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Wastewater, which is full of pollutants that contain nitrogen, can be directly fed into a new chemical reactor that converts it into ammonia, with purified water and oxygen as by-products

Nanotubes can serve as biosensors. They change their fluorescence when they bind to certain molecules. Until now, it was unclear why. Researchers have gained new insights into the cause of the fluorescence.

We may be already seeing the makings of next solar cycle, peeking out through the current one.

It’s been a wild ride. Thus far, Solar Cycle Number 25 has been one of the strongest cycles in recent memory, producing several massive sunspot groups. The current large region turned Earthward (Active Region 3780) is now easily visible with eclipse glasses… no magnification needed. Cycle 25 started back in 2019.

Massive sunspot rotates into view. Credit: NASA/SDO A Stormy Year

To be sure, the latest solar cycle will be one for the history books, as it heads towards an active maximum in 2025. But even though Cycle 25 will run out through the remainder of the current decade, there are already signs that Cycle 26 could be beginning, just under the roiling solar surface. A study out of the University of Birmingham recently presented at the Royal Astronomical Society’s National Astronomical Meeting in Hull (United Kingdom) shows that key indicators for the start of the next cycle may already be in place.

Numbering the solar cycle under current the convention goes all the way back to the start of Cycle 1 in 1755. The pattern for numbering cycles was started in 1852 by astronomer Rudolf Wolf.

We know that a new solar cycle has formally started when sunspots appear at higher solar latitudes. These also typically have a reversed polarity, versus the previous cycle. These then push down near the solar equator as the cycle progresses. Spot from two cycles can also mix as the transition gets underway.

A large sunspot group from May 2024. Credit: NASA/SDO

Laying out spots from successive cycles versus latitude creates a butterfly diagram that demonstrates this effect, in what’s known as Spörer’s Law.

A butterfly graph (top) showing sunspots versus latitude over time. Credit: NASA/MSFC Peering Inside the Sun

But there’s more to the Sun than meets the eye. As a large ball of hydrogen and helium gas, the Sun does not rotate as a single solid mass. Instead, it rotates faster at the equator (25 days) versus near the poles (34 days). Scientists can probe the solar interior via a method known as solar helioseismology, which looks at waves crossing the solar photosphere in an effort to model the interior.

These internal sound waves form bands in a phenomenon known as solar torsional oscillation. Faster-rotation belts appear as a harbinger of the next cycle. These move along with visible sunspots towards the solar equator as the cycle progresses.

“The indication of Cycle 26 that we see is that the solar rotation has been speeding up at around 50 degrees latitude and now appears to be leveling off,” Rachel Howe (University of Birmingham) told Universe Today. “This forms part of a pattern called the torsional oscillation, where bands of slightly faster and slower rotation emerge at mid-latitudes before the cycle officially starts and move down to lower latitudes, alongside the sunspot activity, as the cycle develops. In earlier cycles we have seen that the faster-rotating band associated with the cycle can be traced back to around the maximum of the previous cycle, and we think we’re seeing the beginning of the pattern again. It will still be several years before we can expect to see sunspots belonging to the new cycle, though!”

A solar cycle map, showing speed and torsional oscillations over time versus latitude for the last three solar cycles… and the start of Solar Cycle 26 (upper right). Credit: Rachel Howe. Monitoring the Sun Around the Clock

The Global Oscillation Network Group (GONG) makes the science of helioseismology possible. This is a worldwide network that monitors the Sun continuously. In space, the Helioseismic Magnetic Imager aboard the joint ESA/NASA Solar and Heliospheric Observatory (SOHO) compliments this effort. The Michelson Doppler Imager (MDI) on NASA’s Solar Dynamics Observatory (SDO) also plays a key role in this campaign. This effort goes back to 1995, spanning the last three solar cycles.

Big Bear Lake and Solar Observatory, part of the GONG network monitoring the Sun.

This gives researchers a look at the start of the last two solar cycles. It also hints at what might be in store for the start of Solar Cycle 26. “If we can understand how this flow pattern relates to the sunspot cycle, we may be able to do better at predicting how strong the next solar maximum will be and when it will occur,” says Howe.

Sunspots from July 31st, 2024. Credit: Eliot Herman.

