Technological revolutions can bring about dramatic changes in various fields, some of which are only tangentially related to the field being disrupted. Occasionally, a few technological revolutions happen simultaneously, enabling concepts that would have been impossible without any of them. Such revolutions are currently happening in the space industry. With rockets more massive than ever coming online, and mega-constellations of satellites roaming our skies, there is plenty of disruption going on. Now a team from MIT hopes to use those technologies to look at an area of astronomy that has never been seen before – low-frequency radio astronomy.
Giant radio telescopes, such as the now-defunct Arecibo, have one major disadvantage – they are located on Earth. Our ionosphere neatly blocks the very low-frequency radio spectrum, from frequencies of 100 kHz to around 15 MHz. So while those massive telescopes are theoretically capable of detecting those signals, none of them make it through the ionosphere for them to detect.
Alternatively, telescopes in space would be perfectly capable of detecting these low frequencies. But they would have to be absolutely massive to do so – on the order of hundreds of meters in diameter, which is currently far beyond the capability of even the most powerful rockets proposed. So far, building a radio telescope for detecting low-frequency signals in space has been a non-starter.
There are other places in the solar system that could support a interferometer – like the far side of the Moon.
But there may be an alternative. Newer radio telescopes, such as MeerKAT, use a technique called interferometry. Instead of requiring one colossal telescope, interferometry telescopes use a series of small ones bound together by the laws of physics and mathematics to detect low-frequency radio waves that would usually be seen only by giant detectors.
What Mary Krupp and her team at MIT have suggested seems like a logical next step – why not build an interferometric telescope in space? Their project, known as the Great Observatory for Long Wavelengths, or, since astronomers are so fond of acronyms, Go-LoW, was recently funded by NASA’s Institute for Advanced Concepts, and its premise is relatively simple.
Take an interferometric system similar to MeerKAT and launch it to the L5 Lagrange point. The idea takes ideas from a few current technological advances and combines them. The first would be how to make hundreds of thousands of satellites inexpensively.
Discussion of the MeerKAT telescope, a interferometer that is currently in use here on Earth.
Credit – CreamerMedia YouTube Channel
For that, they rely on the technologies developed by SpaceX for their Starlink mega constellation. Its 40000+ planned satellites have significantly decreased the cost of small satellite components, making it economically feasible to build that many satellites without breaking the bank.
The second technological development is the advent of heavy-launch rockets. With the power of Starship or the SLS, thousands of satellites can be launched to Earth-Sun L5 Lagrange point about 1.5 million kilometers away. While it might not necessarily be cheap to do so, it certainly wouldn’t be as expensive as it had been in past generations.
Now seems like an ideal time for such an idea, though NIAC is known for backing projects in the very early stages. The MIT team will work on conceptual aspects of the mission in this Phase I grant, which lasts for nine months. Ultimately, they hope to have a road map to making the project a reality in the next 10-20 years. They might just be able to catch that technological wave at the right time and change our understanding of radio astronomy forever.
The average temperature of the universe is downright cold – right around 3 degrees above absolute zero.
In order to measure the temperature deep space there must be a substance, because this is how we define temperature. The temperature of the room you’re sitting in right now is determined by the average motion of all the air molecules in the room. The more energy they have, the faster they fly around, and the higher the temperature. If you touch a really hot object, its atom and molecules are vibrating furiously, giving it a very high temperature.
There isn’t a lot of matter in interstellar space. The average density of the universe is roughly only one hydrogen atom per cubic meter. This makes it very difficult to assign a temperature to the matter of interstellar space. But space itself is soaked in something else, an unending sea of radiation that is very, very cold.
This radiation comes from stars, galaxies and more, but by far the largest source of radiation in the universe is the cosmic microwave background (or CMB). The CMB emerged when the universe was about 380,000 years old. At that time our cosmos was about a million times smaller than it is today and it was in a hot dense plasma state. As the universe expanded and cooled the universe became neutral, releasing radiation that had a temperature of about 10,000 Kelvin, the same temperature as the surface of the Sun.
That radiation accounts for over 99.999% of all the radiation remaining in the cosmos. Since the time it was released, our universe has expanded, which has diluted that same radiation, lowering its temperature. In addition, the cosmic expansion stretches on light itself moving it to longer, cooler wavelengths.
The combined action of this expansion has dropped the temperature of the CMB to right around 3 degrees above absolute zero. That means that if you were to sit in interstellar space, your body would cool and cool and cool towards absolute zero. But it would be prevented from reaching that temperature because the cosmic microwave background radiation would always be hitting you, transferring their energy into your body. So you wouldn’t reach absolute zero, but you would come into equilibrium with the CMB, and that’s how we determine the (cold) temperature of interstellar space.
To date, 5,250 extrasolar planets have been confirmed in 3,921 systems, with another 9,208 candidates awaiting confirmation. Of these, 195 planets have been identified as “terrestrial” (or “Earth-like“), meaning that they are similar in size, mass, and composition to Earth. Interestingly, many of these planets have been found orbiting within the circumsolar habitable zones (aka. “Goldilocks zone”) of M-type red dwarf stars. Examples include the closest exoplanet to the Solar System (Proxima b) and the seven-planet system of TRAPPIST-1.
These discoveries have further fueled the debate of whether or not these planets could be “potentially-habitable,” with arguments emphasizing everything from tidal locking, flare activity, the presence of water, too much water (i.e., “water worlds“), and more. In a new study from the University of Padua, a team of astrobiologists simulated how photosynthetic organisms (cyanobacteria) would fare on a planet orbiting a red dwarf. Their results experimentally demonstrated that oxygen photosynthesis could occur under red suns, which is good news for those looking for life beyond Earth!
