SPACE
Hubble sees boulders escaping from asteroid dimorphos
IMAGE: IMAGE OF THE ASTEROID DIMORPHOS, WITH COMPASS ARROWS, SCALE BAR, AND COLOR KEY FOR REFERENCE. THE NORTH AND EAST COMPASS ARROWS SHOW THE ORIENTATION OF THE IMAGE ON THE SKY. NOTE THAT THE RELATIONSHIP BETWEEN NORTH AND EAST ON THE SKY (AS SEEN FROM BELOW) IS FLIPPED RELATIVE TO DIRECTION ARROWS ON A MAP OF THE GROUND (AS SEEN FROM ABOVE). view more
CREDIT: CREDITS: NASA, ESA, DAVID JEWITT (UCLA); ALYSSA PAGAN (STSCI)
The popular 1954 rock song "Shake, Rattle and Roll," could be the theme music for the Hubble Space Telescope's latest discovery about what is happening to the asteroid Dimorphos in the aftermath of NASA's DART (Double Asteroid Redirection Test) experiment. DART intentionally impacted Dimorphos on September 26, 2022, slightly changing the trajectory of its orbit around the larger asteroid Didymos.
Astronomers using Hubble's extraordinary sensitivity have discovered a swarm of boulders that were possibly shaken off the asteroid when NASA deliberately slammed the half-ton DART impactor spacecraft into Dimorphos at approximately 14,000 miles per hour.
The 37 free-flung boulders range in size from three feet to 22 feet across, based on Hubble photometry. They are drifting away from the asteroid at little more than a half-mile per hour – roughly the walking speed of a giant tortoise. The total mass in these detected boulders is about 0.1% the mass of Dimorphos.
"This is a spectacular observation – much better than I expected. We see a cloud of boulders carrying mass and energy away from the impact target. The numbers, sizes, and shapes of the boulders are consistent with them having been knocked off the surface of Dimorphos by the impact," said David Jewitt of the University of California at Los Angeles, a planetary scientist who has been using Hubble to track changes in the asteroid during and after the DART impact. "This tells us for the first time what happens when you hit an asteroid and see material coming out up to the largest sizes. The boulders are some of the faintest things ever imaged inside our solar system."
Jewitt says that this opens up a new dimension for studying the aftermath of the DART experiment using the European Space Agency's upcoming Hera spacecraft, which will arrive at the binary asteroid in late 2026. Hera will perform a detailed post-impact survey of the targeted asteroid. "The boulder cloud will still be dispersing when Hera arrives," said Jewitt. "It's like a very slowly expanding swarm of bees that eventually will spread along the binary pair's orbit around the Sun."
The boulders are most likely not shattered pieces of the diminutive asteroid caused by the impact. They were already scattered across the asteroid's surface, as evident in the last close-up picture taken by the DART spacecraft just two seconds before collision, when it was only seven miles above the surface.
Jewitt estimates that the impact shook off two percent of the boulders on the asteroid's surface. He says the boulder observations by Hubble also give an estimate for the size of the DART impact crater. "The boulders could have been excavated from a circle of about 160 feet across (the width of a football field) on the surface of Dimorphos," he said. Hera will eventually determine the actual crater size.
Long ago, Dimorphos may have formed from material shed into space by the larger asteroid Didymos. The parent body may have spun up too quickly or could have lost material from a glancing collision with another object, among other scenarios. The ejected material formed a ring that gravitationally coalesced to form Dimorphos. This would make it a flying rubble pile of rocky debris loosely held together by a relatively weak pull of gravity. Therefore, the interior is probably not solid, but has a structure more like a bunch of grapes.
It's not clear how the boulders were lifted off the asteroid's surface. They could be part of an ejecta plume that was photographed by Hubble and other observatories. Or a seismic wave from the impact may have rattled through the asteroid – like hitting a bell with a hammer – shaking lose the surface rubble.
"If we follow the boulders in future Hubble observations, then we may have enough data to pin down the boulders' precise trajectories. And then we’ll see in which directions they were launched from the surface," said Jewitt.