Solar Cycle 25 has thus far been extremely active, far beyond expectations. This follows the historic lull that preceded it between Cycles 24 and 25. Observers saw few sunspots during this profound minimum. Still, this fell in line with many predictions made by astronomers who study the Sun, suggesting a stronger than usual cycle on rebound.

Looking Ahead to Cycle 26

“The Sun is always surprising,” says Howe. “Some of the most exciting discoveries recently have come from the spacecraft—Solar Orbiter and Parker Solar Probe—that are flying closer to the Sun than ever before, helping scientists to unravel the connections between what we see on the Sun’s surface and the ‘space weather’ events that affect us on Earth. We’re looking at the surface of the Sun in more detail than ever before, but there’s also a place for long-term studies (which this work is a part of) that follow the large-scale patterns inside the Sun over decades.”

A magnetic view of the Sun, courtesy of SDO. Credit: NASA/SDO

The May 10th solar storm was thus far the most impressive one of the cycle. This storm sent aurora to latitudes far south as Spain and Mexico, areas where aurorae are rarely seen. We were treated to a persistent red glow watching from central Germany, an unforgettable sight.

Solar Cycles and More

Historically, the Wolf Sunspot Number defines the level of solar activity. Astronomers refer to this as the Relative or Zürich Sunspot Number. One 2013 study suggested that the orientation and strength of the heliospheric current sheet is a better indicator of the health of the current solar cycle, rather than the sunspot number.

We usually say it’s an 11-year solar cycle from one minima/maxima to the next… but it’s actually double that length. The Sun’s magnetic field flips every 11-years, returning to the same relative orientation every 22 years.

We see ‘starspot cycles’ on other suns as well. It is also unclear why an 11-year cycle is ‘baked in’ to our Sun. We’re also unsure if this has always been the case throughout its 4.6-billion year life span.

This research provides a great model to test the next solar cycle, as we struggle to understand and live with our tempestuous star.

The post The Next Solar Cycle Has Started… But the Current One Hasn’t Finished Yet appeared first on Universe Today.

A previously unknown mechanism of active matter self-organization essential for bacterial cell division follows the motto 'dying to align': Misaligned filaments 'die' spontaneously to form a ring structure at the center of the dividing cell. The work could find applications in developing synthetic self-healing materials.

Researchers have introduced a new advancement in the fight against climate change. Their study showcases a novel method for understanding the mechanisms of carbon dioxide re-utilization leading to fuels and chemicals. This work paves the road for the further optimization of this catalytic process driven by renewable electricity.

MRI scans could replace invasive heart tests, as new research shows they can reliably estimate pressures inside the heart to predict if a patient will develop heart failure.

Radiation is a powerful tool for treating cancer, but prolonged exposure can damage the skin. Radiation-induced skin injuries are painful and increase a person's chances of infection and long-term inflammation. Now, researchers report an aspirin-containing hydrogel that mimics the nutrient-rich fluid between cells and accelerates healing of skin damaged by radiation in animals. With further development, the new salve could provide effective and rapid wound healing for humans.

In a new study, researchers created a sort of simulated voting booth -- a space where people, or mathematical 'agents,' with various biases could deliberate over decisions. The results may help to reveal the mathematics of how the human brain acts when it needs to make a choice.

A research team has developed full-color fiber light-emitting diodes utilizing perovskite quantum wires (PeQWs), paving the way for innovative wearable lighting and display devices.

A research team has developed full-color fiber light-emitting diodes utilizing perovskite quantum wires (PeQWs), paving the way for innovative wearable lighting and display devices.

Researchers have published a programmable framework that overcomes a key computational bottleneck of optics-based artificial intelligence systems. In a series of image classification experiments, they used scattered light from a low-power laser to perform accurate, scalable computations using a fraction of the energy of electronics.

Researchers have published a programmable framework that overcomes a key computational bottleneck of optics-based artificial intelligence systems. In a series of image classification experiments, they used scattered light from a low-power laser to perform accurate, scalable computations using a fraction of the energy of electronics.

All living creatures use only the left or right-handed forms of certain molecules, and now we might understand why

Evidence suggests that cynicism is bad for your health. Neuroscientist Jamil Zaki describes the three ways to conquer your inner cynic to boost your well-being

Scientists discovered the Andromeda galaxy, known as M31, hundreds of years ago, and around a century ago, we realized that it had negative radial velocity toward the Milky Way. In other words, eventually, the two galaxies would merge spectacularly. That has been common knowledge for astronomers since then, but is it really true? A new paper from researchers at the University of Helsinki looks at several confounding factors, including the gravitational influence of other galaxies in our local group, and finds only a 50% chance that the Milky Way will merge with the Andromeda galaxy in the next 10 billion years. 