The “pale orange dot.” Artist’s impression of what early Earth would have looked like. Credit: NASA/Goddard Space Flight Center/Francis Reddy
The subject of M-type stars, photosynthesis, and the implications for astrobiology has been explored at length in recent decades. Not only are red dwarfs the most common type of star in the Universe, accounting for 75% of stars in the Milky Way alone. Recent surveys have shown they are also very good at forming rocky planets that orbit within the parent star’s habitable zone (in many cases, tidally locked with their stars). Given the unstable nature of red dwarfs, their tendency to flare, and other factors, the jury is still out on whether or not they could support life – especially in their early phases. As Dr. Battistuzzi told Universe Today via email:
“M-dwarfs can profoundly change their activity depending on their stage of evolution. 25% of early-life M-dwarfs release X-rays and UV through flares and chromospheric activity. Instead, quiescent stars emit little UV radiation and have no flares. Planets orbiting around M-dwarfs often receive high doses of these kinds of radiation during stellar flares, changing rapidly the radiation environment on the surface and possibly eroding the ozone shield, if present, as well as part of the atmosphere.
“However, it has been pointed out that these planets could remain habitable. Atmospheric erosion could be avoided through a strong magnetic field or with thick atmospheres. Also, in addition to this, possible organisms could develop UV-protecting pigments and DNA repair mechanisms as happens on Earth or develop in subsurface niches, underwater or under the ice, where radiation is less intense.”
On Earth, life is theorized to have emerged during the Archean Eon (ca. 4 billion years ago) in the form of simple, single-celled (prokaryote) bacteria. Earth’s atmosphere was still largely composed of carbon dioxide, methane, and other volcanic gases at this time. Between 3.4 and 2.9 billion years ago, the first photosynthetic organisms – green-blue microbes called cyanobacteria – began flourishing in Earth’s oceans. These organisms metabolized carbon dioxide with water and sunlight to create gaseous oxygen (O2), eventually leading to more complex, multi-celled organisms (eukaryotes).
Artist’s impression of the Archean Eon. Credit: Tim Bertelink
Hence the concern regarding young red dwarf suns and their rocky planets. These dimmer, cooler stars emit the majority of their radiation in the red and infrared wavelengths (lower energy than the yellow light of the Sun peaks). As a result, scientists have speculated that additional photons would be needed to achieve excitation potentials comparable to those needed for photosynthesis on Earth. For their study, La Rocca and Battistuzzi sought to determine experimentally if this was the case. According to Battistuzzi, this consisted of subjecting cyanobacteria to different wavelengths of light and monitoring the bacteria’s growth:
“We exposed a couple of cyanobacteria to a simulated M-dwarf light spectrum and measured their growth, acclimation responses (for example, the changes in the pigment composition and the organization of the photosynthetic apparatus, crucial to absorbing light and converting it into sugars), and oxygen production capabilities under this light spectrum. We compared these data to 2 different control conditions: a monochromatic far-red light and a solar light spectrum.”
The experiment utilized two types of cyanobacteria. This included Chlorogloeopsis fritschii, a small group of cyanobacteria capable of synthesizing special pigments (chlorophyll d and f) that are able to absorb far-red light. Unlike most other photosynthetic organisms (like plants), this gives this strain the ability to grow and produce oxygen using far-red light alone or in addition to visible light. The second strain, Synechocystis sp., is a broader group of freshwater cyanobacteria that cannot utilize far-red light alone for photosynthesis and needs visible light.
“The monochromatic far-red light was used as a control to ensure different responses of the far-red utilizing cyanobacterium and the non-far utilizing one: the first should grow in far-red, and the second one should not,” added Battistuzzi. “The simulated solar light spectrum was used as a control to check the growth, acclimation responses, and oxygen production in optimal conditions (terrestrial organisms evolved under the Sun’s spectrum, so they are adapted to it).”
Three of the TRAPPIST-1 planets – TRAPPIST-1e, f, and g – dwell in their star’s so-called “habitable zone.” Credit: NASA/JPL
As they indicate in their study, the results were surprisingly encouraging. Both cyanobacteria grew at a similar rate under the red dwarf and Solar light conditions. This was impressive, considering that visible light is rather scarce in the M-type stellar spectrum. In the case of C. fritschii, the results could be explained by its capability of synthesizing the necessary pigments to harvest far-red light and its ability to harness visible light. While Synechocystis sp. did not grow under far-red light alone, it could also grow at a similar rate to C. fritschii when exposed to both. While the exact cause is not certain, Battistuzzi and La Rossa have some theories:
“This could be explained by recent studies on plants showing that far-red light just helps oxygenic photosynthesis when in combination with visible light, while instead is poorly utilized when provided alone (as demonstrated in this work by Synechocystis sp., which could not grow under this only light source).
“The acclimations of both cyanobacteria moreover led to efficient O2 evolution under the M-dwarf light spectrum. This shows the potentiality of cyanobacteria to utilize light regimes that could arise on tidally locked planets orbiting the Habitable Zone of M-dwarf stars, and also their potential in producing O2 biosignatures detectable from remote.”
In a previous study conducted in 2021, La Rocca, Battistuzzi, and their teammates conducted a similar experiment where they studied the growth and acclimation of cyanobacteria. This study was led by Riccardo Claudi of the Astronomical Observatory of Padua (INAF-OAPD), a co-author of the current paper. For this experiment, the team relied on solid media to cultivate cyanobacteria as biofilms, which allowed them to obtain results more rapidly but limited the amount and the type of experiments they could conduct.
Artist’s impression of a water world, where half of its mass consists of water. Just like our Moon, the planet is bound to its star by tidal forces and always shows the same face to its host star. Credit: Pilar Montañés
This time, the cyanobacteria were cultivated in liquid media, which yielded more samples. This, in turn, allowed far more detailed examinations of the growth, acclimation processes, and oxygen evolution of cyanobacteria exposed to different light conditions. The implications of these latest experiments and what they revealed are potentially groundbreaking. According to Battistuzzi, this includes a new understanding under which photosynthesis can occur, better prospects for red dwarf habitability, and new opportunities for detected biotic oxygen in exoplanet atmospheres:
“Even if the visible light in the M-dwarf spectrum is very low, it can still be utilized by some oxygenic photosynthetic organisms efficiently. This highlights the importance of taking into account the huge diversity of oxygenic photosynthetic organisms, which not only comprise plants but also basal plants, and microalgae, down to the simplest cyanobacteria.