The DART and LICIACube (Light Italian CubeSat for Imaging of Asteroids) teams have also been studying boulders detected in images taken by LICIACube’s LUKE (LICIACube Unit Key Explorer) camera in the minutes immediately following DART's kinetic impact.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble and Webb science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.
This is the last complete image of the asteroid Dimorphos, as seen by NASA's DART (Double Asteroid Redirection Test) impactor spacecraft two seconds before impact. The Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO) imager aboard captured a 100-foot-wide patch of the asteroid. The DART spacecraft streamed these images from its DRACO camera back to Earth in real time as it approached the asteroid. DART successfully impacted its target on September 26, 2022.
CREDIT
Credits: NASA, APL
The puzzle of the galaxy with no dark matter
IMAGE: COMPARISON BETWEEN A CONVENTIONAL GALAXY (ESO 325-G004) ENVELOPED IN A HALO OF DARK MATTER, OCCUPYING THE HEAVIEST PLATE ON THE WEIGHT SCALE, AND THE GALAXY NGC 1277 (ON THE LEFT), IN WHICH THE STUDY OF THE MASS DISTRIBUTION REVEALS THE ABSENCE OF DARK MATTER. view more
CREDIT: DESIGN: GABRIEL PÉREZ DÍAZ (IAC). IMAGE OF NGC 1277: NASA, ESA, AND M. BEASLEY (IAC). IMAGE OF ESO 325-G004: NASA, ESA, AND THE HUBBLE HERITAGE TEAM (STSCI/AURA); J. BLAKESLEE (WASHINGTON STATE UNIVERSITY)
A team of scientists, led by the researcher at the IAC and the University of La Laguna (ULL) Sebastién Comerón, has found that the galaxy NGC 1277 does not contain dark matter.This is the first time that a massive galaxy (it has a mass several times that of the Milky Way) does not show evidence for this invisible component of the universe. “This result does not fit in with the currently accepted cosmological models, which include dark matter” explains Comerón.
In the current standard model cosmology massive galaxies contain substantial quantities of dark matter, a type of matter which does not interact in the same way as normal matter; the only evidence for its existence is the strong gravitational pull which it exerts on the stars and the gas nearby, and this interacton is observable.
NGC 1277 is considered a prototype “relic galaxy” which means a galaxy which has had no interactions with its neighbours. Galaxies of this type are very rare, and they are considered the remnants of giant galaxies which formed in the early days of the universe.
“The importance of relic galaxies in helping us to understand how the first galaxies formed was the reason we decided to observe NGC 1277 with an integral field spectrograph” explains Comerón. “From the spectra we made kinematic maps which enabled us to work out the distribution of mass within the galaxy out to a radius of some 20,000 light years” he adds.
The team discovered that the mass distribution in NGC 1277 was just the distribution of the stars, and from this they inferred that within the radius observed there cannot be more than 5% of dark matter, although the observations are consistent with the complete absence of this component.
However, present cosmological models predict that a galaxy with the mass of NGC 1277 should have at least 10 % of their mass in the form of dark matter, with a maximum of 70 % in this form. "This discrepancy between the observations and what we would expect is a puzzle, and maybe even a challenge for the standard model” notes Ignacio Trujillo, a researcher at the IAC and the ULL, who participated in the study.
The article suggests two possible explanations for the lack of dark matter in NGC 1277. “One is that the gravitational interaction with the surrounding medium within the galaxy cluster in which this galaxy is situated has stripped out the dark matter” comments Anna Ferré-Mateu, a researcher at the IAC and the ULL who also participated in the study. “The other is that the dark matter was driven out of the system when the galaxy formed by the merging of protogalactic fragments, which gave rise to the relic galaxy”.
