The first targets will be the sun and Jupiter, which are expected to have strong emissions at low frequencies. But the team also hopes to pick up much weaker signals from the ‘Cosmic Dawn’—when the first stars lit up around 12 billion years ago—and even ultra-faint signals from the preceding Cosmic Dark Ages. Detections would give unprecedented insights into these formative periods of the universe.
Space is open for business, and some entrepreneurs plan to make the final frontier into a manufacturing hub. There’s plenty of real estate. But it takes a few thousand dollars to launch a kilogram of stuff into space.
“The key question is: What is it that justifies the expense of doing these things in low Earth orbit?” says William Wagner, director of the University of Pittsburgh’s McGowan Institute for Regenerative Medicine, which will conduct biomedical research on the International Space Station (ISS).
Here are some technologies that might merit the “made in space” label.
Made from fluoride glass, a kind of fiber-optic cable called ZBLAN could have as little as one-tenth the signal loss of silica-based optical fibers.
But quality ZBLAN fibers are hard to make on Earth. As the molten glass is stretched into fibers as thin as fishing line and then cooled, tiny crystals sometimes form, which can weaken signals. Microgravity suppresses the formation of these crystals, so fibers made in space would carry more data over longer distances.
More data plus the need for fewer repeaters under the ocean would justify a higher price, says Austin Jordan of Made in Space, which plans to produce such fibers in space for terrestrial clients. “The math works. It would pay for itself and drive a profit,” he says.
There are 120,000 people waiting for an organ transplant in the United States alone. “Most will never see one, there is such a shortage,” says Eugene Boland, chief scientist at Techshot, which wants to print human hearts in space.
The heart, with its four empty chambers and highly organized muscle tissue made of different types of cells, is virtually impossible to print on the ground. On Earth, tissues printed with runny bioinks made of gel and human stem cells collapse under their own weight. Scientists must add toxic chemicals or a scaffold.
Printing hearts and other organs in microgravity could be done using pure bioinks. “The cylindrical shape extruded from the nozzle is maintained, so you can build a more fragile 3D structure that would allow cells in the gels to secrete their own matrix and strengthen up,” says Wagner. And the printed layers fuse together without forming the striations seen in constructs printed on the ground, Boland says.
Techshot, which is based in Greenville, Ind., is partnering with 3D-bioprinter manufacturer nScrypt. Their first bioprinter went to the ISS in July, but the small patch of heart muscle it printed didn’t survive reentry. The next mission, which launched in November, should result in thicker tissue that can be tested on Earth when it returns in January.
Outer space is the perfect place to make metal alloys. Microgravity allows the metals and other elements to mix together more evenly.
Magnesium alloys for medical implants have especially high potential. At half the weight of titanium alloys, magnesium alloys more closely match the density and strength of bone, and they harmlessly biodegrade in the body, says University of Pittsburgh bioengineering professor Prashant Kumta, who is working with Techshot to produce his patented alloys in a high-temperature furnace on the ISS.
Making these alloys involves melting highly reactive magnesium with other elements such as calcium and zinc, keeping the melted materials in a vacuum for a long time so the elements mix evenly, and then cooling it all down.
On Earth, impurities settle to the bottom, and the upper layer oxidizes to form an unusable skin. Both have to be thrown out. Even the usable middle layer has pores and pockets of unmixed elements and must be further processed to make a quality material. None of these problems occur when alloys are manufactured in microgravity.
What Techshot and nScrypt want to do with human organs, Israeli food-tech startup Aleph Farms plans to do with meat. The two-year-old Rehovot-based company grows cultured beefsteaks that look and taste like the real thing. “While other companies use only muscle cell, we also grow connective tissue, blood vessels, and fat cells, which lets us make beefsteaks instead of patties,” says Yoav Reisler, external relations manager at the company.
In September, the company teamed up with Russian company 3D Bioprinting Solutions to create the first tiny piece of meat on the ISS. It isn’t a huge technical advance, but it could feed astronauts on long-term crewed missions, as well as future space settlers as they set up a permanent base.
This article appears in the December 2019 print issue as “ 4 Products To Manufacture In Orbit.”
New supercomputer simulations have successfully modeled a mysterious process believed to produce some of the hottest and most dangerous solar flares—flares that can disrupt satellites and telecommunications networks, cause power outages, and otherwise wreak havoc on the grid. And what researchers have learned may also help physicists design more efficient nuclear fusion reactors.
