 04125+2902 b – is really just a baby: only 3 million years old. And because such infant worlds are usually hidden inside obscuring disks of debris, it is the youngest planet so far discovered using the dominant method of planet detection.
Key facts
The massive planet, likely still glowing from the heat of its formation, lies in the Taurus Molecular Cloud, an active stellar nursery with hundreds of newborn stars some 430 light-years away. The cloud’s relative closeness makes it a prime target for astronomers. But while the cloud offers deep insight into the formation and evolution of young stars, their planets are usually a closed book to telescopes like TESS, the Transiting Exoplanet Survey Satellite. These telescopes rely on the “transit method,” watching for the slight dip in starlight when a planet crosses the face of its host star. But such planetary systems must be edge-on, from Earth’s vantage point, for the transit method to work. Very young star systems are surrounded by disks of debris, however, blocking our view of any potentially transiting planets.
A research team has just reported an extraordinary stroke of luck. Somehow, the outer debris disk surrounding this newborn planet, IRAS 04125+2902 b, has been sharply warped, exposing the baby world to extensive transit observations by TESS.
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While the warped outer disk is a great coincidence, it’s also a great mystery. Possible explanations include a migration of the planet itself, moving closer to the star and, in the process, diverging from the orientation of the outer disk – so that, from Earth, the planet’s orbit is edge-on, crossing the face of the star, but the outer disk remains nearly face-on to us. One problem with this idea: Moving a planet so far out of alignment with its parent disk would likely require another (very large) object in this system. None has been detected so far.
The system’s sun happens to have a distant stellar companion, also a possible culprit in the warping of the outer disk. The angle of the orbit of the companion star, however, matches that of the planet and its parent star. Stars and planets tend to take the gravitational path of least resistance, so such an arrangement should push the disk into a closer alignment with the rest of the system – not into a radical departure.
Another way to get a “broken” outer disk, the study authors say, would not involve a companion star at all. Stellar nurseries like the Taurus Molecular Cloud can be densely packed, busy places. Computer simulations show that rains of infalling material from the surrounding star-forming region could be the cause of disk-warping. Neither simulations nor observations have so far settled the question of whether warped or broken disks are common or rare in such regions.
Fun facts
Combining TESS’s transit measurements with another way of observing planets yields more information about the planet itself. We might call this second approach the “wobble” method. The gravity of a planet tugs its star one way, then another, as the orbiting planet makes its way around the star. And that wobble can be detected by changes in the light from the star, picked up by specialized instruments on Earth. Such “radial velocity” measurements of this planet reveal that its mass, or heft, amounts to no more than about a third of our own Jupiter. But the transit data shows the planet’s diameter is about the same. That means the planet has a comparatively low density and, likely, an inflated atmosphere. So this world probably is not a gas giant like Jupiter. Instead, it could well be a planet whose atmosphere will shrink over time. When it finally settles down, it could become a gaseous “mini-Neptune” or even a rocky “super-Earth.” These are the two most common planet types in our galaxy – despite the fact that neither type can be found in our solar system.
The discoverers
A science team led by astronomer Madyson G. Barber of the University of North Carolina at Chapel Hill published the study, “A giant planet transiting a 3 Myr protostar with a misaligned disk,” in the journal Nature in November 2024.
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By NASA
On Nov. 16, 2009, space shuttle Atlantis began its 31st trip into space, on the third Utilization and Logistics Flight (ULF3) mission to the International Space Station, the 31st shuttle flight to the orbiting lab. During the 11-day mission, the six-member STS-129 crew worked with the six-person Expedition 21 crew during seven days of docked operations. The mission’s primary objectives included delivering two external logistics carriers and their spare parts, adding nearly 15 tons of hardware to the station, and returning a long-duration crew member, the last to return on a shuttle. Three of the STS-129 astronauts conducted three spacewalks to transfer spare parts and continue assembly and maintenance of the station. As a group of 12, the joint crews celebrated the largest and most diverse Thanksgiving gathering in space.
