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Future Space Telescopes Could be 100 Meters Across, Constructed in Space, and Then Bent Into a Precise Shape
It is an exciting time for astronomers and cosmologists. Since the James Webb Space Telescope (JWST), astronomers have been treated to the most vivid and detailed images of the Universe ever taken. Webb‘s powerful infrared imagers, spectrometers, and coronographs will allow for even more in the near future, including everything from surveys of the early Universe to direct imaging studies of exoplanets. Moreover, several next-generation telescopes will become operational in the coming years with 30-meter (~98.5 feet) primary mirrors, adaptive optics, spectrometers, and coronographs.
Even with these impressive instruments, astronomers and cosmologists look forward to an era when even more sophisticated and powerful telescopes are available. For example, Zachary Cordero
of the Massachusetts Institute of Technology (MIT) recently proposed a telescope with a 100-meter (328-foot) primary mirror that would be autonomously constructed in space and bent into shape by electrostatic actuators. His proposal was one of several concepts selected this year by the NASA Innovative Advanced Concepts (NIAC) program for Phase I development.
Corder is the Boeing Career Development Professor in Aeronautics and Astronautics at MIT and a member of the Aerospace Materials and Structures Lab (AMSL) and Small Satellite Center. His research integrates his expertise in processing science, mechanics, and design to develop novel materials and structures for emerging aerospace applications. His proposal is the result of a collaboration with Prof. Jeffrey Lang (from MIT’s Electronics and the Microsystems Technology Laboratories) and a team of three students with the AMSL, including Ph.D. student Harsh Girishbhai Bhundiya.
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Their proposed telescope addresses a key issue with space telescopes and other large payloads that are packaged for launch and then deployed in orbit. In short, size and surface precision tradeoffs limit the diameter of deployable space telescopes to the 10s of meters. Consider the recently-launched James Webb Space Telescope (JWST), the largest and most powerful telescope ever sent to space. To fit into its payload fairing (atop an Ariane 5 rocket), the telescope was designed so that it could be folded into a more compact form.
This included its primary mirror, secondary mirror, and sunshield, which all unfolded once the space telescope was in orbit. Meanwhile, the primary mirror (the most complex and powerful ever deployed) measures 6.5 meters (21 feet) in diameter. Its successor, the Large UV/Optical/IR Surveyor (LUVOIR), will have a similar folding assembly and a primary mirror measuring 8 to 15 meters (26.5 to 49 feet) in diameter – depending on the selected design (LUVOIR-A or -B). As Bhundiya explained to Universe Today via email:
“Today, most spacecraft antennas are deployed in orbit (e.g., Northrop Grumman’s Astromesh antenna) and have been optimized to achieve high performance and gain. However, they have limitations: 1) They are passive deployable systems. I.e. once you deploy them you cannot adaptively change the shape of the antenna. 2) They become difficult to slew as their size increases. 3) They exhibit a tradeoff between diameter and precision. I.e. their precision decreases as their size increases, which is a challenge for achieving astronomy and sensing applications that require both large diameters and high precision (e.g. JWST).”
While many in-space construction methods have been proposed to overcome these limitations, detailed analyses of their performance for building precision structures (like large-diameter reflectors) are lacking. For the sake of their proposal, Cordero and his colleagues conducted a quantitative, system-level comparison of materials and processes for in-space manufacturing. Ultimately, they determined that this limitation could be overcome using advanced materials and a novel in-space manufacturing method called Bend-Forming.
This technique, invented by researchers at the AMSL and described in a recent paper co-authored by Bhundiya and Cordero, relies on a combination of Computer Numerical Control (CNC) deformation processing and hierarchical high-performance materials. As Harsh explained it:
“Bend-Forming is a process for fabricating 3D wireframe structures from metal wire feedstock. It works by bending a single strand of wire at specific nodes and with specific angles, and adding joints to the nodes to make a stiff structure. So to fabricate a given structure, you convert it into bending instructions which can be implemented on a machine like a CNC wire bender to fabricate it from a single strand of feedstock. The key application of Bend-Forming is to manufacture the support structure for a large antenna on orbit. The process is well-suited for this application because it is low-power, can fabricate structures with high compaction ratios, and has essentially no size limit.”
In contrast to other in-space assembly and manufacturing approaches, Bend-Forming is low-power and is uniquely enabled by the extremely low-temperature environment of space. In addition, this technique enables smart structures that leverage multifunctional materials to achieve new combinations of size, mass, stiffness, and precision. Additionally, the resulting smart structures leverage multifunctional materials to achieve unprecedented combinations of size, mass, stiffness, and precision, breaking the design paradigms that limit conventional truss or tension-aligned space structures.