In the past, solar physicists have had to get creative when trying to understand and predict flares and solar storms. It’s difficult, to put it mildly, to simulate the surface of the sun in a lab. Doing so would involve creating and then containing an extended region of dense plasma with extremely high temperatures (between thousands of degrees and one million degrees Celsius) as well as strong magnetic fields (of up to 100 Tesla).
However, a team of researchers based in the United States and France developed a supercomputer simulation (originally run on Oak Ridge National Lab’s recently retiredTitan machine) that successfully modeled a key part of a mysterious process that produces solar flares. The group presented its results last month at the annual meeting of the American Physical Society’s (APS) Plasma Physics division, in Fort Lauderdale, Fla.
When General Motors briefly first wowed the world with its EV-1 electric car, back in 1990, it relied on lead-acid batteries that packed a piddling 30 to 40 watt-hours per kilogram. The project eventually died, in part because that metric was so low (and the cost was so high).
It was the advent of new battery designs, above all the lithium-ion variant, that launched today’s electric-car wave. Today’s Tesla Model 3’s lithium-ion battery pack has an estimated 168 Wh/kg. And important as this energy-per-weight ratio is for electric cars, it’s more important still for electric aircraft.
Now comes Oxis Energy, of Abingdon, UK, with a battery based on lithium-sulfur chemistry that it says can greatly increase the ratio, and do so in a product that’s safe enough for use even in an electric airplane. Specifically, a plane built by Bye Aerospace, in Englewood, Colo., whose founder, George Bye, described the project in this 2017 article for IEEE Spectrum.
It will be China’s first independent attempt at an interplanetary mission, and comes with two ambitious goals. Launching in 2020, China’s Mars mission will attempt to put a probe in orbit around Mars and, separately, land a rover on the red planet.
The mission was approved in early 2016 but updates have few and far between. Last week, a terse update (available here in Chinese) from the Xi’an Aerospace Propulsion Institute, a subsidiary of CASC, China’s main space contractor, revealed that the spacecraft’s propulsion system had passed all necessary tests.
According to the report, the Shanghai Institute of Space Propulsion has completed tests of the spacecraft’s propulsion system for the hovering, hazard avoidance, slow-down, and landing stages of a Mars landing attempt. The successful tests verified the performance and control of the propulsion system, in which one engine producing 7,500 Newtons of thrust will provide the majority of force required to decelerate the spacecraft for landing.
On Earth, no natural phenomenon is quite as dependable as gravity. Even a child playing on a beach knows that the sand she is excavating will just sit there in her trowel, pulled downward by this powerful force.
But on small, low-gravity celestial bodies like asteroids, the rules of gravity that we know so well no longer apply—at least, not in the ways that we’re used to. And that’s a problem for the scientists who collect samples of regolith, the dusty or pebbly material found on the surfaces of these bodies.
Asteroids are remnants of the early solar system: essentially chunks of material that did not become planets. Regolith samples from asteroids and other small celestial bodies are critical for researchers to better understand how the solar system began, and how it has evolved since.
In the absence of strong gravitational influences, even electrostatic forces that would be considered weak to negligible on Earth may hold outsized importance in space. Hartzell, a participating scientist on the OSIRIS-REx mission currently orbiting the asteroid Bennu, studies these electrostatic forces. A better understanding of electrostatic forces on particles improves understanding of the natural evolution of asteroids and helps inform the design of sampling methods and instruments on future asteroid exploration missions.
Electrostatic forces occur when oppositely charged particles interact with each other. This causes regolith particles to behave curiously in three ways.
First, they cause dusty particles that rub against each other to stick together, or clump. Second, dust exposed to the flow of charged particles from solar wind plasma can detach, or loft away from the surface, drawn to opposite charges in the solar wind flowing past. Third, particles can levitate after being kicked up by a small meteorite impact or blasted by a visiting spacecraft, because the electrostatic forces on those particles cancel out any gravitational pull.
And it’s possible that it’s not just tiny dust particles that may behave unusually—but larger grains, due to the extremely weak effects of gravity on asteroids, as well.
The catch, however, is that none of these behaviors have been directly observed in space, nor the forces causing them to occur measured there. Though Hartzell’s work has demonstrated these forces in laboratory experiments, many questions remain about what they look like on an asteroid, to what degree electrostatic forces affect dust behavior, how strong those forces are, and how the presence of a spacecraft in close proximity to an asteroid’s surface might change the environment.
