NASA’s Hybrid Computer Enables Raven’s Autonomous Rendezvous Capability

A Young star rebels against its parent cloud

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10 Things: Mysterious 'Oumuamua

The interstellar object ‘Oumuamua perplexed scientists in October 2017 as it whipped past Earth at an unusually high speed. This mysterious visitor is the first object ever seen in our solar system that is known to have originated elsewhere.  Here are five things we know and five things we don’t know about the first confirmed interstellar object to pass through our solar system.

1. We know it’s not from around here.

 The object known as 1I/2017 U1 (and nicknamed ‘Oumuamua) was traveling too fast (196,000 mph, that’s 54 miles per second or 87.3 kilometers per second) to have originated in our solar system. Comets and asteroids from within our solar system move at a slower speed, typically an average of 12 miles per second (19 kilometers per second) . In non-technical terms, 'Oumuamua is an “interstellar vagabond.”

Artist impression of the interstellar object ‘Oumuamua. Credit: ESA/Hubble, NASA, ESO, M. Kornmesser

2. We’re not sure where it came from.

'Oumuamua entered our solar system from the rough direction of the constellation Lyra, but it’s impossible to tell where it originally came from. Thousands of years ago, when 'Oumuamua started to wander from its parent planetary system, the stars were in a different position so it’s impossible to pinpoint its point of origin. It could have been wandering the galaxy for billions of years.

3. We know it’s out of here.

'Oumuamua is headed back out of our solar system and won’t be coming back. It’s rapidly headed in the direction of the constellation Pegasus and will cross the orbit of Neptune in about four years and cover one light year’s distance in about 11,000 years.

4. We don’t really know what it looks like.

We’ve only seen it as a speck of light through a telescope (it is far away and less than half a mile in length), but its unique rotation leads us to believe that it’s elongated like a cigar, about 10 times longer than it is wide. We can’t see it anymore. Artist’s concepts are the best guesses at what it might look like.

5. We know it got a little speed boost.

A rapid response observing campaign allowed us to watch as 'Oumuamua got an unexpected boost in speed. The acceleration slightly changed its course from earlier predictions.

“This additional subtle force on ′Oumuamua likely is caused by jets of gaseous material expelled from its surface,” said Davide Farnocchia of the Center for Near Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory. “This same kind of outgassing affects the motion of many comets in our solar system.”

6. We know it’s tumbling.

Unusual variations in the comet’s brightness suggest it is rotating on more than one axis.

This illustration shows ‘Oumuamua racing toward the outskirts of our solar system. As the complex rotation of the object makes it difficult to determine the exact shape, there are many models of what it could look like. Credits: NASA/ESA/STScI

7. We don’t know what it’s made of.

Comets in our solar system kick off lots of dust and gas when they get close to the Sun, but 'Oumuamua did not, which led observers to consider defining it as an asteroid.

Karen Meech, an astronomer at the University of Hawaii’s Institute of Astronomy, said small dust grains, present on the surface of most comets, may have eroded away during ′Oumuamua’s long journey through interstellar space. “The more we study ′Oumuamua, the more exciting it gets.” she said. It could be giving off gases that are harder to see than dust, but it’s impossible to know at this point.

8. We knew to expect it.

Just not when. The discovery of an interstellar object has been anticipated for decades. The space between the stars probably has billions and billions of asteroids and comets roaming around independently. Scientists understood that inevitably, some of these small bodies would enter our own solar system. This interstellar visit by ‘Oumuamua reinforces our models of how planetary systems form.

9. We don’t know what it’s doing now.

After January 2018, ’Oumuamua was no longer visible to telescopes, even in space. But scientists continue to analyze the data gathered during the international observing campaign and crack open more mysteries about this unique interstellar visitor.

10. We know there’s a good chance we’ll see another one…eventually.

Because ′Oumuamua is the first interstellar object ever observed in our solar system, researchers caution that it’s difficult to draw general conclusions about this newly-discovered class of celestial bodies. Observations point to the possibility that other star systems regularly eject small comet-like objects and there should be more of them drifting among the stars. Future ground- and space-based surveys could detect more of these interstellar vagabonds, providing a larger sample for scientists to analyze. Adds, Karen Meech, an astronomer at the University of Hawaii’s Institute of Astronomy: “I can hardly wait for the next interstellar object!“

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

I’m thinking of how to structure this whole podcast dealie so it’s more interactive, and what I’ve come up with is presenting a choice at the end of each episode of what people want to hear about next. Like a choose-your-own-adventure, except the adventure is me doing more research on a topic that I mentioned in the current podcast. I will retain veto power because there are some things I DEFINITELY want to cover, but it would be a cool way to see what other people are interested in with regards to space, to history, to technology, or to people!