In addition to their native precision, Large Bend-Formed structures can use their electrostatic actuators to contour a reflector surface with sub-millimeter precision. This, said Harsh, will increase the precision of their fabricated antenna in orbit:
“The method of active control is called electrostatic actuation and uses forces generated by electrostatic attraction to precisely shape a metallic mesh into a curved shape which acts as the antenna reflector. We do this by applying a voltage between the mesh and a ‘command surface’ which consists of the Bend-Formed support structure and deployable electrodes. By adjusting this voltage, we can precisely shape the reflector surface and achieve a high-gain, parabolic antenna.”
Harsh and his colleagues deduce that this technique will allow for a deployable mirror measuring more than 100 meters (328 ft) in diameter that could achieve a surface precision of 100 m/m and a specific area of more than 10 m2/kg. This capability would surpass existing microwave radiometry technology and could lead to significant improvements in storm forecasts and an improved understanding of atmospheric processes like the hydrologic cycle. This would have significant implications for Earth Observation and exoplanet studies.
The team recently demonstrated a 1-meter (3.3 ft) prototype of an electrostatically-actuated reflector with a Bend-Formed support structure at the 2023 American Institute of Aeronautics and Astronautics (AIAA) SciTech Conference, which ran from January 23rd to 27th in National Harbor, Maryland. With this Phase I NIAC grant, the team plans to mature the technology with the ultimate aim of creating a microwave radiometry reflector.
Looking ahead, the team plans to investigate how Bend-Forming can be used in geostationary orbit (GEO) to create a microwave radiometry reflector with a 15km (9.3 mi) field of view, a ground resolution of 35km (21.75 mi) and a proposed frequency span of 50 to 56 GHz – the super-high and extremely-high frequent range (SHF/EHF). This will enable the telescope to retrieve temperature profiles from exoplanet atmospheres, a key characteristic allowing astrobiologists to measure habitability.
“Our goal with the NIAC now is to work towards implementing our technology of Bend-Forming and electrostatic actuation in space,” said Harsh. “We envision fabricating 100-m diameter antennas in geostationary orbit with have Bend-Formed support structure and electrostatically-actuated reflector surfaces. These antennas will enable a new generation of spacecraft with increased sensing, communication, and power capabilities.”
Further Reading: NASA
A trash heap 62 meters high shows the scale of India’s climate challenge
New Delhi
CNN
—
At the Bhalswa landfill in northwest Delhi, a steady flow of jeeps zigzag up the trash heap to dump more garbage on a pile now over 62 meters (203 feet) high.
Fires caused by heat and methane gas sporadically break out – the Delhi Fire Service Department has responded to 14 fires so far this year – and some deep beneath the pile can smolder for weeks or months, while men, women and children work nearby, sifting through the rubbish to find items to sell.
Some of the 200,000 residents who live in Bhalswa say the area is uninhabitable, but they can’t afford to move and have no choice but to breathe the toxic air and bathe in its contaminated water.
Bhalswa is not Delhi’s largest landfill. It’s about three meters lower than the biggest, Ghazipur, and both contribute to the country’s total output of methane gas.
Methane is the second most abundant greenhouse gas after carbon dioxide, but a more potent contributor to the climate crisis because methane traps more heat. India creates more methane from landfill sites than any other country, according to GHGSat, which monitors methane via satellites.
And India comes second only to China for total methane emissions, according to the International Energy Agency’s (IEA) Global Methane Tracker.
As part of his “Clean India” initiative, Indian Prime Minister Narendra Modi has said efforts are being made to remove these mountains of garbage and convert them into green zones. That goal, if achieved, could relieve some of the suffering of those residents living in the shadows of these dump sites – and help the world lower its greenhouse gas emissions.
India wants to lower its methane output, but it hasn’t joined the 130 countries who have signed up to the Global Methane Pledge, a pact to collectively cut global methane emissions by at least 30% from 2020 levels by 2030. Scientists estimate the reduction could cut global temperature rise by 0.2% – and help the world reach its target of keeping global warming under 1.5 degrees Celsius.
India says it won’t join because most of its methane emissions come from farming – some 74% from farm animals and paddy fields versus less than 15% from landfill.
In a statement last year, Minister of State for Ministry of Environment, Forest and Climate change Ashwini Choubey said pledging to reduce India’s total methane output could threaten the livelihood of farmers and affect India’s trade and economic prospects.