Whether or not lofting occurs depends on the strength of the forces causing particles to stick together and, by extension, to other objects, such as spacecraft surfaces and optics. Hartzell is developing an experimental method to measure this cohesion.
How the method will work: an electrically charged plate is placed at a set distance above a surface with dusty particles, in an area of known gravity. By controlling the height and electrical charge of the plate, the electrostatic forces on the dust grains can be controlled. A camera is used to observe the size of dust grains and when they begin to be drawn to the plate. By controlling the electrostatic force and knowing the gravity, the unknown, cohesive force can be mathematically derived.
Hartzell’s method could potentially be used for actual sampling, as well. She suggests that charged plates could be used to attract dust samples, then drop them into sample collectors or directly onto analysis instruments by removing the plate’s charge.
More likely, however, is that the method might be employed to better characterize the surface of a site intended for longer-term use by, for example, an asteroid mining mission. Early planning stages would involve understanding the chemistry and behavior of any dusty surface, including how its cohesive properties may affect the function of tools like drill bits.
Harnessing electrostatic forces to control dusty particles might also mean cleaner, better functioning solar panels on Mars. An electrostatic dust shield could use coils embedded in solar arrays to “bounce” dust grains off the surface via alternating electrical charges.
But for now, Hartzell’s work involves a lot of creative lab experimentation and lab-based modeling, but with one goal in mind.
“We want to keep the spacecraft safe during operations,” she says.
I’ll never forget the first time I saw a rocket materialize before my eyes.
In October 2018, I stood in a small room and watched a massive robotic arm move elegantly around a large metal shape, which was rapidly growing larger as I gazed at it. The arm precisely deposited a stream of liquid aluminum to build up the structure, layer by layer, while two other arms waited, with finishing tools at the ready. I was standing in the Los Angeles headquarters of the upstart rocket company Relativity Space, staring in awe as a piece of its first launch vehicle, the Terran 1 rocket, came into existence.
I had only recently arrived at Relativity as the first engineer hired for its avionics department. Relativity offered quite a change of scenery from my prior jobs, even though the other companies I’d worked for also built rockets. But they did so in massive rooms, measuring thousands of square meters, enough to hold ranks of bulky manufacturing tools such as metal rollers, dome spinners, and friction-stir welding machines. At Relativity, though, most of the launch vehicle is built inside the small room where I was standing, which measures just 9 meters across.
The room contained Stargate, the largest metal 3D printer in the world. Relativity invented the Stargate printer for the audacious purpose of 3D printing an entire rocket that’s intended to fly to low Earth orbit. We hope our rockets will eventually fly even farther. Perhaps one day we’ll ship our 3D printers to Mars, so rockets can be constructed on the Red Planet. From there, who knows where they’ll go.
Does this sound crazy? Crazy ambitious, maybe. But plenty of people are taking our idea seriously. Four commercial customers have signed up for launches to Earth orbitbeginning in early 2021. The U.S. Air Force has approved our request to build a launch site at Cape Canaveral, the famed Florida facility that launched many historic human spaceflight missions. And NASA has leased us a building at its Stennis Space Center, in Bay St. Louis, Miss., where Relativity will build a factory capable of turning out 24 rockets per year. Such mass production will represent a revolution in rocketry. By embracing additive manufacturing—that is, 3D printing—we believe we can pull it off.
Launching a rocket into orbit is a binary proposition: Either you succeed or you fail. During the roughly 10-minute flight from launchpad to space, a mind-boggling array of systems must work together perfectly—plumbing, avionics, software, pyrotechnics, and pneumatics, to name just a few. If any component fails, the whole endeavor can literally come crashing down.
The cost of a rocket is not determined by its raw materials; those are pretty cheap. It’s largely driven by the human labor needed to work those materials into usable components and verify that they will function for flight. There are two ways to reduce these labor costs: You can reduce the total number of parts in a rocket so less labor is needed, or you can change manufacturing processes to reduce the need for human minds and hands.
Blue Origin, SpaceX, and Virgin Orbit—companies that are leading the charge in the new commercial space sector—have tried a combination of these two methods to reduce labor costs. But these companies’ reliance on traditional “subtractive” manufacturing techniques, in which chunks of raw material are cut down and shaped, limits their options. The companies have automated much of their supply chains, yet they still have tens of thousands of parts to track through complex manufacturing systems. Automating the manufacturing process has reduced human labor, but it requires expensive customized tooling that matches the dimensions of a particular rocket.
