The hardware pipeline consists of three parts: antenna, signal conditioners, and computer, as per the above graphic by [Jack Phelps]. The solid lines are low-loss microwave coax LMR-400 cable, and the dotted line represents USB 3.0 between the RTL-SDR and Raspberry Pi 4 system. This Raspberry Pi 4 runs a pre-made OS image (NsfSdr) by [Dr. Glenn Langston] at the National Science Foundation, which contains scripts for hydrogen line observation, calibration and data processing.
After calibration, the findings were verified using publicly available data, and the setup could be used to detect hydrogen by pointing the antenna at the intended target in space. Although a one-meter parabolic dish isn’t going to give you the most sensitivity, it’s still pretty rad that using effectively all off-the-shelf components and freely available software, you too can have your own radio telescope.
It may be blurry and blotchy, but it’s ours. The first images of the supermassive black hole at the center of the Milky Way galaxy were revealed this week, and they caused quite a stir. You may recall the first images of the supermassive black hole at the center of the M87 galaxy from a couple of years ago: spectacular images that captured exactly what all the theories said a black hole should look like, or more precisely, what the accretion disk and event horizon should look like, since black holes themselves aren’t much to look at. That black hole, dubbed M87*, is over 55 million light-years away, but is so huge and so active that it was relatively easy to image. The black hole at the center of our own galaxy, Sagittarius A*, is comparatively tiny — its event horizon would fit inside the orbit of Mercury — a much closer at only 26,000 light-years or so. But, our black hole is much less active and obscured by dust, so imaging it was far more difficult. It’s a stunning technical achievement, and the images are certainly worth checking out.
Another one from the “Why didn’t I think of that?” files — contactless haptic feedback using the mouth is now a thing. This comes from the Future Interfaces Group at Carnegie-Mellon and is intended to provide an alternative to what ends up being about the only practical haptic device for VR and AR applications — vibrations from off-balance motors. Instead, this uses an array of ultrasonic transducers positioned on a VR visor and directed at the user’s mouth. By properly driving the array, pressure waves can be directed at the lips, teeth, and tongue of the wearer, providing feedback for in-world events. The mock game demonstrated in the video below is a little creepy — not sure how many people enjoyed the feeling of cobwebs brushing against the face or the splatter of spider guts in the mouth. Still, it’s a pretty cool idea, and we’d like to see how far it can go.
Starting projects is easy. It’s the finishing part that many of us have trouble with. We can hardly imagine completing a project after more than a decade, but seeing the breathtaking results of [J-P Metsavainio]’s gigapixel composite image of our galaxy might just make us reconsider. The photograph, which we highly suggest you go check out in its full glory, has been in progress since 2009, features 1250 total hours of exposure time, and spans across 125 degrees of sky. It is simply spectacular.
Of course, it wasn’t an absolutely continuous effort to make this one image over those twelve years. Part of the reason for the extended time span is many frames of the mosaic were shot, processed, and released as their own individual pieces; each of the many astronomical features impressive in its own right. But, over the years, he’s filled in the gaps between and has been able to release a more and more complete picture of our galactic home.
A project this long, somewhat predictably, eventually outlives the technology used to create it. Up until 2014, [Metsavainio]’s setup included a Meade 12-inch telescope and some modified Canon optics. Since then, he’s used a dedicated equatorial mount, astrocamera, and a Tokina lens (again, modified) with an 11-inch Celestron for longer focal lengths. He processes the frames in Photoshop, accounting for small exposure and color differences and aligning the images based on background stars. He’s had plenty of time to get his process down, though, so the necessary tweaking is relatively minor.
We as humans are limited in the ways we can look at things ourselves, and rely on on the different perspectives and insights of others to help make sense of things. All it takes is one person to look at a data set and find something completely different that changes our fundamental perception of the universe.
Cecilia Payne-Gaposchkin discovered that stars are primarily made of hydrogen and helium, at a time when astronomers thought that the Sun and the Earth had no significant elemental differences. She proposed that hydrogen wasn’t only more common, but that it was a million times more common.
This outlandish conclusion was roundly dismissed at the time, and she aquiesced to tone down some of the conclusions in her thesis, until her findings were widely confirmed a few years later. Truly groundbreaking, the discovery of the prevalence of hydrogen in stars paved the way for our current understanding of their role as the furnaces for the heavier elements that we know and love, and indeed are composed of.
Meteorites, Comets, and Bee Orchids
Cecilia Helena Payne was born May 10th, 1900 in Wendover, Buckinghamshire, England. She was one of three children born to Emma and Edward, a lawyer, historian, and musician. Her father died with she was four years old, leaving her mother to raise the family alone. Continue reading “Cecilia Payne-Gaposchkin Saw Through The Stars”→
Decades ago, Einstein predicted the existence of something he didn’t believe in — black holes. Ever since then, people have been trying to get a glimpse of these collapsed stars that represent the limits of our understanding of physics.
For the last 25 years, Andrea Ghez has had her sights set on the black hole at the center of our galaxy known as Sagittarius A*, trying to conclusively prove it exists. In the early days, her proposal was dismissed entirely. Then she started getting lauded for it. Andrea earned a MacArthur Fellowship in 2008. In 2012, she was the first woman to receive the Crafoord Prize from the Royal Swedish Academy of Sciences.