But it’s also facing challenges in reducing methane from its steaming mounds of trash.
When Narayan Choudhary, 72, moved to Bhalswa in 1982, he said it was a “beautiful place,” but that all changed 12 years later when the first rubbish began arriving at the local landfill.
In the years since, the Bhalswa dump has grown nearly as tall as the historic Taj Mahal, becoming a landmark in its own right and an eyesore that towers over surrounding homes, affecting the health of people who live there.
Choudhary suffers from chronic asthma. He said he nearly died when a large fire broke out at Bhalswa in April that burned for days. “I was in terrible shape. My face and nose were swollen. I was on my death bed,” he said.
“Two years ago we protested … a lot of residents from this area protested (to get rid of the waste),” Choudhary said. “But the municipality didn’t cooperate with us. They assured us that things will get better in two years but here we are, with no relief.”
The dump site exhausted its capacity in 2002, according to a 2020 report on India’s landfills from the Center for Science and Environment (CSE), a nonprofit research agency in New Delhi, but without government standardization in recycling systems and greater industry efforts to reduce plastic consumption and production, tonnes of garbage continue to arrive at the site daily.
Bhalswa isn’t the only dump causing distress to residents nearby – it is one of three landfills in Delhi, overflowing with decaying waste and emitting toxic gases into the air.
Across the country, there are more than 3,100 landfills. Ghazipur is the biggest in Delhi, standing at 65 meters (213 feet), and like Bhalswa, it surpassed its waste capacity in 2002 and currently produces huge amounts of methane.
According to GHGSat, on a single day in March, more than two metric tons of methane gas leaked from the site every hour.
“If sustained for a year, the methane leak from this landfill would have the same climate impact as annual emissions from 350,000 US cars,” said GHGSat CEO Stephane Germain.
Methane emissions aren’t the only hazard that stem from landfills like Bhalswa and Ghazipur. Over decades, dangerous toxins have seeped into the ground, polluting the water supply for thousands of residents living nearby.
In May, CNN commissioned two accredited labs to test the ground water around the Bhalswa landfill. And according to the results, ground water within at least a 500-meter (1,600-foot) radius around the waste site is contaminated.
In the first lab report, levels of ammonia and sulphate were significantly higher than acceptable limits mandated by the Indian government.
Results from the second lab report showed levels of total dissolved solids (TDS) – the amount of inorganic salts and organic matter dissolved in the water – detected in one of the samples was almost 19 times the acceptable limit, making it unsafe for human drinking.
The Bureau of Indian Standards sets the acceptable limit of TDS at 500 milligrams/liter, a figure roughly seen as “good” by the World Health Organization (WHO). Anything over 900 mg/l is considered “poor” by the WHO, and over 1,200 mg/l is “unacceptable.”
According to Richa Singh from the Center for Science and Environment (CSE), the TDS of water taken near the Bhalswa site was between 3,000 and 4,000 mg/l. “This water is not only unfit for drinking but also unfit for skin contact,” she said. “So it can’t be used for purposes like bathing or cleaning of the utensils or cleaning of the clothes.”
Dr. Nitesh Rohatgi, the senior director of medical oncology at Fortis Memorial Research Institute, Gurugram, urged the government to study the health of the local population and compare it to other areas of the city, “so that in 15 to 20 years’ time, we are not looking back and regretting that we had a higher cancer incidence, higher health hazards, higher health issues and we didn’t look back and correct them in time.”
Most people in Bhalswa rely on bottled water for drinking, but they use local water for other purposes – many say they have no choice.
“The water we get is contaminated, but we have to helplessly store it and use it for washing utensils, bathing and at times drinking too,” said resident Sonia Bibi, whose legs are covered in a thick, red rash.
Jwala Prashad, 87, who lives in a small hut in an alleyway near the landfill, said the pile of putrid trash had made his life “a living hell.”
“The water we use is pale red in color. My skin burns after bathing,” he said, as he tried to soothe red gashes on his face and neck.
“But I can’t afford to ever leave this place,” he added.
More than 2,300 tonnes of Municipal Solid Waste arrive at Delhi’s largest dump in Ghazipur every day, according to a report released in July by a joint committee formed to find a way to reduce the number of fires at the site.
That’s the bulk of the waste from the surrounding area – only 300 tonnes is processed and disposed of by other means, the report said. And less than 7% of legacy waste had been bio-mined, which involves excavating, treating and potentially reusing old rubbish.