For the authors of the study neither of these explanations is fully satisfactory “so the puzzle of how a massive galaxy can form without dark matter remains a puzzle” insists Comerón. In order to continue researching the mystery the team plans to make new observations with the WEAVE instrument on the William Herschel Telescope (WHT) at the Roque de los Muchachos Observatory, in the Canary Island of La Palma
If this the result, that NGC 1277 does not have dark matter, is confirmed, it would cast strong doubt on alternative models for dark matter, namely theories in which gravity is modified and the major part of the gravitational attraction within galaxies is due to a slight change in the law of gravity on large scales. “Although the dark matter in a specific galaxy can be lost, a modified law of gravity must be universal, it cannot have exceptions, so that a galaxy without dark matter is a refutation of this type of alternatives to dark matter” notes Trujillo.
JOURNAL
Astronomy and Astrophysics
ARTICLE TITLE
The massive relic galaxy NGC 1277 is dark matter deficient. From dynamical models of integral-field stellar kinematics out to five effective radii
SwRI-led team finds ancient, high-energy impacts could have fueled Venus volcanism
Models show Venus’ superheated core could produce extended volcanism, long-lived resurfacing
Peer-Reviewed PublicationIMAGE: AN SWRI-LED TEAM COMPARED THE EARLY IMPACT HISTORY OF VENUS AND EARTH, DETERMINING THAT VENUS EXPERIENCED HIGHER-ENERGY IMPACTS CREATING A SUPERHEATED CORE. MODELS SHOW THESE CONDITIONS COULD CREATE VENUS’ EXTENDED VOLCANISM AND YOUNGER SURFACE. view more
CREDIT: SOUTHWEST RESEARCH INSTITUTE
SAN ANTONIO —July 20, 2023 —A Southwest Research Institute-led team has modeled the early impact history of Venus to explain how Earth’s sister planet has maintained a youthful surface despite lacking plate tectonics. The team compared the early collision histories of the two bodies and determined that Venus likely experienced higher-speed, higher-energy impacts creating a superheated core that promoted extended volcanism and resurfaced the planet.
“One of the mysteries of the inner solar system is that, despite their similar size and bulk density, Earth and Venus operate in strikingly distinct ways, particularly affecting the processes that move materials through a planet,” said Dr. Simone Marchi, lead author of a new paper about these findings in Nature Astronomy.
The Earth’s shifting plates continuously reshape its surface as chunks of the crust collides to form mountains ranges, and in places promote volcanism. Venus has more volcanos than any other planet in the solar system but has only one continuous plate for its surface. More than 80,000 volcanos — 60 times more than Earth — have played a major role in renewing the planet’s surface through floods of lava, which may continue to this day. Previous simulations struggled to create scenarios to support this level of volcanism.
“Our latest models show that long-lived volcanism driven by early, energetic collisions on Venus offer a compelling explanation for its young surface age,” said Professor Jun Korenaga, a co-author from Yale University. “This massive volcanic activity is fueled by a superheated core, resulting in vigorous internal melting.”
Earth and Venus formed in the same neighborhood of the solar system as solid materials collided with each other and gradually combined to form the two rocky planets. The slight differences in the planets’ distances from the Sun changed their impact histories, particularly the number and outcome of these events. These differences arise because Venus is closer to the Sun and moves faster around it, energizing impact conditions. In addition, the tail of collisional growth is typically dominated by impactors originating from beyond Earth’s orbit that require higher orbital eccentricities to collide with Venus rather than Earth, resulting in more powerful impacts.
“Higher impact velocities melt more silicate, melting as much as 82% of Venus’ mantle,” said Dr. Raluca Rufu, a Sagan Fellow and SwRI co-author. “This produces a mixed mantle of molten materials redistributed globally and a superheated core.”
If impacts on Venus had significantly higher velocity than on Earth, a few large impacts could have had drastically different outcomes, with important implications for the subsequent geophysical evolution. The multidisciplinary team combined expertise in large-scale collision modeling and geodynamic processes to assess the consequences of those collisions for the long-term evolution of Venus.
“Venus internal conditions are not well known, and before considering the role of energetic impacts, geodynamical models required special conditions to achieve the massive volcanism we see at Venus,” Korenaga said. “Once you input energetic impact scenarios into the model, it easily comes up with the extensive and extended volcanism without really tweaking the parameters.”