That seems like a pretty big thing to get the physics wrong on. So, how did the authors come to that conclusion? They accounted for a problem that has been popularized in media as of late – the three-body – or in this case, four-body – problem. And with that problem comes a lot of uncertainty, which is why there’s still a 50% chance that this huge event might still happen. 

Thinking of Andromeda and the Milky Way in isolation doesn’t account for the other galaxies in what we know as the “Local Group.” This comprises approximately 100 smaller galaxies at various orientations, distances, and speeds. The largest of the remaining galaxies is the Triangulum galaxy, M33, which is about 2.7 million light-years away and consists of upwards of a mere 40 billion stars. That’s about 40% of the approximately 100 billion stars in the Milky Way but a mere 4% of the nearly 1 trillion stars estimated to exist in Andromeda. Still, they would have their own gravitational pull, contorting the simplistic dynamic between Andromeda and the Milky Way.

Fraser explains some of the orbital mechanics around Andromeda’s motion.

Further confounding that dynamic is the Large Magellanic Cloud, which is either the second or third closest galaxy to our own at a distance of only 163,000 light years. This is slightly larger than the Milky Way’s diameter, at 105,700. It also houses around 20 billion stars, so while it’s even less massive than M33, it still exerts a hefty gravitational pull.

The authors accounted for the gravitational pull of both of those other galaxies in their calculations of the paths of the Milky Way and Andromeda over the next few billion years. They found that the complicated dance of astronomical giants could potentially result in a scenario where the two galaxies don’t merge. However, there was another significant factor in their calculations: uncertainty.

Scientists never like uncertainty. In fact, much of their research tries to place bounds on certain parameters, like the rotational speed of galaxies or the distances between them. Unfortunately, despite their proximity, there are many uncertainties surrounding the four galaxies used in the study, and those uncertainties make precise calculations of the effects of their gravitational and rotational pull difficult.

Fraser discusses what stars, if any, we can see in Andromeda.

Developing estimates rather than concrete numbers is one-way scientists often deal with uncertainty, and in this case, that estimate fell right at the 50% mark in terms of whether or not the two galaxies would collide. However, there is still a lot of uncertainty in that estimate, and plenty more confounding factors, including the other galaxies in the local group, will influence the final outcome. Ultimately, time will help solve the mystery, but that is a very long time on the scale of galaxy mergers. If it happens at all, a merger between the Milky Way and Andromeda will happen long after our own Sun has burnt out, and humans will either die out with it or find a way to expand to new stars. And if, at that point, we get easy access to an additional galaxy’s worth of resources, it would be all the better for us.

Learn More:
Sawala et al. – Apocalypse When? No Certainty of a Milky Way — Andromeda Collision
UT – Are Andromeda and the Milky Way Already Exchanging Stars?
UT – What a Mess. When the Milky Way and Andromeda Merge, it’ll Look Like This
UT – We Might Be Able to Measure Dark Energy Through the Milky Way’s Collision With Andromeda

Lead Image:
This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth’s night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull.
Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger

The post Are Andromeda and the Milky Way Doomed to Collide? Maybe Not appeared first on Universe Today.

Today was a special day in Capetown: the day I got to visit the site of Boulders on the coast, one of the few breeding sites of a rare species of penguin that I hadn’t seen before: the African Penguin (Spheniscus demersus), also known as the Cape Penguin.

But before that, let’s not forget a few of the local endemic flowers. First, pincushion (Leucospermum sp.)

An aloe (Aloe), another from the garden here.

A Cape Honeysuckle (Tecomaria capensis).

The lovely house where I’m staying is the one to the left with the shiny roof. It looks out over the Indian Ocean, shortly before it joins the south Atlantic to the west, and yesterday we saw a southern right whale (Eubalaena australis) swimming around right below.

Not far away is the fishing village of Kalk Bay, where ships pull in with a piscine haul, seals bask in the sun, and chippies surround the harbor to feed the catch to hungry visitors.

