When Dwarfs Meet Giants, And Other True Cosmic Fairy Tales

How Well Do You Know Mercury?

Mercury is the smallest planet in our solar system and is only slightly larger than Earth’s moon. To give you some perspective, if the sun were as tall as a typical front door, Earth would be the size of a nickel and Mercury would be about as big as a green pea.

Mercury is the closest planet to the sun. Daytime temperatures can reach 430 degrees Celsius (800 degrees Fahrenheit) and drop to –180 degrees Celsius (-290 degrees Fahrenheit) at night.

Here are a few fun facts about Mercury:

Mercury takes only 88 Earth days to orbit the sun

If we could stand on Mercury’s surface when it is at its closest point to the sun, the sun would appear more than three times larger than it does here on Earth

Mercury is home to one of the largest impact basins in the solar system: the Caloris Basin. The diameter of this impact basin is the length of 16,404 football fields (minus the end zones) placed end to end!

Mercury is one of only two planets in our solar system that do not have moons (Venus is the other one)

Mercury completes three rotations for every two orbits around the sun. That means that if you wanted to stay up from sunrise to sunrise on Mercury, you’d be up for 176 Earth days…you’d need a LOT of coffee! 

Two missions have visited Mercury:

Mariner 10 was the first mission to Mercury, and 30 years later, our MESSENGER mission was the second to visit the planet. Mariner 10 was also the first spacecraft to reach one planet by using the gravity of another planet (in this case, Venus) to alter its speed and trajectory.

MESSENGER was the first spacecraft to orbit Mercury, The spacecraft had its own shades to protect it from the light of the sun. This is important since sunlight on Mercury can be as much as 11 times brighter than it is here on Earth. The spacecraft was originally planned to orbit Mercury for one year, but exceeded expectations and worked for over four years capturing extensive data. On April 30, 2015, the spacecraft succumbed to the pull of solar gravity and impacted Mercury’s surface.

Water Ice?

The MESSENGER spacecraft observed compelling support for the long-held hypothesis that Mercury harbors abundant water ice and other frozen volatile materials in its permanently shadowed polar craters.

This radar image of Mercury’s north polar region. The areas shown in red were captured by MESSENGER, compared to the yellow deposits imaged by Earth-based radar. These areas are believed to consist of water ice.

Mercury Transit of the Sun

For more than seven hours on Monday, May 9, Mercury will be visible as a tiny black dot crossing the face of the sun. This rare event – which happens only slightly more than once a decade – is called a transit.

Where: Skywatchers in Western Europe, South America and eastern North America will be able to see the entirety of the transit. The entire 7.5-hour path across the sun will be visible across the Eastern U.S. – with magnification and proper solar filters – while those in the West can observe the transit in progress at sunrise.

Watch: We will stream a live program on NASA TV and the agency’s Facebook page from 10:30 to 11:30 a.m. – an informal roundtable during which experts representing planetary, heliophysics and astrophysics will discuss the science behind the Mercury transit. Viewers can ask questions via Facebook and Twitter using #AskNASA. Unlike the 2012 Venus transit of the sun, Mercury is too small to be visible without magnification from a telescope or high-powered binoculars. Both must have safe solar filters made of specially-coated glass or Mylar; you can never look directly at the sun.

To learn more about our solar system and the planets, visit: http://solarsystem.nasa.gov/

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Solar System: Things to Know This Week

Like sailors of old, the Cassini mission team fondly thinks of the spacecraft as "she."  On April 22, she begins her Grand Finale, a spectacular end game—22 daring dives between the planet's atmosphere and innermost rings. Here are 10 things to know about her Grand Finale.

1. She's Broadcasting Live This Week

On Tuesday, April 4 at 3 p.m. EDT  (noon PDT), At Jet Propulsion Laboratory, the Cassini team host a news briefing to discuss the mission's Grand Finale.

