It Could be Possible to Transfer Data Through Gravitational Waves

On February 11th, 2016, scientists at the Laser Interferometer Gravitational-wave Observatory (LIGO) made history when they announced the first detection of gravitational waves. Originally predicted made by Einstein’s Theory of General Relativity a century prior, these waves are essentially ripples in space-time that are formed by major astronomical events – such as the merger of a binary black hole pair.

This discovery not only opened up an exciting new field of research, but has opened the door to many intriguing possibilities. One such possibility, according to a new study by a team of Russian scientists, is that gravitational waves could be used to transmit information. In much the same way as electromagnetic waves are used to communicate via antennas and satellites, the future of communications could be gravitationally-based.

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A New Solution to the Space Junk Problem. Spacecraft with Plasma Beams to Force Space Junk to Burn Up

A satellite using a bi-directional plasma thruster can direct one beam at space junk, sending it harmlessly into Earth's atmosphere. The other opposite beam can stabilize the position of the satellite itself. Image: Takahashi et. al. 2018.

Space junk is a growing problem. For decades we have been sending satellites into orbit around Earth. Some of them de-orbit and burn up in Earth’s atmosphere, or crash into the surface. But most of the stuff we send into orbit is still up there.

This is becoming an acute problem as years go by and we launch more and more hardware into orbit. Since the very first satellite—Sputnik 1—was launched into orbit in 1957, over 8000 satellites have ben placed in orbit. As of 2018, an estimated 4900 are still in orbit. About 3000 of those are not operational. They’re space junk. The risk of collision is growing, and scientists are working on solutions. The problem will compound itself over time, as collisions between objects create more pieces of debris that have to be dealt with.

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Look at all the Aerosols Pushed into the Atmosphere, from Fires, Volcanoes and Pollution. Even Sea Salt Thrown into the Air from Hurricanes

Stand outside and take deep breath. Do you know what you’re breathing? For most people, the answer is simple – air. And air, which is essential to life as we know it, is composed of roughly twenty-percent oxygen gas (O²) and seventy-eight percent nitrogen gas (N²). However, within the remaining one-percent and change are several other trace gases, as well as few other ingredients that are not always healthy.

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A Satellite With a Harpoon, Net and Drag Sail to Capture Space Junk is in Orbit and Will be Tested Soon

After almost seventy years of spaceflight, space debris has become a rather serious problem. This junk, which floats around in Low Earth Orbit (LEO), consists of the spent first rocket stages and non-functioning satellites and poses a major threat to long-term missions like the International Space Station and future space launches. And according to numbers released by the Space Debris Office at the European Space Operations Center (ESOC), the problem is only getting worse.

In addition, space agencies and private aerospace companies hope to launch considerably more in the way of satellites and space habitats in the coming years. As such, NASA has begun experimenting with a revolutionary new idea for removing space debris. It is known as the RemoveDebris spacecraft, which recently deployed from the ISS to conduct a series of Active Debris Removal (ADR) technology demonstrations.

This satellite was assembled by Surrey Satellite Technology Ltd. and the Surrey Space Center (at the University of Surrey in the UK) and contains experiments provided by multiple European aerospace companies. It measures roughly 1 meter (3 feet) on a side and weighs about 100 kg (220 lbs), making it the largest satellite deployed to the ISS to date.

The purpose of the RemoveDebris spacecraft is to demonstrate the effectiveness of debris nets and harpoons at capturing and removing space debris from orbit. As Sir Martin Sweeting, the Chief Executive of SSTL, said in a recent statement:

“SSTL’s expertise in designing and building low cost, small satellite missions has been fundamental to the success of RemoveDEBRIS, a landmark technology demonstrator for Active Debris Removal missions that will begin a new era of space junk clearance in Earth’s orbit.”

Aside from the Surrey Space Center and SSTL, the consortium behind the RemoveDebris spacecraft includes Airbus Defense and Space – the world’s second largest space company – Airbus Safran Launchers, Innovative Solutions in Space (ISIS), CSEM, Inria, and Stellenbosch University. The spacecraft, according to the Surrey Space Center’s website, consists of the following:

“The mission will comprise of a main satellite platform (~100kg) that once in orbit will deploy two CubeSats as artificial debris targets to demonstrate some of the technologies (net capture, harpoon capture, vision-based navigation, dragsail de-orbitation). The project is co-funded by the European Commission and the project partners, and is led by the Surrey Space Centre (SSC), University of Surrey, UK.”