And the timing of this new explanation is serendipitous. In 2021, NASA committed to two new Venus missions, VERITAS and DAVINCI, while the European Space Agency is planning one called EnVision.
“Interest in Venus is high right now,” Marchi said. “These findings will have synergy with the upcoming missions, and the mission data could help confirm the findings.”
The paper “Long-lived volcanic resurfacing of Venus driven by early collisions” appears in Nature Astronomy and can be accessed at https://doi.org/10.1038/s41550-023-02037-2.
For more information, visit https://www.swri.org/planetary-science.
Computer simulation illustrate [VIDEO] |
This high resolution (1 million particles) computer simulation illustrates an 1,800-mile-diameter (3,000-kilometer) projectile striking Venus head-on at 18 miles per second (30 km/s). On the left, the colors indicate different materials — brown for Venus' core; white for the projectile's core; and green for the silicate mantle of both objects. The colors on right side indicate the temperature of the materials.
Ancient, high-energy impacts c [VIDEO] |
A Southwest Research Institute-led team has modeled the early impact history of Venus to explain how Earth’s sister planet has maintained a youthful surface despite lacking plate tectonics. The new model suggests that the planets’ distances from the Sun resulted in higher-energy, higher-velocity impacts to Venus. These powerful collisions created a superheated core that promoted extended, extensive volcanism and resurfaced the planet.
Ancient, high-energy impacts c [VIDEO] |
A Southwest Research Institute-led team has modeled the early impact history of Venus to explain how Earth’s sister planet has maintained a youthful surface despite lacking plate tectonics. The new model suggests that the planets’ distances from the Sun resulted in higher-energy, higher-velocity impacts to Venus. These powerful collisions created a superheated core that promoted extended, extensive volcanism and resurfaced the planet.
CREDIT
Southwest Research Institute
Southwest Research Institute
JOURNAL
Nature Astronomy
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
“Long-lived volcanic resurfacing of Venus driven by early collisions”
NASA's ComPair gamma-ray hunting mission prepares for balloon flight
IMAGE: TEAM MEMBERS WORK ON THE COMPAIR BALLOON INSTRUMENT BEFORE IT BEGINS THERMAL VACUUM CHAMBER TESTING AT NASA’S GODDARD SPACE FLIGHT CENTER IN GREENBELT, MARYLAND. COMPAIR PROJECT MANAGER REGINA CAPUTO (FRONT RIGHT), GRADUATE STUDENT NICHOLAS KIRSCHNER (GEORGE WASHINGTON UNIVERSITY, LEFT), AND RESEARCH SCIENTIST NICHOLAS CANNADY (UNIVERSITY OF MARYLAND BALTIMORE COUNTY, REAR) EXAMINE COMPAIR'S VARIOUS COMPONENTS TO DETERMINE WHAT NEEDS TO BE “HARNESSED,” OR CONNECTED VIA CABLE TO POWER SYSTEMS AND THE ONBOARD COMPUTER. view more
CREDIT: NASA’S GODDARD SPACE FLIGHT CENTER/SCOTT WIESSINGER
Engineers and scientists have shipped NASA’s ComPair instrument to Fort Sumner, New Mexico, ahead of its scheduled August flight early in NASA’s 2023 fall balloon campaign.
ComPair’s goal is to test new technologies for studying gamma rays, the highest-energy form of light. It was assembled and tested at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
“The gamma-ray energy range we’re targeting with ComPair isn’t well covered by current observatories,” said Carolyn Kierans, the instrument’s principal investigator at Goddard. “We hope that after a successful balloon test flight, future versions of the technologies will be used in space-based missions.”
ComPair is designed to detect gamma rays with energies between 200,000 and 20 million electron volts. (For comparison, the energy of visible light is 2 to 3 electron volts.) Supernovae and gamma-ray bursts, the most powerful explosions in the cosmos, glow brightest in this range, as do the most massive and distant active galaxies, which are powered by supermassive black holes. Scientists know this because they see a fraction of the light emitted by these galaxies with NASA’s Fermi Gamma-ray Space Telescope, which observes higher-energy gamma rays.