Tune in Tuesday: youtube.com/nasajpl/live

2. She's Powered in Part By ... Titan

Cassini left Earth with less than 1/30th of the propellant needed to power all her adventures at Saturn. The navigation team used the gravity of Saturn's giant moon Titan to change course and extend the spacecraft's exploration of Saturn. Titan also provides the gravity assist to push Cassini into its final orbits.

More on Cassini's navigation: saturn.jpl.nasa.gov/mission/spacecraft/navigation/

3. She's a Robot

Cassini is an orbiter that was named for 18th century astronomer Giovanni Domenico Cassini. She was designed to be captured by Saturn's gravity and then explore it in detail with a suite of 12 powerful science instruments.

More on the Spacecraft: saturn.jpl.nasa.gov/mission/spacecraft/cassini-orbiter/

4. She Brought a Friend to Saturn

Cassini carried the European Space Agency's Huygens Probe, which in 2005 descended through Titan's thick, perpetual clouds and made the most distant landing to date in our solar system.

More on Huygens: saturn.jpl.nasa.gov/mission/spacecraft/huygens-probe/

5. She's a Great Photographer

Your mobile phone likely captures dozens of megapixels in images. Cassini, using 1990s technology closer to one megapixel cameras, has returned some of the most stunning images in the history of solar system exploration.

Cassini Hall of Fame Images: go.nasa.gov/2oec6H2 More on Cassini's Cameras: saturn.jpl.nasa.gov/imaging-science-subsystem/

6. She's an Inspiration

Those great images have inspired artist's and amateur image processors to create truly fantastic imagery inspired by the beauty of Saturn. Feeling inspired? There's still time to share your Cassini-inspired art with us.

Cassini Inspires Campaign: saturn.jpl.nasa.gov/mission/cassiniinspires/

7. She's Got a Long History

Two decades is a long time to live in the harsh environment of outer space (respect to the fast-approaching 40-year-old twin Voyager spacecraft). Launched in 1997, Cassini logged a lot of milestones over the years.

Explore the Cassini Timeline: saturn.jpl.nasa.gov/the-journey/timeline/

8. She Keeps a Diary

And, you can read it. Week after week going back to 1997, Cassini's adventures, discoveries and status have been chronicled in the mission's weekly significant events report.

Read It: https://saturn.jpl.nasa.gov/news/?topic=121

9. She's Got a Fancy New App

Cassini was the prototype for NASA's Eyes on the Solar System 3-D visualization software, so it's fitting the latest Cassini module in the free, downloadable software is the most detailed, elaborate visualization of any mission to date.

Fly the Mission - Start to Finish: http://eyes.nasa.gov/cassini

10. She's Going Out in a Blaze of Glory

In addition to all the new information from 22 orbits in unexplored space, Cassini's engineers reprogrammed the spacecraft to send back details about Saturn's atmosphere to the very last second before the giant planet swallows her up on Sept. 15, 2017.

More on the Grand Finale: saturn.jpl.nasa.gov/grandfinale

Discover more lists of 10 things to know about our solar system HERE.

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Solar System: Things to Know This Week

Be a scientist for a day, solstice on the Red Planet, historic launches and more!

1. Scientist for a Day!

This year's Scientist for a Day essay contest was announced last week. Write an essay on one of the three images above. Essays are due in Feb. 2017. Students in grades 5-12 in U.S. schools, after-school and home-school programs, scout troops and museum programs are eligible to participate.

+ Learn more

2. Tuesday is Winter Solstice on Mars' Northern Hemisphere

Mars' orbit is much more eccentric than Earth's. The winters in the northern hemisphere are warm and short, as Mars is near perihelion—closer to the sun. This means that the winters in the southern hemisphere are long and cold.

