Science
NASA proves there’s a defense against killer asteroids
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by Saswato R. Das
The stock market is dipping, inflation is on the rise and there is no end in sight to the war in Ukraine. But not all the news is bad: Our planet just got a bit safer, thanks to NASA.
In a feat previously relegated to the realms of science fiction, NASA scientists successfully deflected an asteroid from its path.
On Sept. 26, DART, a spacecraft the size of a commercial dryer, hit a nonthreatening asteroid called Dimorphos—and proved that we humans might be capable of mounting an Earthly defense, should a killer asteroid one day head our way.
Such a scenario is not far-fetched. Every school kid knows that the reason we don’t see dinosaurs roaming the Earth is that the impact of a giant asteroid wiped them out some 66 million years ago.
In a modern example, an object—perhaps a rocky asteroid, perhaps an icy comet—the size of a 15-story skyscraper exploded over the Tunguska River in Siberia in 1908, releasing energy equivalent to approximately 12-15 megatons of TNT (about a thousand times as powerful as the atom bomb that destroyed Hiroshima).
Most asteroids and comets that enter Earth’s atmosphere vaporize quickly because of the heat produced by friction. The object in Siberia, however, got within 10 miles of the planet’s surface. It flattened 80 million trees over 230 square miles. It left no crater, but the circular pattern of immense destruction is sobering.
Evidence of such events exists all over Earth. Scientists think an explosion similar to Tunguska destroyed Tall el-Hammam, an ancient walled city close to the Dead Sea, around 1650 BC.
One tell-tale sign of a planetary asteroid impact is the presence of the mineral coesite, a variant of quartz that forms only under intense heat and pressure. Mile-wide Meteor Crater in Arizona contains a lot of coesite, as do other sites across the globe. Fortunately, collisions involving an asteroid of the size (about 100 to 170 feet across), makeup and speed that produced Meteor Crater are infrequent, happening once every few hundred years, and are much more likely to hit open ocean or empty territory than a population center.
Still, such a collision could spell the end of a city like Los Angeles, and bigger asteroids could spell the end of the human race. There are thousands of these orbiting rocks in our solar system, and quite a few are on paths that bring them perilously near Earth. NASA has been finding and tracking them for more than two decades in a program sanctioned by Congress. So far none has posed a real threat.
But because the chance is not zero, NASA has looked to develop a defense mechanism. DART (short for Double Asteroid Redirection Test) tested the feasibility of changing the orbit of an asteroid, steering it away from Earth by bumping it into a new trajectory.
DART crashed into Dimorphos at a speed of just over 4 miles per second. More than three dozen telescopes around the world were watching the impact, as were the Hubble and James Webb space telescopes and the LICIACube, an Italian spacecraft designed expressly to observe DART’s slamming into Dimorphos.
On Tuesday, when NASA announced that Dimorphos had indeed been diverted, it also revealed that its experiment worked better than had been predicted. Calculations had estimated that Dimorphos’ orbit around its larger parent asteroid Didymos, which was 11.9 hours, would speed up by 10 minutes after DART crashed into it. The actual time observed was 32 minutes.
Watching NASA’s live telecast on Sept. 26 made for fascinating viewing. DART’s camera spotted Dimorphos only an hour before impact, as a faint spot of light, and it was just five minutes before the crash that the asteroid really came into focus. In the final seconds before DART made contact, the asteroid’s surface—looking like a rocky, boulder-strewn field—filled the screen. Then, true to plan, the screen went dark and the scientists watching it sent up a cheer.
The DART mission isn’t over yet; the data it generated is still being analyzed. The results are nonetheless in: DART has to be classed among the most successful spacecraft NASA has ever launched. For the first time in the history of our species, we’ve shown we might be able to defend the planet from a massive invader from space.
2022 Los Angeles Times.Distributed by Tribune Content Agency, LLC.
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Good news for a change—NASA proves there’s a defense against killer asteroids (2022, October 17)
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Science
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Science
Dragonfly: NASA greenlights most important mission of the century – Earth.com
In a remarkable development, NASA has given the green light to the Dragonfly mission, a revolutionary rotorcraft designed to investigate the complex chemistry of Saturn‘s moon Titan.
This confirmation allows the mission to proceed with the final design, construction, and testing of the spacecraft and its scientific instruments.
Deciphering the prebiotic chemistry on Titan
The Dragonfly mission, led by Dr. Melissa Trainer of NASA’s Goddard Space Flight Center, will carry a cutting-edge instrument called the Dragonfly Mass Spectrometer (DraMS).
This powerful tool will help scientists delve into the intricate chemistry at work on Titan, potentially shedding light on the chemical processes that led to the emergence of life on Earth, known as prebiotic chemistry.
“We want to know if the type of chemistry that could be important for early pre-biochemical systems on Earth is taking place on Titan,” explains Dr. Trainer, a planetary scientist and astrobiologist specializing in Titan.
Titan: Dragonfly’s target
Titan, the largest moon of Saturn, is shrouded in a dense nitrogen-rich atmosphere, bears a striking resemblance to Earth in many ways. With a diameter of 5,150 kilometers, Titan is the second-largest moon in our solar system, surpassed only by Jupiter’s Ganymede.
Dense atmosphere and unique climate
One of Titan’s most distinctive features is its thick atmosphere, which is composed primarily of nitrogen and methane. This dense atmosphere creates a surface pressure 1.5 times higher than Earth’s, making it the only moon in our solar system with a substantial atmosphere.