Relativity approaches the labor challenge head on by leveraging additive manufacturing to print complex components, using a single operation to turn raw material into finished product. This approach dramatically reduces part count because one of our components is often the equivalent of dozens of small parts made via traditional manufacturing. Our process also relies on our 3D printers rather than fixed tooling, which enables us to be nimble and inventive. We can make large design changes with relatively little cost or time lost.
Rocketry operates on a different scale than other manufacturing sectors. Consider that the Volkswagen plant in Wolfsburg, Germany, turns out about 3,500 vehicles per day. In contrast, any aerospace company that could build 100 rockets in a year would be monumentally successful. What’s considered high-volume production in rocketry is relatively low-volume in other industries. That means that additive manufacturing can have a big impact on the industry. Because only dozens or hundreds of a particular part may be needed in a year, it doesn’t necessarily make sense to invest in highly optimized tooling to turn out that part in mass quantities—the tools might not pay for themselves before the part becomes obsolete.
Making a new part using a 3D printer requires little to no up-front cost. For example, one of our Stargate printers can produce a 2-meter-diameter propellant tank followed by a 3-meter-diameter tank with minimal downtime. Rather than having to retool an entire manufacturing facility to fabricate the next piece of hardware in the queue, we have to make only a few software-configuration changes.
Our company’s cofounders,Jordan Noone and Tim Ellis, met in college at the University of Southern California’s Rocket Propulsion Laboratory, in Los Angeles. Noone went on to work at SpaceX and Ellis at Blue Origin before they got back together and formed Relativity in 2015.
Both of their former companies use additive manufacturing to build some rocket components, but Noone and Ellis wanted to take the approach much further. They saw an opportunity to completely rethink how rockets are designed and manufactured. By simplifying designs and production processes, they figured, they would also simplify the mental labor, the “cognitive overhead,” involved in building a rocket.
Rockets typically have a huge number of individual parts: The space-shuttle system, for example, consisted of 2.5 million moving parts. All the pieces must fit together just right and can’t unexpectedly add up to an out-of-tolerance assembly. Every part must be manufactured, tested, installed, and tested again. More work ensues if a part needs to be fixed. And all these processes require engineers, technicians, tooling, and paperwork.
With additive manufacturing, you can design parts that incorporate several pieces that would traditionally be manufactured separately and assembled. Fewer parts means fewer interfaces and fewer chances for something to go wrong.
Our approach to designing and building our rocket engine is a case in point. Inside a typical rocket engine you’ll find an injector that mixes the fuel with the oxidizer as they enter the combustion chamber, where an igniter starts the fire. The combustion produces hot gas, which moves through a nozzle to create thrust. It sounds simple in principle, but the reality is staggeringly complex. Consider that Rocketdyne’s F-1 engine, which launched Saturn V rockets during NASA’s Apollo program, contained a combustion chamber and nozzle assembly composed of more than 5,000 individually manufactured parts (and that’s not including the injector).
Relativity’s engine, Aeon 1, is a different story. To build the engine, we employ commercial 3D printers that use a process called direct metal laser sintering, in which a laser fuses together particles of metal powder, creating the required structure layer by layer. The simplest variant of the engine, a pressure-fed version that uses pressurized gas to push the fuel and oxidizer from their tanks into the combustion chamber, is manufactured by pressing the printer’s on button three times (to print three parts). And we’re going further: We expect commercial printers to become available soon that will allow us to print the injector, igniter, combustion chamber, and nozzle as a single part.
We use that pressure-fed engine for development and testing; the engine that will eventually fly will use turbopumps instead of simple pressurized gas to move the fuel (liquid methane) and oxidizer (liquid oxygen). These turbopumps, which are better suited for rockets with large fuel tanks, will increase the part count, but the manufacturing process will still be vastly simpler than any before.
Many rocket engines use a technique called regenerative cooling, in which liquid fuel is pumped through cooling channels around the combustion chamber to suck heat away. In a traditional manufacturing and assembly process, a thick piece of copper is shaped by spinning it rapidly while applying pressure to form the inner contours of the combustion chamber. It is then milled to create intricate cooling channels on the outside. A strong outer jacket is then brazed onto the copper structure, and a fuel-inlet manifold is welded onto the outer jacket. The whole engine assembly requires finish machining to hold tight tolerances where things fit together. Each of these processes is an opportunity for design or manufacturing error. The Aeon engine also uses regenerative cooling, but its combustion chamber is created in a single print. What’s more, 3D printing enables us to incorporate many more tiny cooling channels than can be produced by milling the metal.