What's Made in a Thunderstorm and Faster Than Lightning? Gamma Rays!

A flash of lightning. A roll of thunder. These are normal stormy sights and sounds. But sometimes, up above the clouds, stranger things happen. Our Fermi Gamma-ray Space Telescope has spotted bursts of gamma rays - some of the highest-energy forms of light in the universe - coming from thunderstorms. Gamma rays are usually found coming from objects with crazy extreme physics like neutron stars and black holes. 

So why is Fermi seeing them come from thunderstorms?

Thunderstorms form when warm, damp air near the ground starts to rise and encounters colder air. As the warm air rises, moisture condenses into water droplets. The upward-moving water droplets bump into downward-moving ice crystals, stripping off electrons and creating a static charge in the cloud.

The top of the storm becomes positively charged, and the bottom becomes negatively charged, like two ends of a battery. Eventually the opposite charges build enough to overcome the insulating properties of the surrounding air - and zap! You get lightning.

Scientists suspect that lightning reconfigures the cloud’s electrical field. In some cases this allows electrons to rush toward the upper part of the storm at nearly the speed of light. That makes thunderstorms the most powerful natural particle accelerators on Earth!

When those electrons run into air molecules, they emit a terrestrial gamma-ray flash, which means that thunderstorms are creating some of the highest energy forms of light in the universe. But that’s not all - thunderstorms can also produce antimatter! Yep, you read that correctly! Sometimes, a gamma ray will run into an atom and produce an electron and a positron, which is an electron’s antimatter opposite!

The Fermi Gamma-ray Space Telescope can spot terrestrial gamma-ray flashes within 500 miles of the location directly below the spacecraft. It does this using an instrument called the Gamma-ray Burst Monitor which is primarily used to watch for spectacular flashes of gamma rays coming from the universe.

There are an estimated 1,800 thunderstorms occurring on Earth at any given moment. Over the 10 years that Fermi has been in space, it has spotted about 5,000 terrestrial gamma-ray flashes. But scientists estimate that there are 1,000 of these flashes every day - we’re just seeing the ones that are within 500 miles of Fermi’s regular orbits, which don’t cover the U.S. or Europe.

The map above shows all the flashes Fermi has seen since 2008. (Notice there’s a blob missing over the lower part of South America. That’s the South Atlantic Anomaly, a portion of the sky where radiation affects spacecraft and causes data glitches.)

Fermi has also spotted terrestrial gamma-ray flashes coming from individual tropical weather systems. The most productive system we’ve seen was Tropical Storm Julio in 2014, which later became a hurricane. It produced four flashes in just 100 minutes!

Learn more about what Fermi’s discovered about gamma rays over the last 10 years and how we’re celebrating its accomplishments.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

Until I get this show rolling, I’m going to be posting some of the things I’ve collected over the years that might make for interesting things to do podcasts about down the line!

Ep. 18 Zombie Stars and Supernovae - HD and the Void

Zombie stars were in the news in November but get in the holiday spirit by hearing about them now! Learn about the life cycle of a star, the power of a supernova, and what undeath looks like in a star.

In November, a couple lovely people brought my attention to articles about a recent discovery that headlines consistently referred to as the ‘zombie star.’ What the heck is a zombie star? What makes it a zombie? I found a zombie star from 2014 in addition to the one in 2017 and I dug into the life cycle of the average star to get a sense of what undeath looks like in stars.

Below the cut are my sources, music credits, a vocab list, and the transcript of this episode. Suggest what you think I should research next by messaging me here, tweeting at me at @HDandtheVoid, or asking me to my face if you know me. Please subscribe on iTunes, rate it and maybe review it, and tell friends if you think they’d like to hear it! Also, welcome if you found me through PodCon!

(My thoughts on the next episode are the International Space Station, the transit of Venus, or astronaut training practices. The next episode will allegedly be up on New Year’s Day, January 1st. We’ll see about that.)

