Enlarge/ Image of Epsilon Indi A at two wavelengths, with the position of its host star indicated by an asterisk.
T. Müller (MPIA/HdA), E. Matthews (MPIA)
We have a couple of techniques that allow us to infer the presence of an exoplanet based on its effects on the light coming from its host star. But there’s an alternative approach that sometimes works: image them directly. It’s much more limited, since the planet has to be pretty big and orbiting far away enough from its star to avoid having light coming from the planet swamped by the far more intense starlight.
Still, it has been done. Massive exoplanets have been captured relatively shortly after their formation, when the heat generated by the collapse of material into the planet causes them to glow in the infrared. But the Webb telescope is far more sensitive than any infrared observatory we’ve ever built, and it has managed to image a relatively nearby exoplanet that’s roughly as old as the ones in our Solar System.
Looking directly at a planet
What do you need to directly image a planet that’s orbiting a star light-years away? The first thing is a bit of hardware called a coronagraph attached to your telescope. This is responsible for blocking the light from the star the planet is orbiting; without it, that light will swamp any other sources in the exosolar system. Even with a good coronagraph, you need the planets to be orbiting at a significant distance from the star so that they’re cleanly separated from the signal being blocked by the coronagraph.
Then, you need the planet to emit a fair bit of light. While the right surface composition might allow the planet to be highly reflective, that’s not going to be a great option considering the distances we’d need the planet to be orbiting to be visible at all. Instead, the planets we’ve spotted so far have been young and still heated by the processes that brought material together to form a planet in the first place. Being really big doesn’t hurt matters either.
Put that all together, and what you expect to be able to spot is a very young, very distant planet that’s massive enough to fall into the super-Jupiter category.
But the launch of the Webb Space Telescope has given us new capabilities in the infrared range, and a large international team of researchers pointed it at a star called Epsilon Indi A. It’s a bit less than a dozen light years away (which is extremely close in astronomical terms), and the star is both similar in size and age to the Sun, making it an interesting target for observations. Perhaps most significantly previous data had suggested a large exoplanet would be found, based on indications that the star was apparently shifting as the exoplanet tugged on it during its orbit.
And there was in fact an indication of a planet there. It just didn’t look much like the expected planet. “It’s about twice as massive, a little farther from its star, and has a different orbit than we expected,” said Elisabeth Matthews, one of the researchers involved.
At the moment, there’s no explanation for the discrepancy. The odds of it being an unrelated background object are extremely small. And a reanalysis of data on the motion of Epsilon Indi A suggests that this is likely to be the only large planet in the system—there could be additional planets, but they’d be much smaller. So, the researchers named the planet Epsilon Indi Ab, even though that was the same name given to the planet that doesn’t seem to match this one’s properties.
Big, cold, and a bit enigmatic
The revised Epsilon Indi Ab is a large planet, estimated at roughly six times the mass of Jupiter. It’s also orbiting at roughly the same distance as Neptune. It’s generally bright across the mid-infrared, consistent with a planet that’s roughly 275 Kelvin—not too far off from room temperature. That’s also close to what we would estimate for its temperature simply based on the age of the planet. That makes it the coolest exoplanet ever directly imaged.
While the signal from the planet was quite bright at a number of wavelengths, the planet couldn’t even be detected in one area of the spectrum (3.5 to 5 micrometers, for the curious). That’s considered an indication that the planet has high levels of elements heavier than helium, and a high ratio of carbon to oxygen. The gap in the spectrum may influence estimates of the planet’s age, so further observations will probably need to be conducted to clarify why there are no emissions at these wavelengths.
The researchers also suggest that imaging more of these cool exoplanets should be a priority, given that we should be cautious about extrapolating anything from a single example. So, in that sense, this first exoplanet imaging provides an important confirmation that, with Webb and its coronagraph, we’ve now got the tools we need to do so, and they work very well.
who refused to isolate and get treatment for her active case of infectious tuberculosis for over a year. She even spent around three months on the lam, dodging police as they tried to execute a civil arrest warrant. During her time as a fugitive, police memorably reported that she took a city bus to go to a casino.
The woman, identified only as V.N. in court documents, had court orders to get treatment for her tuberculosis infection beginning in January of 2022. She refused to comply as the court renewed the orders on a monthly basis and held at least 17 hearings on the matter. The judge in her case issued an arrest warrant in March of 2023, but V.N. evaded law enforcement. She was finally arrested in June of last year and spent 23 days getting court-ordered treatment behind bars before being released with conditions.
This week, James Miller, a health officer for Washington’s Tacoma-Pierce County, where V.N. resides, announced the happy ending.
“The woman cooperated with Pierce County Superior Court’s orders and our disease investigators. She’s tested negative for tuberculosis (also called TB) multiple times. She gained back weight she’d lost and is healthy again,” Miller reported. He noted that V.N. and her family gave the county permission to share the news and said they are now happy she received the treatment she needed.
Amid the legal attempts to get V.N. treated, the health department noted in court documents that V.N. had been in a car accident in January 2023, after which she had gone to an emergency department complaining of chest pain. Doctors there—who did not know she had an active case of tuberculosis—took X-rays of her lungs. The images revealed that her lungs were in such bad shape that the doctors thought she had cancer. In fact, the images revealed that her tuberculosis case was worsening.
Risky infection
Tuberculosis is a potentially life-threatening bacterial infection caused by Mycobacterium tuberculosis, which mostly infects the lungs but can invade other areas of the body as well. The bacteria spread through the air when an infected person coughs, sneezes, spits, or otherwise launches bacterial cells into the air around them. Although transmission mostly occurs from close, prolonged contact, inhaling only a few of the microscopic germs is enough to spark an infection. According to the World Health Organization, tuberculosis killed 1.3 million people in 2022 and infected an estimated 10.6 million. Worldwide, it was the second leading infectious killer after COVID-19 that year.