“It is also important to consider how the new findings demonstrate the role of far-red light in helping photosynthetic performance and the growth of all photosynthetic organisms (higher plants included). If life evolved oxygenic photosynthesis on an exoplanet orbiting the habitable zone of an M-dwarf, this process could be far more similar to what happens on Earth than previously anticipated.”
“If oxygenic photosynthesis evolved in M-dwarf’s exoplanets, with the right conditions, oxygen could, in theory, accumulate in their atmospheres, as happened on Earth billions of years ago during the Great Oxidation Event, becoming a permanent component. This would allow astronomers to detect such biologically produced oxygen, a biosignature, in the atmosphere and infer from that the presence of life from remote.”
Artist’s conception of a rocky Earth-mass exoplanet like Wolf 1069 b orbiting a red dwarf star. If the planet has retained its atmosphere, chances are high that it would feature liquid water and habitable conditions over a wide area of its dayside. Credit: NASA/Ames Research Center/Daniel Rutter
This last implication is especially significant, as astronomers and astrobiologists have explored the possibility that when it comes to red dwarfs, oxygen might not be the smoking gun we tend to think it is. Red dwarfs have an extended pre-main sequence phase (roughly 1 billion years), which means that planets orbiting in what will eventually become their habitable zones would be exposed to elevated radiation. This could trigger a runaway greenhouse effect where water is evaporated and broken down by radiation exposure into hydrogen and oxygen (photolysis).
The hydrogen gas would then be lost to space while the oxygen would be retained as a thick abiotic oxygen atmosphere. Such atmospheres would be inherently hostile to photosynthetic bacteria and other terrestrial organisms that existed when the Earth was young. In short, what is considered a leading biosignature and indicator of life could actually be an indication that a planet is sterile. But as Battistuzzi adds, there is plenty of uncertainty here, and more research is needed before any conclusions can be drawn:
“Of course, these are big ifs. It is not a guarantee that life would evolve even if habitability conditions are met on an exoplanet orbiting an M-dwarf, and it is not a guarantee that life would evolve oxygenic photosynthesis at all, as it could also evolve anoxygenic photosynthesis, a kind of photosynthesis which still uses light but does not produce oxygen as a by-product.”
Stars are born in molecular clouds, massive clouds of hydrogen that can contain millions of stellar masses of material. But how do molecular clouds form? There are different theories and models of that process, but the cloud formation is difficult to observe.
A new study is making some headway, and showing how the process occurs more rapidly than thought.
Molecular clouds are an important part of the interstellar medium (ISM) and are embedded in atomic gas, the other main component of the ISM. The third component of the ISM is ionic gas, and all three play roles in star formation.
There are unanswered questions about how molecular hydrogen clouds form from the ISM and then form stars. Molecular hydrogen is notoriously difficult to observe because of its lack of absorption lines in visible, infrared, and UV light. New research shows how one component of the ionized gas in the ISM—ionized carbon (CII)—can be observed to trace how molecular clouds form.
The research focuses on Cygnus X, a massive star-forming region about 4,600 light-years away in the constellation Cygnus. It’s associated with one of the largest molecular hydrogen clouds scientists know of. Studies show that Cygnus X has been forming stars rapidly for the last 10 million years and is still forming them today.
This is an infrared image of the star-forming region Cygnus X. The bright regions contain new stars that are carving bubbles out of the cloud with their outflows and UV radiation. Image Credit: NASA/IPAC/MSX
Stars are born in clouds of molecular hydrogen, but astrophysicists wind the clock back further than that to find their origins. Molecular hydrogen clouds form from reservoirs of atomic hydrogen (HI) in galaxies, though the exact mechanism is not clearly understood. Astrophysicists have developed different models of the mechanism. Some lay out a slow process where gravity, turbulence, and magnetic fields are in equilibrium until disturbed by stellar feedback or spiral arm density. Once disturbed, there’s a slow buildup of density that forms pockets of molecular hydrogen gas. Stars are eventually formed in those pockets.
Other models point to a more rapid, dynamic process. In these models, the large-scale movement of the galaxies themselves triggers the process as warm, tenuous, mostly atomic gas called the warm neutral medium (WNM) transitions to cooler, denser clouds of molecular hydrogen called the cold neutral medium (CNM.) Stellar feedback and supernovae explosions also play a role in driving the gas to greater densities and forming stars. This complicates observations. “It is thus challenging to find the right observational tracers for both the dynamic interaction between gas flows and the thermal and chemical transitions between WNM and CNM,” the authors write in their paper.
The team used observations from SOFIA‘s FEEDBACK program in their work. They compared the distribution of three components of the ISM in Cygnus X: ionized carbon, molecular carbon monoxide and atomic hydrogen. SOFIA’s unique capabilities allowed it to spot faint CII (ionized carbon) radiation from the periphery of the clouds that’s never before been detected. The new research shows that star formation can happen much more rapidly than thought. That rapidity might also explain how massive stars form.
SOFIA (Stratospheric Observatory for Infrared Astronomy) is a converted Boeing 747 that acted as an airborne observatory. It housed a 2.5 m (8.2 ft) diameter infrared telescope. SOFIA was a joint mission between NASA and the German DLR. Its final flight was in September 2022. Image Credit: NASA/DLR
Cygnus X is a vast agglomeration of clouds of luminous gas and dust. Observations of spectral lines of ionized carbon (CII) showed that the clouds have formed there over several million years. In astronomy, that is a very fast process. Not only does this disrupt our understanding of star formation, but it also helps answer a question that slow star formation can’t answer: how do massive stars form if it takes so long?