It’s normally a monumental task to get a single engine designed, fabricated, and on the test stand. This process takes 10 to 12 months using traditional methods. A major redesign takes almost as long. But we’re able to iterate much faster. In our initial tests of the Aeon engine, we tried out five versions within 14 months, firing the engines more than 100 times.
As NASA astronautDonald Pettit explained in his brilliant article “The Tyranny of the Rocket Equation,” published on the NASA website, getting out of Earth’s gravity well is not an easy task. Rockets are largely empty vessels waiting to be filled with fuel. Pettit explains that 94 percent of the mass of a can of soda comes from the soda, and 6 percent from the can. The space shuttle’s external fuel tank was 96 percent fuel and 4 percent tank, an impressive improvement over soda-can technology when you consider that the fuel tank held cryogenic liquids that had to be pumped out at a rate of 1.5 metric tons of fuel per second.
The entire Terran 1 rocket is designed for simplicity. The tanks that hold the fuel and oxidizer are “autogenously pressurized,” which means a small percentage of vaporized fuel and oxidizer is pumped back into their respective tanks to replace the volume of liquid as it drains. To continue Pettit’s analogy, picture an unopened soda can, which is rigid and strong despite the thin shell of the can; once the can has been opened, though, it can be crushed with ease. Similarly, rockets use internal pressure to help create a lightweight yet strong vehicle.
These autogenous systems on Terran 1’s tanks eliminate the need for the special pressure vessel that many rockets use inside their fuel and oxidizer tanks. Those pressure vessels hold inert gases such as helium at extremely high pressures until they’re ready to be released into the tank to provide internal pressure. These vessels are notoriously difficult systems to engineer and manufacture and have been involved in several rocket failures in the last decade, including the explosion of a SpaceX Falcon 9 rocket in 2015.
Commercial printers that use metal laser sintering are suitable for manufacturing our engines, but they wouldn’t be practical for producing the tanks. Those printers work by selectively melting the desired portions of metal powder to create the solid material in each layer of a part. Because the powder bed needs to be flat and even for each layer, the entire work space of a printer must be filled with powder, regardless of how much material will actually be solidified. Most of that powder can be recycled, but some is lost on every print. Producing a tank using a laser sintering printer would require an unrealistic amount of metal powder and would be very slow.
That’s why we designed and built Stargate, our enormous 3D printer of a different kind. It uses an existing technique called directed energy deposition but operates at a scale never before seen. The printer feeds a metal wire into the deposition area and uses energy (typically a powerful laser) to melt the wire, building up printed parts layer by layer.
Stargate places molten metal only where it is needed to build the structure, which significantly cuts down on wasted material. It uses three massive robotic arms, one of which terminates in the printer head that feeds out the wire; the two others hold working tools for finishing the printed component. We also wrote proprietary software to manage the “path planning” involved in turning a design into detailed instructions for the robotic arms.
Stargate has a few limitations. Its robotic arms move its working tools through free space as it prints, which means the geometries that can be printed are constrained by the kinematics of the robotic arms—they can reach only so far and must avoid colliding with the printed structure. And as the wire melts, the bead size resulting from the welding process sets the minimum resolution of the print. But these restrictions aren’t serious when it comes to large pressure vessels and structural elements.
Our Stargate printer is a novel piece of technology, and we believe it opens up new frontiers in aerospace manufacturing. But the novelty of this printing process also means that we cannot rely on preexisting material data or process parameters to achieve high-quality products. Relativity has in-house metallurgists who are honing the process, ensuring that our components meet the strict quality standards for aerospace hardware.
In traditional aerospace manufacturing, a design change can require almost a year of retooling and adjustments. Because hardware changes take so long, the avionics department is usually the most agile part of an aerospace company. Avionics teams (which handle the electronics that manage the rocket’s guidance, navigation, communications, and more) are accustomed to implementing last-minute software changes to fix issues on other parts of the vehicle.
The situation is completely reversed at Relativity, where the hardware team can make substantial design changes and still produce a new tank or engine within days. They can revise their plans so quickly that they challenge the avionics team’s ability to produce printed circuit boards (PCBs) and construct the cable harnessing that connects all the electronics and wiring. Avionics has to adapt to an ever-changing and improving rocket.