ComPair gets its name from the two ways it detects and measures gamma rays: Compton scattering and pair production. Compton scattering occurs when light hits a particle, such as an electron, and transfers some energy to it. Pair production happens when a gamma ray grazes the nucleus of an atom. The interaction converts the gamma ray into a pair of particles – an electron and its antimatter counterpart, a positron.
The ComPair instrument has four major components:
- A tracker containing 10 layers of silicon detectors that determines the positions of incoming gamma rays.
- A high-resolution calorimeter that precisely measures lower-energy Compton-scattered gamma rays.
- Another calorimeter that measures the higher-energies of electron-positron pairs.
- An anticoincidence detector that notes the entry of high-energy charged particles called cosmic rays, allowing ComPair's other instruments to ignore them.
The mission team assembled all the components and tested them in a large thermal vacuum chamber at Goddard to assess how they’ll function at balloon altitudes. The next step is to fly the instrument. The flight will carry ComPair to a height of about 133,000 feet (40,000 meters), or nearly four times the cruising altitude of a commercial airliner.
ComPair will piggyback with one of the primary balloon payloads that will fly during NASA’s annual Fort Sumner balloon campaign. NASA’s scientific balloons offer frequent, low-cost access to near-space to conduct scientific investigations and technology maturation in fields such as astrophysics, heliophysics, and atmospheric research, as well as training for the next generation of leaders in engineering and science.
ComPair is a collaboration among Goddard, the Naval Research Laboratory in Washington, Brookhaven National Laboratory in Upton, New York, and Los Alamos National Laboratory in New Mexico.
New study reveals NASA's roman could find 400 earth-mass rogue planets
New research by scientists from NASA and Japan’s Osaka University suggests that our galaxy’s rogue planets far outnumber the hundred billion or so worlds that orbit stars. The results imply that NASA’s Roman Space Telescope could find a staggering 400
IMAGE: THIS ARTIST'S CONCEPT SHOWS AN ICE-ENCRUSTED, EARTH-MASS ROGUE PLANET DRIFTING THROUGH SPACE ALONE. view more
CREDIT: NASA’S GODDARD SPACE FLIGHT CENTER
New research by scientists from NASA and Japan’s Osaka University suggests that rogue planets – worlds that drift through space untethered to a star – far outnumber planets that orbit stars. The results imply that NASA’s Nancy Grace Roman Space Telescope, set to launch by May 2027, could find a staggering 400 Earth-mass rogue worlds. Indeed, this new study has already identified one such candidate.
“We estimate that our galaxy is home to 20 times more rogue planets than stars – trillions of worlds wandering alone,” said David Bennett, a senior research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a co-author of two papers describing the results. “This is the first measurement of the number of rogue planets in the galaxy that is sensitive to planets less massive than Earth.”
The team’s findings stem from a nine-year survey called MOA (Microlensing Observations in Astrophysics), conducted at the Mount John University Observatory in New Zealand. Microlensing events occur when an object such as a star or planet comes into near-perfect alignment with an unrelated background star from our vantage point. Because anything with mass warps the fabric of space-time, light from the distant star bends around the nearer object as it passes close by. The nearer object acts as a natural lens, creating a brief spike in the brightness of the background star’s light that gives astronomers clues about the intervening object that they can’t get any other way.
“Microlensing is the only way we can find objects like low-mass free-floating planets and even primordial black holes,” said Takahiro Sumi, a professor at Osaka University, and lead author of the paper with a new estimate of our galaxy’s rogue planets. “It’s very exciting to use gravity to discover objects we could never hope to see directly.”
The roughly Earth-mass rogue planet the team found marks the second discovery of its kind. The paper describing the finding will appear in a future issue of The Astronomical Journal. A second paper, which presents a demographic analysis that concludes that rogue planets are six times more abundant than worlds that orbit stars in our galaxy, will be published in the same journal.
Pint-Sized Planets
In only a few decades, we've gone from wondering whether the worlds in our solar system are alone in the cosmos to discovering more than 5,300 planets outside our solar system. The vast majority of these newfound worlds are either huge, extremely close to their host star, or both. By contrast, the team’s results suggest that rogue planets tend to be on the petite side.