Massive stars are comparatively rare, but we can still see them in the night sky. This image is of the constellation Orion, and the massive star Rigel is the bright blue star in the lower right corner. It’s about 21 solar masses, and is young; only about 8 million years old. It will eventually explode as a supernova, but not for a long time. Credit: NASA Astronomy Picture of the Day Collection NASA
Massive stars are defined as those 8 times more massive than the Sun. They’re particularly interesting to astrophysicists because they’re so rare: less than 1% of stars in the Milky Way are massive. Several types of feedback impede their formation. Outflows, radiation pressure and magnetic fields are all barriers to stars becoming massive. Massive stars also emit massive amounts of material from the polar jets as they form, further restricting their growth. Astrophysicists have struggled to develop a thorough model that can explain how massive stars form. Since they’re responsible for fusing so many of the heavy elements, scientists are very interested in them.
But by observing the radiation from ionized carbon (CII) on the edges of interstellar gas clouds, this group of researchers has made some headway.
Contrary to previous understanding, the researchers found that the interstellar gas clouds, whose shells are made of molecular hydrogen, are travelling more rapidly than thought, at up to 20 km s-1. “This high speed compresses the gas into denser molecular regions where new, mainly massive stars form. We needed the CII observations to detect this otherwise ‘dark’ gas,” said lead author Schneider.
This figure from the study presents some of the findings. It shows DR21, one of the bright, dense, star-forming molecular clouds in Cygnus X. The large scale cloud structure that DR21 is embedded in is only visible in CII (ionized carbon) emissions (left.) Image Credit: Schneider et al. 2023.
This may be the first time that CII has been used as a tracer to probe how molecular clouds form and give rise to massive stars. But it won’t be the last. “We conclude that the [CII] 158??m line is an excellent tracer to witness the processes involved in cloud interactions and anticipate further detections of this phenomenon in other regions,” the authors write.
The data may be in the archives of the now-defunct SOFIA mission. The FEEDBACK program surveyed multiple regions with a wide range of massive star formation activity. The goal was to “… quantify the relationship between star formation activity and energy injection and the negative and positive feedback processes,” the FEEDBACK website explains.
The researchers are already busy working with the FEEDBACK data. In a press release, lead author Schneider said, “In the list of FEEDBACK sources, there are other gas clouds in different stages of evolution, where we are now looking for the weak CII radiation at the peripheries of the clouds to detect similar interactions as in the Cygnus X region.”
The planet Mars is arguably the most extensively studied planetary body in the entire Solar System, which began with telescopic observations by Galileo Galilei in 1609, with such telescopic observations later being taken to the extreme by Percival Lowell in the late 19th century when he reported seeing what he believed were artificial canals made by an advanced intelligent race of Martians. But it wasn’t until the first close up image of Mars taken by NASA’s Mariner 4 in 1965 that we saw the Red Planet for what it really was: a cold and dead world with no water and no signs of life, whatsoever.
Despite this, we kept studying this intriguing world by sending more orbiters, landers, and rovers to search for life on Mars, with each mission becoming more technologically advanced and challenging. These missions currently include NASA’s Curiosity and Perseverance rovers and China’s Zhurong rover, though it’s been reported that Zhurong hasn’t moved in months. However, despite all our searching, we still haven’t found life on Mars. But, why?
Short Video on Mars Exploration History
This very question is why an international team of researchers led by the Center of Astrobiology (CAB) in Spain have recently examined how current robotic instruments being used on Mars to search for past life might not be sufficient to get the job done, and that samples returned to Earth from the Red Planet might be a better option in identifying signs of present or past life there.
The research team, which includes co-author Dr. Alberto G. Fairén, who is a visiting scientist in the Department of Astronomy at Cornell University and a research professor at CAB, claim detecting organic materials within Martian rocks using current instruments and methods on Mars could prove to be difficult, if not impossible.
For the study, the researchers used four instruments that are either presently being used on Mars, or will be in the future, to examine sedimentary rocks from the Red Stone Jurassic fossil delta in the Atacama Desert of northwestern Chile, which is an alluvial fan that is approximately 100 to 163 million years old that formed under very dry conditions with little to no rain. Along with the dry conditions, Red Stone also contains large amounts of hematite and mudstones comprised of clays, which makes both characteristics geologically comparable to Mars.
Lead author, Dr. Armando Azua-Bustos, made this in-depth video about both the study and the Red Stone Jurassic fossil delta in the Atacama Desert.
While the team was successful in identifying a biosignature combination of present and past microorganisms, they found these microorganisms were rather difficult to detect despite the team’s state-of-the-art laboratory equipment. The team also identified what they referred to as “dark microbiome”, which are microorganisms whose classification cannot be determined.
These findings indicate that the instruments being sent to Mars, both now and in the future, might not possess the sensitivity to detect biosignatures, which would also depend on a combination of the instrument being used and the organic compound being searched for. More precisely, “the chance of obtaining false negatives in the search for life on Mars highlights the need for more powerful tools,” said Dr. Armando Azua-Bustos, who is a research scientist on Dr. Fairén’s team at CAB, and lead author of the study.
NASA’s Perseverance rover examining “paver stones” in Jezero Crater on Mars in July 2021, which was the rover’s first sampling location. (Credit: JPL-Caltech/NASA)
The researchers noted two options in the study: sending better instruments to Mars or examining samples returned from the Red Planet “to conclusively address whether life ever existed on Mars,” the researchers note in the study. Dr. Fairén says both options are extremely difficult.
“You need to decide whether is more advantageous having limited capability for analysis on the surface of Mars to interrogate a wide variety of samples or having limited samples to be analyzed with the wide variety of state-of-the-art instrumentation on Earth,” said Dr. Fairén.
Analyzing samples on Earth would require a sample return mission from Mars, which is currently being spearheaded by NASA and the European Space Agency, with the samples being slowly collected and dropped around the Martian surface by NASA’s Perseverance rover.