Treatment for tuberculosis requires lengthy antibiotic regimens, which are typically taken for four to nine months. Drug-resistant infections require second-line, more toxic drugs. In the past, treatment for multi-drug resistant tuberculosis could last up to 20 months, but newer clinical guidances prioritize shorter regimens.
Given the risks to herself and those around her, county health officials did all they could to get V.N. treated. “Seeking a court order is our last resort after we exhaust all other options,” Miller said. “It’s a difficult process that takes a lot of time and coordination with other agencies.”
But according to Miller, V.N. softened to the idea of being treated once she was in custody and county disease investigators worked to gain her trust. “At that point, she realized how serious her situation was and decided to treat her illness,” he said. With treatment, she “regained her health over time.”
“She is now cured, which means that tuberculosis no longer poses a risk to her health,” he concluded. “This also means she is no longer at risk of infecting others.”
On Friday, the US Court of Appeals for the DC Circuit denied a request to put a hold on recently formulated rules that would limit carbon emissions made by fossil fuel power plants. The request, made as part of a case that sees 25 states squaring off against the EPA, would have put the federal government’s plan on hold while the case continued. Instead, the EPA will be allowed to continue the process of putting its rules into effect, and the larger case will be heard under an accelerated schedule.
Here we go again
The EPA’s efforts to regulate carbon emissions from power plants go back all the way to the second Bush administration, when a group of states successfully sued the EPA to force it to regulate greenhouse gas emissions. This led to a formal endangerment finding regarding greenhouse gases during the Obama administration, something that remained unchallenged even during Donald Trump’s term in office.
Obama tried to regulate emissions through the Clean Power Plan, but his second term came to an end before this plan had cleared court hurdles, allowing the Trump administration to formulate a replacement that did far less than the Clean Power Plan. This took place against a backdrop of accelerated displacement of coal by natural gas and renewables that had already surpassed the changes envisioned under the Clean Power Plan.
In any case, the Trump plan was thrown out by the courts on the day before Biden’s administration, allowing his EPA to start with a clean slate. Biden’s original plan, which would have had states regulate emissions from their electric grids by regulating them as a single system, was thrown out by the Supreme Court, which ruled that emissions would need to be regulated on a per-plant basis in a decision termed West Virginia v. EPA.
So, that’s what the agency is now trying to do. Its plan, issued last year, would allow fossil-fuel-burning plants that are being shut down in the early 2030s to continue operating without restrictions. Others will need to either install carbon capture equipment, or natural gas plants could swap in green hydrogen as their primary fuel.
And again
In response, 25 states have sued to block the rule (you can check out this filing to see if yours is among them). The states also sought a stay that would prevent the rule from being implemented while the case went forward. In it, they argue that carbon capture technology isn’t mature enough to form the basis of these regulations (something we predicted was likely to be a point of contention). The suit also suggests that the rules would effectively put coal out of business, something that’s beyond the EPA’s remit.
The DC Court of Appeals, however, was not impressed, ruling that the states’ arguments regarding carbon capture are insufficient: “Petitioners have not shown they are likely to succeed on those claims given the record in this case.” And that’s the key hurdle for determining whether a stay is justified. And the regulations don’t pose a likelihood of irreparable harm, as the court notes that states aren’t even expected to submit a plan for at least two years, and the regulations won’t kick in until 2030 at the earliest.
Meanwhile, the states cited the Supreme Court’s West Virginia v. EPA decision to argue against these rules, suggesting they represent a “major question” that requires input from Congress. The Court was also not impressed, writing that “EPA has claimed only the power to ‘set emissions limits under Section 111 based on the application of measures that would reduce pollution by causing the regulated source to operate more cleanly,’ a type of conduct that falls well within EPA’s bailiwick.”
To respond to the states’ concerns about the potential for irreparable harm, the court plans to consider them during the 2024 term and has given the parties just two weeks to submit proposed schedules for briefings on the case.
Enlarge/ With Dragon and Falcon, SpaceX has become an essential contractor for NASA.
SpaceX
There is an emerging truth about NASA’s push toward commercial contracts that is increasingly difficult to escape: Companies not named SpaceX are struggling with NASA’s approach of awarding firm, fixed-price contracts for space services.
This belief is underscored by the recent award of an $843 million contract to SpaceX for a heavily modified Dragon spacecraft that will be used to deorbit the International Space Station by 2030.
The recently released source selection statement for the “US Deorbit Vehicle” contract, a process led by NASA head of space operations Ken Bowersox, reveals that the competition was a total stomp. SpaceX faced just a single serious competitor in this process, Northrop Grumman. And in all three categories—price, mission suitability, and past performance—SpaceX significantly outclassed Northrop.
Although it’s wonderful that NASA has an excellent contractor in SpaceX, it’s not healthy in the long term that there are so few credible competitors. Moreover, a careful reading of the source selection statement reveals that NASA had to really work to get a competition at all.
“I was really happy that we got proposals from the companies that we did,” Bowersox said during a media teleconference last week. “The companies that sent us proposals are both great companies, and it was awesome to see that interest. I would have expected a few more [proposals], honestly, but I was very happy to get the ones that we got.”
Commercial initiatives struggling
NASA’s push into “commercial” space began nearly two decades ago with a program to deliver cargo to the International Space Station. The space agency initially selected SpaceX and Rocketplane Kistler to develop rockets and spacecraft to accomplish this, but after Kistler missed milestones, the company was subsequently replaced by Orbital Sciences Corporation. The cargo delivery program was largely successful, resulting in the Cargo Dragon (SpaceX) and Cygnus (Orbital Sciences) spacecraft. It continues to this day.
A commercial approach generally means that NASA pays a “fixed” price for a service rather than paying a contractor’s costs plus a fee. It also means that NASA hopes to become one of many customers. The idea is that, as the first mover, NASA is helping to stimulate a market by which its fixed-priced contractors can also sell their services to other entities—both private companies and other space agencies.
