Distant Stars // Shooting Star Testing // NASA’s Deep Space Network | S27E06

[00:00:00] This is SpaceTime Series 27 Episode 6 for broadcast on the 12th of January 2024. Coming up on SpaceTime, distant stars spotted in the Magellanic Stream for the first time, NASA begins testing its new Shooting Star spaceplane, and the Deep Space Network turns 60. All that and more coming up on SpaceTime.

[00:00:25] Welcome to SpaceTime with Stuart Gary. Astronomers have discovered 13 stars in the Magellanic Stream, a colossal ribbon of high-velocity neutral hydrogen gas spanning the Magellanic Cloud galaxies, which are two of the Milky Way galaxies' nearest cosmic neighbors. The Magellanic Stream leading arm extends over 600,000 light-years from the large and

[00:01:03] small Magellanic Cloud galaxies through the galactic south pole of the Milky Way. Its composition suggests that it's mostly composed of gas from the small Magellanic Cloud, which is less massive and so less able to hold onto its gas.

[00:01:18] A separate stream of neutral hydrogen known as the Magellanic Bridge links the two Magellanic Clouds. Observations have already shown there's a continuous stream of stars throughout the Magellanic Bridge with a greater constellation of stars nearer the small Magellanic Cloud.

[00:01:33] But for nearly 50 years, astronomers have been coming up empty when they searched for stars in the Magellanic Stream. Now the star search is finally over, with astronomers identifying 13 stars whose distances, motion, and chemical makeup place the stars squarely within the enigmatic stream.

[00:01:52] And locating these stars has now finally also pinned down the true distance to the Magellanic Stream, revealing that it extends from 150,000 light-years to more than 400,000 light-years away. The findings reported in the Astrophysical Journal paved the way for astronomers to map

[00:02:08] and model the Magellanic Stream in unprecedented detail, thereby offering new insights into the history and characteristics of both our galaxy and its two near neighbors. The study's lead author, Vinant Chandra from the Harvard-Smithsonian Center for Astrophysics, says the Magellanic Stream dominates the southern hemisphere skies.

[00:02:27] And with these results, scientists hope to gain a far greater understanding of the formation of the Magellanic Stream and the Magellanic Clouds, as well as their past and future interactions with our own galaxy, the Milky Way.

[00:02:39] With the advent of increasingly powerful telescopes able to perceive phenomena too faint for the human eye to see, astronomers in the early 1970s discovered a gigantic plume of hydrogen gas apparently cast out by the Magellanic Clouds.

[00:02:54] Studies of the gas within this Magellanic Stream as it became known further showed the stream to have two interwoven filaments, with one originating from each cloud. And these suggest that the gravity of the Milky Way galaxy might have pulled the Magellanic Stream out of the clouds.

[00:03:10] Yet exactly how the Magellanic Stream formed has remained challenging to nail down, partly because its presumed stellar components have until now remained indiscernible. So Chandra began by studying the uncharted frontier of the Milky Way, the scant stars

[00:03:25] dotting our galaxy's outskirts, which have been little studied because our solar system is smack bang in the middle of the starry disk of the Milky Way. And that's like a concertgoer near the stage trying to see someone who's just entered the

[00:03:37] arena and is still at the outer edge of the crowd. But over the past decade, deep observational catalogues have been compiled by new instruments, including the European Space Agency's Gaia spacecraft. This has allowed astronomers to start spying stellar objects that might just be these elusive frontier stars.

[00:03:55] Then using the 6.5-metre Magellan Baid telescope at the Las Campanas Observatory in Chile, Chandra and colleagues were able to perform spectroscopy on 200 far-flying Milky Way stars, which when completed will be the largest such sample surveyed to date.

[00:04:11] Spectroscopy involves collecting enough light from an object to detect specific chemical signatures, imprints within the light's colour bands that, like fingerprints, uniquely identify individual chemical elements. These signatures disclose the chemical makeup of an object and therefore speak to its origins.