That’s why we designed the avionics of the Terran 1 rocket to be as modular as possible. We assume that sensors and actuators will be changed, and so we designed the electronics in a way that would limit the impact of such modifications. To accomplish this feat we devised a few proprietary methods of busing, minimizing the number of connectors and pins. We make every effort to reduce the amount of harnessing, which is one of the least reliable parts of the avionics on a rocket—every connection of every wire is a potential failure point. Wherever possible, we use standards such as the Controller Area Network bus protocol (for enabling communication between microcontrollers and devices) and Ethernet, and thus can use existing industry tools for testing and development. This approach means we don’t waste time hunting for bugs in custom protocols and can instead focus on ensuring the proper operation of our avionics in their specific use cases.
As we consider each small design choice in the avionics systems, we aim for global rather than local optimization. For example, we use standard tools that automate electronics design, such as Altium Designer, to create basic spaceflight-qualified circuits that we can use in multiple ways throughout the rocket. We call these “bread and butter circuits,” and we use them in voltage converters, processors, sensor interfaces, and other components. When our engineers tackle a new problem, they build on the work that’s already been done, rather than starting from scratch. While this may sound like a commonsense approach, you’d be surprised at how many rockets contain a complicated assortment of circuit designs simply because different engineers solved the same problem in slightly different ways.
Another example can be found in our firmware. For internal communications within our avionics boxes, we don’t always use a protocol that’s optimized for PCBs, which would provide tiny benefits in performance and mass. Instead we sometimes use a protocol that we also use for external box-to-box communications. This method cuts the cost and time of firmware development considerably. What’s more, it gives us flexibility for our design solutions: We can make changes within a centralized box, or we can add on some last-minute sensor in the harnessing, but the software doesn’t know the difference. This approach may not be optimal for the avionics systems viewed in isolation, but it gives us many advantages elsewhere in regard to designing, building, and flying rockets.
Relativity CEO Ellis often reminds us that we should put at least as much thought into designing and producing our company’s culture as we do into designing and building our rocket. Relativity is focused on maintaining flexibility, so experimentation is encouraged. This attitude is antithetical to the culture of traditional aerospace companies, which try to lock down their designs as soon as possible. We have an aggressive goal—to launch Terran 1 by early 2021. So we leverage our modular approach to swap out pieces, and we’re constantly tweaking to optimize our designs for the world’s first 3D-printed rocket.
The Terran 1, which is about 30 meters tall and 2 meters wide, is intended to launch modestly sized satellites into low Earth orbit at a cost that is radically lower than competitors can offer. It will enable smaller companies to book the whole payload of a rocket and send it to their desired orbit on their own schedule, rather than having to piggyback on the flight of a bigger rocket whose destination orbit and schedule is controlled by another company.
Relativity Space may stumble, but with our emphasis on design and manufacturing flexibility we can afford to fail many times over. We learn from every failure and forge ahead. We’re watching the future of rocketry materialize before our eyes.
This article appears in the November 2019 print issue as “3D Printing a Rocket.”
For the first time, we have a complete, representative number for the overall orbital collision risk of a satellite mega-constellation.
Last month, Amazon provided the U.S. Federal Communications Commission (FCC) with data for its planned fleet of 3,236 Kuiper System broadband Internet satellites.
If one in 10 satellites fails while on orbit, and loses its ability to dodge other spacecraft or space junk, Amazon’s figures [PDF] show that there is a 12 percent chance that one of those failed satellites will suffer a collision with a piece of space debris measuring 10 centimeters or larger. If one in 20 satellites fails—the same proportion as failed in rival SpaceX’s first tranche of Starlink satellites—there is a six percent chance of a collision.
More than a third of all the orbital debris being tracked today came from just two collisions that occurred about a decade ago. Researchers are concerned that more explosions or breakups could accelerate the Kessler Syndrome—a runaway chain reaction of orbital collisions that could render low earth orbit (LEO) hostile to almost any spacecraft.
A new nuclear weapons inspection technology could enhance inspectors’ ability to verify that a nuclear warhead has been dismantled without compromising state secrets behind the weapon’s design.
This new non-proliferation tool, its inventors argue, would greatly assist the often delicate dance of nuclear weapons inspectors—who want to know they haven’t been hoaxed but are also sensitive to a military’s fear that spies may have infiltrated their ranks.