For the sake of the demonstration, the “mothership” will deploy two cubesates which will simulate two pieces of space junk. For the first experiment, one of the CubeSats  – designated DebrisSat 1 – will inflate its onboard balloon in order to simulate a larger piece of junk. The RemoveDebris spacecraft will then deploy its net to capture it, then guide it into the Earth’s atmosphere where the net will be released.

The second CubeSat, named DebrisSat 2, will be used to test the mothership’s tracking and ranging lasers, its algorithms, and its vision-based navigation technology. The third experiment, which will test the harpoon’s ability to capture orbiting space debris, is set to take place next March. For legal reasons, the harpoon will not be tested on an actual satellite, and will instead consist of the mothership extending an arm with a target on the end.

The harpoon will then be fired on a tether at 20 meters per second (45 mph) to tests it accuracy. After being launched to the station back on April 2nd, the satellite was deployed from the ISS’ Japanese Kibo lab module on June 20th by the stations’ Canadian robotic arm. As Guillermo Aglietti, the director of the Surrey Space Center, explained in an interview with SpaceFlight Now before the spacecraft was launched to the ISS:

“The net, as a way to capture debris, is a very flexible option because even if the debris is spinning, or has got an irregular shape, to capture it with a net is relatively low-risk compared to … going with a robotic arm, because if the debris is spinning very fast, and you try to capture it with a robotic arm, then clearly there is a problem. In addition, if you are to capture the debris with a robotic arm or a gripper, you need somewhere you can grab hold of your piece of debris without breaking off just a chunk of it.”

The net experiment is currently scheduled for September of 2018 while the second experiment is scheduled for October. When these experiments are complete, the mothership will deploy its dragsail to act as a braking mechanism. This expandable sail will experience collisions with air molecules in the Earth’s outer atmosphere, gradually reducing its orbit until it enters the denser layers of Earth’s atmosphere and burns up.

This sail will ensure that the spacecraft deorbits within eights weeks of its deployment, rather than the estimated two-and-half years it would take to happen naturally. In this respect, the RemoveDebris spacecraft will demonstrate that it is capable of tackling the problem of space debris while not adding to it.

In the end, the RemoveDebris spacecraft will test a number of key technologies designed to make orbital debris removal as simple and cost-effective as possible. If it proves effective, the ISS could be receiving multiple RemoveDebris spacecraft in the ftureu, which could then be deployed gradually to remove larger pieces of space debris that threaten the station and operational satellites.

Conor Brown is the external payloads manager of Nanoracks LLC, the company that developed the Kaber system aboard the Kibo lab module to accommodate the increasing number of MicroSats being deployed from the ISS. As he expressed in a recent statement:

“It’s wonderful to have helped facilitate this ground-breaking mission. RemoveDebris is demonstrating some extremely exciting active debris removal technologies that could have a major impact to how we manage space debris moving forward. This program is an excellent example of how small satellite capabilities have grown and how the space station can serve as a platform for missions of this scale. We’re all excited to see the results of the experiments and impact this project may have in the coming years.”

In addition to the RemoveDebris spacecraft, the ISS recently received a new tool for detecting space debris. This is known as the Space Debris Sensor (SDS), a calibrated impact sensor mounted on the exterior of the station to monitor impacts caused by small-scale space debris. Coupled with technologies designed to clean up space debris, improved monitoring will ensure that the commercialization (and perhaps even colonization) of LEO can begin.

Further Reading: Spaceflight Now, RemoveDEBRIS

Musk Says that SpaceX will use a Giant Party Balloon to Bring an Upper Stage Back. Wait, what?

When Elon Musk of SpaceX tweets something interesting, it generates a wave of excitement. So when he tweeted recently that SpaceX might be working on a way to retrieve upper stages of their rockets, it set off a chain of intrigued responses.

SpaceX has been retrieving and reusing their lower stages for some time now, and it’s lowered the cost of launching payloads into space. But this is the first hint that they may try to do the same with upper stages.

Twitter responders wanted to know exactly what SpaceX has in mind, and what a “giant party balloon” might be. Musk hasn’t elaborated yet, but one of his Twitter followers had something interesting to add.

Quinn Kupec, a student at the University of Maryland’s James Clark School of Engineering tweeted to Musk:

Universe Today contacted Mr. Kupec to see if he could help us understand what Musk may have been getting at. But first, a little background.