[00:04:29] Now importantly, these chemical signatures also shift based depending on the object's distance, or really the speed at which it's moving away from us, which in turn is an expression of distance. The spectroscopic analysis revealed a set of 13 stars with distances and velocities

[00:04:45] that fall right within the range expected for the Magellanic Stream. The stars' chemical abundances match those for the Magellanic Clouds. For example, they were distinctively deficient in heavier elements astronomers call metals. By obtaining solid distance and velocity measurements for the Magellanic Stream by way of these

[00:05:04] stars, the authors showed that a gravitational tidal stream generated by the huge mass of the Milky Way best explained what was going on. The researchers were also able to calculate the stream's overall gas distribution with higher confidence compared to previous estimates.

[00:05:19] And the distribution indicates the stream is actually about twice as massive as previously thought. The findings also mean that the Milky Way itself will continue producing many more stars for many, many more generations. That's because the stream is actively falling into our galaxy, thereby serving as a primary

[00:05:38] provider of cold neutral hydrogen gas which is needed for fresh Milky Way stars. Further studies of the Magellanic Stream will also help astronomers learn more about the composition of our own galaxy. Because the stream is thought to trace the past paths of the Magellanic Clouds, modelling

[00:05:54] the evolution of the relatively large Magellanic Cloud by way of the stream will improve measurements of the Milky Way's own mass distribution. Much of that mass is in the form of mysterious dark matter, an invisible, poorly understood gravity-exerting substance.

[00:06:10] Better gauging the mass of our own galaxy out to its distant hinterlands will aid in accounting for ordinary matter versus dark matter contents constraining the possible properties of the latter. This is Space Time.

[00:06:24] Still to come, NASA begins testing its new shooting star space plane and the Deep Space Network turns 60. All that and more still to come on Space Time. Okay, let's take a break from our show for a word from our sponsor NordVPN.

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[00:08:56] Your safer digital universe awaits. And now it's back to our show. This is Space Time with Steward Gary. The first completed Dream Chaser spaceplane Tenacity is now undergoing a comprehensive testing campaign at NASA's Neil Armstrong Test Facility in Ohio in preparation for its

[00:09:17] first orbital flight to the International Space Station. And Tenacity has now been joined in Ohio by the first completed Shooting Star cargo module, which will eventually be attached to the rear of the spaceplane to increase capacity.

[00:09:31] Shooting Star is an expendable pressurized cargo module capable of carrying an additional 4.5 tons of supplies and equipment on top of the 5 tons the Dream Chaser will transport. It boasts three external mounting ports, enhancing its versatility in space operations.

[00:09:48] Under NASA's Commercial Resupply Services 2 contract, the Dream Chaser and Shooting Star will transport critical science, food and other cargo to the space station from this year. The reusable Dream Chaser spaceplane will return to Earth after each mission, loaded

[00:10:03] with completed experiments and equipment, landing on the former Space Shuttle runway at the Kennedy Space Center. Shooting Star, however, is expendable. It will be filled with space station disposable waste and then undocked and allowed to burn up in Earth's atmosphere.

[00:10:20] Dream Chaser was originally designed to transport up to seven people on crew transfer missions to the space station, but it lost out to SpaceX's Dragon capsule and the troubled Boeing CST-100 Starliner in NASA's Commercial Crew Transport contract.

[00:10:35] Instead, Dream Chaser has been awarded a commercial cargo contract, and it's lucrative enough that as well as Tenacity, a second Dream Chaser is currently under construction. A third Dream Chaser was built as an engineering demonstrator for ground and flight verification validation tests.

[00:10:52] Once approved for spaceflight by NASA, the Dream Chaser system will launch with its wings folded inside a 5-meter fairing aboard a United Launch Alliance Vulcan Centaur rocket from Space Launch Complex 41 at the Cape Canaveral Space Force Station in Florida.

[00:11:07] The fairing panels are designed to protect the spacecraft during its ascent into orbit and their jettisoned once-clear of Earth's atmosphere. Sierra Space say each of their Dream Chaser spaceplanes will be able to fly at least 15 missions over a 10-year lifespan.

[00:11:22] Sierra Space also plans to use Dream Chaser to launch and build its own orbiting habitat in space before NASA retires the International Space Station in 2030. The Dream Chaser lifting body design isn't new. In fact, it goes back over 60 years with its origins in the United States Air Force's

[00:11:40] 1957 X-20 Dinosaur spacecraft, a manned spaceplane which would be launched aboard a modified Titan III rocket. When NASA was formed in 1958, it continued with the development of the Dream Chaser concept through the 1960s and early 70s. There were a range of experimental spacecraft, all variations of the same design.