Here is a warning:

I was duly warned, but couldn’t avoid getting about seven feet away from this sleeping beauty, the African subspecies of the Brown Fur Seal (also called the Cape Fur Seal), Arctocephalus pusillus pusillus. As you see from the figure below, there’s also a subspecies that lives and breeds on the tip of SE Australia.

It’s the world’s largest fur seal. This one was sleeping peacefully on the dock:

A close-up of its adorable face. Don’t you just want to kiss it? But don’t–they bite!

The distribution of the two subspecies of this species. See caption for details and credit.

From Wikipedia: “Distribution of the brown fur seal, dark blue: breeding colonies; light blue: nonbreeding individuals.” Figure by Mirko Thiessen, CC BY-SA 3.0, via Wikimedia Commons.

And then. . . on to the penguins!

About the African Penguin. More facts from Wikipedia:

The African penguin is a pursuit diver and feeds primarily on fish and squid. Once extremely numerous, the African penguin is declining rapidly due to a combination of several threats and is classified as endangered. It is a charismatic species and is popular with tourists. Other vernacular names of the species include black-footed penguin and jackass penguin, due to the species’ loud, donkey-like noise (although several related species of South American penguins produce the same sound). They can be found along the coast of South Africa and Namibia.

They have built artificial burrows for the penguins to live and breed in; they look like amphoras cut in half and placed on their side. The explanation for creating these is below:

. . . and, a lovely African penguin. I love its pink eye ring:

A closeup of the face:

A beach full o’ penguins. But Rita, who has been coming here for 20 years or so, says that there used to be four times as many penguins on this beach. A combination of factors, not least among them competition for fish with local fishermen who range widely, has drastically reduced the population size. These wonderful birds are now classified as endangered.

First-year penguins molt their down before they develop their adult feathers (remember this from Antarctica?).  Here are three babies (fed fish by their mom), losing their down.

This chick looks surprised.

And this one looks obstreperious:

A panorama of the beach (click to enlarge):

This penguin carried a stick all the way from the woods above (where the nests are) down into the water. Why? Who knows? Could it be a display?

These penguins have already been fishing and are exiting the water. They swim around a bit in the bay before they come ashore.

These are the artificial penguin nests; they’re in thick shrubbery up above the beach.

Me and my penguin (photo by Rita):

And with more penguins (also by Rita):

There was a shop full of penguin paraphrenalia, but I already have too many penguin-related items and forced myself not to buy anything. But I did admire this penguin made out of discarded plastic utensils and cup lids.

Don’t mess with the penguins!

These next two signs suggest to me (I’m a worrier) that some hapless motorist squashed a penguin at least once in the past.

Check your car! (Photo by Rita.)

In the vegetation near the penguins I saw a rock hyrax (Procavia capensis), locally called the “dassie”.  They are herbivores and are found widely throughout Africa.  Surprisingly, despite its small size it is the land mammal most closely related to the elephant, though whether manatees and dugongs are more closely related to elephants is undecided.

A female chacma baboon (Papio ursinus), hanging around the garbage bins in town. Don’t mess with these primates!

A quick trip to the grocery store, which happens to be Woolworth’s, said to have the best produce in this area.  Ground ostrich meat and extra lean venison (which is a synonym here for antelope) were both purchased for the next two dinners.

Ingredients: “Gemsbock and/or Wildebeest and/or Kudu and/or Hartebeest and/or Eland and/or Impala and/or Springbok and/or Blezbok”—all antelopes. You never know what you bought!

And I took the gang out for fish and chips at Kalky’s in the harbor, a downmarket local favorite. The entrance:

The menu. Remember that one rand is about 6¢ US, so my hake and chips meal, which was quite good, cost about six bucks:

The line, which got quite long, and in front of that the dining room. You pay (cash only) and pick up your order when it’s called.

You would never have gotten a crowd this mixed in the bad old days of apartheid, when people were strictly segregated into four classes: black, white, Indian, and colored (mixtures of black and white). Curiously, Chinese were lumped with the most oppressed class, blacks, while Japanese counted as white.

Hake ‘n’ chips: very good!

Red-winged starling (Onychognathus morio), a species found in East Africa from Ethiopia to South Africa. The underside of its wings are red, but you can’t see that in this photo.

Today: a visit to the Cape Peninsula.

Meanwhile, in Dobrzyn, Hili is on the look-out for her arch-enemies:

A: Where are you going?
Hili: To check whether the hazelnuts are ripe.
A: Why?
Hili: Because when they are squirrels are sometimes coming.