NASA has since extended this commercial approach to crew, with SpaceX and Boeing winning large contracts in 2014. However, only SpaceX has flown operational astronaut missions, while Boeing remains in the development and test phase, with its ongoing Crew Flight Test. Whereas SpaceX has sold half a dozen private crewed missions on Dragon, Boeing has yet to announce any.
Such a commercial approach has also been tried with lunar cargo delivery through the “Commercial Lunar Payload Services” program, as well as larger lunar landers (Human Landing System), next-generation spacesuits, and commercial space stations. Each of these programs has a mixed record at best. For example, NASA’s inspector general was highly critical of the lunar cargo program in a recent report, and one of the two spacesuit contractors, Collins Aerospace, recently dropped out because it could not execute on its fixed-price contract.
Some of NASA’s most important traditional space contractors, including Lockheed Martin, Boeing, and Northrop Grumman, have all said they are reconsidering whether to participate in fixed-price contract competitions in the future. For example, Northrop CEO Kathy Warden said last August, “We are being even more disciplined moving forward in ensuring that we work with the government to have the appropriate use of fixed-price contracts.”
So the large traditional space contractors don’t like fixed-price contracts, and many new space companies are struggling to survive in this environment.
Enlarge/ Image of some of the atmospheric circulation seen during NeuralGCM runs.
Google
Right now, the world’s best weather forecast model is a General Circulation Model, or GCM, put together by the European Center for Medium-Range Weather Forecasts. A GCM is in part based on code that calculates the physics of various atmospheric processes that we understand well. For a lot of the rest, GCMs rely on what’s termed “parameterization,” which attempts to use empirically determined relationships to approximate what’s going on with processes where we don’t fully understand the physics.
Lately, GCMs have faced some competition from machine-learning techniques, which train AI systems to recognize patterns in meteorological data and use those to predict the conditions that will result over the next few days. Their forecasts, however, tend to get a bit vague after more than a few days and can’t deal with the sort of long-term factors that need to be considered when GCMs are used to study climate change.
On Monday, a team from Google’s AI group and the European Centre for Medium-Range Weather Forecasts are announcing NeuralGCM, a system that mixes physics-based atmospheric circulation with AI parameterization of other meteorological influences. Neural GCM is computationally efficient and performs very well in weather forecast benchmarks. Strikingly, it can also produce reasonable-looking output for runs that cover decades, potentially allowing it to address some climate-relevant questions. While it can’t handle a lot of what we use climate models for, there are some obvious routes for potential improvements.
Meet NeuralGCM
NeuralGCM is a two-part system. There’s what the researchers term a “dynamical core,” which handles the physics of large-scale atmospheric convection and takes into account basic physics like gravity and thermodynamics. Everything else is handled by the AI portion. “It’s everything that’s not in the equations of fluid dynamics,” said Google’s Stephan Hoyer. “So that means clouds, rainfall, solar radiation, drag across the surface of the Earth—also all the residual terms in the equations that happen below the grid scale of about roughly 100 kilometers or so.” It’s what you might call a monolithic AI. Rather than training individual modules that handle a single process, such as cloud formation, the AI portion is trained to deal with everything at once.
Critically, the whole system is trained concurrently rather than training the AI separately from the physics core. Initially, performance evaluations and updates to the neural network were performed at six-hour intervals since the system isn’t very stable until at least partially trained. Over time, those are stretched out to five days.
The result is a system that’s competitive with the best available for forecasts running out to 10 days, often exceeding the competition depending on the precise measure used (in addition to weather forecasting benchmarks, the researchers looked at features like tropical cyclones, atmospheric rivers, and the Intertropical Convergence Zone). On the longer forecasts, it tended to produce features that were less blurry than those made by pure AI forecasters, even though it was operating at a lower resolution than they were. This lower resolution means larger grid squares—the surface of the Earth is divided up into individual squares for computational purposes—than most other models, which cuts down significantly on its computing requirements.
Despite its success with weather, there were a couple of major caveats. One is that NeuralGCM tended to underestimate extreme events occurring in the tropics. The second is that it doesn’t actually model precipitation; instead, it calculates the balance between evaporation and precipitation.
But it also comes with some specific advantages over some other short-term forecast models, key among them being that it isn’t actually limited to running over the short term. The researchers let it run for up to two years, and it successfully reproduced a reasonable-looking seasonal cycle, including large-scale features of the atmospheric circulation. Other long-duration runs show that it can produce appropriate counts of tropical cyclones, which go on to follow trajectories that reflect patterns seen in the real world.
Enlarge/ File photo of a Falcon 9 launch on May 6 from Cape Canaveral Space Force Station, Florida.
SpaceX
It was only about 10 days ago that the Falcon 9 rocket’s upper stage failed in flight, preventing the rocket from delivering its 20 Starlink satellites into a proper orbit. Because they were released lower than expected—about 135 km above the Earth’s surface and subject to atmospheric drag—these satellites ultimately reentered the planet’s atmosphere and burnt up.
Typically, after a launch failure, a rocket will be sidelined for months while engineers and technicians comb over the available data and debris to identify a cause, perform tests, and institute a fix.
However, according to multiple sources, SpaceX was ready to launch the Falcon 9 rocket as soon as late last week. Currently, the company has a launch opportunity for no earlier than 12: 14 am ET (04: 14 UTC) on Wednesday for its Starlink 10-4 mission.
A quick fix?
In a summary of the anomaly posted shortly afterward, SpaceX did not identify the cause of the failure beyond saying, “The Merlin Vacuum engine experienced an anomaly and was unable to complete its second burn.”
Officially, the company has provided no additional information since then. However, the company’s engineers were able to identify the cause of the failure almost immediately and, according to sources, the fix was straightforward.
SpaceX was confident enough in this determination to resume launches of the Falcon 9 rocket one week after the failure. However, it is precluded from doing so while the US Federal Aviation Administration conducts a mishap investigation.