[00:12:02] These include the Northrop M-2, the Martin X-23 Prime, the Martin Marinetta X-24, and the Northrop HL-10. Then during the 1990s, NASA used the same basic design to develop the HL-20, an experimental spaceplane which eventually evolved into the X-38 Emergency Crew Return Vehicle, which

[00:12:21] was meant to be an emergency escape pod transported to the International Space Station in the payload bay of the space shuttle. It would then have simply docked to the orbiting outpost until needed. However, that project was cancelled in 2002 following budget cuts.

[00:12:37] As for the Shooting Star Cargo module which will be attached to the Dream Chaser, well the Pentagon has been looking at that as a potential autonomous unmanned military space station for research and development, training and operational missions in low-Earth orbit.

[00:12:51] Sierra Space Planet are designing a version of the module using guidance, navigation and control systems to sustain free flight operations. It would host specialized payloads, undertake experimental testing, the manufacture and assembly of components in microgravity, and carry a range of logistics.

[00:13:09] Longer term plans would include higher elliptical and geosynchronous Earth orbits as well as more distant lunar missions. This is Space Time. Still to come, NASA's Deep Space Network turns 60, and later in the Science Report,

[00:13:24] new studies warn that droughts will become more frequent and more severe as climate change takes hold. All that and more still to come on Space Time. NASA's Deep Space Network, which provides crucial communications and navigation services for dozens of missions, has just turned 60.

[00:13:58] The Deep Space Network's roots extend back to 1957 when JPL, the Jet Propulsion Laboratory in Pasadena, California, which is attached to Caltech, was contracted by the US Army to deploy portable radio tracking stations to receive telemetry from the first successful US satellite, Explorer 1, which was also built by JPL.

[00:14:19] Few days after Explorer 1's launch, but before the creation of NASA later that year, JPL was tasked with figuring out what would be needed to create an unprecedented telecommunications network capable of supporting future deep space operations, beginning with the Pioneer missions.

[00:14:35] After NASA was formed in 1958, JPL's ground stations were named Deep Space Information Facilities and they operated largely independently from one another until 1963. That's when the Deep Space Network was officially founded and the ground stations were connected to JPL's new Network Control Center, which was then nearing completion.

[00:14:57] Called the Space Flight Operations Facility, the building remains the center of the universe, through which data from the Deep Space Network's three global complexes flow. The dazzling galactic images captured by the James Webb Space Telescope, the cutting-edge

[00:15:11] science being sent back to Earth by the Mars Perseverance rover, and historic images sent from the far side of the Moon by the Artemis 1 mission, all reach Earth by where the network's giant radio dish antennas.

[00:15:24] Currently more than 40 missions depend on the network, but that's expected to more than double over the coming years. And because of this, NASA are expanding and modernizing its crucial infrastructure with new dishes and new technologies. To ensure spacecraft are always connected with Earth, the Deep Space Network's 14 antennas

[00:15:42] are divided between three complexes spaced equally around the world. They're located in Goldstone, California, Madrid, Spain, and at Tidbinbilla, just outside Canberra in Australia. The 60th anniversary comes as the network undertakes a major modernization program.

[00:16:00] To make sure the network can maximize coverage between so many missions, NASA's also been busy making improvements to increase capacity. These range from upgrading and adding new dishes, to developing new technologies that will help support more spacecraft and dramatically increase the amount of data that can be delivered.

[00:16:18] This includes new laser optical communications systems, which enable far more data to be packed into a transmission. The Deep Space Network's Deputy Project Manager Amy Smith from JPL says laser communications could transform how NASA communicates with faraway space missions.

[00:16:35] After successfully testing the technique first in Earth orbit and then out as far as the moon, NASA is currently using the Deep Space Optical Communications Technology demonstration to test laser communications from even greater distances aboard the Psyche mission.

