The Stellar Buddy System

The Legacy of Viking

On this day in 1976, we landed an ambitious mission on Mars –– the Viking 2 mission.

One of a pair of identical spacecraft, Viking found a place in history when it became the first U.S. mission to successfully land on Mars and return images of the surface.

Viking imaged and collected different types of data on the Martian surface. It also conducted experiments specifically designed to look for possible signs of life.

These experiments discovered unexpected chemical activity in the Martian soil but provided no clear evidence for the presence of living microorganisms.

Viking didn’t find unambiguous signs of life on Mars, but it made astrobiologists wonder if we devised the right tests. To this day, the results from Viking are helping to shape the development of life detection strategies at NASA.

So, what’s next in our search for life?

Our Mars 2020 Perseverance rover is the first mission designed to seek possible signs of past Martian life. For astrobiologists, the answers to questions about Mars’ habitability are in Perseverance’s “hands.” The robot astrobiologist and geologist launched earlier this year on July 30 and will touch down on Mars on Feb. 18, 2021.

Discover more about Viking and the history of exploration at Mars with our “Missions To Mars” graphic history novel here.

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What is the weirdest thing you had to account for when building the perseverance rover?

Sea Level Rise is on the Rise

As our planet warms, sea levels are rising around the world – and are doing so at an accelerating rate. Currently, global sea level is rising about an eighth of an inch every year.

That may seem insignificant, but it’s 30% more than when NASA launched its first satellite mission to measure ocean heights in 1992 – less than 30 years ago. And people already feel the impacts, as seemingly small increments of sea level rise become big problems along coastlines worldwide.

Higher global temperatures cause our seas to rise, but how? And why are seas rising at a faster and faster rate? There are two main reasons: melting ice and warming waters.

 The Ice We See Is Getting Pretty Thin

About two-thirds of global sea level rise comes from melting glaciers and ice sheets, the vast expanses of ice that cover Antarctica and Greenland. In Greenland, most of that ice melt is caused by warmer air temperatures that melt the upper surface of ice sheets, and when giant chunks of ice crack off of the ends of glaciers, adding to the ocean.

In Antarctica – where temperatures stay low year-round – most of the ice loss happens at the edges of glaciers. Warmer ocean water and warmer air meet at the glaciers’ edges, eating away at the floating ice sheets there.

NASA can measure these changes from space. With data from the Ice, Cloud and land Elevation Satellite-2, or ICESat-2, scientists can measure the height of ice sheets to within a fraction of an inch. Since 2006, an average of 318 gigatons of ice per year has melted from Greenland and Antarctica’s ice sheets. To get a sense of how big that is: just one gigaton is enough to cover New York City’s Central Park in ice 1,000 feet deep – almost as tall as the Chrysler Building.

With the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission – a partnership with the German Research Centre for Geosciences – scientists can calculate the mass of ice lost from these vast expanses across Greenland and Antarctica.

It’s not just glaciers in Antarctica and Greenland that are melting, though. Nearly all glaciers have been melting in the last decade, including those in Alaska, High Mountain Asia, South America, and the Canadian Arctic. Because these smaller glaciers are melting quickly, they contribute about the same amount to sea level rise as meltwater from massive ice sheets.

The Water’s Getting Warm

As seawater warms, it takes up more space. When water molecules get warmer, the atoms in those molecules vibrate faster, expanding the volume they take up. This phenomenon is called thermal expansion. It’s an incredibly tiny change in the size of a single water molecule, but added across all the water molecules in all of Earth’s oceans – a single drop contains well over a billion billion molecules – it accounts for about a third of global sea level rise.

So Much to See

While sea level is rising globally, it’s not the same across the planet. Sea levels are rising about an eighth of an inch per year on average worldwide. But some areas may see triple that rate, some may not observe any changes, and some may even experience a drop in sea level. These differences are due to ocean currents, mixing, upwelling of cold water from the deep ocean, winds, movements of heat and freshwater, and Earth’s gravitational pull moving water around. When ice melts from Greenland, for example, the drop in mass decreases the gravitational pull from the ice sheet, causing water to slosh to the shores of South America.

That’s where our view from space comes in. We’re launching Sentinel-6 Michael Freilich, an international partnership satellite, to continue our decades-long record of global sea level rise.

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The Exploration Behind the Inspiration at NASA

Are we alone? How did we get here? Where are we headed?

At NASA, our mission is to explore. We visit destinations in our solar system and study worlds beyond to better understand these big questions.

We also dream. We dream of traveling to distant worlds, and what that might be like. In the video above you can see fanciful, imagined adventures to real places we’ve studied at NASA.

How We Did It

Check out how we created these otherworldly scenes in the video below. A NASA videographer used green screens to add motion and real people to bring life to our series of solar system and exoplanet travel posters.

Let’s dive into one example from the video. The shot of kayaking on Titan showcases the real rivers and lakes of liquid methane and ethane that slosh and flow on Saturn's largest moon. Titan's mysterious surface was revealed by our Cassini spacecraft, which also deployed the European Space Agency’s Huygens probe to the surface. The atmosphere on Titan is so thick, and the gravity so light, that with each strike of a paddle, you might be lofted above the swift current as you ride the tides through a narrow strait called the Throat of Kraken. NASA scientist Mike Malaska studies Titan and collaborated on the poster featured in the video. His research informed the artwork, and so did a hobby: kayaking. Those ultra-cold chemical seas might be even more of a challenge than shown here. Your boat might crack, or even dissolve, Malaska said.