The Municipal Corporation of Delhi deploys drones every three months to monitor the size of the trash heap and is experimenting with ways to extract methane from the trash mountain, the report said.
But too much rubbish is arriving every day to keep up. The committee said bio-mining had been “slow and tardy” and it was “highly unlikely” the East Delhi Municipal Corporation (which has now merged with North and South Delhi Municipal Corporations) would achieve its target of “flattening the garbage mountain” by 2024.
“No effective plans to reduce the height of the garbage mountain have been made,” the report said. Furthermore, “it should have proposed a long time ago that future dumping of garbage in them would pollute the groundwater systems,” the report added.
CNN sent a series of questions along with the data from the water testing questionnaire to India’s Environment and Health Ministries. There has been no response from the ministries.
In a 2019 report, the Indian government recommended ways to improve the country’s solid waste management, including formalizing the recycling sector and installing more compost plants in the country.
While some improvements have been made, such as better door-to-door garbage collection and processing of waste, Delhi’s landfills continue to accumulate waste.
In October, the National Green Tribunal fined the state government more than $100 million for failing to dispose of more than 30 million metric tonnes of waste across its three landfill sites.
“The problem is Delhi doesn’t have a concrete solid waste action plan in place,” said Singh from the CSE. “So we are talking here about dump site remediation and the treatment of legacy waste, but imagine the fresh waste which is generated on a regular basis. All of that is getting dumped everyday into these landfills.”
“(So) let’s say you are treating 1,000 tons of legacy (waste) and then you are dumping 2,000 tons of fresh waste every day it will become a vicious cycle. It will be a never ending process,” Singh said.
“Management of legacy waste, of course, is mandated by the government and is very, very important. But you just can’t start the process without having an alternative facility of fresh waste. So that’s the biggest challenge.”
CNN team near Mykolaiv just meters away from incoming artillery rounds
The United States is supporting a multinational team to collect and analyze evidence of atrocities in Ukraine, State Department spokesperson Ned Price said Monday.
“Right now, at the request of the Prosecutor General of Ukraine, the United States is supporting a multinational team of international prosecutors to the region to directly support the efforts of the Prosecutor General’s War Crimes Unit to collect, preserve and analyze evidence of atrocities with a view towards pursuing criminal accountability,” Price said at a State Department briefing.
“Those responsible for atrocities must be held accountable, as must those who ordered them. They cannot and will not act with impunity,” Price added.
Price also said that based on the reports the US has seen, the atrocities “are not the act of a rogue soldier,” but rather “part of a broader, troubling campaign.”
He noted that “as Russia’s forces have retreated over the past few days, the world has been shocked by the horrifying images of the Kremlin’s brutality in Bucha and other cities near Kyiv. Civilians, many with their hands tied apparently executed in the streets, others in mass graves.”
“We are seeing credible reports of torture, rape, and civilians executed alongside their families,” he said. “There are reports and images of a nightmare litany of atrocities including reports of landmines and booby traps left behind by Putin’s forces to injure even more civilians and slow the stabilization and recovery of devastated communities after they failed in their objective and withdrew.”
“In keeping with its long track record of accusing others of its own heinous acts, the Kremlin issued a baseless and shameless denial of what we can all clearly see in Bucha and throughout the liberated towns of Kyiv oblast,” he said.
More background: US Secretary of State Antony Blinken announced on March 23 that the US government had determined that members of the Russian armed forces are committing war crimes in Ukraine.
At the time, Beth Van Schaack, ambassador-at-Large for global criminal justice, said the US government would “continue to track reports coming out of Ukraine of war crimes, and we will share this information with our friends and allies and with international and multilateral institutions, as appropriate.”
“This is going to be an ongoing process throughout this conflict,” she said.
Blinken reiterated this in his interview with CNN’s State of the Union Sunday, saying, “Since the aggression, we’ve come out and said that we believe that Russian forces have committed war crimes and we’ve been working to document that, to provide the information that we have to the relevant institutions and organizations that will put all of this together, and there needs to be accountability for it.”
The Speed of Sound on Mars Is Strangely Different, Scientists Reveal
Scientists have confirmed the speed of sound on Mars, using equipment on the Perseverance rover to study the red planet’s atmosphere, which is very different to Earth’s.
What they discovered could have some strange consequences for communication between future Martians.
The findings suggest that trying to talk in Mars’ atmosphere might produce a weird effect, since higher-pitched sound seems to travel faster than bass notes. Not that we’d try, since Mars’ atmosphere is unbreathable, but it’s certainly fun to think about!
