Space Radiation: Hazard Of Stealth

1,000 Days in Orbit: MAVEN’s Top 10 Discoveries at Mars

On June 17, our MAVEN (Mars Atmosphere and Volatile Evolution Mission) will celebrate 1,000 Earth days in orbit around the Red Planet.

Since its launch in November 2013 and its orbit insertion in September 2014, MAVEN has been exploring the upper atmosphere of Mars. MAVEN is bringing insight to how the sun stripped Mars of most of its atmosphere, turning a planet once possibly habitable to microbial life into a barren desert world.

Here’s a countdown of the top 10 discoveries from the mission so far:

10. Unprecedented Ultraviolet View of Mars

Revealing dynamic, previously invisible behavior, MAVEN was able to show the ultraviolet glow from the Martian atmosphere in unprecedented detail. Nightside images showed ultraviolet “nightglow” emission from nitric oxide. Nightglow is a common planetary phenomenon in which the sky faintly glows even in the complete absence of eternal light.

9. Key Features on the Loss of Atmosphere

Some particles from the solar wind are able to penetrate unexpectedly deep into the upper atmosphere, rather than being diverted around the planet by the Martian ionosphere. This penetration is allowed by chemical reactions in the ionosphere that turn the charged particles of the solar wind into neutral atoms that are then able to penetrate deeply.

8. Metal Ions

MAVEN made the first direct observations of a layer of metal ions in the Martian ionosphere, resulting from incoming interplanetary dust hitting the atmosphere. This layer is always present, but was enhanced dramatically by the close passage to Mars of Comet Siding Spring in October 2014.

7. Two New Types of Aurora

MAVEN has identified two new types of aurora, termed “diffuse” and “proton” aurora. Unlike how we think of most aurorae on Earth, these aurorae are unrelated to either a global or local magnetic field.

6. Cause of the Aurorae

These aurorae are caused by an influx of particles from the sun ejected by different types of solar storms. When particles from these storms hit the Martian atmosphere, they can also increase the rate of loss of gas to space, by a factor of ten or more.

5. Complex Interactions with Solar Wind

The interactions between the solar wind and the planet are unexpectedly complex. This results due to the lack of an intrinsic Martian magnetic field and the occurrence of small regions of magnetized crust that can affect the incoming solar wind on local and regional scales. The magnetosphere that results from the interactions varies on short timescales and is remarkably “lumpy” as a result.

4. Seasonal Hydrogen

After investigating the upper atmosphere of the Red Planet for a full Martian year, MAVEN determined that the escaping water does not always go gently into space. The spacecraft observed the full seasonal variation of hydrogen in the upper atmosphere, confirming that it varies by a factor of 10 throughout the year. The escape rate peaked when Mars was at its closest point to the sun and dropped off when the planet was farthest from the sun.

3. Gas Lost to Space

MAVEN has used measurements of the isotopes in the upper atmosphere (atoms of the same composition but having different mass) to determine how much gas has been lost through time. These measurements suggest that 2/3 or more of the gas has been lost to space.

2. Speed of Solar Wind Stripping Martian Atmosphere

MAVEN has measured the rate at which the sun and the solar wind are stripping gas from the top of the atmosphere to space today, along with details of the removal process. Extrapolation of the loss rates into the ancient past – when the solar ultraviolet light and the solar wind were more intense – indicates that large amounts of gas have been lost to space through time.

1. Martian Atmosphere Lost to Space

The Mars atmosphere has been stripped away by the sun and the solar wind over time, changing the climate from a warmer and wetter environment early in history to the cold, dry climate that we see today.

Maven will continue its observations and is now observing a second Martian year, looking at the ways that the seasonal cycles and the solar cycle affect the system.

For more information about MAVEN, visit: www.nasa.gov/maven

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What dose it feel like being inside a space suit?

The suit weighs about 300 pounds. We are made neutrally buoyant in the pool, but over time we can become negatively buoyant. The suit can feel heavy, even the bearings can become stiff, so it can be difficult to operate in the suit. With practice and the help of a great spacewalk team, we can make a spacewalk look seamless.

Thanks everyone for your fantastic questions! Sorry I couldn’t answer all of them. I hope you have fun on Monday, Aug. 21st and share your photos and experiences with us! https://www.flickr.com/groups/nasa-eclipse2017/ 

Safe viewing and talk to you later!  https://eclipse2017.nasa.gov/safety 

Astronomy Night at the White House

NASA took over the White House Instagram today in honor of Astronomy Night to share some incredible views of the universe and the world around us. Check out more updates from the astronauts, scientists, and students on South Lawn.