“We found that Earth-size rogues are more common than more massive ones,” Sumi said. “The difference in star-bound and free-floating planets’ average masses holds a key to understanding planetary formation mechanisms.”
World-building can be chaotic, with all of the forming celestial bodies gravitationally interacting as they settle into their orbits. Planetary lightweights aren’t tethered as strongly to their star, so some of these interactions end up flinging such worlds off into space. So begins a solitary existence, hidden amongst the shadows between stars.
In one of the early episodes of the original Star Trek series, the crew encounters one such lone planet amid a so-called star desert. They were surprised to ultimately find Gothos, the starless planet, habitable. While such a world may be plausible, the team emphasizes that the newly detected “rogue Earth” probably doesn’t share many other characteristics with Earth beyond a similar mass.
Roman’s Hunt for Hidden Worlds
Microlensing events that reveal solitary planets are extraordinarily rare, so one key to finding more is to cast a wider net. That’s just what Roman will do when it launches by May 2027.
“Roman will be sensitive to even lower-mass rogue planets since it will observe from space,” said Naoki Koshimoto, who led the paper announcing the detection of a candidate terrestrial-mass rogue world. Now an assistant professor at Osaka University, he conducted this research at Goddard. “The combination of Roman’s wide view and sharp vision will allow us to study the objects it finds in more detail than we can do using only ground-based telescopes, which is a thrilling prospect.”
Previous best estimates, based on planets found orbiting stars, suggested Roman would spot 50 terrestrial-mass rogue worlds. These new results suggest it could actually find about 400, though we’ll have to wait until Roman begins scanning the skies to make more certain predictions. Scientists will couple Roman’s future data with ground-based observations from facilities such as Japan's PRIME (Prime-focus Infrared Microlensing Experiment) telescope, located at the South African Astronomical Observatory in Sutherland. This 1.8-meter telescope will build on MOA’s work by conducting the first wide-area microlensing survey in near-infrared light. It’s equipped with four detectors from Roman’s detector development program, contributed by NASA as part of an international agreement with JAXA (Japan Aerospace Exploration Agency).
Each microlensing event is a one-time occurrence, meaning astronomers can’t go back and repeat the observations once they’re over. But they’re not instantaneous.
“A microlensing signal from a rogue planet can take from a few hours up to about a day, so astronomers will have a chance to do simultaneous observations with Roman and PRIME,” Koshimoto said.
Seeing them from both Earth and Roman’s location a million miles away will help scientists measure the masses of rogue planets much more accurately than ever before, deepening our understanding of the worlds that grace our galaxy.
The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA's Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. The primary industrial partners are Ball Aerospace and Technologies Corporation in Boulder, Colorado; L3Harris Technologies in Melbourne, Florida; and Teledyne Scientific & Imaging in Thousand Oaks, California.
JOURNAL
The Astronomical Journal
ARTICLE TITLE
TERRESTRIAL AND NEPTUNE MASS FREE-FLOATING PLANET CANDIDATES FROM THE MOA-II 9-YEAR GALACTIC BULGE SURVEY [and] FREE-FLOATING PLANET MASS FUNCTION FROM MOA-II 9-YEAR SURVEY TOWARDS THE GALACTIC BULGE
NASA selects SwRI to lead DIMPLE lunar lander/rover instrument suite
Novel CODEX instrument will assess the age of a unique patch of basalt on the Moon’s nearside
Business AnnouncementIMAGE: NASA HAS SELECTED SOUTHWEST RESEARCH INSTITUTE TO LEAD THE DATING AN IRREGULAR MARE PATCH WITH A LUNAR EXPLORER, OR DIMPLE, PAYLOAD TEAM. THE LUNAR LANDER/ROVER INSTRUMENT SUITE WILL USE A CAMERA AND RADIOISOTOPE-BASED DATING TO DETERMINE THE AGE AND COMPOSITION OF THIS MYSTERIOUSLY YOUNG-LOOKING PATCH OF BASALT KNOWN AS INA, SHOWN HERE IN LUNAR RECONNAISSANCE ORBITER IMAGE. view more
CREDIT: NASA/GSFC/ARIZONA STATE UNIVERSITY
SAN ANTONIO — July 19, 2023 —NASA has selected Southwest Research Institute to lead a $50 million lunar lander/rover instrument suite, Dating an Irregular Mare Patch with a Lunar Explorer, or DIMPLE, designed to understand if the Moon has been volcanically active in the geologically recent past. DIMPLE, which was developed by SwRI, will use cameras and radioisotope-based dating to determine the age and composition of an anomalously young-looking patch of basalt named Ina.