From a science perspective, the findings, announced at the 53rd Lunar and Planetary Science Conference by planetary scientist Baptiste Chide of the Los Alamos National Laboratory, reveal high temperature fluctuations at the surface of Mars that warrant further investigation.
The speed of sound is not a universal constant. It can change, depending on the density and temperature of the medium through which it travels; the denser the medium, the faster it goes.
That’s why sound travels about 343 meters (1,125 feet) per second in our atmosphere at 20 degrees Celsius, but also at 1,480 meters per second in water, and at 5,100 meters per second in steel.
Mars’ atmosphere is a lot more tenuous than Earth’s, around 0.020 kg/m3, compared to about 1.2 kg/m3 for Earth. That alone means that sound would propagate differently on the red planet.
But the layer of the atmosphere just above the surface, known as the Planetary Boundary Layer, has added complications: During the day, the warming of the surface generates convective updrafts that create strong turbulence.
Conventional instruments for testing surface thermal gradients are highly accurate, but can suffer from various interference effects. Fortunately, Perseverance has something unique: microphones that can allow us to hear the sounds of Mars, and a laser that can trigger a perfectly timed noise.
The SuperCam microphone was included to record acoustic pressure fluctuations from the rover’s laser-induced breakdown spectroscopy instrument as it ablates rock and soil samples at the Martian surface.
NASA’s Perseverance rover on Mars. (NASA/JPL-Caltech/MSSS)
This came with an excellent benefit, as it turns out. Chide and his team measured the time between the laser firing and the sound reaching the SuperCam microphone at 2.1 meters altitude, to measure the speed of sound at the surface.
“The speed of sound retrieved by this technique is computed over the entire acoustic propagation path, which goes from the ground to the height of the microphone,” the researchers write in their conference paper.
“Therefore, at any given wavelength it is convoluted by the variations of temperature and wind speed and direction along this path.”
The results back up predictions made using what we know of the Martian atmosphere, confirming that sounds propagate through the atmosphere near the surface at roughly 240 meters per second.
However, the quirk of Mars’ shifting soundscape is something completely out of the blue, with conditions on Mars leading to a quirk not seen anywhere else.
“Due to the unique properties of the carbon dioxide molecules at low pressure, Mars is the only terrestrial-planet atmosphere in the Solar System experiencing a change in speed of sound right in the middle of the audible bandwidth (20 Hertz to 20,000 Hertz),” the researchers write.
At frequencies above 240 Hertz, the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state. The result of this is that sound travels more than 10 meters per second faster at higher frequencies than it does at low ones.
This could lead to what the researchers call a “unique listening experience” on Mars, with higher-pitched sounds arriving sooner to the listener than lower ones.
Given that any human astronauts traveling to Mars anytime soon will need to be wearing pressurized spacesuits with comms equipment, or living in pressurized habitat modules, this is unlikely to pose an immediate problem – but it could be a fun concept for science-fiction writers to tinker with.
Because the speed of sound changes due to temperature fluctuations, the team was also able to use the microphone to measure large and rapid temperature changes on the Martian surface that other sensors had not been able to detect. This data can help fill in some of the blanks on Mars’ rapidly changing planetary boundary layer.
The team plans to continue using SuperCam microphone data to observe how things like daily and seasonal variations might affect the speed of sound on Mars. They also plan to compare acoustic temperature readings to readings from other instruments to try to figure out the large fluctuations.
You can read the conference paper on the conference website.
Scientists use seismic noise to image first hundred meters of Mars
Enlarge / InSight places a wind shield over its seismometer.
NASA’s InSight lander installed a seismograph on Mars, and the marsquakes it detected have helped us map the planet’s interior. This data provides the big picture of Mars’ internals—how big the core is, whether anything is molten, and so on. But it doesn’t capture the small details, like what the ground immediately below InSight looks like.
This week, researchers described how they’ve managed to find quiet periods on Mars that lets them image closer to the surface. The results, combined with some nearby surface features, reveal that InSight is likely above two large lava flows, separated by layers of sediment.
Be very quiet
Marsquakes aren’t useful for sorting out local features. If their seismic waves arrive from far enough away, then their behavior is mostly influenced by the materials they spent most of their time traveling through. If the marsquake happens nearby, then things are too energetic to make out the fine details caused by local features. So, in order to look at the local geology, you need to look at the background seismic noise that’s constantly being picked up by InSight.
On Earth, most of the seismic noise is generated by either human activities or the oceans. But Mars lacks both of these noise sources, and its background is dominated by the wind interacting with features on Mars.