While nuclear non-proliferation treaties have historically verified the dismantlement of weapons delivery systems like ICBMs and cruise missiles, there have in fact never been any verified dismantlements of nuclear warheads themselves (in part for the reasons described above).
Yet there are 13,000 nuclear warheads in the world, meaning the entire globe is still just a hair trigger away from apocalypse—even as we approach the thirtieth anniversary of the Berlin Wall’s collapse.
As UN Secretary-General Antonio Guterres told world leaders last month, “I worry that we are slipping back into bad habits that will once again hold the entire world hostage to the threat of nuclear annihilation.”
How, then, to verifiably dismantle a nuclear bomb?
This whitepaper explains the process of specifying cable assemblies and will be ideal for Engineers wishing to learn the basics of the process, and as a refresher for the more experienced Engineer. Particular focus is given to sectors that require high-levels of reliability and details the criteria required to ensure a long operational life-span.
For the foreseeable future, access to space will remain very expensive. Even with tricks like reusing rockets or launching from balloons and giant airplanes, it still costs thousands of dollars per kilogram to put something into low Earth orbit. And once you’ve put something up there, that thing is generally on its own (with very few exceptions), and hopefully does what it needs to until it runs out of fuel, at which point most satellites are completely useless.
It’s hard enough to grow tomatoes from seeds out in a sunny garden patch. To do it in sun-synchronous orbit—that is to say, in outer space—would seem that much harder. But is it?
That’s what plant biologists and aerospace engineers in Cologne and Bremen, Germany are set to find out. Researchers are preparing in the next couple of weeks to send a software upload to a satellite orbiting at 575 kilometers (357 miles) above the Earth. Onboard the satellite are two small greenhouses, each greenhouse bearing six tiny tomato seeds and a gardener’s measure of hope. The upload is going to tell these seeds to go ahead and try to sprout.
The experiment aims to not only grow tomatoes in space but to examine the workings of combined biological life support systems under specific gravitational conditions, namely, those on the moon and on Mars. Eu:CROPIS, which is the name of the satellite as well as the orbital tomato-growing program, is right now spinning at a rate which generates the exact gravitational field found on the moon.
The environment is designed to work as a closed loop: the idea is to employ algae, lava filters, plants, and recycled human urine to create the cycle by which plants absorb nitrates and produce oxygen. Being able to accomplish all these tasks will be crucial to any long-term stay in space, be it on a moon base or a year-long flight to Mars. Any humans along for that kind of ride will be glad to get away from tinned applesauce and surely welcome fresh greens or, say, a tomato.
A newly developed graphene-based telescope detector may usher in a new wave of astronomical observations in a band of radiation between microwaves and infrared light. Applications including medical imaging, remote sensing, and manufacturing could ultimately be beneficiaries of this detector, too.
Microwave and radio wave radiation oscillate at frequencies measured in gigahertz or megahertz—slow enough to be manipulated and electronically processed in conventional circuits and computer systems. Light in the infrared range (with frequencies beginning around 20 THz) can be manipulated by traditional optics and imaged by conventional CCDs.
But the no-man’s land between microwaves and infrared (known as the “terahertz gap”) has been a challenging although not entirely impossible band in which astronomers could observe the universe.
To observe terahertz waves from astronomical sources first requires getting up above the atmosphere or at least up to altitudes where the Earth’s atmosphere hasn’t completely quenched the signal. The state-of-the-art in THz astronomy today is conducted with superconducting detectors, says Samuel Lara-Avila, associate research professor in the Department of Microtechnology and Nanoscience at Chalmers University of Technology in Sweden.
Observatories like the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile and the South Pole Telescope might use such detectors combined with local oscillators pumping out reference signals at frequencies very close to the target signal the astronomers are trying to detect. If a telescope is looking for radiation at 1 THz, adding a local oscillator at 1.001 THz would produce a combined signal with beat frequencies in the 1 GHz (0.001 THz) range, for instance. And gigahertz signals represent a stream of data that won’t overwhelm a computer’s ability to track it.
Sounds simple. But here’s the rub: According to Lara-Avila, superconducting detectors require comparatively powerful local oscillators—ones that operate in the neighborhood of a microwatt of power. (That may not sound like much, but the detectors operate at cryogenic temperatures. So a little bit of local oscillator power goes a long way.)