[00:16:49] The latest tests to send video communications by way of laser are over a distance of 31 million kilometers, and the current plan is to send high bandwidth data from beyond Mars. Smith says NASA's proving that laser communications is viable, and so the team is now looking

[00:17:07] at ways to build optical terminals inside the existing radio antennas. These hybrid antennas will still be able to transmit and receive radio frequencies, but will also support the new optical frequencies. As well as communications and navigation, the Deep Space Network is also used for scientific

[00:17:24] research such as gravity and radio wave experiments. These can tell scientists characteristics about celestial bodies being visited by spacecraft, as this report from NASA TV explains. NASA has dozens of robotic spacecraft exploring our solar system and beyond. Scientists and engineers communicate with and navigate faraway spacecraft using the

[00:17:47] Deep Space Network, NASA's international collection of giant radio antennas used to communicate with spacecraft at the moon and beyond. But the Deep Space Network, or DSN, is more than just a messaging service. In fact, scientists use the DSN to perform radio and gravity science experiments.

[00:18:07] But what is radio and gravity science, and how can it help us learn more about the planets, moons, and other small bodies in our solar system? We are all familiar with gravity. It's the force by which an object attracts other objects, such as a planet pulling a

[00:18:22] spacecraft toward it. Gravity is also the force that keeps all of the planets in orbit around the sun. Here on Earth we experience this every day. If you drop an object, it will accelerate toward the ground because Earth's gravity causes it to fall faster and faster.

[00:18:39] And the acceleration of a spacecraft toward a planet depends on the mass of the planet. Less mass means less gravitational pull. These properties of gravity, combined with our understanding of radio waves, help us use gravity to study other planetary bodies in our solar system.

[00:18:56] After reaching its destination, a spacecraft uses radio antennas to communicate with the deep space network on Earth, which in turn transmits radio signals back to the spacecraft. Every spacecraft travels in a predetermined path, emitting radio signals as it orbits around its target.

[00:19:14] Scientists and engineers can infer the spacecraft's location and how fast it's going by measuring changes in the spacecraft's radio signal frequency. This is made possible by the Doppler effect, the same phenomenon that causes a siren to sound different as it travels towards and away from you.

[00:19:31] The Doppler phenomenon is observed here when the spacecraft and the DSN antenna move in relation to each other. Differences between the frequency of radio signals sent by the spacecraft as it orbits and signals received on Earth give us details about the gravitational field of a planetary body.

[00:19:49] For example, if the gravity is slightly stronger, the spacecraft will accelerate slightly more. If gravity is slightly weaker, the spacecraft will accelerate slightly less. By developing a model of the planetary body's gravitational field, which can be mapped as

[00:20:03] a gravitational shape, scientists and researchers can deduce information about its internal structure – all while using the deep space network. This is Space Time, and time now to take another brief look at some of the other stories making news in science this week with the Science Report.

[00:20:37] A latest study into reducing your risk of getting Alzheimer's disease claims getting at least 140 minutes of vigorous exercise every week is optimal. The findings, reported in the Lancet Medical Journal, use data from a long-term health survey in the United States looking at how moderate and vigorous exercise interacted

[00:20:55] with the risk of going on to die as a result of Alzheimer's. The researchers say they did not find an association between moderate exercise and Alzheimer's risk, however vigorous exercise between 20 and 190 minutes a week was associated with

[00:21:09] a lower risk of death from Alzheimer's, with 140 minutes estimated to be the optimal amount. A new study has confirmed that droughts will become more frequent and more severe under climate change. The findings, reported by the United Nations Convention to Combat Desertification, outlines

[00:21:27] how different regions are already experiencing more numerous and intense droughts, and how food insecurity will further increase in the coming decades. The report's authors warn that drought can often be a silent hazard compared to other

[00:21:40] disasters that occur more rapidly, however they have severe impacts on lives and economies wherever they occur. A new study warns that living at home with your parents well into your adulthood isn't good for your mental health.

[00:21:54] The rate of young adults who are still living at home with their parents well into their twenties has increased by about 18 percent over the past 20 years. The findings, reported in the journal PLOS One, are based on a large Australian Housing,

[00:22:08] Income and Work database looking at the amount and types of young people staying at home with their parents. The authors found the number of young people staying at home has increased most sharply among people living outside major cities, among older adults, and among women and low-income groups.