Now Andrea has become the fourth woman ever to receive a Nobel Prize in Physics for her discovery. She shares the prize with Roger Penrose and Reinhard Genzel for discoveries relating to black holes. UCLA posted her gracious reaction to becoming a Nobel Laureate.
A Star is Born
Andrea Mia Ghez was born June 16th, 1965 in New York City, but grew up in the Hyde Park area of Chicago. Her love of astronomy was launched right along with Apollo program. Once she saw the moon landing, she told her parents that she wanted to be the first female astronaut. They bought her a telescope, and she’s had her eye on the stars ever since. Now Andrea visits the Keck telescopes — the world’s largest — six times a year.
Andrea was always interested in math and science growing up, and could usually be found asking big questions about the universe. She earned a BS from MIT in 1987 and a PhD from Caltech in 1992. While she was still in graduate school, she made a major discovery concerning star formation — that most stars are born with companion star. After graduating from Caltech, Andrea became a professor of physics and astronomy at UCLA so she could get access to the Keck telescope in Mauna Kea, Hawaii.
The Keck telescopes and the Milky Way. Image via Flickr
The Center of the Galaxy
Since 1995, Andrea has pointed the Keck telescopes toward the center of our galaxy, some 25,000 light years away. There’s a lot of gas and dust clouding the view, so she and her team had to get creative with something called adaptive optics. This method works by deforming the telescope’s mirror in real time in order to overcome fluctuations in the atmosphere.
Thanks to adaptive optics, Andrea and her team were able to capture images that were 10-30 times clearer than what was previously possible. By studying the orbits of stars that hang out near the center, she was able to determine that a supermassive black hole with four millions times the mass of the sun must lie there. Thanks to this telescope hack, Andrea and other scientists will be able to study the effects of black holes on gravity and galaxies right here at home. You can watch her explain her work briefly in the video after the break. Congratulations, Dr. Ghez, and here’s to another 25 years of fruitful research.
Since its launch in March 2009, the Kepler Space Telescope has provided us with an incredible amount of data about exoplanets within our galaxy, proving these worlds are more varied and numerous than we could ever have imagined. Before its launch we simply didn’t know how common planets such as ours were, but today we know the Milky Way contains billions of them. Some of these worlds are so hot they have seas of molten rock, others experience two sunsets a day as they orbit a pair of stars. Perhaps most importantly, thousands of the planets found by Kepler are much like our own: potentially playing host to life as we know it.
Kepler lived a fruitful life by any metric, but it hasn’t been an easy one. Too far into deep space for us to repair it as we did Hubble, hardware failures aboard the observatory nearly brought the program to a halt in 2013. When NASA announced the spacecraft was beyond hope of repair, most assumed the mission would end. Even by that point, Kepler was an unqualified success and had provided us with enough data to keep astronomers busy for years. But an ingenious fix was devised, allowing it to continue collecting data even in its reduced capacity.
Leaning into the solar wind, Kepler was able to use the pressure of sunlight striking its solar panels to steady itself. Kepler’s “eyesight” was never quite the same after the failure of its reaction wheels, and it consumed more propellant than originally intended to maintain this careful balancing act, but the science continued. The mission that had already answered many of our questions about our place in the galaxy would push ahead in spite of a failure which should have left it dead in space.
As Kepler rapidly burned through its supply of propellant, it became clear the mission was on borrowed time. It was a necessary evil, as the alternative was leaving the craft tumbling through space, but mission planners understood that the fix they implemented had put an expiration date on Kepler. Revised calculations could provide an estimate as to when the vehicle would finally run its tanks dry and lose attitude control, but not a definitive date.
For the last several months NASA has known the day was approaching, but they decided to keep collecting data until the vehicle’s thrusters sputtered and failed. So today’s announcement that Kepler has at long last lost the ability to orient itself came as no surprise. Kepler has observed its last alien sunset, but the search for planets, and indeed life, in our corner of the galaxy doesn’t end today.
[Adric Menning] has an unfortunate allergy. He’s allergic to chocolate. Instead of eating the stuff, he’s using it to build model rocket engines. The project stems from the Quelab Hackerspace’s chocolate hacking challenge which spawned a number of interesting hacks. [Adric’s] doesn’t use pure chocolate (an experiment with a Hershey’s bar was a bust) but manages to ignite using a Milky Way bar.
This is not as unorthodox as you might think. Sugar and potassium nitrate have long been used to create solid rocket propellant. The chocolate version is swapping out plain old sugar for the candy bar. It was chopped into 10 gram chunks to make proportion calculations easier later on. The chunks go into the freezer to make them easier to grind using a mortar and pestle. Once it’s a somewhat chunk-free powder he mixes it with the potassium nitrate which previously had its own trip through the grinder. After being packed into a chunk of PVC pipe and fitted with an exhaust nozzle the engine is ready to go.
You can check out the test-fire video after the break. There’s a burn restriction in his area due to drought so this is just an engine test and not an actual rocket launch.