+ Read Mars: The Other Terrestrial Planet

+ Seasons on Mars (Malin Space Science Systems) 

3. Launch-iversaries!

We’re celebrating two launch anniversaries. Before Curiosity. Before Spirit and Opportunity, there was Pathfinder and the hardy Sojourner rover, launched on Dec. 4, 1996. Pathfinder was a demonstration of the technology necessary to deliver a lander and a free-ranging robotic rover to the surface of Mars in a cost-effective and efficient manner. The lander, formally named the Carl Sagan Memorial Station following its successful touchdown, and the rover, named Sojourner after American civil rights crusader Sojourner Truth, both outlived their design lives — the lander by nearly three times, and the rover by 12 times! We continued the tradition with Spirit and Opportunity. Now there is the Mars Science Laboratory (with the Curiosity rover in stowage), which was launched on Nov. 26, 2011. It landed successfully in Gale Crater at 1:31 am EDT on Aug. 6, 2012. 

+ Go Back in Time

+ Video: Where Were You When Curiosity Landed on Mars? 

4. Mars Ice Deposit Holds as Much Water as Lake Superior

Water ice makes up half or more of an underground layer in a large region of Mars, about halfway from the equator to the north pole. The amount of water in this deposit—assessed using a radar aboard NASA's Mars Reconnaissance Orbiter—is about as much as in Lake Superior.

+ Read More

5. A Little Bit of History

Finally, it’s been seven years since Cassini caught one of its most stunning views of the plume on Saturn's moon Enceladus.

+ Read More

Discover the full list of 10 things to know about our solar system this week HERE.

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For the second time in history, a human-made object has reached the space between the stars. Our Voyager 2 probe now has exited the heliosphere – the protective bubble of particles and magnetic fields created by the Sun.

Comparing data from different instruments aboard the trailblazing spacecraft, mission scientists determined the probe crossed the outer edge of the heliosphere on Nov. 5. This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium. Its twin, Voyager 1, crossed this boundary in 2012, but Voyager 2 carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.

Voyager 2 now is slightly more than 11 billion miles (18 billion kilometers) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.

Read more at https://go.nasa.gov/2QG2s16 or follow along with the mission @NASAVoyager on Twitter.

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View these celestial beauties taken by the Hubble Space Telescope and released as a set of views in a modern day "Messier Catalog." 

Spotting comets was all the rage in the middle of the 18th century, and at the forefront of the comet hunt was a young French astronomer named Charles Messier. In 1774, in an effort to help fellow comet seekers steer clear of astronomical objects that were not comets (something that frustrated his own search for these elusive entities), Messier published the first version of his “Catalog of Nebulae and Star Clusters,” a collection of celestial objects that weren’t comets and should be avoided during comet hunting. Today, rather than avoiding these objects, many amateur astronomers actively seek them out as interesting targets to observe with backyard telescopes, binoculars or sometimes even with the naked eye.

Hubble’s version of the Messier catalog includes eight newly processed images never before released by NASA. The images were extracted from more than 1.3 million observations that now reside in the Hubble data archive. Some of these images represent the first Hubble views of the objects, while others include newer, higher resolution images taken with Hubble’s latest cameras.

Learn more: https://www.nasa.gov/content/goddard/hubble-s-messier-catalog

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Looking 50 Years in the Future with NASA Earth Scientists

In the 50 years since the first Earth Day, the view from space has revolutionized our understanding of Earth’s interconnected atmosphere, oceans, freshwater, ice, land, ecosystems and climate that have helped find solutions to environmental challenges.

If NASA’s Earth science has changed this much in 50 years, what will it look like in 50 more years?

We asked some researchers what they thought. Here are their answers, in their own words.

Mahta Moghaddam is a professor of electrical and computer engineering at the University of Southern California. She’s building a system that helps sensors sync their measurements.

I am interested in creating new ways to observe the Earth. In particular, my team and I are building and expanding a system that will allow scientists to better study soil moisture. Soil moisture plays a vital role in the water and energy cycle and drives climate and weather patterns. When soil is wet and there is enough solar radiation, water can evaporate and form clouds, which precipitate back to Earth. Soil also feeds us – it nourishes our crops and sustains life on Earth. It’s one of the foundations of life! We need to characterize and study soil in order to feed billions of people now and in the future.