Left: Official photograph of the STS-129 crew of Leland D. Melvin, left, Charles O. Hobaugh, Michael J. Foreman, Robert “Bobby” L. Satcher, Barry “Butch” E. Wilmore, and Randolph “Randy” J. Bresnik. Middle: The STS-129 crew patch. Right: The ULF3 payload patch.
The six-person STS-129 crew consisted of Commander Charles O. Hobaugh, Pilot Barry “Butch” E. Wilmore, and Mission Specialists Randolph “Randy” J. Bresnik, Michael J. Foreman, Leland D. Melvin, and Robert “Bobby” L. Satcher. Primary objectives of the mission included launch and transfer to the station of the first two EXPRESS Logistics Carriers (ELC-1 and ELC-2) and their multiple spare parts, and the return of NASA astronaut and Expedition 20 and 21 Flight Engineer Nicole P. Stott, the last astronaut to rotate on the shuttle.
Left: In the Orbiter Processing Facility (OPF) at NASA’s Kennedy Space Center in Florida, workers finish processing Atlantis for STS-129. Right: Space shuttle Atlantis rolls over from the OPF to the Vehicle Assembly Building.
Left: Atlantis rolls out to Launch Pad 39A. Right: The STS-129 crew during the Terminal Countdown Demonstration Test.
Atlantis returned to NASA’s Kennedy Space Center (KSC) from its previous mission, STS-125, on June 2, 2009, and workers towed it to the Orbiter Processing Facility (OPF) to prepare it for STS-129. The orbiter rolled over to the Vehicle Assembly Building on Oct. 6, and after mating with its external tank and twin solid rocket boosters, rolled out to Launch Pad 39A on Oct. 14, targeting a Nov. 16 launch. Six days later, the six-member crew participated in the Terminal Countdown Demonstration Test, essentially a dress rehearsal of the actual countdown for launch, returning to Houston for final training. They returned to KSC on Nov. 13 to prepare for launch.
Left: With Atlantis sitting on Launch Pad 39A, the Ares 1-X rocket lifts off from Launch Pad 39B. Right: The payload canister arrives at Launch Pad 39A.
Left: The STS-129 astronauts leave crew quarters for the ride to Launch Pad 39A. Right: Liftoff of space shuttle Atlantis on STS-129.
On Nov. 16, at 2:28 p.m. EST, space shuttle Atlantis lifted off from Launch Pad 39A to begin its 31st trip into space, carrying its six-member crew on the ULF3 space station outfitting and resupply mission. Eight and a half minutes later, Atlantis and its crew had reached orbit. The flight marked Hobaugh’s third time in space, having flown on STS-104 and STS-118, Foreman’s and Melvin’s second, having flown on STS-123 and STS-122, respectively, while Wilmore, Bresnik, and Satcher enjoyed their first taste of weightlessness.
Left: The two EXPRESS Logistics Carriers in Atlantis’ payload bay. Middle: Leland D. Melvin participates in the inspection of Atlantis’ thermal protection system. Right: The Shuttle Remote Manipulator System grasps the Orbiter Boom Sensor System for the inspection.
After reaching orbit, the crew opened the payload bay doors, deployed the shuttle’s radiators, and removed their bulky launch and entry suits, stowing them for the remainder of the flight. The astronauts spent six hours on their second day in space conducting a detailed inspection of Atlantis’ nose cap and wing leading edges, with Hobaugh, Wilmore, Melvin, and Bresnik taking turns operating the Shuttle Remote Manipulator System (SRMS), or robotic arm, and the Orbiter Boom Sensor System (OBSS).
Left: The International Space Station as seen from Atlantis during the rendezvous and docking maneuver. Middle: Atlantis as seen from the space station, showing the two EXPRESS Logistics Carriers (ELC) in the payload bay. Right: View of the space station from Atlantis during the rendezvous pitch maneuver, with the Shuttle Remote Manipulator System grasping ELC-1 in preparation for transfer shortly after docking.