To that end, a week ago on July 15, SpaceX submitted a request to the FAA to resume launching its Falcon 9 rocket while this investigation into the anomaly continues. “The FAA is reviewing the request and will be guided by data and safety at every step of the process,” the FAA said in a statement at the time.
Crewed missions on deck
So, as of today, SpaceX is waiting for a determination from the FAA as to whether it will be allowed to resume Falcon 9 launches less than two weeks after the failure occurred.
The company plans to launch at least three Starlink missions in rapid succession from its two launch pads in Florida and one in California to determine the effectiveness of the fix. It would like to demonstrate the reliability of the Falcon 9 rocket, which had recorded more than 300 successful missions since its last failure during a pad accident in September 2016, before two upcoming crewed missions.
There is still a slight possibility that the Polaris Dawn mission, led by commercial astronaut Jared Isaacman, could launch in early August. This would be followed by the Crew-9 mission for NASA, which will carry four astronauts to the International Space Station.
Notably, neither of these crewed missions requires a second burn of the Merlin engine, which is where the failure occurred earlier this month during the Starlink mission.
Enlarge/ Artist concept of the Demonstration for Rocket to Agile Cislunar Operations (DRACO) spacecraft.
DARPA
Phoebus 2A, the most powerful space nuclear reactor ever made, was fired up at Nevada Test Site on June 26, 1968. The test lasted 750 seconds and confirmed it could carry first humans to Mars. But Phoebus 2A did not take anyone to Mars. It was too large, it cost too much, and it didn’t mesh with Nixon’s idea that we had no business going anywhere further than low-Earth orbit.
But it wasn’t NASA that first called for rockets with nuclear engines. It was the military that wanted to use them for intercontinental ballistic missiles. And now, the military wants them again.
Nuclear-powered ICBMs
The work on nuclear thermal rockets (NTRs) started with the Rover program initiated by the US Air Force in the mid-1950s. The concept was simple on paper. Take tanks of liquid hydrogen and use turbopumps to feed this hydrogen through a nuclear reactor core to heat it up to very high temperatures and expel it through the nozzle to generate thrust. Instead of causing the gas to heat and expand by burning it in a combustion chamber, the gas was heated by coming into contact with a nuclear reactor.
Tokino, vectorized by CommiM at en.wikipedia
The key advantage was fuel efficiency. “Specific impulse,” a measurement that’s something like the gas mileage of a rocket, could be calculated from the square root of the exhaust gas temperature divided by the molecular weight of the propellant. This meant the most efficient propellant for rockets was hydrogen because it had the lowest molecular weight.
In chemical rockets, hydrogen had to be mixed with an oxidizer, which increased the total molecular weight of the propellant but was necessary for combustion to happen. Nuclear rockets didn’t need combustion and could work with pure hydrogen, which made them at least twice as efficient. The Air Force wanted to efficiently deliver nuclear warheads to targets around the world.
The problem was that running stationary reactors on Earth was one thing; making them fly was quite another.
Space reactor challenge
Fuel rods made with uranium 235 oxide distributed in a metal or ceramic matrix comprise the core of a standard fission reactor. Fission happens when a slow-moving neutron is absorbed by a uranium 235 nucleus and splits it into two lighter nuclei, releasing huge amounts of energy and excess, very fast neutrons. These excess neutrons normally don’t trigger further fissions, as they move too fast to get absorbed by other uranium nuclei.
Starting a chain reaction that keeps the reactor going depends on slowing them down with a moderator, like water, that “moderates” their speed. This reaction is kept at moderate levels using control rods made of neutron-absorbing materials, usually boron or cadmium, that limit the number of neutrons that can trigger fission. Reactors are dialed up or down by moving the control rods in and out of the core.
Translating any of this to a flying reactor is a challenge. The first problem is the fuel. The hotter you make the exhaust gas, the more you increase specific impulse, so NTRs needed the core to operate at temperatures reaching 3,000 K—nearly 1,800 K higher than ground-based reactors. Manufacturing fuel rods that could survive such temperatures proved extremely difficult.
Then there was the hydrogen itself, which is extremely corrosive at these temperatures, especially when interacting with those few materials that are stable at 3,000 K. Finally, standard control rods had to go, too, because on the ground, they were gravitationally dropped into the core, and that wouldn’t work in flight.
Los Alamos Scientific Laboratory proposed a few promising NTR designs that addressed all these issues in 1955 and 1956, but the program really picked up pace after it was transferred to NASA and Atomic Energy Commission (AEC) in 1958, There, the idea was rebranded as NERVA, Nuclear Engine for Rocket Vehicle Applications. NASA and AEC, blessed with nearly unlimited budget, got busy building space reactors—lots of them.
On April 11, a small company called Graphyte began pumping out beige bricks, somewhat the consistency of particle board, from its new plant in Pine Bluff, Arkansas. The bricks don’t look like much, but they come with a lofty goal: to help stop climate change.
Graphyte, a startup backed by billionaire Bill Gates’ Breakthrough Energy Ventures, will bury its bricks deep underground, trapping carbon there. The company bills it as the largest carbon dioxide removal project in the world.
Scientists have long warned of the dire threat posed by global warming. It’s gotten so bad though that the long-sought mitigation, cutting carbon dioxide emissions from every sector of the economy, might not be enough of a fix. To stave off the worst—including large swaths of the Earth exposed to severe heat waves, water scarcity, and crop failures—some experts say there is a deep need to remove previously emitted carbon, too. And that can be done anywhere on Earth—even in places not known for climate-friendly policies, like Arkansas.
Graphyte aims to store carbon that would otherwise be released from plant material as it burns or decomposes at a competitive sub-$100 per metric ton, and it wants to open new operations as soon as possible, single-handedly removing tens of thousands of tons of carbon annually, said Barclay Rogers, the company’s founder and CEO. Nevertheless, that’s nowhere near the amount of carbon that will have to be removed to register as a blip in global carbon emissions. “I’m worried about our scale of deployment,” he said. “I think we need to get serious fast.”