One such future mission that Dr. Fairén mentions is the first European Mars rover, Rosalind Franklin, previously known as the ExoMars rover, which is currently scheduled to launch as soon as 2028, and had one of its instruments used in this study.
Rosalind Franklin “will carry a drill with the unprecedented capability of reaching down to a depth of 2 meters (6 ½ feet) to analyze sediments better protected against the harsh conditions on the Martian surface,” Dr. Fairén said. “If biosignatures are better preserved at depth, which we expect, there will be more abundance and diversity, and better preservation of biosignatures, in those deep samples. Our instruments in the rover will therefore have more chances to detect them.”
Has Mars ever had life, or has it always been a barren and dead world? Will we be able to develop the appropriate instruments to find life there directly, or will we have to find it within samples returned to Earth? Only time will tell, and this is why we science!
We’re lucky to have a neighbour like Venus, even though it’s totally inhospitable, wildly different from the other rocky planets, and difficult to study. Its thick atmosphere obscures its surface, and only powerful radar can penetrate it. Its extreme atmospheric pressure and high temperatures are barriers to landers or rovers.
It’s like having a mysterious exoplanet next door.
We’ve been watching Venus with the naked eye for millennia and with telescopes for centuries. In many ways, it’s still shrouded in mystery. We’re in a similar predicament with exoplanets; only it’s their distance that shrouds them.
Venus’ inhospitable nature means we struggle to explore it. We know way more about other worlds in our Solar System—Mars, for example—because they’re more amenable to observation by orbiters. And in Mars’ case, visitation by multiple landers and rovers has revealed a lot about that planet’s history. So even though we’ve sent orbiters—and ill-fated landers—to Venus, our lack of understanding means that, in some ways, it’s more like an exoplanet than another planet in our Solar System.
In the last 30 years, scientists have found thousands of exoplanets. Every one of them is interesting in its own right, but much of our interest in exoplanets concerns their atmospheres and their potential habitability. This is where Venus and exoplanet science intersect.
Learning more about Venus can teach us about exoplanets, and the reverse is also true, according to the authors of a new research article. The article is “Synergies between Venus & Exoplanetary Observations.” It’s published in Space Science Reviews, and the lead author is Dr. Michael Way. Way is a Physical Scientist at NASA’s Goddard Institute for Space Studies. The study examines how General Circulation Models (GCMs) are used to understand exoplanets and how we can leverage them to unravel Venus’ history.
“Here, we examine how our knowledge of present-day Venus can inform terrestrial exoplanetary science and how exoplanetary science can inform our study of Venus,” the authors explain in their introduction. “In a superficial way, the contrasts in knowledge appear stark.” But are they?
This image shows how different spacecraft and the Very Large Array ground-based telescope have observed Venus. Image Credit: O’Rourke et al, 2023.
Even though Venus is challenging to study, scientists have made progress. Evidence suggests the planet was once habitable. Venus may have been warm and wet in the past before runaway greenhouse heating cooked the planet. The planet may even have harboured surface oceans before it became too hot. If Venus was habitable in the past, what processes led to its extremely inhospitable climate today? What can its transformation tell us about exoplanets?
To try to answer that question, researchers turn to one of their main tools: General Circulation Models (GCMs.) They use them to model how atmospheres and oceans influence the climate on Earth, and they’re also useful in the study of other planets. GCMs are mathematical models of how atmospheres circulate, and researchers use them to understand how insolation and rotation rates affect planetary climates.
This is the first video in a series of three videos that explain GCMs. Credit: The UK Met Office
Can exoplanet climate modelling help explain Venus’ climate?
“It may sound preposterous to propose that terrestrial exoplanets, which are far from being explored in-situ, and which present challenges even to detection of their atmospheres, can in any way inform Venus’ evolutionary history,” the authors write. “Yet exoplanetary science has already provided a means to put ancient Venus 4.2 billion years ago within the habitable zone.”
Scientists know a few things about ancient Venus. It received about 40% more solar radiation 4.2 billion years ago compared to present-day Earth. On the face of it, that would preclude any habitability.
But a paper published in 1971 showed that Venus could’ve had temperate conditions despite higher solar radiation if it had 100% cloud cover. With that much cloud, the albedo would’ve been high enough to reflect much of the Sun’s radiation. The cloud cover could’ve lowered the planet’s surface temperature to less than 27 Celsius (80 F.) At that temperature, Venus would’ve been able to maintain surface water and oceans.
That paper didn’t provide any rationale for 100% cloud cover. But as our knowledge of exoplanets grew, discoveries provided a rationale. Among the more than 5,000 exoplanets we know of, a good portion of them are very close to their stars and are either tidally locked or rotate very slowly. A 2014 study used GCMS to show that slowly rotating planets close to their stars could maintain surface temperatures of 26 Celsius (80 F) even when the planet received 2.5 times more solar insolation than Earth does. But only if the cloud cover was thick and high, just like the 1971 paper proposed.
The exoplanets’ slow rotation allowed this type of cloud cover to form. This ties in with Venus, which takes 243 Earth days to complete one rotation, the slowest rotation in the Solar System.
Other studies on slowly rotating exoplanets close to their stars used different GCMs and showed similar results. These results shaped how we think of Venus. Previous thinking showed that Venus may have had a relatively brief habitable period before becoming inhospitable. But if slowly rotating exoplanets with thick cloud cover maintained long-term habitability even when receiving abundant solar insolation, maybe Venus did, too.
We’re all probably wishing that Venus was habitable for a long period of time. It’s in our nature. Thus far, multiple studies based on five different GCMs have largely confirmed what the 2014 study showed. They’ve all shown that slowly rotating planets can produce the type of thick, high cloud cover that keeps an exoplanet’s surface temperate even when close to their stars. But while heartening, this still isn’t conclusive. Scientists need better observations of exoplanets before they can be certain.
