If Jason Bankowski is right, the road to interstate space begins in a shipping container behind a laboratory high bay in Maryland. Setup looks something like a low-budget film anika vaij: LED is one of thousands of container wall Lined with, a messy metal lattice runs down the center, and thick black curtains partially obscure the device. This is the Johns Hopkins University Applied Physics Laboratory Solar Simulator, a device that glows with an intensity of 20 suns. On Thursday afternoon, Benkowski applied a black-and-white tile to the purple and pulled a black curtain around the setup before exiting the shipping container. Then he hit the light switch.
Once the solar simulator was heating up, Benkowski began pumping liquid helium through a small embedded tube, which was released further from the slab. Helium absorbs heat from the LED as it is wound through the channel and expands until it is finally released through a small nozzle. It may not look like this, but Bancoski and his team only demonstrated solar thermal propulsion, a previous theoretical type of rocket engine powered by solar heat. They believe it could be the key to interdisciplinary research.
The material called Benkowski says, “Someone reject this idea and say, ‘In the back of the envelope, it looks pretty cool, but if you really build it, you’ll never get that theoretical number.’ The leader of the team working on the scientific and solar thermal propulsion system at the Applied Physics Laboratory. “What this is showing is that solar thermal propulsion is not just a fantasy. It can really work.”
Only two spacecraft, Voyager 1 and Voyager 2, have left our solar system. But it was a scientific bonus after his main goal of exploring Jupiter and Saturn was accomplished. Neither was the spacecraft equipped with the proper instruments to study the fiduciary of our stellar planets and the boundaries of the rest of the universe. Plus, Voyager has twins Slow down. Plowing at 30,000 miles per hour, it took them almost half a century to escape the effects of the sun.
But the fact that they sent the data back from the edge is tantalizing. It shows that the predictions made by physicists about the edge of the solar system were very wrong. Surprisingly, a large group of astrophysicists, cosmologists and planetary scientists are calling for an international investigation dedicated to exploring this new frontier.
In 2019, NASA tapped the Applied Physics Laboratory to study the concepts for a dedicated stellar mission. At the end of next year, the team will submit its research to the Heliophysics Decadal Survey of the National Academy of Sciences, Engineering and Medicine, which sets the priorities of solar science for the next 10 years. APL researchers working on the Interstellar Probe program are studying all aspects of the mission, from cost estimating to instrumentation. But simply how to get any reasonable amount of interseller space is the biggest and most important part of this puzzle.
Don’t stop at heliposes
The edge of the solar system, called heliopause, is very far away. Until it reaches a spacecraft to Pluto, it is a third way between the stars. And the APL team is studying an investigation that will go three times beyond the edge of the solar system, traveling 50 billion miles, in about half the time it took the Voyager spacecraft just to reach the edge. To pull off that kind of mission, they would need to check against anything that was ever built. “We want to build a spacecraft that can move faster and closer to the sun than anything else,” says Benkowski. “It’s probably the hardest thing you can do.”
In mid-November, international testing researchers met met online for a week-long conference to share updates as the study enters its final year. At the conference, APL and NASA teams shared the results of their work on solar thermal propulsion, which they believe is the fastest way to get an international space probe. The idea is to power the rocket engine with heat from the sun instead of combustion. According to Bankowski’s calculations, this engine will be three times more efficient than the best conventional chemical engine available today. “From a physics point of view, it’s hard for me to imagine anything that could beat solar thermal propulsion in terms of efficiency,” says Bankowski. “But can you save it from exploding?”
Unlike the conventional engine installed in the rear of the rocket, the solar thermal engine that the researchers are studying will be integrated with the spacecraft’s ieldal. The rigid flat shell is made from a black carbon foam with one side coated in white reflective material. Externally, it will look similar to the heat shield on the Parker Solar Probe. The decisive difference is the tertiary pipeline hidden beneath the surface. If intarasetalara probe passes close to the sun and hydrogen is broken down veskyulacaramam alani its ield, will expand to a nozzle of a hydrogen explosion at the end of a pipe. Heat shield will produce thrust.