Hundreds of carbon removal startups have popped up over the past few years, but the fledgling industry has made little progress so far. That leads to the inevitable question: Could Graphyte and companies like it actually play a major role in combating climate change? And will a popular business model among these companies, inviting other companies to voluntarily buy “carbon credits” for those buried bricks, actually work?
Whether carbon emissions are cut to begin with, or pulled out of the atmosphere after they’ve already been let loose, climate scientists stress that there is no time to waste. The clock began ticking years ago, with the arrival of unprecedented fires and floods, superstorms, and intense droughts around the world. But carbon removal, as it’s currently envisioned, also poses additional sociological, economic, and ethical questions. Skeptics, for instance, say it could discourage more pressing efforts on cutting carbon emissions, leaving some experts wondering whether it will even work at all.
Still, the Intergovernmental Panel on Climate Change, the world’s forefront group of climate experts, is counting on carbon removal technology to dramatically scale up. If the industry is to make a difference, experimentation and research and development should be done quickly, within the next few years, said Gregory Nemet, professor of public affairs who studies low-carbon innovation at the University of Wisconsin-Madison. “Then after that is the time to really start going big and scaling up so that it becomes climate-relevant,” he added. “Scale-up is a big challenge.”
Enlarge/ Renditions of a possible composition of LHS 1140 b, with a patch of ocean on the side facing its host star. Earth is included at right for scale.
Of all the potential super-Earths—terrestrial exoplanets more massive than Earth—out there, an exoplanet orbiting a star only 40 light-years away from us in the constellation Cetus might be the most similar to have been found so far.
Exoplanet LHS 1140 b was assumed to be a mini-Neptune when it was first discovered by NASA’s James Webb Space Telescope toward the end of 2023. After analyzing data from those observations, a team of researchers, led by astronomer Charles Cadieux, of Université de Montréal, suggest that LHS 1140 b is more likely to be a super-Earth.
If this planet is an alternate version of our own, its relative proximity to its cool red dwarf star means it would most likely be a gargantuan snowball or a mostly frozen body with a substellar (region closest to its star) ocean that makes it look like a cosmic eyeball. It is now thought to be the exoplanet with the best chance for liquid water on its surface, and so might even be habitable.
Cadieux and his team say they have found “tantalizing evidence for a [nitrogen]-dominated atmosphere on a habitable zone super-Earth” in a study recently published in The Astrophysical Journal Letters.
Sorry, Neptune…
In December 2023, two transits of LHS 1140 b were observed with the NIRISS (Near-Infrared Imager and Slitless Spectrograph) instrument aboard Webb. NIRISS specializes in detecting exoplanets and revealing more about them through transit spectroscopy, which picks up the light of an orbiting planet’s host star as it passes through the atmosphere of that planet and travels toward Earth. Analysis of the different spectral bands in that light can then tell scientists about the specific atoms and molecules that exist in the planet’s atmosphere.
To test the previous hypothesis that LHS 1140 b is a mini-Neptune, the researchers created a 3D global climate model, or GCM. This used complex math to explore different combinations of factors that make up the climate system of a planet, such as land, oceans, ice, and atmosphere. Several different GCMs of a mini-Neptune were compared with the light spectrum observed via transit spectroscopy. The model for a mini-Neptune typically involves a gas giant with a thick, cloudless or nearly cloudless atmosphere dominated by hydrogen, but the spectral bands of this model did not match NIRISS observations.
With the possibility of a mini-Neptune being mostly ruled out (though further observations and analysis will be needed to confirm this), Cadieux’s team turned to another possibility: a super-Earth.
An Earth away from Earth?
The spectra observed with NIRISS were more in line with GCMs of a super-Earth. This type of planet would typically have a thick nitrogen or CO2-rich atmosphere enveloping a rocky surface on which there was some form of water, whether in frozen or liquid form.
The models also suggested a secondary atmosphere, which is an atmosphere formed after the original atmosphere of light elements, (hydrogen and helium) escaped during early phases of a planet’s formation. Secondary atmospheres are formed from heavier elements released from the crust, such as water vapor, carbon dioxide, and methane. They’re usually found on warm, terrestrial planets (Earth has a secondary atmosphere).
The most significant Webb/NIRISS data that did not match the GCMs was that the planet has a lower density (based on measurements of its size and mass) than expected for a rocky world. This is consistent with a water world with a mass that’s about 10 to 20 percent water. Based on this estimate, the researchers think that LHS 1140 b might even be a hycean planet—an ocean planet that has most of the attributes of a super-Earth, but an atmosphere dominated by hydrogen instead of nitrogen.
Since it orbits a dim star closely enough to be tidally locked, some models suggest a mostly icy planet with a substellar liquid ocean on its dayside.
While LHS 1140 b may be a super-Earth, the hycean planet hypothesis might end up being ruled out. Hycean planets are prone to the runaway greenhouse effect, which occurs when enough greenhouse gases accumulate in a planet’s atmosphere and prevent heat from escaping. Liquid water will eventually evaporate on a planet that cannot cool itself off.
Though we are getting closer to finding out what kind of planet LHS 1140 b is, and whether it could be habitable, further observations are needed. Cadieux wants to continue this research by comparing NIRISS data with data on other super-Earths that had previously been collected by Webb’s Near-Infrared Spectrograph, or NIRSpec, instrument. At least three transit observations of the planet with Webb’s MIRI, or Mid-Infrared instrument, are also needed to make sure stellar radiation is not interfering with observations of the planet itself.
“Given the limited visibility of LHS 1140b, several years’ worth of observations may be required to detect its potential secondary atmosphere,” the researchers said in the same study.
So could this planet really be a frozen exo-earth? The suspense is going to last a few years.