There are lots of exoplanets in what exoplanet scientists call the Venus Zone (VZ.) The Venus Zone is an orbital zone around a star where an Earth-similar planet would suffer a runaway Greenhouse Effect like Venus has. Observations of these planets are critical to understanding Venus because of the underlying questions that apply to both exoplanets in the Venus Zone and Venus itself.
This image shows the Venus Zone and the Habitable Zone. The Venus Zone is where planets could experience the Runaway Greenhouse Effect. Image Credit: Chester Harman/NASA/JPL
How long did magma ocean phases last, and how does that affect atmosphere development and evolution? How does it affect the types of clouds that form? Since the exoplanets we find in Venus Zones have different ages, observations can help answer these questions by building a sort of evolutionary timeline for slowly rotating planets close to their stars. This will strengthen our GCMs and their results for both Venus and exoplanets.
Venus is like an exoplanet in our backyard. The authors of this paper point out that we can gather detailed observations of Venus and, eventually, in-situ observations, which will not only shed light on Venus but on Venus Zone exoplanets, too. At the same time, surveys of Venus Zone exoplanets at different ages and different proximities to different types of stars can also help us understand Venus.
This is in line with what the recent Planetary Science and Astrobiology Decadal Survey said. That survey covers a lot of territory, and it showed the links between Venus and exoplanets and how the study of each can inform the other. The authors of the paper made a table of parts of the Decadal Survey that link Venus and Exoplanet science.
The authors created a table from the Decadal Survey that highlights the links between Venus science and exoplanet science. Image Credit: Way et al. 2023.
There’s no strong consensus on Venus and its ancient oceans and potential habitability. Different studies have arrived at different conclusions. Some showed that Venus may have had oceans for a few hundred million years, some for two billion years, and some showed that there were never any oceans.
If it was once habitable, what happened? What can that tell scientists about exoplanets? “If Venus did evolve from an earlier temperate period with surface water reservoirs to its present hothouse state, exactly how did it occur, and what are the key processes involved?” the authors ask. Scientists have struggled for decades to understand how Venus could have evolved from an early habitable period to such an extremely inhospitable state.
Fortunately, we may gain some clarity soon. NASA and other space agencies are planning missions to Venus in the near future. NASA is planning the VERITAS and DAVINCI+ missions, and the ESA is planning the EnVision mission. All three are orbiters, and DAVINCI+ also includes an atmospheric probe. More ambitious surface missions are in the conceptual stage.
This illustration shows DAVINCI+’s atmospheric probe descending through Venus’ atmosphere. The probe will help scientists understand the connections between Venus’ surface and its atmosphere, which could shed light on the planet’s history and potential ancient habitability. Image Credit: NASA/GSFC – NASA/GSFC, https://ift.tt/4czULji, Public Domain, https://ift.tt/9raAEQi
With three Venus missions coming in the future, some are calling the 2030s the Venus Decade. And when it comes to exoplanets, that field of study is already in full bloom. The JWST, CHEOPS, TESS, and others are pushing the frontier of exoplanet science. TESS uses the transit method of finding exoplanets, and that method is biased toward planets with shorter orbital periods. It discovered a large number of rocky planets in the Venus Zone. While all planets in the VZ won’t have liquid surface water, some might. In any case, TESS’s VZ planets can act as a guide for more follow-up observations with the JWST and other missions.
This figure from the study shows 208 terrestrial Venus Zone planets. Way et al. 2023.
The JWST has already detected the chemical makeup of one exoplanet named WASP 39-b. Though it’s not a terrestrial planet, it does orbit its star very closely.
“We expected JWST to be a powerful tool to study exoplanet atmospheres, and these observations are among the first real evidence that that is true,” said JHUAPL astrophysicist Erin May, who was involved in the JWST WASP 39-b results. “The precision of these measurements is unmatched by previous telescopes, and we’re really just scratching the surface of what we’ll be able to learn about exoplanets going forward.”
A similar sense of optimism surrounds the upcoming missions to Venus. “No previous mission within the Venus atmosphere has measured the chemistry or environments at the detail that DAVINCI’s probe can do,” said DAVINCI principal investigator Jim Garvin. “DAVINCI will build on what Huygens probe did at Titan and improve on what previous in situ Venus missions have done, but with 21st-century capabilities and sensors.”
Venus and Earth started out quite similar. But somehow, Venus followed a different evolutionary pathway than Earth. While it may seem like its proximity to the Sun is the obvious reason why, this study shows how there could be more to it.
“How can a world that was receiving, 4.2 billion years ago, 1.4 times the incident solar radiation that Earth receives today be inside the habitable zone?” the authors ask in their paper. The answer comes from GCMs. ” … an efficient cloud albedo feedback from a slowly rotating Venus may have kept ancient Venus temperate according to GCM modelling assuming sufficient surface liquid water and a short-lived magma ocean phase,” they explain.
Artist’s concept of the VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) spacecraft. VERITAS is scheduled to launch in 2031. Image Credit: NASA/JPL-Caltech
There’s only one path forward to test how accurate our understanding of Venus and VZ exoplanets is. Along with missions to Venus, we need to find more VZ planets and study them. And as this study makes clear, both efforts are linked.
” … observing a statistically relevant sample of VZ worlds in different evolutionary phases could help us bound the parameter space in ways we may only scarcely comprehend today,” the authors write. It’ll also help us understand Venus, our exoplanet next door.
While Earth and Venus are approximately the same size and both lose heat at about the same rate, the internal mechanisms that drive Earth’s geologic processes differ from its neighbor. It is these Venusian geologic processes that a team of researchers led by NASA’s Jet Propulsion Laboratory (JPL) and the California Institute of Technology hope to learn more about as they discuss both the cooling mechanisms of Venus and the potential processes behind it.