An “ultra low ballistic entry coefficient decelerator” is a bit of a mouthful. The ballistic coefficient measures how well a vehicle can overcome air resistance in flight. A high ballistic coefficient means a re-entry vehicle would not lose velocity quickly, and would reach Earth at high speeds. An ultra low ballistic entry coefficient decelerator would lose speed quickly, meaning that a vehicle would be travelling at low, subsonic speeds before reaching the ground.

To recover an upper stage booster, low speeds are desirable, since they generate less heat. But according to Kupec, there’s another problem that must be overcome.

“What happens when these things slow down to landing velocities? If your center of gravity is offset significantly behind your center of drag, as would be the case with a returning upper stage, it can get unstable. If the center of gravity of the re-entry vehicle is too high, it can become inverted, which is obviously not desirable.”

So the trick is to lower the speed of the re-entry vehicle to the point where the heat generated by reentry isn’t damaging the booster, and to do it without causing the vehicle to invert or otherwise become unstable. This isn’t a problem for the main stage boosters that SpaceX now routinely recovers; they have their own retro-rockets to guide their descent and landing. But for the upper stage boosters, which reach orbital velocities, it’s an obstacle that has to be overcome.

“My research is specifically focused on how high you can push the center of gravity and still maintain the proper flight configuration,” said Kupec.

But what about the “giant party balloon” that Musk tweeted about?

Musk could be referring, in colorful terms, to what’s called a ballute. The word is a combination of the words balloon and parachute. They were invented in the 1950’s by Goodyear Aerospace. They can arrest the descent of entry vehicles and provide stability during the descent.

“…the balloon would have to be 120 ft. in diameter, and made of a high-temperature fabric…” – Professor Dave Akin, University of Maryland

Universe Today contacted Professor Dave Akin of the University of Maryland for some insight into Musk’s tweet. Professor Akin has been working on reentry systems for over 2 decades.

In an e-mail exchange, Professor Akin told us, “There have been concepts proposed for deploying a large balloon on a cable that is towed behind you on entry. The balloon lowers your ballistic coefficient, which means you decelerate higher in the atmosphere and the heat load is less.” So the key is to scrub your speed before you get closer to Earth, where the atmosphere is thicker and generates more heat.

But according to Professor Akin, this won’t necessarily be easy to do. “To get the two orders of magnitude reduction in ballistic coefficient that Elon has been talking about the balloon would have to be 120 ft. in diameter, and made of a high-temperature fabric, so it’s not going to be all that easy.”

But Musk’s track record shows he doesn’t shy away from things that aren’t easy.

Retrieving upper rocket stages isn’t all about lowering launch costs, it’s also about space junk. The European Space Agency estimates that there are over 29,000 pieces of space junk orbiting Earth, and some of that junk is spent upper stage boosters. There have been some collisions and accidents already, with some satellites being pushed into different orbits. In 2009, the Iridium 33 communications satellite and the defunct Russian Cosmos 2251 communications satellite collided with each other, destroying both. If SpaceX can develop a way to retrieve its upper stage boosters, that means less space junk, and fewer potential collisions.

There’s a clear precedent for using balloons to manage reentry. With people like Professor Akin and Quinn Kupec working on it, SpaceX won’t have to reinvent the wheel. But they’ll still have a lot of work to do.

Musk tweeted one other thing shortly after his “giant party balloon” tweet:

No word yet on what that might mean.

Elon Musk’s “giant party balloon” tweet: https://twitter.com/elonmusk/status/985655249745592320
Quinn Kupec’s tweet: https://twitter.com/QuinnKupec/status/985736260827471872

Launching Rockets from Balloons is About to be a Thing, But We Need a Better Name than “Rockoons”

One of the technological hurdles of our age is to get people and equipment into space more cheaply. SpaceX gets a lot of the headlines around that, with their reusable rockets. And so does Blue Origin, to some degree. Now a small start-up affiliated with Purdue University is tackling the problem and making some headway.

The company is called Leo Aerospace LLC and they’re using balloons to lower the cost of putting micro-satellites into orbit, rather than reusable rockets. The balloons will be reusable, but the rockets won’t.

Leo Aerospace plans to revive a decades-old method of putting satellites into space. They’re using hot air balloons to lift the rocket and its micro-satellite payload 18 km (11 miles) above Earth. At that altitude, there’s 95% less atmosphere. This means much less drag on the rocket, which translates into smaller rockets with less fuel. This is an intriguing idea, if not for the unfortunate name.