It is simple in theory but incredibly difficult in practice. The solar thermal rocket is only effective if it can pull the Orth maneuver, the orbital-mechanics hack that turns the sun into a giant slingshot. The Sun’s gravitational force acts like a multiplier, increasing the speed of the spacecraft dramatically if a spacecraft fires its engines while looting around the star. The closer a spacecraft gets to the sun during a berth maneuver, the faster it will go. In APL’s mission design, interstellar probes will pass only one million miles from the Sun’s rotating surface.
To put this in perspective, by the time NASA’s Parker Solar Probe makes its closest approach in 2025, it will be within 4 million miles of the Sun’s surface and will be booking about 430,000 miles per hour. The desire to hit the interplanetary probe is almost doubled, and the Parker Solar Probe has accelerated over seven years with the help of the Sun and Venus’ gravity. The interstellar probe has to accelerate from 30,000 miles per hour to 200,000 miles per hour in a single shot around the sun, which means moving closer to the star. Really close.
Dean Cheech, a material technologist at NASA’s Jet Propulsion Laboratory, who presented a case study on solar thermal rockets during a recent conference, says that enduring up to a sun-sized thermonuclear explosion poses all sorts of material challenges. For the APL mission, the probe will spend about 2.5 hours at a temperature of about 4,500 degrees Fahrenheit as it completes its Oberth maneuver. It’s hot enough to melt through the heat shield of the Parker Solar Probe, so the Czech team at NASA found new material that could be coated on the outside to reflect thermal energy. Combined with the cooling effect of hydrogen flowing through the channels in the heat shield, this layer will keep the international probe cool when it is bleached by the sun. “You want to increase the amount of energy you are kicking back,” says Chekh. “Even small differences in the reflection of the content of your spacecraft starts to significantly warm.”
“We don’t have many options”
Yet how to operate the Hot Hydrogen flowing through channels that are also a big problem. At extremely high temperatures, hydrogen eats through the carbon-based core of the heat shield, which means that the channels must remain coated in a strong material. The team identified some materials that might work, but not much data on their performance, especially at extreme temperatures. “There’s not a lot of stuff that can meet these demands,” Chek says. “In some ways it’s good, because we just have to look at these materials. But it’s even worse because we don’t have a lot of options. “
A major measure of their research, says Chekh, is the need to conduct many tests on heat shield materials before sending solar thermal rockets around the sun. But he is not a deal breaker. In fact, the material vij in anamam incredible achievements was conceived for the first time by the US Air Force engineers after the idea is ultimately possible for more than 60 years. “I thought I came up with this great idea independently, but people were talking about it in 1956,” says Bankowski. “Additive manufacturing is a key component of this, and we couldn’t do that 20 years ago. Now I can 3D-print the metal in the lab. “
Although Benkowski was not the first to float the idea of solar thermal propulsion, he believes he is the first to demonstrate a prototype engine. During their experiments with channeled tiles in shipping containers, Benkowski and his team showed that it is possible to generate thrust by using sunlight to heat the gas, as it passes through tubes embedded in the heat shield. These experiments had many limitations. They did not use the same material or propellant that would be used on the actual mission, and the tests came at a temperature that would be the bottom of the stars check. Importantly, the data from low-temperature experiments matched the models, which predicts how an interseller will investigate its actual mission once adjustments have been made for different materials, says Bankowski. “We did it on a system that doesn’t really fly. “Now the second step is that we start rotating each of these components with the material you would put on a real spacecraft for a berth maneuver,” says Bankowski.
The concept is to go a long way before it is ready to be used on a mission – and with only one year left in an international investigative study, there is not enough time to launch a small satellite to conduct experiments in low Earth orbit. But by the time Bankoski and his colleagues at the APL submit their report next year, they will have generated a wealth of data that will lay the foundation for space tests. There is no guarantee that national academies will choose the international-verification concept as a top priority in the next decade. But whenever we are ready to leave the sun behind, there is a good chance that we will have to use it to move forward through the door.
The story originally appeared on Wired.com.