The geologic processes that occur on Earth are primarily due to our planet having tectonic plates that are in constant motion from the heat escaping the core of the planet, which then rises through the mantle to the lithosphere, or the rigid outer rocky layer, that surrounds it. Once this heat is lost to space, the uppermost region of the mantle cools, while the ongoing mantle convection moves and shifts the currently known 15 to 20 tectonic plates that make up the lithosphere. These tectonic processes are a big reason why the Earth’s surface is constantly being reshaped. Venus, on the other hand, does not possess tectonic plates, so scientists have been puzzled as to how the planet both loses heat and reshapes its surface.
“For so long we’ve been locked into this idea that Venus’ lithosphere is stagnant and thick, but our view is now evolving,” said Dr. Suzanne Smrekar, who is a senior research scientist at NASA JPL, and lead author of the study.
For the study, the researchers examined radar images from NASA’s Magellan mission taken in the early 1990s depicting quasi-circular geological features on Venus’ surface known as coronae. The reason why the images were taken using radar is because Venus’ atmosphere is so thick that normal images taken in the visual spectrum are unable to penetrate Venus’ thick, cloudy atmosphere.
Composite radar image of Quetzalpetlatl Corona on Venus taken by NASA’s Magellan spacecraft over the course of approximately 70 orbits and sent back to the Arecibo Observatory in Puerto Rico. (Credit: NASA/JPL)Radar image of circular fracture patterns encircling “Aine” corona taken by NASA’s Magellan spacecraft. (Credit: NASA/JPL)
Upon taking measurements of 65 previously unstudied coronae within the Magellan images and calculating the lithosphere’s thickness around them, the researchers found these coronae form and exist where Venus’ lithosphere is the thinnest. Using computer models, they found the lithosphere around each corona is approximately 11 kilometers (7 miles) thick, which turns out to be much thinner than suggested by previous studies. The researchers also suggest the coronae could be geologically active since these areas exhibit a greater average heat flow than Earth.
“While Venus doesn’t have Earth-style tectonics, these regions of thin lithosphere appear to be allowing significant amounts of heat to escape, similar to areas where new tectonic plates form on Earth’s seafloor,” Dr. Smrekar explains.
It is this greater heat flow that might also help scientists better understand the behavior of the lithosphere on ancient Earth, as well.
“What’s interesting is that Venus provides a window into the past to help us better understand how Earth may have looked over 2.5 billion years ago,” said Dr. Smrekar, who is also the principal investigator of NASA’s upcoming Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy (VERITAS) mission, which is currently scheduled to launch no earlier than 2027. “It’s in a state that is predicted to occur before a planet forms tectonic plates.”
Launched from the Space Shuttle Atlantis in May 1989, Magellan arrived at Venus in August 1990, and is considered to be one of the most successful deep space missions ever. Despite this, Magellan’s data consists of low resolution and large margins of error, so VERTIAS will essentially act as Magellan 2.0 by producing three-dimensional global maps of Venus using a state-of-the-art synthetic aperture radar, along with learning more about the surface composition with a near-infrared spectrometer.
Learn more about NASA’s forthcoming VERITAS and DAVINCI missions!
But the exterior of Venus won’t be the only location being studied, as VERITAS will study the planet’s interior by examining its gravitational field. Altogether, VERITAS will paint scientists a greater picture of both ancient and present geologic processes on our twin-sized and mysterious neighbor.
“VERITAS will be an orbiting geologist, able to pinpoint where these active areas are, and better resolve local variations in lithospheric thickness. We’ll even be able to catch the lithosphere in the act of deforming,” explains Dr. Smrekar. “We’ll determine if volcanism really is making the lithosphere ‘squishy’ enough to lose as much heat as Earth, or if Venus has more mysteries in store.”
Another Venus mission of importance will be NASA’s DAVINCI mission, whose objective will be to plunge through the Venusian atmosphere and examine its composition in greater detail than ever before.
What new insights will we learn from Venus and its geologic processes in the coming years and decades? Only time will tell, and this is why we science!
Perseverance has been on Mars for two years. Are black holes the source of dark energy? Universe-breaking galaxies found. And an early warning system for asteroids.
Mars Anniversary
NASA’s Perseverance Rover is about to begin its third year exploring Mars. NASA released this cool two-year animation of images from the rover’s Front Left Hazard Avoidance Camera to celebrate. During the timelapse, you can see various rocks that Perseverance stopped to study with its robotic arm and sensors. The rover initially landed in Jezero Crater on Feb. 18th, 2020, and has now travelled almost 15 km and taken 18 samples of rocks, regolith, and even the Martian atmosphere.
“The Universe Breakers”: Six Galaxies That are Too Big, Too Early
New images from JWST show six galaxies at a time when the Universe was only 3% of its current age, 500-700 million years after the Big Bang. They should be baby galaxies, but they contain 100 times more stellar mass than astronomers were expecting to see soon after the beginning of the Universe. If true, this calls the current thinking of galaxy formation into question or challenges most models of cosmology.
A 500-Meter-Long Asteroid Flew Past Earth and Astronomers Were Watching
An asteroid the size of the Empire State Building flew past Earth on Feb. 3rd, coming within 1.8 million km of our planet. For context, that’s about five times the distance between the Earth and the Moon. Astronomers turned the Goldstone Solar System Radar dish on the space rock, mapping its surface. The asteroid, called 2011 AG5, is one of the most elongated objects ever seen, with a length-to-width ratio of 10:3. It’ll have another close flyby in 2040 when it comes within three times the Earth-Moon distance.
A new paper was released suggesting that there might be a link between dark energy and the growth of supermassive black holes. Researchers speculate that, in fact, black holes can be the source of dark energy. If true (which we yet need to prove) this can be ground-breaking.
To shed more light on the research here’s an in-depth interview with Dr Chris Pearson from STFC RAL Space, who is a co-author of the paper.