The rockoons will be used to launch rockets into sub-orbital and orbital flights. Sub-orbitals are often used by researchers because it gives them access to zero gravity and to vacuum, both of which are necessary for some experiments. According to Leo Aerospace, there’s something revolutionary about their plans.

“We’re targeting the microsatellites by saying, ‘You don’t have to ride-share with anyone. We can guarantee you will be our only payload and we will be focused on you.’” – Drew Sherman, Leo Aerospace’s Head of Vehicle Development.

They intend on targeting micro-satellite developers. Micro-satellites are often hitch-hikers on larger payloads, which basically means they’re second-class customers. They have to wait until there’s room for their micro-satellite on a traditional rocket carrying a larger payload. This can mean long delays of several months, and that micro-satellite developers have to compromise when it comes to the orbits they can obtain. It can also make micro-satellite missions difficult to plan and execute efficiently and economically. Micro-satellites are becoming more and more capable, so having a launch system tailor-made for them could indeed be revolutionary.

“We’re targeting the microsatellites by saying, ‘You don’t have to ride-share with anyone. We can guarantee you will be our only payload and we will be focused on you,’” said Drew Sherman, Leo Aerospace’s head of vehicle development. “‘We will work with you exclusively to get you into orbit. You won’t have to worry about other payloads or getting dropped off in the wrong spot.’”

The flexibility of the rockoon system that Leo Aerospace is developing will be intriguing for micro-satellites. Rockoons will give micro-satellites the flexibility they need to operate efficiently. The launch can be scheduled and adapted to the needs of the individual satellite. “Our goal is to give people access to space. The only way to do that right now is to help people get their satellite into orbit. That’s where we want to leave our mark,” said Abishek Murali, Head of Mission Engineering at Leo Aerospace.

“Our goal is to give people access to space.” – Abishek Murali, Head of Mission Engineering at Leo Aerospace

The rockoon itself is a hybrid of a balloon and a rocket. The hybrid design takes advantage of physics by using the balloon to float the rocket 18 km high before launching the rocket. The rockoon has Leo Aerospace’s own patent-pending technology to control the pitch and angle of the launch, allowing for precision launches.

Rockoons were first used by the US Air Force back in the 1950s. But this next generation of rockoons, coupled with modern micro-satellites, will be much more capable than the 1950s technology.

Leo Aerospace LLC was started by five then-Purdue University students as a club and then turned into a business. The founders are, from left, Mike Hepfer, head of product development; Drew Sherman, head of vehicle development; Abishek Murali, head of mission engineering; Dane Rudy; chief executive officer; and Bryce Prior, head of operations and strategy. Image: Leo Aerospace.

Currently, Leo Aerospace is in the development and funding phase. They’ve obtained some funding from the National Science Foundation, and from a venture capital firm. They have about half of the $250,000 they need. They plan to conduct their first sub-orbital flight in 2020, and to launch their first micro-satellite into orbit in 2022. They intend to use existing approved launch sites.

Leo Aerospace was founded by five then-students at Purdue University. Leo started as a club, but the former students have turned it into a business. And that business seems to have a bright future. They conducted a customer discovery and market validation study and found a large demand for a better way to launch micro-satellites.

“We want to be part of the space market,” Murali said. “People are interested in space and creating technologies that not only can operate in space but also help people back on Earth. What we’re trying to do is help them get there.”

But they still need a better name than “rockoons.”

Now That NASA’s Missing IMAGE Satellite Has Been Found, Talking To It Is Going To Be Difficult

It’s easy to imagine the excitement NASA personnel must have felt when an amateur astronomer contacted NASA to tell them that he might have found their missing IMAGE satellite. After all, the satellite had been missing for 10 years.

IMAGE, which stands for Imager for Magnetopause-to-Aurora Global Exploration, was launched on March 25th, 2000. In Dec. 2005 the satellite failed to make routine contact, and in 2007 it failed to reboot. After that, the mission was declared over.

NASA’s IMAGE satellite. Credit: NASA

It’s astonishing that after 10 years, the satellite has been found. It’s even more astonishing that it was an amateur who found it. As if the story couldn’t get any more interesting, the amateur astronomer who found it—Scott Tilly of British Columbia, Canada—was actually looking for a different missing satellite: the secret ZUMA spy satellite launched by the US government on January 7, 2018. (If you’re prone to wearing a tin foil hat, now might be a good time to reach for one.)