Our novel tool aims to observe changes in soil moisture using sensors that talk to each other and make decisions in real time. For instance, if one sensor in a crop field notes that soil is dry in a plot, it could corroborate it with other sensors in the area and then notify a resource manager or decision maker that an area needs water. Or if a sensor in another location senses that soil moisture is changing quickly due to rain or freeze/thaw activity, it could send a command to launch a drone or even to notify satellites to start observing a larger region. We live in one big, connected world, and can and will use many different scales of observations – local to global – from point-scale in-situ sensors to the scales that can be covered by drones, airplanes, and satellites. In just a few years from now, we might see much more vastly automated systems, with some touching not only Earth observations, but other parts of our lives, like drone deliveries of medical tests and supplies.

Odele Coddington is a scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. She’s building an instrument to measure how much solar energy Earth reflects back into space.

My research is focused on the Earth system response to the Sun’s energy. I spend half of my time thinking about the amount and variability of the Sun’s energy, also known as the solar irradiance. I’m particularly interested in the solar spectral irradiance, which is the study of the individual wavelengths of the Sun’s energy, like infrared and ultraviolet. On a bright, clear day, we feel the Sun’s warmth because the visible and infrared radiation penetrate Earth’s atmosphere to reach the surface. Without the Sun, we would not be able to survive. Although we’ve been monitoring solar irradiance for over 40 years, there is still much to learn about the Sun’s variability. Continuing to measure the solar irradiance 50 years from now will be as important as it is today.

I spend the other half of my time thinking about the many processes driven by the Sun’s energy both within the atmosphere and at the surface. I’m excited to build an instrument that will measure the integrated signal of these processes in the reflected solar and the emitted thermal radiation. This is my first foray into designing instrumentation and it has been so invigorating scientifically. My team is developing advanced technology that will measure Earth’s outgoing radiation at high spatial resolution and accuracy. Our instrument will be small from the onset, as opposed to reducing the size and mass of existing technology. In the future, a constellation of these instruments, launched on miniaturized spacecraft that are more flexible to implement in space, will give us more eyes in the sky for a better understanding of how processes such as clouds, wildfires and ice sheet melting, for instance, alter Earth’s outgoing energy.

Sujay Kumar is a research physical scientist at NASA’s Goddard Space Flight Center. He works on the Land Information System.

Broadly, I study the water cycle, and specifically the variability of its components. I lead the development of a modeling system called the Land Information System that isolates the land and tries to understand all the processes that move water through the landscape. We have conceptual models of land surface processes, and then we try to constrain them with satellite data to improve our understanding. The outputs are used for weather and climate modeling, water management, agricultural management and some hazard applications.

I think non-traditional and distributed platforms will become more the norm in the future. So that could be things like CubeSats and small sats that are relatively cheaper and quicker than large satellites in terms of how much time it takes to design and launch. One of the advantages is that because they are distributed, you’re not relying on a single satellite and there will be more coverage. I also think we’ll be using data from other “signals of opportunity” such as mobile phones and crowd-sourced platforms. People have figured out ways to, for example, retrieve Earth science measurements from GPS signals.

I feel like in the future we will be designing our sensors and satellites to be adaptive in terms of what the observational needs on the ground are. Say a fire or flood happens, then we will tell the satellite to look over there more intensely, more frequently so that we can benefit. Big data is a buzzword, but it’s becoming a reality. We are going to have a new mission call NISAR that’s going to collect so much data that we really have to rethink how traditional modeling systems will work. The analogy I think of is the development of a self-driving car, which is purely data driven, using tons and tons of data to train the model that drives the car. We could possibly see similar things in Earth science.

Hear from more NASA scientists on what they think the future will bring for Earth science: 

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5 Fun Things To Do Without Gravity

Astronauts onboard the International Space station are typically active for at least 9 1/2 hours per day doing science, exercising and maintaining systems. Excluding scheduled time for sleep and lunch, astronauts have only 4 hours of free time during the work week, and that includes time for meals and general hygiene.