New Spacecraft Can See Into the Permanently Shadowed Craters on the Moon
The permanently shadowed craters at the Moon’s south pole are exciting because they contain vast reserves of water ice that future human explorers could use. But studying these craters is difficult because they’re in shadow and have no direct illumination falling inside them. NASA’s new ShadowCam instrument is at the Moon, flying with Korea’s Pathfinder Lunar Orbiter. ShadowCam can see in such low light that it can reveal incredible details in these shadowed craters as if they were lit in sunlight.
ESA is considering their own mission to search for potentially dangerous asteroids. The spacecraft will be called NEOMIR and it will go to the Earth-Sun L1 Lagrange point. This way it will be able to see incoming space rocks that will otherwise be missed because of the Sun blinding the telescopes. NEOMIR will also operate in the infrared, which will make its task even easier.
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The crew of the International Space Station can now breathe a little easier. An uncrewed replacement Soyuz docked safely to the station, meaning NASA astronaut Frank Rubio and Roscosmos cosmonauts Sergey Prokopyev and Dmitri Petelin can make it back home to Earth.
The new Soyuz MS-23 will replace MS-22, which suffered a serious radiator coolant leak on December 14, 2022. After much deliberation, Russian controllers decided that it would be safer to send a replacement Soyuz to the ISS rather than risk the crew returning in a spacecraft without coolant.
The Soyuz MS-23, the new ride home for NASA astronaut Frank Rubio and Roscosmos cosmonauts Sergey Prokopyev and Dmitri Petelin, docked to the space station at 7:58pm ET as the station flew 260 miles above northern Mongolia. Read more.. https://t.co/kKxGu1ILGzpic.twitter.com/OwRwUBMDsh
The damaged Soyuz is expected to undock from the station in late March and will attempt an uncrewed landing so Roscosmos can analyze how well an uncooled spacecraft can handle re-entry.
The passengerless Soyuz docked at the station’s Poisk module at 7:58 p.m. EST on February 25, after launching on February 23 from the Baikonur Cosmodrome in Kazakhstan. Roscosmos officials said they had determined that the leak resulted from a small hole caused by an impact by a micrometeoroid. The plans to launch a replacement Soyuz were called into question when a Russian Progress cargo ship experienced a similar coolant leak on February 11, but all has gone well so far with the new Soyuz.
Screenshot from NASA TV showing coolant spewing into space from the Soyuz spacecraft docked to the ISS.
“The Russians are continuing to take a very close look at both the Soyuz and the Progress coolant leaks,” Dana Weigel, NASA’s the space station’s deputy manager said during a briefing last week. Weigel added that a commission was formed to assess the anomalies, analyzing potential causes from the time the capsules launched through their stay on orbit.
The new Soyuz arrived just a day and a half before NASA and SpaceX plan to launch the Crew-6 mission to the station. Launch for that mission is slated for early Monday morning, February 27. Crew-6 includes NASA astronauts Stephen Bowen and Warren “Woody” Hoburg as well as Sultan Alneyadi, an astronaut with the United Arab Emirates, and Roscosmos cosmonaut Andrey Fedyaev.
The Crew-5 astronauts currently on board the ISS will return home from their five-month stay on board the SpaceX Crew Dragon capsule. Weigel said that the coolant leaks experienced on the Soyuz and Progress vehicles would not have any impact on the SpaceX missions and that no similar issues were discovered on Crew Dragon vehicles.
However, the leak has affected other crew member rotations. Originally, cosmonauts Oleg Kononenko and Nikolai Chub and NASA astronaut Loral O’Hara were expected to launch to the space station on March 16 aboard MS-23. Instead, Prokopyev, Petelin and Rubio will serve extended time on the space station, perhaps until September. If that timeline holds, the three crewmates will be on orbit for approximately a year instead of the planned six months.
Roscosmos has not yet provided a new timeline for when Kononenko, Chub and O’Hara might launch to the ISS.
The universe is filled with magnetic fields. Although the universe is electrically neutral, atoms can be ionized into positively charged nuclei and negatively charged electrons. When those charges are accelerated, they create magnetic fields. One of the most common sources of magnetic fields on large scales comes from the collisions between and within interstellar plasma. This is one of the major sources of magnetic fields for galactic-scale magnetic fields.
But magnetic fields should also exist on even larger scales. At the largest scale of the cosmos, the matter is distributed in a structure known as the cosmic web. Large superclusters of galaxies are separated by barren voids, like clusters of soapy water among a vast region of soap bubbles. Thin filaments of intergalactic material stretch between these superclusters, creating a cosmic web of matter. Much of this web is ionized, so it should create vast but faint intergalactic magnetic fields. At least that’s the theory. Astronomers haven’t been able to observe these web magnetic fields. But a new study has made the first detections of them.
We can’t directly detect magnetic fields that are billions of light-years away. Instead, we observe them through their effects on charged particles. When electrons and other particles spiral along magnetic field lines, they emit radio light. By mapping this radio signal astronomers can map galactic magnetic fields. But cosmic web filaments are so diffuse that the radio light they emit is very faint. Too faint to be easily detected. And since nearby galaxies create even stronger radio signals, the web signal can be drowned out by galactic radio noise.
Three different observations of the cosmic web (gas, radio, and magnetic) accompanied by a composite image. Credit: K. Brown
To overcome this challenge, the team focused on polarized radio light. These are radio emissions that have a specific orientation. Since the orientation is related to the overall orientation of a filament, the team could more easily pull this signal out of the cosmic radio background. They used data from all-sky radio maps such as the Global Magneto-Ionic Medium Survey, the Planck Legacy Archive, the Owens Valley Long Wavelength Array, and the Murchison Widefield Array. By stacking this data and comparing it to maps of the comic web, the team confirmed the polarized radio signal emitted by the web.
This result is not just the first detection of cosmic web magnetic fields, it is also strong evidence to support the existence of collision shockwaves within intergalactic filaments. These shockwaves have been seen in computer simulations of cosmic structures, but this is the first evidence to support the idea that these simulation features are accurate.