Ja: Gdzie idziesz?
Hili: Sprawdzić, czy orzechy laskowe już dojrzały.
Ja:Czemu?
Hili: Bo wtedy czasem przychodzą do nas wiewiórki.

The cultural effects of the COVID pandemic can still be felt reverberating through society. One of the positive effects, in my opinion, was the sudden boost to remote technology – connecting remotely for meetings and other uses through Zoom or a similar application. This development has been a little controversial, but I think on the whole has been a net positive, especially as we move into the era of voluntary remote connections and hybrid meetings.

Prior to the pandemic having a hybrid or remote meeting was still the exception rather than the rule. We were slowly progressing in this direction, but it was still uncommon and looked upon with suspicion. For example, my wife obtained her PhD through a hybrid online program (partly online, partly in person). This worked well and was very convenient, considering we live in CT and the program is based in Oregon. But she definitely faced some professional headwinds in terms of acceptance of the concept of online learning. At K-12 schools remote learning was essentially not a thing.

While virtual meetings were already a thing, they too were not routine. For me personally, for example, all of my meetings, lectures, rounds, and workshops were in person. There wasn’t even an option to attend remotely. This is despite the fact that we have the technology. Grand rounds, for example, was streamed to an outside location where some of our physicians work so that they could attend.

Clinically there was a lot of discussion about virtual office visits, and again we saw the beginnings of this technology and very tentative explorations. Mostly this was used to provide expert-level consultations to remote areas or local hospitals lacking such experts. For routine use, however, it was non-existent, and there were many bureaucratic obstacles, such as state licensing rules and insurance reimbursement.

Then, of course, COVID hit and the world was forced to do as much as possible remotely. This partly worked and partly failed, based at least partly on infrastructure and execution. Looking back now it seems the K-12 remote learning experience was a bad one. Keep in mind, this was still a complex situation. Many teachers had to say out of work because they tested positive for COVID, so school was going to be negatively impacted no matter what we did. And we don’t know what would have happened if all schools remained open in terms of the pandemic itself. But we definitely did underestimate the negative impact of forced online schooling. But a lot of this was due to the fact that many schools and homes were simply not prepared, and you can’t simply run a class online. The experience has to be designed and optimized for being online.

Now that we are post pandemic, we appear to be settling into the best of both worlds – a hybrid situation where voluntary use of remote presence when appropriate. My hope is, this will continue and we will gain more experience and comfort with remote meetings to gain the advantages while minimizing the disadvantages.

For learning some types of content are actually better online. I attend many lectures remotely, and they are great. You have the slides right on your computer, with a inset picture of the lecturer. You can type questions, or ask them live. I have also given such lectures online, and this too can work very well. However, there are types of classes that don’t work online, those that function more like workshops. If you need a lot of interaction with the audience, Zoom can be a problem. It’s hard to know if someone is paying attention, and it can be challenging to direct questions to individual attendees. Physical presence does have it’s advantages.

For small meetings virtual setups, I think, are optimal. Everyone can see and hear everyone and it’s easy to share desktops and content. Clinically, telehealth is also idea for some types of encounters, but not for others. If all I need to do is talk to my patient, give them orders or prescriptions, and document everything in the chart, telehealth is ideal. If I need to examine them, then they need to come in.

This is why the hybrid situation we are evolving towards is ideal. Even for individual meetings, some people can be present while others attend remotely. I think one thing we learned is that having the option for remote attendance is great to have and is an important way to level the field for everyone. Some patients, for example, have a really hard time physically getting into the office for a visit – they need to arrange transportation, take time off from work or home responsibilities, and navigate with sometimes severe physical limitations. Contrast this to sitting on your couch, or going into a break room at work, and just connecting on your phone for 10 minutes. The convenience and efficiency gain is massive, and leads to better medical care. These same patients have a high risk of no-showing to appointments because they could just not make it in.

For business meetings, conferences, and learning experiences, having the option to attend remotely helps individuals who have child care responsibilities, who would otherwise be at a disadvantage in terms of professional progress.

Not to mention, there is a large environmental benefit to hybrid conferences. If the longest-distance speakers or attendees can attend remotely, that reduces long-distance travel.