Glossary

Chandrasekhar limit - the upper limit for the mass of an astronomical body that can support extreme density without imploding: about 1.4 times the mass of our Sun. Any white dwarf star that has less than that mass will stay a white dwarf forever; any star that exceeds the Chandrasekhar limit will end in a supernova. 

dwarf nova - a close binary system of a red dwarf, a white dwarf, and an accretion disk around the white dwarf. They brighten by 2 to 6 magnitudes depending on the stability of the disk, which loses material to the white dwarf. Categorized as a cataclysmic variable.

neutron star - a type of star that has gone supernova, when the surviving core is 1.5 to 3 solar masses and contracts into a small, very dense, very fast-spinning star.

nova - a close binary system of a white dwarf and a secondary star that’s a little cooler than the Sun. The system brightens 7 to 16 magnitudes in 1 to 100 days, and then the star fades slowly to the initial brightness over a period of several years or decades. At maximum brightness, it’s similar to an A or F giant star. Recurrent novae are similar to this category of variable but have several outbursts during their recorded history. Categorized as a cataclysmic variable.

pulsar - a type of neutron star that spins very, very fast. Also a kind of variable star that emits light pulses usually between 0.0014 seconds and 8.5 seconds. 

reflection telescope - reflects light rays off the concave surface of a parabolic mirror to get an image of a distant object. Higher contrast image, worse color quality. 

spectroscopy - the study of light from an incandescent source (or, more recently, electromagnetic radiation and other radiative energy) that has its wavelength dispersed by a prism or other spectroscopic device that can disperse an object’s wavelength. The spectra of distant astronomical objects like the Sun, stars, or nebulae are patterns of absorption lines that correspond to elements that these objects are made up of.

supernova - a massive star that explodes with a magnitude increase of 20 or more. Supernovae have led us to realize that the expansion of the Universe is accelerating.

supernova progenitors - the kinds of stars and conditions that will result in certain types of supernovae.

white dwarf star - a star that has exhausted all of its nuclear fuel (i.e. no longer has hydrogen to convert into helium through nuclear fusion). It is the hot, dense core of a star. Unless it is acquiring/accreting matter from a nearby star, it will cool over time and become a dead star.

Script/Transcript

Sources

Chandrasekhar limit via PBS, Jan 2012

“The Chandrasekhar Limit is therefore not just as upper limit to the maximum mass of an ideal white dwarf, but also a threshold. A star surpassing this threshold no longer hoards its precious cargo of heavy elements. Instead, it delivers them to the universe at large in a supernova that marks its own death but makes it possible for living beings to exist.”

Type I and Type II supernovae via Space.com

Type Ia supernovae via Swinburne University of Technology

Type Ia Supernova Progenitors via Swinburne University of Technology

Zombie star via NASA, Aug 2014

Curtis McCully “I was very surprised to see anything at the location of the supernova. We expected the progenitor system would be too faint to see, like in previous searches for normal Type Ia supernova progenitors. It is exciting when nature surprises us.” 

The abstract of the article McCully and his team wrote on Type 1ax supernovae via Nature Magazine, Aug 2014

Zombie star via CNN, Nov 2017

Arcavi: "My first thought was that this must be some nearby star in our galaxy, just varying its brightness. But when we got the first spectrum of it, we saw that it was in fact a supernova 500 million light-years away. My mind was blown. The fact that it got bright and dim five times was very unusual. We'd never seen a supernova do that before."

Arcavi: "This means that we still have a lot to learn about how massive stars evolve and how they explode." 

Robert Evans via Sky and Telescope, Sept 2005

2017 zombie star articles I didn’t use because there were too many of them:

Air and Space Magazine, Nov 2017

The Atlantic, Nov 2017

BBC News, Nov 2017

BGR, Nov 2017

Carnegie Science, Nov 2017

Earth Sky, Nov 2017

Express UK, Nov 2017

The Guardian, Nov 2017

Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity

Filler Music: 'Toll Free’ by the Shook Twins off their album What We Do

Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught

Galaxy NGC 7714 After Collision : Is this galaxy jumping through a giant ring of stars? Probably not. Although the precise dynamics behind the featured image is yet unclear, what is clear is that the pictured galaxy, NGC 7714, has been stretched and distorted by a recent collision with a neighboring galaxy. This smaller neighbor, NGC 7715, situated off to the left of the featured frame, is thought to have charged right through NGC 7714. Observations indicate that the golden ring pictured is composed of millions of older Sun-like stars that are likely co-moving with the interior bluer stars. In contrast, the bright center of NGC 7714 appears to be undergoing a burst of new star formation. NGC 7714 is located about 100 million light years away toward the constellation of the Fish . The interactions between these galaxies likely started about 150 million years ago and should continue for several hundred million years more, after which a single central galaxy may result. via NASA