On the mission’s third day, Hobaugh assisted by his crewmates brought Atlantis in for a docking with the space station. During the rendezvous, Hobaugh stopped the approach at 600 feet and completed the Rendezvous Pitch Maneuver so astronauts aboard the station could photograph Atlantis’ underside to look for any damage to the tiles. Shortly after docking, the crews opened the hatches between the two spacecraft and the six-person station crew welcomed the six-member shuttle crew. After the welcoming ceremony, Stott joined the STS-129 crew, leaving a crew of five aboard the station. Melvin and Bresnik used the SRMS to pick up ELC-1 from the payload bay and hand it off to Wilmore and Expedition 21 NASA astronaut Jeffrey N. Williams operating the Space Station Remote Manipulator System (SSRMS), who then installed it on the P3 truss segment.
Images from the first spacewalk. Left: Michael J. Foreman unstows the S-band Antenna Support Assembly prior to transferring it to the station. Middle: Robert “Bobby” L. Satcher lubricates the robotic arm’s Latching End Effector. Right: Satcher’s image reflected in a Z1 radiator panel.
During the mission’s first of three spacewalks on flight day four, Foreman and Satcher ventured outside for six hours and 37 minutes. During the excursion, with robotic help from their fellow crew members, they transferred a spare S-band Antenna Support Assembly from the shuttle’s payload bay to the station’s Z1 truss. Satcher, an orthopedic surgeon by training, performed “surgery” on the station’s main robotic arm as well as the robotic arm on the Kibo Japanese module, by lubricating their latching end effectors. One day after joining Atlantis’ crew, Stott celebrated her 47th birthday.
Left: Space station crew member Jeffery N. Williams assists STS-129 astronaut Leland D. Melvin in operating the space station’s robotic arm to transfer and install the second EXPRESS Logistics Carrier (ELC2) on the S3 truss. Middle: The station robotic arm installs ELC2 on the S3 truss. Right: Michael J. Foreman, left, and Randolph J. Bresnik during the mission’s second spacewalk.
On the mission’s fifth day, the astronauts performed another focused inspection of the shuttle’s thermal protection system. The next day, through another coordinated robotic activity involving the shuttle and station arms, the astronauts transferred ELC-2 and its complement of spares from the payload bay to the station’s S3 truss. Foreman and Bresnik completed the mission’s second spacewalk. Working on the Columbus module, they installed the Grappling Adaptor to On-Orbit Railing (GATOR) fixture that includes a system used for ship identification and an antenna for Ham radio operators. They next installed a wireless video transmission system on the station’s truss. This spacewalk lasted six hours and eight minutes.
Left: Randolph J. Bresnik during the third STS-129 spacewalk. Middle: Robert “Bobby” L. Satcher during the third spacewalk. Right: The MISSE 7 exposure experiment suitcases installed on ELC2.
Following a crew off duty day, on flight day eight Satcher and Bresnik exited the airlock for the mission’s third and final spacewalk. Their first task involved moving an oxygen tank from the newly installed ELC-2 to the Quest airlock. They accomplished this task with robotic assistance from their fellow crew members. Bresnik retrieved the two-suitcase sized MISSE-7 experiment containers from the shuttle cargo bay and installed them on the MISSE-7 platform on ELC-2, opening them to begin their exposure time. This third spacewalk lasted five hours 42 minutes.
Left: An early Thanksgiving meal for 12 aboard the space station. Right: After the meal, who has the dishes?
Thanksgiving Day fell on the day after undocking, so the joint crews celebrated with a meal a few days early. The meal represented not only the largest Thanksgiving celebration in space with 12 participants, but also the most international, with four nations represented – the United States, Russia, Canada, and Belgium (representing the European Space Agency).
Left: The 12 members of Expedition 21 and STS-129 pose for a final photograph before saying their farewells. Right: The STS-129 crew, now comprising seven members.