Enlarge/ This artist’s concept shows the possible appearance of ESA’s RAMSES spacecraft, which will release two small CubeSats for additional observations at Apophis.
For nearly 20 years, scientists have known an asteroid named Apophis will pass unusually close to Earth on Friday, April 13, 2029. But most officials at the world’s space agencies stopped paying much attention when updated measurements ruled out the chance Apophis will impact Earth anytime soon.
Now, Apophis is again on the agenda, but this time as a science opportunity, not as a threat. The problem is there’s not much time to design, build and launch a spacecraft to get into position near Apophis in less than five years. The good news is there are designs, and in some cases, existing spacecraft, that governments can repurpose for missions to Apophis, a rocky asteroid about the size of three football fields.
Scientists discovered Apophis in 2004, and the first measurements of its orbit indicated there was a small chance it could strike Earth in 2029 or in 2036. Using more detailed radar observations of Apophis, scientists in 2021 ruled out any danger to Earth for at least the next 100 years.
“The three most important things about Apophis are: It will miss the Earth. It will miss the Earth. It will miss the Earth,” said Richard Binzel, a professor of planetary science at MIT. Binzel has co-chaired several conferences since 2020 aimed at drumming up support for space missions to take advantage of the Apophis opportunity in 2029.
“An asteroid this large comes this close only once per 1,000 years, or less frequently,” Binzel told Ars. “This is an experiment that nature is doing for us, bringing a large asteroid this close, such that Earth’s gravitational forces and tidal forces are going to tug and possibly shake this asteroid. The asteroid’s response is insightful to its interior.”
It’s important, Binzel argues, to get a glimpse of Apophis before and after its closest approach in 2029, when it will pass less than 20,000 miles (32,000 kilometers) from Earth’s surface, closer than the orbits of geostationary satellites.
“This is a natural experiment that will reveal how hazardous asteroids are put together, and there is no other way to get this information without vastly complicated spacecraft experiments,” Binzel said. “So this is a once-per-many-thousands-of-years experiment that nature is doing for us. We have to figure out how to watch.”
This week, the European Space Agency announced preliminary approval for a mission named RAMSES, which would launch in April 2028, a year ahead of the Apophis flyby, to rendezvous with the asteroid in early 2029. If ESA member states grant full approval for development next year, the RAMSES spacecraft will accompany Apophis throughout its flyby with Earth, collecting imagery and other scientific measurements before, during, and after closest approach.
The challenge of building and launching RAMSES in less than four years will serve as good practice for a potential future real-world scenario. If astronomers find an asteroid that’s really on a collision course with Earth, it might be necessary to respond quickly. Given enough time, space agencies could mount a reconnaissance mission, and if necessary, a mission to deflect or redirect the asteroid, likely using a technique similar to the one demonstrated by NASA’s DART mission in 2022.
“RAMSES will demonstrate that humankind can deploy a reconnaissance mission to rendezvous with an incoming asteroid in just a few years,” said Richard Moissl, head of ESA’s planetary defense office. “This type of mission is a cornerstone of humankind’s response to a hazardous asteroid. A reconnaissance mission would be launched first to analyze the incoming asteroid’s orbit and structure. The results would be used to determine how best to redirect the asteroid or to rule out non-impacts before an expensive deflector mission is developed.”
Shaking off the cobwebs
In order to make a 2028 launch feasible for RAMSES, ESA will reuse the design of a roughly half-ton spacecraft named Hera, which is scheduled for launch in October on a mission to survey the binary asteroid system targeted by the DART impact experiment in 2022. Copying the design of Hera will reduce the time needed to get RAMSES to the launch pad, ESA officials said.
“Hera demonstrated how ESA and European industry can meet strict deadlines and RAMSES will follow its example,” said Paolo Martino, who leads ESA’s development of Ramses, which stands for the Rapid Apophis Mission for Space Safety.
ESA’s space safety board recently authorized preparatory work on the RAMSES mission using funds already in the agency’s budget. OHB, the German spacecraft manufacturer that is building Hera, will also lead the industrial team working on RAMSES. The cost of RAMSES will be “significantly lower” than the 300-million-euro ($380 million) cost of the Hera mission, Martino wrote in an email to Ars.
“There is still so much we have yet to learn about asteroids but, until now, we have had to travel deep into the Solar System to study them and perform experiments ourselves to interact with their surface,” said Patrick Michel, a planetary scientist at the French National Center for Scientific Research, and principal investigator on the Hera mission.
“For the first time ever, nature is bringing one to us and conducting the experiment itself,” Michel said in a press release. “All we need to do is watch as Apophis is stretched and squeezed by strong tidal forces that may trigger landslides and other disturbances and reveal new material from beneath the surface.”
Assuming it gets the final go-ahead next year, RAMSES will join NASA’s OSIRIS-APEX mission in exploring Apophis. NASA is steering the spacecraft, already in space after its use on the OSIRIS-REx asteroid sample return mission, toward a rendezvous with Apophis in 2029, but it won’t arrive at its new target until a few weeks after its close flyby of Earth. The intricacies of orbital mechanics prevent a rendezvous with Apophis any earlier.
Observations from OSIRIS-APEX, a larger spacecraft than RAMSES with a sophisticated suite of instruments, “will deliver a detailed look of what Apophis is like after the Earth encounter,” Binzel said. “But until we establish the state of Apophis before the Earth encounter, we have only one side of the picture.”
Enlarge/ At its closest approach, asteroid Apophis will closer to Earth than the ring of geostationary satellites over the equator.
Scientists are also urging NASA to consider launching a pair of mothballed science probes on a trajectory to fly by Apophis some time before its April 2029 encounter with Earth. These two spacecraft were built for NASA’s Janus mission, which the agency canceled last year after the mission fell victim to launch delays with NASA’s larger Psyche asteroid explorer. The Janus probes were supposed to launch on the same rocket as Psyche, but problems with the Psyche mission forced a delay in the launch of more than one year.