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Cassini Just Sent Back Closest Ever Images of Saturn, And They're Incredible

NASA's Cassini probe is plunging to its death. The nuclear-powered spacecraft has orbited Saturn for 13 years, and sent back hundreds of thousands of images. The photos include close-ups of the gaseous giant, its famous rings, and its enigmatic moons - including Titan, which has its own atmosphere, and icy Enceladus, which has a subsurface ocean that could conceivably harbour microbial life.

YO THAT SHIT BALLER AS FUCK HOLY SHIT

Here’s a great example of the kinds of experiments astronauts perform on the International Space Station, just like I talked about in Episode 19! I absolutely want to high-five whoever called is ISS-CREAM.

From Frozen Antarctica to the Cold Vacuum of Space

A new experiment that will collect tiny charged particles known as galactic cosmic rays will soon be added to the International Space Station. The Cosmic Ray Energetics And Mass for the International Space Station payload, nicknamed ISS-CREAM, will soon be installed in its new home on the Station’s Japanese Experiment Module Exposed Facility. ISS-CREAM will help scientists understand more about galactic cosmic rays and the processes that produce them.

Wait, what are cosmic rays?

Cosmic rays are pieces of atoms that move through space at nearly the speed of light. Galactic cosmic rays come from beyond our solar system. 

They provide us with direct samples of matter from distant places in our galaxy.

Why do these things go so fast?

Galactic cosmic rays have been sped up by extreme processes. When massive stars die, they explode as supernovas. The explosion’s blast wave expands into space along with a cloud of debris. 

Particles caught up in this blast wave can bounce around in it and slowly pick up speed. Eventually they move so fast they can escape the blast wave and race away as a cosmic ray.

Where can we catch cosmic rays?

Cosmic rays are constantly zipping through space at these super-fast speeds, running into whatever is in their path – including Earth.  

But Earth’s atmosphere is a great shield, protecting us from 99.9 percent of the radiation coming from space, including most cosmic rays.  This is good news for life on Earth, but bad news for scientists studying cosmic rays.  

So… how do you deal with that?

Because Earth has such an effective shield against cosmic rays, the best place for scientists to study them is above our atmosphere – in space.  Since the 1920s, scientists have tried to get their instruments as close to space as possible. One of the simplest ways to do this is to send these instruments up on balloons the size of football stadiums. These balloons are so large because they have to be able to both lift their own weight and that of their cargo, which can be heavier than a car. Scientific balloons fly to 120,000 feet or more above the ground – that’s at least three times higher than you might fly in a commercial airplane!  

Credit: Isaac Mognet (Pennsylvania State University)

Earlier versions of ISS-CREAM’s instruments were launched on these giant balloons from McMurdo Station in Antarctica seven times, starting in 2004, for a total of 191 days near the top of the atmosphere.  Each of these flights helped the team test their hardware and work towards sending a cutting-edge cosmic ray detector into space!  

How is going to space different than flying balloons?

Balloon flights allowed the team to collect a lot of cosmic rays, but even at 120,000 feet, a lot of the particles are still blocked. Scientists at the University of Maryland, College Park, who operate ISS-CREAM, expect to get about 10 times as much data from their new home on the International Space Station. 

That’s because it will be both above the atmosphere and fly far longer than is possible with a balloon. As you might imagine, there are large differences between flying something on a balloon and launching it into space. The science instruments and other systems had to be changed so ISS-CREAM could safely launch on a rocket and work in space.

What will ISS-CREAM do?

While on the space station, ISS-CREAM will collect millions of cosmic rays – electrons, protons and atomic nuclei representing the elements found in the solar system. These results will help us understand why cosmic rays reach the wicked-fast speeds they do and, most important, what limits those speeds.

ISS-CREAM launches to the International Space Station aboard the latest SpaceX Dragon spacecraft, targeted to launch August 14. Want to learn more about ISS-CREAM and some of our scientific balloons? Check out our recent feature, NASA’s Scientific Balloon Program Reaches New Heights.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Views of Pluto Through the Years.

via reddit