[00:22:25] The researchers found that living with parents was associated with poorer mental health. But this association differed depending on the young person, with those aged 18 to 21 likely to actually have better mental health if they lived at home longer.

[00:22:39] The association between living with parents and poorer mental health were strongest among older groups who had seen the highest increase in living at home over the study period. The Indian government is once again actively pushing worthless pseudoscience as medical treatments.

[00:22:56] Tim Mindham from Australian Skeptic says the issue has now become so bad, legitimate medical practitioners are being cancelled by government officials so as to keep the fake treatments going. The Indian government has a department, a ministry called AYUSH, which stands for Ayurveda, Yoga, Unani, Siddha and Homeopathy.

[00:23:18] And it is promoting, one is promoting research on these things which is a decent thing to do to see if they actually work. Two, it's promoting the modalities because they think it works already.

[00:23:28] And strangely homeopathy is in that mix even though they're about as un-Indian as you can get. That's a European based thing which is thoroughly debunked and shouldn't be mixed in with anything. Ayurveda is a traditional Indian medicine, it's quite widely used in India especially

[00:23:42] in a place where there's sort of proper medical facilities aren't that widespread or aren't that effective. Yoga we know about, it's because the exercise routine has a spiritual element to it. Naturopathy, another Western idea based on the idea of vitalism that the body can cure

[00:23:54] itself all you need is a bit of a nut. And Unani and Siddha which are variations of Ayurveda, they all rely on the humours, earth, air, sky, water or blood, bile, would it be one of the particular ones you want to

[00:24:06] use and depending on which one it has various different numbers of humours. Unani is actually a Western Indian and keep going West Persian Arabic system that relies on the humours to cure things instead of ancient background in ancient Greek medicine.

[00:24:22] Hippocrates, Siddha is similar mainly in the south of India again based on humours. There's a lot of practitioners of this stuff and hundreds of thousands of practitioners going through especially rural India where medical facilities are not good if they exist

[00:24:35] and therefore people easily going through and they're offering herbal cures and all sorts of various things like that. The problem is that it's unregulated, the practitioners are not certified, it's various slackness as far as the standardized doses go, you got unknown ingredients in a lot

[00:24:51] of them, they might be adulterated in any case, they might be dangerous contaminated ingredients and all sorts of issues with them. One of which someone complains is that some of the homeopathic treatments have too much

[00:25:01] alcohol in them which is interesting thing that you take a homeopathic treatment, you get drunk. The government is pushing this because it is a traditional thing, it's a little pride thing the same way as the Chinese government pushing traditional Chinese medicine.

[00:25:12] It also acts as a bit of a buffer against poor medical evidence-based medicine facilities especially in regional areas, small towns, that sort of thing and there is a movement against it. There is a scientist coming out and the scientific bodies actually saying that this is rubbish

[00:25:26] and it's certainly not helpful and one guy in particular who's quite well known, he calls himself the liver doc on his social media. He's actually Dr. Suryak Abbey Phillips, he's an Indian hepatologist which I think

[00:25:38] is a liver doctor and he's seen first of all some of these patients using these treatments, these alternative treatments having problems with their liver, it was damaging them. So he has now come out, he's a bit of a social media figure and because he's public and making

[00:25:51] criticisms for people who's criticizing get upset. There's one particular group that I think was called the Himalaya Wellness Corporation which objected to his criticism of their products and they had him banned through the courts from X or Twitter. We used to call it Twitter, yeah.

[00:26:07] But we used to actually call it Twitter anyway so you know, I can't say X, it sounds silly. And but yes, again, I mean sort of you probably come across this situation where someone doesn't like what you're saying and the same thing happened to this liver doc.

[00:26:19] Now he's quite well known, he appears regularly, you can look him up and find out what he's saying. He's waging this campaign as a solo performer if you like against a lot of highly, not just disproven but dangerous products.

[00:26:30] But also other scientific bodies are doing the same thing. Despite this, the government in India has set up this ministry to promote it. So they're in a cleft stick there. But they will continue to try and they have little successes.

[00:26:40] It's not the old story, one step forward, two steps sideways, three back. But they'll keep doing it as the skeptics keep doing it because it's the right thing to do. Cancer culture is everywhere. Yeah. That's Tim Endam from Australian Skeptics. And that's the show for now.

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