But when the data was examined at times of day when winds were generally high, the noise turned out to be dominated by frequencies that were produced by the wind interacting with the lander itself. So the researchers focused on what was early evening, Mars time, when the winds tended to die down. At that point, most of the seismic noise is generated by weak winds interacting with nearby geology rather than with the lander itself.
Geologists have used seismic noise to reconstruct features on Earth by comparing the horizontal and vertical components of the noise. This is a process that can be consistent with a large collection of potential structures near the surface of Mars. To constrain the list of possibilities, the researchers focused on features that showed up in the majority of potential solutions. They also looked at the rocks exposed in nearby craters to search for visible features that correlated to the things their models were suggesting might exist.
What’s underneath
Closest to the surface, the regolith of Mars is formed by dust and rock fragments produced by impacts. It appears to be only 1.5 meters thick, although the researchers caution that the data on the uppermost 20 meters of material is very uncertain. By three meters below the surface, there appears to be a layer of volcanic rock, formed by major eruptions in Mars’ distant past.
Below that, from roughly 30 meters to 80 meters (these figures are pretty inexact), is another layer of material where seismic signals move slowly. The researchers conclude this is likely to be a layer of sedimentary rock. Below that are further volcanic deposits.
The researchers conclude that the deepest volcanic deposits date back to the Hesperian, a period of widespread volcanic activity that ended over 3 billion years ago. The overlying sediment deposit formed while Mars experienced cold, dry conditions similar to its present state. After it consolidated, and sometime during Mars’ Amazonian period, additional eruptions covered the sediments. Since then, impacts and Mars’ winds have deposited a layer of loose material on top of the volcanic layers.
Obviously, all of this is consistent with what can be observed in nearby craters. Still, it’s impressive how much information the researchers were able to extract from just a bit of noise.
Nature Communications, 2021. DOI: 10.1038/s41467-021-26957-7 (About DOIs).
Listing image by NASA/JPL-Caltech
Mars Breakthrough Peers Under The Red Planet’s Surface in Scientific First
Peering deeper below the surface of Earth can tell us a lot about its history and geological make-up, and it’s the same for any other planet.
Now the InSight lander on the surface of Mars has provided our first in-depth look at what lies just beneath the red planet’s surface.
The seismometer on board InSight – called SEIS or the Seismic Experiment for Interior Structure – points to a shallow sedimentary layer sandwiched between hardened rocks resulting from lava flows, going down to a depth of around 200 meters or about 650 feet.
This could tell us a lot about how Mars was originally formed, how it evolved over time, and the sort of geological factors that are still in play today. In particular, the lava flows can be connected to what we know of the planet’s volcanic past.
(Géraldine Zenhäusern/ETH Zürich)
Above: Artist’s impression of the InSight lander in the Homestead Hollow, a small impact crater.
“Seismic studies of the shallow subsurface around the InSight landing site so far have been limited to the uppermost 10-20m using seismic-travel time measurements and ground compliance estimates, leaving structures at few tens to several hundreds of meters depth uncharted,” the researchers explain in their paper.
InSight arrived on Mars in November 2018, landing in the wide and flat plain known as Elysium Planitia. Here, the lander’s instruments measured the slight ambient vibrations of the ground, caused by the winds flowing over the surface of the planet, in order to figure out what was out of view underneath.
The same technique was developed on Earth to assess subsurface composition and the associated earthquake risk. On Mars, the pattern of waves were consistent with two dense layers of rocks, such as basalt, with a thinner, less dense layer of material in the middle, most likely sedimentary in nature.
From what we know about Mars’ history from the craters still visible on the planet today, the researchers suggest the uppermost layer of hardened lava is around 1.7 billion years old, formed during the cold, arid Amazonian period on Mars when there were relatively few meteorite and asteroid impacts.
The deeper layer looks to be some 3.6 billion years old, created during the Hesperian period when there was much more volcanic activity on the Red Planet. These ancient periods have molded Mars into the planet that we are seeing and exploring today.
“This helps to tie this to trying to figure out what the timing was between the various different activities,” geophysicist Bruce Banerdt, from the Jet Propulsion Laboratory at the California Institute of Technology, told Inverse.
“The fact that you’ve got this sedimentary layer that is sandwiched between these two volcanic stones tells that there was a pause in the volcanic activity, a fairly long pause because it takes a long time for the sedimentary rocks to form.”