Despite the delay, Psyche could still reach its destination in the asteroid belt, but the new launch trajectory meant Janus would be unable to visit the two binary asteroids scientists originally wanted to explore with the probes. After spending nearly $50 million on the mission, NASA put the twin Janus spacecraft, each about the size of a suitcase, into long-term storage.
At the most recent workshop on Apophis missions in April, scientists heard presentations on more than 20 concepts for spacecraft and instrument measurements at Apophis.
They included an idea from Blue Origin, Jeff Bezos’s space company, to use its Blue Ring space tug as a host platform for multiple instruments and landers that could descend to the surface of Apophis, assuming research institutions have enough time and money to develop their payloads. A startup named Exploration Laboratories has proposed partnering with NASA’s Jet Propulsion Laboratory on a small spacecraft mission to Apophis.
“At the conclusion of the workshop, it was my job to try to bring forward some consensus, because if we don’t have some consensus on our top priority, we may end up with nothing,” Binzel said. “The consensus recommendation for ESA was to more forward with RAMSES.”
Workshop participants also gently nudged NASA to use the Janus probes for a mission to Apophis. “Apophis is a mission in search of a spacecraft, and Janus is a spacecraft in search of a mission,” Binzel said. “As a matter of efficiency and basic logic, Janus to Apophis is the highest priority.”
A matter of money
But NASA’s science budget, and especially funding for its planetary science vision, is under stress. Earlier this week, NASA canceled an already-built lunar rover named VIPER after spending $450 million on the mission. The mission had exceeded its original development cost by greater than 30 percent, prompting an automatic cancellation review.
The funding level for NASA’s science mission directorate this year is nearly $500 million less than last year’s budget, and $900 million below the White House’s budget request for fiscal year 2024. Because of the tight budget, NASA officials have said, for now, they are not starting development of any new planetary science missions as they focus on finishing projects already in the pipeline, like the Europa Clipper mission, the Dragonfly quadcopter to visit Saturn’s moon Titan, and the Near-Earth Object (NEO) Surveyor telescope to search for potentially hazardous asteroids.
Enlarge/ These grainy radar views of asteroid Apophis were captured using radars at NASA’s Goldstone Deep Space Communications Complex in California and Green Bank Telescope in West Virginia.
NASA has asked the Janus team to look at the feasibility of launching on the same rocket as NEO Surveyor in 2027, according to Dan Scheeres, the Janus principal investigator at the University of Colorado. With such a launch in 2027, Janus could capture the first up-close images of Apophis before RAMSES and OSIRIS-APEX get there.
“This is something that we’re currently presenting in some discussions with NASA, just to make sure that they understand what the possibilities are there,” Scheeres said in a meeting last week of the Small Bodies Advisory Group, which represents the asteroid science community.
“These spacecraft are capable of performing future scientific flyby missions to near-Earth asteroids,” Scheeres said. “Each spacecraft has a high-quality Malin visible imager and a thermal infrared imager. Each spacecraft has the ability to track and image an asteroid system through a close, fast flyby.”
“The scientific return from an Apophis flyby by Janus could be one of the best opportunities out there,” said Daniella DellaGiustina, lead scientist on the OSIRIS-APEX mission from the University of Arizona.
Binzel, who has led the charge for Apophis missions, said there is also some symbolic value to having a spacecraft escort the asteroid by Earth. Apophis will be visible in the skies over Europe and Africa when it is closest to our planet.
“When 2 billion people are watching this, they are going to ask, ‘What are our space agencies doing?’ And if the answer is, ‘Oh, we’ll be there. We’re getting there,’ which is OSIRIS-APEX, I don’t think that’s a very satisfying answer,” Binzel said.
“As the international space community, we want to demonstrate on April 13, 2029, that we are there and we are watching, and we are watching because we want to gain the most knowledge and the most understanding about these objects that is possible, because someday it could matter,” Binzel said. “Someday, our detailed knowledge of hazardous asteroids would be among the most important knowledge bases for the future of humanity.”
Enlarge/ The core stage for NASA’s second Space Launch System rocket rolls aboard a barge that will take it from New Orleans to Kennedy Space Center in Florida.
Welcome to Edition 7.03 of the Rocket Report! One week ago, SpaceX suffered a rare failure of its workhorse Falcon 9 rocket. In fact, it was the first time the latest version of the Falcon 9, known as the Block 5, has ever failed on its prime mission after nearly 300 launches. The world’s launch pads have been silent since the grounding of the Falcon 9 fleet after last week’s failure. This isn’t surprising, but it’s noteworthy. After all, the Falcon 9 has flown more this year than all of the world’s other rockets combined and is fundamental to much of what the world does in space.
As always, we welcome reader submissions. If you don’t want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets as well as a quick look ahead at the next three launches on the calendar.
Astra finally goes private, again. A long-simmering deal for Astra’s founders to take the company private has been finalized, the company announced Thursday, capping the rocket launch company’s descent from blank-check darling to delisting in three years, Bloomberg reports. The launch company’s valuation peaked at $3.9 billion in 2021, the year it went public, and was worth about $12.2 million at the end of March, according to data compiled by Bloomberg. Astra’s chief executive officer, Chris Kemp, and chief technology officer, Adam London, founded the company in 2016 with the goal of essentially commoditizing launch services for small satellites. But Astra’s rockets failed to deliver and fell short of orbit five times in seven tries.