By contrast, the new graphene detector would require less than a nanowatt of local oscillator power, or three orders of magnitude less. The upshot: A superconducting detector in this scenario might generate a single pixel of resolution on the sky, whereas the new graphene technology could enable detectors with as many as 1000 pixels.
“It’s possible to dream about making [THz] detector arrays,” Lara-Avila says.
Probably the most famous observation in THz or near-THz astronomy is the Event Horizon Telescope, which earlier this month won the Breakthrough Prize in Fundamental Physics. (Pictured) Some of the frequencies it operated at, according to Wikipedia, were between 0.23 and 0.45 THz.
The graphene detector pioneered by Lara-Avila and colleagues in Sweden, Finland, and the UK is described in a recent issue of the journal Nature Astronomy.
The group doped its graphene by adding polymer molecules (like good old 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane, or F4-TCNQ ) atop the pure carbon sheets. Tuned just right, these dopants can bring the ensemble to a delicate quantum balance state (the so-called “Dirac point”) in which the system is highly sensitive to a broad range of electromagnetic frequencies from 0.09 to 0.7 THz and, they speculate, potentially higher frequencies still.
All of which adds up to a potential THz detector that, the researchers say, could represent a new standard for THz astronomy. Yet astronomical applications for technology often just represents the first wave of technology that labs and companies spin off for many more down-to-earth applications. That CCD detector powering the cameras on your cellphone originated in no small part from the work of engineers in the 1970s and ‘80s developing sensitive CCDs whose first applications were in astronomy.
Terahertz technologies for medical applications, remote sensing, and manufacturing are already works in progress. This latest graphene detector could be a next-gen development in these or other as yet unanticipated applications.
At this point, says Lara-Avila, his group’s graphene-based detector version 1.0 is still a sensitive and refined piece of kit. It won’t directly beget THz technology that would find its way into consumers’ pockets. More likely, he says, is that this detector could be lofted into space for next-generation THz orbital telescopes.
“It’s like the saying that you shouldn’t shoot a mosquito with a cannon,” Lara-Avila says. “In this case, the graphene detector is a cannon. We need a range and a target for that.”
Researchers with the International Institute for Applied Systems Analysis (IIASA) in Austria recently explored another potential solution: the return of airships to the skies. Airships rely on jet stream winds to propel them forward to their destinations. They offer clear advantages over cargo ships in terms of both efficiency and avoided emissions. Returning to airships, says Julian Hunt, a researcher at the IIASA and lead author of the new study, could “ultimately [increase] the feasibility of a 100 percent renewable world.”
Today, world leaders are meeting in New York for the UN Climate Action Summit to present plans to address climate change. Already, average land and sea surface temperatures have risen to approximately 1 degree C above pre-industrial levels. If the current rate of emissions remains unchecked, the Intergovernmental Panel on Climate Change estimates that by 2052, temperatures could rise by up to 2 degrees C. At that point, as much as 30 percent of Earth’s flora and fauna could disappear, wheat production could fall by 16 percent, and water would become more scarce.
According to Hunt and his collaborators, airships could play a role in cutting future anthropogenic emissions from the shipping sector. Jet streams flow in a westerly direction with an average wind speed of 165 kilometers per hour (km/h). On these winds, a lighter-than-air vessel could travel around the world in about two weeks (while a ship would take 60 days) and require just 4 percent of the fuel consumed by the ship, Hunt says.
New satellite sensor data, combined with info from the terrestrial U.S. National Lightning Detection Network, will help scientists identify the most dangerous lightning strikes
In the time it takes to read this sentence, lightning will strike somewhere in the world. In fact, lightning strikes are thought to occur between 50 and 100 times every second. Most of the time, lightning just puts on a pretty show. But sometimes, it kills people. And then there are the times when it ignites wildfires or damages electrical equipment.
With new tools, researchers can now distinguish the most damaging lightning strikes from the many millions of others that occur every year. All lightning is dangerous—but if we can tell which strikes are more likely to actually inflict harm, that information might help us react more quickly during a storm.
Already, the U.S. National Lightning Detection Network keeps a record of virtually all lightning that strikes the ground anywhere in the United States. That network is maintained by Helsinki-based Vaisala, which built it 30 years ago and sells the data to the National Weather Service and to utilities, airports, seaports, mines, and sporting arenas. Vaisala operates a global lightning detection network, as well.
But the company hasn’t been able to make one specific measurement that could provide clues as to how dangerous a given strike is likely to be—until now.
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