What all this means is that we now have an opportunity to move forward from COVID rather than go back. I hope that those parts of the experience that were negative will not dissuade people from continuing to support remote meetings. It should now become routine and normalized to allow for hybrid and remote access to all types of conferences and meetings. Content should be designed to work remotely, as well as in person. The advantages are just too great to ignore and let slip away. This begins with realizing that we are not talking about the forced experience of the pandemic, but a hybrid voluntary experience that is optimized for everyone.

The post Living a Hybrid Life first appeared on NeuroLogica Blog.

We recently reported on how the mountains of data produced by astronomical instruments are “perfect for AI.” We’ve also started reporting on several use cases for different AI algorithms. Now, a team of researchers from the University of Texas has developed a new use case that focuses on discovering the interior makeup of exoplanets by looking at a specific type of star.

That particular kind of star is known as a “polluted” white dwarf. White dwarves are the end stage of stars that are too small to go supernova. After going through a red giant phase, our sun will turn into one in a few billion years. Typically, they only have hydrogen and helium in their upper atmosphere, making them mundane by the standards of stars – unless they happen to be tearing apart one of their planets.

Every once in a while, a white dwarf draws in one of the planets in its solar system, ripping the planet apart in the process. The planet’s interior materials are then absorbed into the star’s outer shell, making them “polluted” with the heavy metals that typically comprise a planet’s interior. 

Another researcher from Boston University details how “polluting” a white dwarf can be translated into an understanding of planetary makeup.
Credit – Kavli Institute for Theoretical Physics

Analyzing those heavy metals in a star’s atmosphere would allow astronomers to understand the makeup of the former exoplanet. As such, finding polluted white dwarves to analyze has been a focal point of exoplanet hunters for some time. However, saying the process is time-intensive is an understatement. Astronomers have to manually check astronomical surveys to find evidence of heavy metals in white dwarves’ atmospheres, and some of those surveys, needless to say, are big.

However, searching for needles in a haystack sounds like the perfect use case for AI. So, researchers at the University of Texas did just that. They developed an algorithm using an AI technique called manifold learning and let the algorithm loose on data from Gaia, ESA’s astrometry mission. They filtered data from around 100,000 white dwarves, which resulted in 375 potentially polluted candidates.

Follow-up observations on those 375 candidates by the Hobby-Eberly Telescope and the McDonald Observatory, both of which are at least partially controlled by UT, showed that the algorithm was 99% correct in detecting the existence of heavy metals in a star’s atmosphere, thereby classifying it as “polluted.” Given the sheer volume of white dwarves in our galaxy, tens of thousands more candidates can likely be found by allowing the algorithm to trawl through other data collected on them.

Fraser discusses the possibilities of habitable planets around white dwarves.

What that means for astronomers is the ability to understand the interior makeup of exoplanets as their host star is ripping them apart. Understanding their interior makeup would allow astronomers to develop models about their chances for harboring life. So, this paper is a step towards developing that astrobiological model and an excellent use case for AI in astronomy. It just so happens to be built on the back of dying planets that might be taking their own form of nascent biospheres with them.

Learn More:
UT Austin – Astronomers Use AI To Find Elusive Stars ‘Gobbling Up’ Planets
Kao et al. – Hunting for Polluted White Dwarfs and Other Treasures with Gaia XP Spectra and Unsupervised Machine Learning
UT – What Can AI Learn About the Universe?
UT – Astronomy Generates Mountains of Data. That’s Perfect for AI

Lead Image:
Artist’s depiction of a star ripping apart a planet.
Credit – NASA, ESSA, Joseph Olmsted (STScI)

The post Astronomers Use Artificial Intelligence To Find Elusive Stars “Gobbling Up” Planets appeared first on Universe Today.

The construction of the Vera C. Rubin observatory has just crossed a major milestone with the successful installation of its 3.5 meter diameter secondary mirror. The observatory is now one step closer to first light in 2025, when it will begin the Legacy Survey of Space and Time (LSST): a mission to repeatedly image the entire sky, at high resolution, to create a time-lapse record of the Universe.

The construction of the Vera C. Rubin Observatory (https://rubinobservatory.org/) in Chile has crossed a major milestone with the successful installation of the secondary mirror assembly. The 3.5 meter convex mirror is the first permanent optical component to be integrated into the Simonyi Survey Telescope. Construction is expected to be completed by 2025, when it will achieve first light. In its completed state, it will effectively be the largest digital camera in the world, built to perform the Legacy Survey of Space and Time (LSST), a project to create a ten-year time-lapse view of the entire southern sky.