The presence of that middle layer, some 30-40 meters (98-131 feet) thick, is something of a surprise for the researchers, and it’s not clear exactly what it’s made up of or how it was formed. It’s possible that there’s some mixing with the Amazonian basalts, but the accuracy of the seismic readings decreases at lower depths.
Part of the usefulness of this data lies in working out whether life ever existed on Mars, but it also tells us more about Earth’s history and evolution – Earth and Mars are actually pretty similar in terms of geological composition.
Aside from ancient planetary history, there’s a more immediate benefit to knowing what’s underneath the surface of Mars at different points: It enables scientists to work out the best places to put landers, rovers, and (eventually) space stations in the future.
“While the results help to better understand the geological processes in Elysium Planitia, comparison with pre-landing models is also valuable for future landed missions, since it can help to refine predictions,” says seismologist Brigitte Knapmeyer-Endrun from the University of Cologne in Germany.
The research has been published in Nature Communications.
Barred from the 400 meters, Namibia’s Mboma Wins Silver in the 200
TOKYO — As Christine Mboma of Namibia moved up from fifth place toward a silver medal in the homestretch of the women’s Olympic 200 meters on Tuesday, she began screaming in what appeared to be a mix of exertion and elation.
Just 18, Mboma finished second to Elaine Thompson-Herah of Jamaica in 21.81 seconds, the fastest time ever run by a woman under 20 years old.
She called her performance “the best race” of her young life. Yet Mboma was precluded from competing in Tokyo in what is perhaps her best event, the 400 meters, because of restrictions governing women with a rare genetic condition that results in naturally elevated testosterone levels.
Her stirring performance in the 200 meters reignited a complicated debate — and no doubt added to some public confusion — about who should be allowed to compete in certain women’s running events.
And while World Athletics, the sport’s global governing body, defended its rules, critics said that Tuesday’s 200-meter race raised questions about the scientific precision and validity of restrictions placed on athlete eligibility in women’s races from 400 meters to the mile.
Mboma and her Namibian teammate Beatrice Masilingi, who finished sixth in the 200 meters, have run three of the four fastest times in the world this year at 400 meters. Last month, though, they were declared ineligible for the 400 at the Olympics by World Athletics. On Monday, Masilingi called the ruling “very cruel.”
Namibia’s Olympic committee said in a statement in July that Mboma and Masilingi had naturally high levels of testosterone and were unaware of it until they underwent a medical assessment at a training camp in Italy. The two sprinters were declared ineligible for the 400 meters, according to rules pertaining to athletes with so-called disorders of sexual development, or DSDs, the Namibian committee said.
World Athletics rules require that affected athletes who want to compete in women’s running events from 400 meters to the mile — events that require a combination of speed and endurance — must first reduce their elevated testosterone levels below the normal male range.
Mboma and Masilingi qualified for and entered the Olympic 200 meters, which is not governed by the testosterone restrictions.
The World Athletics rules do not restrict athletes who simply have naturally high testosterone levels. They govern intersex athletes with a disorder of sexual development known as 46, XY DSD. These athletes have an X and Y chromosome in each cell, the typical male pattern; genitalia that are not typically male or female; and testosterone in the male range, which, doctors say, suggests testicular tissue or internal testes.
Mboma’s silver medal raised a question: Does the supposed significant physiological advantage gained by intersex athletes begin after 399 meters? Or is the science relied on by World Athletics to institute its restrictions flawed and in need of re-evaluation or expansion to include other running events?
“It shows this is not an evidence-based regulation,” said Roger Pielke Jr., a professor of environmental studies at the University of Colorado who has long questioned the scientific basis of the restrictions. “It’s about World Athletics’s perception as to who is properly a woman and who is not.”
Jackie Brock-Doyle, the director of communications for World Athletics, defended the governing body’s rules. Ten years’ worth of evidence indicates that significant performance advantages for athletes with disordered sexual development exist from 400 meters to the mile, not in shorter or longer events, she said.
“We feel we’ve got this right,” Brock-Doyle said.
Proponents of the restrictions have frequently noted that all three medalists in the 800 meters at the 2016 Olympics in Rio de Janeiro, led by the gold medalist Caster Semenya of South Africa, were athletes with disorders of sexual development. Not so with the women’s 200 meters in Tokyo, where Thompson-Herah, the victor in 21.53 seconds, became the first woman to win the 100 and 200 meters in consecutive Olympics.
Tuesday’s outcome, Brock-Doyle said, demonstrated that “we want to be inclusive and we want to find ways for people to compete, no matter who they are.”