NASA’s half-ton IMAGE satellite being launched from Vandenberg Air Force Base on March 25th, 2000. IMAGE was the first satellite designed to actually “see” most of the major charged particle systems in the space surrounding Earth. Image: NASA

After Tilly contacted NASA, they hurried to confirm that it was indeed IMAGE that had been found. To do that, NASA employed 5 separate antennae to seek out any radio signals from the satellite. As of Monday, Jan. 29, signals received from all five sites were consistent with the radio frequency characteristics expected of IMAGE.

In a press release, NASA said, “Specifically, the radio frequency showed a spike at the expected center frequency, as well as side bands where they should be for IMAGE. Oscillation of the signal was also consistent with the last known spin rate for IMAGE.”

“…the radio frequency showed a spike at the expected center frequency…” – NASA Press Release confirming the discovery of IMAGE

Then, on January 30, the Johns Hopkins Applied Physics Lab (JHUAPL) reported that they had successfully collected telemetry data from the satellite. In that signal was the ID code 166, the code for IMAGE. There were probably some pretty happy people at NASA.

So, now what?

A diagram of NASA’s IMAGE satellite. Image: NASA

NASA’s next step is to confirm without a doubt that this is indeed IMAGE. That means capturing and analyzing the data in the signal. That will be a technical challenge, because the types of hardware and operating systems used in the IMAGE Mission Operations Center no longer exist. According to NASA, “other systems have been updated several versions beyond what they were at the time, requiring significant reverse-engineering.” But that should be no problem for NASA. After all, they got Apollo 13 home safely, didn’t they?

If NASA is successful at decoding the data in the signal, the next step is to attempt to turn on IMAGE’s science payload. NASA has yet to decide how to proceed if they’re successful.

IMAGE was the first spacecraft designed to “see the invisible,” as they put it back then. Prior to IMAGE, spacecraft examined Earth’s magnetosphere by detecting particles and fields they encountered as they passed through them. But this method had limited success. The magnetosphere is enormous, and simply sampling a small path—while better than nothing—did not give us an accurate understanding of it.

During its mission, IMAGE did a lot of great science. In July 2000, a spectacular solar storm caused auroras as far south as Mexico. IMAGE captured these images of those poweful auroras. Credit: NASA

IMAGE was going to do things differently. It used 3-dimensional imaging techniques to measure simultaneously the densities, energies and masses of charged particles throughout the inner magnetosphere. To do this, IMAGE carried a payload of 7 instruments:

  • High Energy Neutral Atom (HENA) imager
  • Medium Energy Neutral Atom (MENA) imager
  • Low Energy Neutral Atom (LENA) imager
  • Extreme Ultraviolet (EUV) imager
  • Far Ultraviolet (FUV) imager
  • Radio Plasma Imager (RPI)
  • Central Instrument Data Processor (CIDP)

These instruments allowed IMAGE to not only do great science, and to capture great images, but also to create some stunning never-seen-before movies of auroral activity.

This is a fascinating story, and it’ll be interesting to see if NASA can establish meaningful contact with IMAGE. Will it have a treasure trove of unexplored data on-board? Can it be re-booted and brought back into service? We’ll have to wait and see.

This story is also interesting culturally. IMAGE was in service at a time when the internet wasn’t as refined as it is currently. NASA has mastered the internet and public communications now, but back then? Not so much. For example, to build up interest around the mission, NASA gave IMAGE its own theme song, titled “To See The Invisible.” Yes, seriously.

But that’s just a side-note. IMAGE was all about great science, and it accomplished a lot. You can read all about IMAGE’s science achievements here.

China Has a Plan to Clean Up Space Junk with Lasers

Orbital debris (aka. space junk) is one of the greatest problems facing space agencies today. After sixty years of sending rockets, boosters and satellites into space, the situation in the Low Earth Orbit (LEO) has become rather crowded. Given how fast debris in orbit can travel, even the tiniest bits of junk can pose a major threat to the International Space Station and threaten still-active satellites.

It’s little wonder then why ever major space agency on the planet is committed to monitoring orbital debris and creating countermeasures for it. So far, proposals have ranged from giant magnets and nets and harpoons to lasers. Given their growing presence in space, China is also considering developing giant space-based lasers as a possible means for combating junk in orbit.