The mirror is made from Corning® ULE® Glass (Ultra-Low Expansion Glass), and was manufactured by Corning Advanced Optics in Canton, New York. After delivery in 2009, it was stored at Harvard University for five years. After this, L3Harris Technologies, in Rochester, New York, got to work finishing and polishing the mirror. They developed new techniques to work the mirror, as it is very technically challenging to work such a large convex mirror to the necessary precise tolerance. They also designed and built the mirror’s cell assembly, which has adaptive optics capabilities. The cell is built on a stiff steel mounting plate and features 72 axial actuators and six tangent actuators. These allow the supporting structure to constantly adjust as the telescope moves, compensating for the distorting effect of its own weight to keep the mirror at exactly the correct shape at all times.

In 2018, the mirror and cell assembly were shipped to the observatory site in Chile. On arrival, it was given its silver coating. Telescope mirrors are usually coated with aluminum, which is hardier and less prone to tarnishing, and so doesn’t need to be renewed as often. But the Simonyi Survey Telescope in the Vera C. Rubin observatory uses silver (for its superior reflectivity) together with a protective coating to seal it away from atmospheric oxygen and extend the life of the coating. After silvering, it was then sealed back into its container to be stored until construction had reached the point where the telescope would be ready for it. Finally, in July 2024, the complete assembly was installed into the telescope, and integrated with its control electronics.

“Working with the mirror again after five years is extremely exciting because it really feels like we’re in the home stretch,” said Sandrine Thomas, Deputy Director for Rubin Observatory Construction, “Now we have glass on the telescope, which brings us a thrilling step closer to revolutionary science with Rubin.”

The mirrors in observatory telescopes need to be removable, so that they can be cleaned and occasionally resurfaced. But these large mirrors are very heavy, and it would be a disaster if so much glass were to be dropped. That’s why installation and removal is done very carefully, with specialized machinery, following a documented process. To install the secondary mirror assembly, engineers in the summit team loaded it onto a custom-built cart, which rotated the mirror to a vertical position. It was then hoisted up into position on the telescope structure, and carefully bolted into place. Once it was securely attached, the electronics were connected, and the software control system was activated.

“Our 55-year legacy of designing and constructing high-end optical systems for space and ground continues with the world’s largest active secondary mirror system built for Rubin Observatory,” said Charles Clarkson, Vice President and General Manager, Imaging Systems, Space and Airborne Systems at L3Harris. “With this milestone, we are closer to pushing scientific frontiers and charting the Universe like never before, and we look forward to the science that will be discovered.”

The next component to be installed will be the Commissioning Camera (ComCam). This is a temporary camera, meant to be used for testing and integration. At “only” 144 megapixels, it’s only a fraction of the size of the LSST camera. This is not the first time that ComCam has been installed – it is used at various stages of construction to test the various components, ensure that they are properly installed, and that they work together as expected. After ComCam has done its job, the team will get to work on integrating the 8.4 meter primary mirror assembly, followed by the LSST camera.

The Vera C Rubin Observatory was named after the astronomer who first provided convincing evidence of Dark Matter. She and a colleague studied over 60 galaxies to measure how fast they were rotating. In 1978, they found that these galaxies were all spinning too fast: Given the amount of visible matter, they should have not had enough gravity to stop themselves from flying apart. There had to be extra invisible mass, and this work was the first convincing proof of the Dark Matter theory.

The telescope itself is a survey instrument: It is designed to take deep, wide-field images of the sky, very rapidly. The design of the telescope allows it to move very quickly, switching from target to target in short order. With an 8.4 meter primary mirror, it is very sensitive, and can see very faint, distant objects. But it also has a very fast focal ratio of f/1.234, giving it a very wide field of view and allowing it to take much faster exposures.

When the LSST camera is installed, it will capture images covering an area of 9.6 square degrees. Each image will be made from two 15 second exposures, at a resolution of 3.2 gigapixels. At this rate, it will be able to image the entire sky every ten days, and it will repeat this process for ten years. The resulting data will be a ten year time-lapse video of the entire universe, monitoring 20 billion galaxies, 17 billion individually resolved stars, and the orbits of around 6 million objects within our Solar System!

For more information, read the original press release at https://noirlab.edu/public/news/noirlab2419/

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