The presence of methane in Titan’s atmosphere leads to a fascinating hydrological cycle, similar to Earth’s water cycle, but with methane as the primary liquid.
Titan’s surface is dotted with numerous lakes and seas of liquid hydrocarbons, predominantly methane and ethane. These liquid bodies, some of which are larger than the Great Lakes on Earth, are the result of Titan’s unique climate and atmospheric conditions.
The Cassini mission, which explored the Saturn system from 2004 to 2017, provided stunning images and data of these extraterrestrial lakes and seas.
Dragonfly mission to search Titan for prebiotic chemistry and life
The complex chemistry occurring on Titan’s surface and in its atmosphere has drawn significant attention from astrobiologists.
With its abundant organic compounds and the presence of liquid methane, Titan is considered a prime candidate for studying prebiotic chemistry and the potential for life to emerge in environments different from Earth.
Beneath Titan’s icy crust lies another intriguing feature: a global subsurface ocean of liquid water and ammonia. This ocean, which is believed to be salty and have a high pH, may potentially host microbial life.
The presence of this subsurface ocean, along with the unique chemistry on Titan’s surface, makes this moon a fascinating target for future exploration and scientific research.
Pushing the boundaries of rotorcraft exploration
Nicky Fox, associate administrator of the Science Mission Directorate at NASA Headquarters, emphasized the significance of the Dragonfly mission, stating, “Exploring Titan will push the boundaries of what we can do with rotorcraft outside of Earth.”
Titan’s unique characteristics, including its abundant complex carbon-rich chemistry, interior ocean, and past presence of liquid water on the surface, make it an ideal destination for studying prebiotic chemical processes and the potential habitability of an extraterrestrial environment.
Innovative design and cutting-edge technology
The Dragonfly robotic rotorcraft will leverage Titan’s low gravity and dense atmosphere to fly between different points of interest on the moon’s surface, spanning several miles apart.
This innovative approach allows the entire suite of instruments to be relocated to new sites once the previous one has been thoroughly explored, providing access to samples from diverse geological environments.
DraMS, developed by the same team responsible for the Sample Analysis at Mars (SAM) instrument suite aboard the Curiosity rover, will analyze surface samples using techniques tested on Mars.
Dr. Trainer emphasized the benefits of this heritage, stating, “This design has given us an instrument that’s very flexible, that can adapt to the different types of surface samples.”
Dragonfly mission challenges and funding
The Dragonfly mission successfully passed its Preliminary Design Review in early 2023. However, due to funding constraints, the mission was asked to develop an updated budget and schedule.
The revised plan, presented and conditionally approved in November 2023, hinged on the outcome of the fiscal year 2025 budget process.
With the release of the president’s fiscal year 2025 budget request, Dragonfly is now confirmed with a total lifecycle cost of $3.35 billion and a launch date set for July 2028.
This reflects a cost increase of approximately two times the initially proposed cost and a delay of more than two years from the original selection in 2019.
Despite the challenges posed by funding constraints, the COVID-19 pandemic, supply chain issues, and an in-depth design iteration, NASA remains committed to the Dragonfly mission.
Additional funding has been provided for a heavy-lift launch vehicle to shorten the mission’s cruise phase and compensate for the delayed arrival at Titan.
Rigorous testing and validation
To ensure the success of the Dragonfly mission, researchers on Earth have conducted extensive testing and validation of the designs and models for the nuclear-powered, car-sized drone.
The mission team has carried out test campaigns at NASA’s Langley Research Center, utilizing the Subsonic Tunnel and the Transonic Dynamics Tunnel (TDT) to validate computational fluid dynamics models and gather data under simulated Titan atmospheric conditions.
Ken Hibbard, Dragonfly mission systems engineer at APL, emphasized the importance of these tests, stating, “All of these tests feed into our Dragonfly Titan simulations and performance predictions.”
As the Dragonfly mission progresses, it marks a new era of exploration and scientific discovery. Dr. Trainer expressed her excitement, saying, “Dragonfly is a spectacular science mission with broad community interest, and we are excited to take the next steps on this mission.”
Turning science fiction into fact with the Dragonfly mission
In summary, the Dragonfly mission embodies the essence of human curiosity and the relentless pursuit of knowledge. As NASA prepares to send this revolutionary rotorcraft to the alien world of Titan, we stand on the brink of a new era of exploration and discovery.
With its innovative design, cutting-edge technology, and the unwavering dedication of the mission team, Dragonfly will unlock the secrets of prebiotic chemistry and shed light on the potential for life beyond Earth.
As we eagerly await the launch of this titanic mission, we can only imagine the wonders that await us on Saturn’s enigmatic moon. The Dragonfly mission is a testament to the indomitable human spirit and our boundless capacity to push the frontiers of knowledge.
In the words of Ken Hibbard, “With Dragonfly, we’re turning science fiction into exploration fact,” and that fact will undoubtedly inspire generations to come.
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Science
Marine plankton could act as alert in mass extinction event: UVic researcher – Langley Advance Times
A University of Victoria micropaleontologist found that marine plankton may act as an early alert system before a mass extinction occurs.
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According to the release, the fossil record is the most complete and extensive archive of biological changes available to science and by applying advanced computational analyses to the archive, researchers were able to detail the global community structure of the oceans dating back millions of years.
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“Considering that three billion people live in the tropics, the lack of biodiversity at higher temperatures is not great news,” paper co-leader Adam Woodhouse said in the release.
Next, the team plans to apply similar research methods to other marine plankton groups.
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