Brock-Doyle said World Athletics would review its regulations “if we see significant advances in anything that looks as if the playing field is no longer fair.”
World Athletics acknowledges that its restrictions, implemented in 2018, are discriminatory, but argues that they are “fair, necessary and proportionate” for female athletes to be able to participate on a level playing field in terms of strength, muscle mass and oxygen-carrying capacity.
Critics have argued that it has not been precisely determined how much of an advantage elevated testosterone levels provide; that treating athletes to lower testosterone levels is unnecessary and can have side effects; and that the restrictions disproportionately affect athletes from developing nations. The World Medical Association has said that the restrictions are based on “weak evidence” and has urged doctors not to help enforce them.
Gabby Thomas of the United States, the bronze medalist in Tuesday’s 200-meter final, was asked about the regulations and the presence of Mboma and Masilingi in the race.
“It’s hard to have an opinion on that when I don’t actually know their biology,” said Thomas, who majored in neurobiology and global health at Harvard. “I don’t know how decisions are being made. So I do my best to stay out of it.”
Noting that she had won a medal, Thomas added, “I’m happy with that.”
Mboma declined to comment about being barred from the 400 meters, saying: “I just keep my head down and concentrate on the 200 meters. Now, I got a medal. Happy.”
She was asked by reporters if she could have won gold in the 400. There was a long pause, and she appeared to nod. Mboma then said she believed she could have won a medal.
“I could have,” she said.
Jeré Longman reported from Philadelphia.
Gigantic Stone ‘Tiger Stripes’ Etched Across Ethiopia Pose an Ancient Mystery
If we want to predict our planet’s future under climate change, we must better understand what has happened on Earth before, even hundreds of thousands of years in the past.
New research into the Ethiopian Highlands during the Last Glacial Period helps do just that. As well as answering some geological questions, it has also raised up a new one: What created the gigantic stone stripes across the central Sanetti Plateau in the Bale Mountains?
As part of the research, scientists looked at moraine boulder samples in the Bale and Arsi Mountains, rocks that would once have been carried along by glaciers.
By studying their physical arrangement and measuring the extent of decay in an isotope of chlorine, they determined that past glaciations would not have been in sync with other similar stretches of mountains.
(Groos et al., Earth Surface Dynamics, 2021)
“Our results show that glaciers in the southern Ethiopian Highlands reached their maximum extent between 40,000 and 30,000 years ago, several thousand years earlier than in other mountainous regions in Eastern Africa and worldwide,” says glaciologist Alexander Groos from the University of Bern in Switzerland.
While these highlands aren’t packed with ice today, between 42,000 and 28,000 years ago – thousands of years before the most recent period in which ice sheets stretched far from the poles – they would have been topped by glaciers that covered as much as 350 square kilometres (about 135 square miles). The relatively early cooling and glacier onset is likely caused by variations in rainfall and mountain features, the researchers say.
In other words, temperature wasn’t the only driver of glacier movement across Eastern Africa during this time. Such insights can help us understand what might happen next, and what the impact on biodiversity and ecosystems is likely to be.
As for the massive stone stripes formed by boulders and basalt columns, they were discovered during the course of the research, just outside the area of the former ice cap. The stripes measure up to 1,000 meters (3,281 feet) long, 15 meters (49 feet) wide, and 2 meters (6.5 feet) deep, and haven’t been seen before in the tropics.
“The existence of these stone stripes on a tropical plateau surprised us, as so-called periglacial landforms of this magnitude were previously only known from the temperate zone and polar regions and are associated with ground temperatures around freezing point,” says Groos.
Another way in which the Ethiopian Highlands are different to their immediate neighbors then, in terms of what went down during the last ice age. The scientists think these stripes are the natural result of periodic freezing and thawing of the ground near the ice cap, which would have drawn similar rocks together.
That would have required substantial drops in the ground and air temperature, however – and what’s less clear is whether this is typical of the way tropical high mountains cooled at the time, or whether it was a regional phenomenon.
We’ll need to wait for future studies of other regions to find out, but the research gives plenty for scientists to go on. Understanding climate shifts in the tropics is crucial – it’s where much of the circulation of the world’s atmosphere and oceans is driven from – and it would seem these mountainous regions might have experienced the Last Glacial Period in a variety of different ways.
“Our findings highlight the importance of understanding the local climatic setting when attempting to draw wider climatic interpretations from glacial chronologies,” conclude the researchers in one of their newly published papers.
The research has been published in Science Advances and Earth Surface Dynamics.