A selection of STS-129 Earth observation images. Left: Maui. Middle: Los Angeles. Right: Houston.
Despite their busy workload, as with all space crews, the STS-129 astronauts made time to look out the windows and took hundreds of photographs of their home planet.
Left: The space station seen from Atlantis during the flyaround. Middle: Atlantis as seen from the space station during the flyaround, with a now empty payload bay. Right: Astronaut Nicole P. Stott looks back at the station, her home for three months, from the departing Atlantis.
On flight day nine, the joint crews held a brief farewell ceremony. European Space Agency astronaut Frank De Winne, the first European to command the space station, handed over command to NASA astronaut Williams. The two crews parted company and closed the hatches between the two spacecraft. The next day, with Wilmore at the controls, Atlantis undocked from the space station, having spent seven days as a single spacecraft. Wilmore completed a flyaround of the station, with the astronauts photographing it to document its condition. A final separation burn sent Atlantis on its way.
The astronauts used the shuttle’s arm to pick up the OBSS and perform a late inspection of Atlantis’ thermal protection system. On flight day 11, Hobaugh and Wilmore tested the orbiter’s reaction control system thrusters and flight control surfaces in preparation for the next day’s entry and landing. The entire crew busied themselves with stowing all unneeded equipment.
Left: Atlantis about to touch down at NASA’s Kennedy Space Center in Florida. Middle: Atlantis touches down. Right: Atlantis deploys its drag chute as it continues down the runway.
Left: Six of the STS-129 astronauts pose with Atlantis on the runway at NASA’s Kennedy Space Center in Florida. Right: The welcome home ceremony for the STS-129 crew at Ellington Field in Houston.
On Nov. 27, the astronauts closed Atlantis’ payload bay doors, donned their launch and entry suits, and strapped themselves into their seats, a special recumbent one for Stott who had spent the last three months in weightlessness. Hobaugh fired Atlantis’ two Orbital Maneuvering System engines to bring them out of orbit and head for a landing half an orbit later. He guided Atlantis to a smooth touchdown at KSC’s Shuttle Landing Facility.
The landing capped off a very successful STS-129 mission of 10 days, 19 hours, 16 minutes. The six astronauts orbited the planet 171 times. Stott spent 90 days, 10 hours, 45 minutes in space, completing 1,423 orbits of the Earth. After towing Atlantis to the OPF, engineers began preparing it for its next flight, STS-132 in May 2010. The astronauts returned to Houston for a welcoming ceremony at Ellington Field.
Enjoy the crew narrate a video about the STS-129 mission.
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By NASA
NASA/Joel Kowsky In this photo, NASA’s SLS (Space Launch System) rocket, carrying the Orion spacecraft, lifts off the pad at Launch Complex 39B at the agency’s Kennedy Space Center in Florida at 1:47 a.m. EST on Nov. 16, 2022. Set on a path to the Moon, this officially began the Artemis I mission.
Since the completion of Orion’s 25.5-day mission around the Moon and back, teams across NASA have been hard at work preparing for the upcoming Artemis II test flight, which will send four astronauts on a 10-day mission around the Moon, paving the way for humans to land on the Moon as part of the Artemis III mission.
Under NASA’s Artemis campaign, the agency will establish the foundation for long-term scientific exploration at the Moon, land the first woman, first person of color, and its first international partner astronaut on the lunar surface, and prepare for human expeditions to Mars for the benefit of all.
Image Credit: NASA/Joel Kowsky
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By NASA
NASA The Apollo 12 spacecraft launches from NASA’s Kennedy Space Center in Florida in this image from Nov. 14, 1969, with astronauts Charles Conrad Jr., Richard F. Gordon Jr., and Alan L. Bean aboard. During liftoff, the Saturn V rocket which carried the Apollo capsule was struck twice by lightning.
On Nov. 19, 1969, the lunar module landed on the Moon. About three hours after landing, Conrad emerged from the lunar module, becoming the third person to step on the Moon. He was followed by Bean.
Image credit: NASA
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