Even with a loaded calendar, the few who have such an opportunity to live in the microgravity environment find ways to make the most of this experience. Here are just a few of their favorite things about living in space: 

Flying

One of the most self-explanatory (and most fun!) aspects of living in space for the astronauts is “flying”. In space there is no up or down, so there is no floor or ceiling. There are rails throughout the space station that astronauts use to push themselves among the modules. 

Eating

Astronauts actually describe the food on the space station as quite tasty! In part, that’s because they have a large role in choosing their own meals. Over time though, a lot of astronauts experience desensitized taste buds from the shifting fluid to their head. Toward the end of their expedition, spicy foods tend to be their favorites because of this phenomenon.

Drinking

Liquid behaves very differently in space than it does on Earth. Astronauts cannot simply pour a cup of coffee into a mug. Without gravity, it would stick to the walls of the cup and would be very difficult to sip. Most of the time, astronauts fill a bag with liquid and use a special straw with a clamp to keep the contents from flying out. 

Playing Games

The space station crew occasionally gets downtime which they can spend however they please. Sometimes they watch a movie, read a book or take photos of Earth from the Cupola windows. Other times they invent games to play with each other, and each crew tends to come up with new games. Sometimes it can be hitting a target, flying from one end of the station to the other fastest or playing zero-gravity sports. 

Going Out For A Walk

Preparing and executing a spacewalk can take around 8 to 12 hours, and can be a jam-packed schedule. Spacewalkers have to be focused on the task at hand and sticking to the timeline. That said, they can still catch a spare moment to see the Earth 250 miles below. Many astronauts describe that view from a spacewalk as one of the most beautiful sights in their lives. 

Watch Commander Scott Kelly and Flight Engineer Kjell Lindgren perform a spacewalk on Oct. 28 at 8:15 a.m. EDT live on NASA Television. 

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Let It Snow for Science

When the weather outside is frightful…

Science in the field gets even more delightful. Two different missions are in the field right now, studying snow and how it affects communities around the country.

From our Wallops Flight Facility in Virginia, the IMPACTS mission is flying up and down the East Coast, investigating how snow forms inside clouds. In Grand Mesa, Colorado, SnowEx’s teams on the ground and in the air are taking a close look at how much water is stored in snow.

Hate going out in the storm? The IMPACTS mission can help with that! IMPACTS uses two planes – a P-3 Orion and an ER-2 – flying through and high above the clouds to study where intense bands of snowfall form. Better understanding where intense snow will fall can improve forecast models down the road — helping prepare communities for snowstorms.

Cameras mounted on the wings of the P3 took microscopic images of snowflakes, like this one.

At the same time, the SnowEx team is in Colorado, studying the depth and density of snow. Researchers are making radar spirals with snowmobiles and working in giant snow pits to measure things like snow water equivalent, or how much water is stored in snow.

SnowEx is helping us better understand snow’s role in ecosystems and human systems, like irrigation for agriculture. If you want to bring some corn for popping, SnowEx’s science can help grow that crop.

Follow along with our teams as they brave the cold and snow: https://twitter.com/nasaexpeditions

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How does the whole sleeping situation work with 0 gravity, or do sleep mid air?

As the sun rises, our Global Hawk is prepped for flight at Armstrong Flight Research Center on Edwards Air Force Base in California. Pre-dawn flights of our Global Hawk help beat hot summer days in Southern California. Electronic components, which are cooled by fuel onboard, only function within temperature limitations, so testing usually ceases by midday, as fuel and onboard computers become too hot to operate. The Global Hawk unmanned aircraft is used for high-altitude, long-duration Earth science missions. The ability of the Global Hawk to autonomously fly long distances, remain aloft for extended periods of time and carry large payloads brings a new capability to the science community for measuring, monitoring and observing remote locations of Earth not feasible or practical with piloted aircraft, most other robotic or remotely operated aircraft, or space satellites. 

For more information, visit HERE. 

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