Spiraling … Astra’s stock price tanked after the spate of launch failures, drying up its funding spigot as Kemp tried to pivot toward a slightly larger, more reliable rocket. Astra acquired a company named Apollo Fusion in 2021, entering a new business segment to produce electric thrusters for small satellites. But Astra’s launch business faltered, and last November Kemp and London submitted an offer to retake ownership of the company. Astra announced the closure of the take-private deal Thursday, with Kemp and London acquiring the company’s outstanding shares for 50 cents per share in cash, below the stock’s final listing price of 53 cents. “We will now focus all of our attention on a successful launch of Rocket 4, delivering satellite engines to our customers, and building a company of consequence,” Kemp said. (submitted by EllPeaTea and Ken the Bin)
Firefly chief leaves company. Launch startup Firefly Aerospace parted ways with CEO Bill Weber, Payload reports. The announcement of Weber’s departure late Wednesday came two days after Payload reported Firefly was investigating claims of an alleged inappropriate relationship between him and a female employee. “Firefly Aerospace’s Board of Directors announced that Bill Weber is no longer serving as CEO of the company, effective immediately,” the company said in a statement Wednesday night. Peter Schumacher takes over as interim CEO while Firefly searches for a new permanent chief executive. Schumacher was an interim CEO at Firefly before Weber’s hiring in 2022.
Two days and gone … Payload published the first report of Weber’s alleged improper relationship with a female employee Monday. Two days later, Weber was gone. Payload reported an executive brought his concerns about the alleged relationship to Firefly’s board and resigned because he lost confidence in leadership at the company. Citing four current and former employees, Payload reported Firefly’s culture became “chaotic” since Weber took the helm in 2022 after its acquisition by AE Industrial Partners. The Texas-based company achieved some success during Weber’s tenure, with four orbital launches of its Alpha rocket, although two of the flights ended up in lower-than-planned orbits. (submitted by Ken the Bin)
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Themis hop tests delayed to next year. The initial hop tests of the European Themis reusable booster, developed by ArianeGroup and funded by ESA, won’t start until next year, European Spaceflight reports. The Swedish Space Corporation, which operates the space center in Sweden where Themis will initially fly, confirmed the schedule change. Once ArianeGroup moves on to higher altitude flights, the testing will be moved to the Guiana Space Center. ESA awarded the first development contract for the Themis booster in 2019, and the first hop tests were then scheduled for 2022. Themis’ hops will be similar to SpaceX’s Grasshopper rocket, which performed a series of up-and-down atmospheric test flights before SpaceX started recovering and reusing Falcon 9 boosters.
Fate of Themis … The Themis booster is powered by the methane-fueled Prometheus engine, also funded by ESA. A large European reusable rocket is unlikely to fly until the 2030s, but a subsidiary of ArianeGroup named MaiaSpace is developing a smaller partially reusable two-stage rocket slated to debut as soon as next year. The Maia rocket will use a modified Themis booster as its first stage. “As a result, for MaiaSpace, the continued and rapid development of the Themis program is essential to ensure it can hit its projected target of an inaugural flight of Maia in 2025,” European Spaceflight reports. (submitted by Ken the Bin)
Enlarge/ Long covid activists attend the Senate Appropriations Subcommittee on Labor, Health and Human Services, Education, and Related Agencies hearing on the “Fiscal Year 2025 Budget Request for the National Institutes of Health,” in Dirksen building on May 23, 2024.
As a summer wave of COVID-19 infections swells once again, a study published this week in the New England Journal of Medicine offers some positive news about the pandemic disease: Rates of long COVID have declined since the beginning of the health crisis, with rates falling from a high of 10.4 percent before vaccines were available to a low of 3.5 percent for those vaccinated during the omicron era, according to the new analysis.
The study, led by Ziyad Al-Aly, chief of research at the VA Saint Louis Health Care System, used data from a wealth of health records in the Department of Veterans Affairs. The researchers ultimately included data from over 440,000 veterans who contracted COVID-19 sometime between March 1, 2020, and January 31, 2022, as well as over 4.7 million uninfected veterans who acted as controls.
Al-Aly and colleagues divided the population into eight groups. People who were infected during the study period were divided into five groupings by the dates of their first infection and their vaccination status. The first group included those infected in the pre-delta era before vaccines were available (March 1, 2020, to June 18, 2021). Then there were vaccinated and unvaccinated groups who were infected in the delta era (June 19, 2021, to December 18, 2021) and the omicron era (December 19, 2021, and January 31, 2022). The uninfected controls made up the final three of eight groups, with the controls assigned to one of the three eras.
On the decline
In the pre-delta/pre-vaccine era, 10.42 out of 100 unvaccinated people infected developed long COVID in the year after their infection, which the researchers referred to as PASC, or postacute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In the delta era, the rate of long COVID among the unvaccinated fell slightly to 9.51 out of 100. But for the vaccinated, the rate fell much further, to 5.35 out of 100. A similar pattern was seen in the omicron era. For the unvaccinated, the rate of long COVID again fell slightly to 7.76 per 100 people, while the vaccinated saw their rate fall to 3.5 per 100.
In a secondary statistical analysis, called a decomposition analysis, the researchers found that vaccines could explain about 72 percent of the cumulative decline in long COVID rates across the eras, while era-related factors explained about 28 percent. Those era-related factors could include differences in the virus, improved treatments, and use of anti-viral medications.
Further, looking at data on the disease categories related to long COVID cases, the researchers also did an analysis finding a shift in symptoms over the eras. The researchers looked at over 10 disease categories: cardiovascular, coagulation and hematologic, fatigue, gastrointestinal, kidney, mental health, metabolic, musculoskeletal, neurologic, and pulmonary. Compared to the two earlier eras, the researchers noted an increase in gastrointestinal, metabolic, and musculoskeletal diseases involved in long COVID cases in the omicron era.
Overall, the study points to a welcomed decline in the rates of long COVID among the infected, particularly for those who are vaccinated. But, it also makes clear that long COVID isn’t a thing of the past: “a substantial residual risk of PASC remains among vaccinated persons who had SARS-CoV-2 infection during the omicron era,” Al-Aly and his colleagues conclude.
The study also has some limitations, leaving lingering questions for further study. One is whether the type or number of vaccines affect the risk of long COVID—that was not included in the study. The study also didn’t allow researchers to assess whether repeat infections increase the burden of long COVID.