One such proposal was made as part of a study titled “Impacts of orbital elements of space-based laser station on small scale space debris removal“, which recently appeared in the scientific journal Optik. The study was led by Quan Wen, a researcher from the Information and Navigation College at China’s Air Force Engineering University, with the help of the Institute of China Electronic Equipment System Engineering Company.

Graphic showing the cloud of space debris that currently surrounds the Earth. Credit: NASA’s Goddard Space Flight Center/JSC

For the sake of their study, the team conducted numerical simulations to see if an orbital station with a high-powered pulsed laser could make a dent in orbital debris. Based on their assessments of the velocity and trajectories of space junk, they found that an orbiting laser that had the same Right Ascension of Ascending Node (RAAN) as the debris itself would be effective at removing it. As they state in their paper:

“The simulation results show that, debris removal is affected by inclination and RAAN, and laser station with the same inclination and RAAN as debris has the highest removal efficiency. It provides necessary theoretical basis for the deployment of space-based laser station and the further application of space debris removal by using space-based laser.”

This is not the first time that directed-energy has been considered as a possible means of removing space debris. However, the fact that China is investigating directed-energy for the sake of debris removal is an indication of the nation’s growing presence in space. It also seems appropriate since China is considered to be one of the worst offenders when to comes to producing space junk.

Back in 2007, China conducted a anti-satellite missile test that resulted in the creation over 3000 of bits of dangerous debris. This debris cloud was the largest ever tracked, and caused significant damage to a Russian satellite in 2013. Much of this debris will remain in orbit for decades, posing a significant threat to satellites, the ISS and other objects in LEO.

The chip in the ISS’ Cupola window, photographed by astronaut Tim Peake. Credit: ESA/NASA/Tim Peake

Of course, there are those who fear that the deployment of lasers to LEO will mean the militarization of space. In accordance with the 1966 Outer Space Treaty, which was designed to ensure that the space exploration did not become the latest front in the Cold War, all signatories agreed to “not place nuclear weapons or other weapons of mass destruction in orbit or on celestial bodies or station them in outer space in any other manner.”

In the 1980s, China was added to the treaty and is therefore bound to its provisions. But back in March of 2017, US General John Hyten indicated in an interview with CNN that China’s attempts to develop space-based laser arrays constitutes a possible breach of this treaty:

“They’ve been building weapons, testing weapons, building weapons to operate from the Earth in space, jamming weapons, laser weapons, and they have not kept it secret. They’re building those capabilities to challenge the United States of America, to challenge our allies…We cannot allow that to happen.”

Such concerns are quite common, and represent a bit of a stumbling block when it comes to the use of directed-energy platforms in space. While orbital lasers would be immune to atmospheric interference, thus making them much more effective at removing space debris, they would also lead to fears that these lasers could be turned towards enemy satellites or stations in the event of war.

As always, space is subject to the politics of Earth. At the same time, it also presents opportunities for cooperation and mutual assistance. And since space debris represents a common problem and threatens any and all plans for the exploration of space and the colonization of LEO, cooperative efforts to address it are not only desirable but necessary.

 

Further Reading: Newsweek, Optik

Astronomy Cast Ep. 462: Modeling the Weather

Have you noticed that weather forecasting has gotten much better in the last few years? Thanks to weather satellites, weather stations, and better forecasting techniques. How do scientists predict the weather with any kind of accuracy days or even weeks in the future.

We usually record Astronomy Cast every Friday at 3:00 pm EST / 12:00 pm PST / 20:00 PM UTC. You can watch us live on AstronomyCast.com, or the AstronomyCast YouTube page.

Visit the Astronomy Cast Page to subscribe to the audio podcast!

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Astronomy Cast Ep. 461: Measuring the Weather with Satellites

What’s the weather doing? Is it going to rain today? How much? What about temperatures? We depend on modern weather forecasting, thanks, in part to the vast network of weather satellites. What instruments do they have, what orbits do they use.

We usually record Astronomy Cast every Friday at 3:00 pm EST / 12:00 pm PST / 20:00 PM UTC. You can watch us live on AstronomyCast.com, or the AstronomyCast YouTube page.

Visit the Astronomy Cast Page to subscribe to the audio podcast!

If you would like to support Astronomy Cast, please visit our page at Patreon here – https://www.patreon.com/astronomycast. We greatly appreciate your support!

If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!