We’ll learn more about Titan when our Dragonfly mission of dual quadcoptors — rotorcraft with eight blades each — visits the icy moon in 2034.

Science Never Stops

Our understanding of other worlds is always evolving, and sometimes we learn new details after we illustrate our science. In one of our travel posters, we show a traveler standing on the surface of exoplanet Kepler-16b with two shadows formed by the planet’s two suns. The planet does indeed orbit two stars, but with later size and mass refinements, we now think it would be hard to stand there and enjoy a binary sunset. There isn't a solid surface to stand on a gas planet, and that's what Kepler-16b now appears to be!

In addition to sharing how sublime science can be, these scenes are a reminder that there are lots of careers in the space program, not just scientist, engineer, or astronaut. A creative team at NASA’s Jet Propulsion Laboratory in Southern California produced the travel posters, originally to help share the work of NASA's Exoplanet Exploration Program. They are the result of lots of brainstorming and discussion with real NASA scientists, engineers, and expert communicators. The video versions of these spacey travel scenes were produced by visualization experts at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

All of this work is meant to inspire, and to explore the edge of possibility. It’s also an invitation. With science, we’re stepping into the future. Join us?

Happy New Year From NASA! The year 2021 was one for the books, so what will 2022 bring? No matter what, remember: You are made of star stuff. Sparkly, glorious star stuff.

What's this image? Click here. Credit: ESA/Hubble and NASA, A. Sarajedini Make sure to follow us on Tumblr for your regular dose of space!

When Dead Stars Collide!

Gravity has been making waves - literally.  Earlier this month, the Nobel Prize in Physics was awarded for the first direct detection of gravitational waves two years ago. But astronomers just announced another huge advance in the field of gravitational waves - for the first time, we’ve observed light and gravitational waves from the same source.

There was a pair of orbiting neutron stars in a galaxy (called NGC 4993). Neutron stars are the crushed leftover cores of massive stars (stars more than 8 times the mass of our sun) that long ago exploded as supernovas. There are many such pairs of binaries in this galaxy, and in all the galaxies we can see, but something special was about to happen to this particular pair.

Each time these neutron stars orbited, they would lose a teeny bit of gravitational energy to gravitational waves. Gravitational waves are disturbances in space-time - the very fabric of the universe - that travel at the speed of light. The waves are emitted by any mass that is changing speed or direction, like this pair of orbiting neutron stars. However, the gravitational waves are very faint unless the neutron stars are very close and orbiting around each other very fast.

As luck would have it, the teeny energy loss caused the two neutron stars to get a teeny bit closer to each other and orbit a teeny bit faster.  After hundreds of millions of years, all those teeny bits added up, and the neutron stars were *very* close. So close that … BOOM! … they collided. And we witnessed it on Earth on August 17, 2017.  

Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

A couple of very cool things happened in that collision - and we expect they happen in all such neutron star collisions. Just before the neutron stars collided, the gravitational waves were strong enough and at just the right frequency that the National Science Foundation (NSF)’s Laser Interferometer Gravitational-Wave Observatory (LIGO) and European Gravitational Observatory’s Virgo could detect them. Just after the collision, those waves quickly faded out because there are no longer two things orbiting around each other!

LIGO is a ground-based detector waiting for gravitational waves to pass through its facilities on Earth. When it is active, it can detect them from almost anywhere in space.

The other thing that happened was what we call a gamma-ray burst. When they get very close, the neutron stars break apart and create a spectacular, but short, explosion. For a couple of seconds, our Fermi Gamma-ray Telescope saw gamma-rays from that explosion. Fermi’s Gamma-ray Burst Monitor is one of our eyes on the sky, looking out for such bursts of gamma-rays that scientists want to catch as soon as they’re happening.

And those gamma-rays came just 1.7 seconds after the gravitational wave signal. The galaxy this occurred in is 130 million light-years away, so the light and gravitational waves were traveling for 130 million years before we detected them.

After that initial burst of gamma-rays, the debris from the explosion continued to glow, fading as it expanded outward. Our Swift, Hubble, Chandra and Spitzer telescopes, along with a number of ground-based observers, were poised to look at this afterglow from the explosion in ultraviolet, optical, X-ray and infrared light. Such coordination between satellites is something that we’ve been doing with our international partners for decades, so we catch events like this one as quickly as possible and in as many wavelengths as possible.

Astronomers have thought that neutron star mergers were the cause of one type of gamma-ray burst - a short gamma-ray burst, like the one they observed on August 17. It wasn’t until we could combine the data from our satellites with the information from LIGO/Virgo that we could confirm this directly.

This event begins a new chapter in astronomy. For centuries, light was the only way we could learn about our universe. Now, we’ve opened up a whole new window into the study of neutron stars and black holes. This means we can see things we could not detect before.

The first LIGO detection was of a pair of merging black holes. Mergers like that may be happening as often as once a month across the universe, but they do not produce much light because there’s little to nothing left around the black hole to emit light. In that case, gravitational waves were the only way to detect the merger.

Image Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

The neutron star merger, though, has plenty of material to emit light. By combining different kinds of light with gravitational waves, we are learning how matter behaves in the most extreme environments. We are learning more about how the gravitational wave information fits with what we already know from light - and in the process we’re solving some long-standing mysteries!

Want to know more? Get more information HERE.

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Bill Nye for most of his career: Imma do science for kids. Science without politics. Nice, tame science for the kiddos.

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