“I am thrilled for the opportunity to send DIMPLE to the Moon to better understand the age and composition of Ina,” said SwRI Staff Scientist Dr. F. Scott Anderson, who is principal investigator of DIMPLE. “We are going to date the rocks at Ina directly using the first-ever purpose-built radioisotope rock dating instrument for use in space, called CODEX (Chemistry Organic and Dating Experiment).”
Ina is an enigmatic formation of unusually smooth mounds surrounded by rough troughs, all inside the central crater of a large volcano. Ina looks much younger than other places on the Moon because it has very few impact craters. Impact craters build up on the lunar surface over time, so older surfaces generally have more impact craters compared to younger surfaces.
“This challenges our understanding of lunar geochemical evolution, since a geologically recent eruption requires unexpectedly long-lived heat sources in the lunar interior,” Anderson said. “If Ina really is as young as it appears, that means that the Moon has been volcanically active much more recently than scientists have thought. Or, if we find that Ina is as old as typical lunar rocks, that indicates that the material properties of certain rocks can fool us, if we are not careful, as we try to understand the ages of planetary surfaces throughout the solar system.”
If rock formations like Ina do not give rise to impact craters, or do not preserve them over the eons, then some current ideas about solar system history could be wrong.
“That’s why radioisotope dating is so important,” says Dr. Jonathan Levine, a physicist at Colgate University who serves as DIMPLE’s deputy principal investigator. “Radioactive decay is a clock that ticks at a known rate. These techniques accurately determine the ages of rocks and minerals, allowing scientists to date events such as crystallization, metamorphism and impacts.”
The CODEX instrument exploits the natural radioactive decay of rubidium into strontium as a measure of how much time has elapsed since a rock sample formed. The SwRI-led team has been developing CODEX for two decades.
“Dating is a challenging process. Traditional techniques are not easily adapted to spaceflight, requiring a sizable laboratory and several months to determine a date,” Anderson said. “By contrast, the entire DIMPLE payload is going to weigh less than 50 kilograms and needs to run autonomously on the Moon. In our lab, we have shown that CODEX can accurately date rock samples like those we expect to find at Ina with a precision of better than ±375 million years, which is more than sufficient to situate the origin of Ina in the billions-of-years-long history of the Moon.”
DIMPLE is part of NASA’s Payloads and Research Investigations on the Surface of the Moon (PRISM), which will be delivered to Ina through the Commercial Lunar Payload Services (CLPS) initiative. A camera, sample collection arm and the CODEX instrument will remain on the lander, while a rover equipped with a camera and rake will scoop and transport samples back to the lander instruments for detailed study. The DIMPLE team includes The Aerospace Corporation, the University of Bern, Colgate University and Lockheed Martin.
CLPS is a key part of NASA’s Artemis lunar exploration plans. The science and technology payloads sent to the Moon’s surface will help lay the foundation for human missions on and around the Moon.
For more information, visit https://www.swri.org/planetary-science.
NASA recently funded the DIMPLE instrument suite shown with a notional lander/rover. SwRI designed the payload project as well as the novel CODEX instrument, which uses radioisotope dating techniques to determine the age of extraterrestrial rocks. With three lasers and a mass spectrometer, the 20-inch-cylinder instrument is designed to vaporize tiny bits of rock and measure the elements and isotopes present to pin down the rock’s age.
CREDIT
Lockheed Martin/SwRI/University of Bern/ Aerospace Corporation