Here’s a nighttime view of Washington, D.C. from the astronauts on the International Space Station on October 17. Can you spot the White House? 

Check out this look at our sun taken by NASA’s Solar Dynamics Observatory. The SDO watches the sun constantly, and it captured this image of the sun emitting a mid-level solar flare on June 25. Solar flares are powerful bursts of radiation. Harmful radiation from a flare can’t pass through Earth’s atmosphere to physically affect humans on the ground. But when they’re intense enough, they can disturb the atmosphere in the layer where GPS and communications signals travel.

Next up is this incredible view of Saturn’s rings, seen in ultraviolet by NASA’s Cassini spacecraft. Hinting at the origin of the rings and their evolution, this ultraviolet view indicates that there’s more ice toward the outer part of the rings than in the inner part.

Take a look at the millions of galaxies that populate the patch of sky known as the COSMOS field, short for Cosmic Evolution Survey. A portion of the COSMOS field is seen here by NASA’s Spitzer Space Telescope. Even the smallest dots in this image are galaxies, some up to 12 billion light-years away. The picture is a combination of infrared data from Spitzer (red) and visible-light data (blue and green) from Japan’s Subaru telescope atop Mauna Kea in Hawaii. The brightest objects in the field are more than ten thousand times fainter than what you can see with the naked eye.

This incredible look at the Cat’s Eye nebula was taken from a composite of data from NASA’s Chandra X-ray Observatory and Hubble Space Telescope. This famous object is a so-called planetary nebula that represents a phase of stellar evolution that the Sun should experience several billion years from now. When a star like the Sun begins to run out of fuel, it becomes what is known as a red giant. In this phase, a star sheds some of its outer layers, eventually leaving behind a hot core that collapses to form a dense white dwarf star. A fast wind emanating from the hot core rams into the ejected atmosphere, pushes it outward, and creates the graceful filamentary structures seen with optical telescopes.

This view of the International Space Station is a composite of nine frames that captured the ISS transiting the moon at roughly five miles per second on August 2. The International Space Station is a unique place—a convergence of science, technology, and human innovation that demonstrates new technologies and makes research breakthroughs not possible on Earth. As the third brightest object in the sky, the International Space Station is easy to see if you know when to look up. You can sign up for alerts and get information on when the International Space Station flies over you at spotthestation.nasa.gov. Thanks for following along today as NASA shared the view from astronomy night at the White House. Remember to look up and stay curious!

That’s a wrap! Thank you all so much for your awesome questions! 

If you’re looking for other ways to enjoy #EarthDayatHome, check out this feature: https://www.nasa.gov/feature/goddard/2020/earthdayathome-with-nasa/

Don’t forget to follow NASA Earth on Twitter, Facebook and Instagram.

You can follow Sandra Cauffman on Twitter, HERE. 

You can follow Dr. Thomas Zurbuchen “Dr. Z” on Twitter, HERE. 

Happy Earth Day!

The Great Conjunction of Jupiter and Saturn

Credits:  NASA/Bill Ingalls

Have you noticed two bright objects in the sky getting closer together with each passing night? It’s Jupiter and Saturn doing a planetary dance that will result in the Great Conjunction on Dec. 21. On that day, Jupiter and Saturn will be right next to each other in the sky – the closest they have appeared in nearly 400 years!

Skywatching Tips from NASA

Credits: NASA/JPL-Caltech

For those who would like to see this phenomenon for themselves, here’s what to do:

Find a spot with an unobstructed view of the sky, such as a field or park. Jupiter and Saturn are bright, so they can be seen even from most cities.

An hour after sunset, look to the southwestern sky. Jupiter will look like a bright star and be easily visible. Saturn will be slightly fainter and will appear slightly above and to the left of Jupiter until December 21, when Jupiter will overtake it and they will reverse positions in the sky.

The planets can be seen with the unaided eye, but if you have binoculars or a small telescope, you may be able to see Jupiter’s four large moons orbiting the giant planet.

How to Photograph the Conjunction

Credits: NASA/Bill Dunford

Saturn and Jupiter are easy to see without special equipment, and can be photographed easily on DSLR cameras and many cell phone cameras. Here are a few tips and tricks:

These planets are visible in the early evening, and you'll have about 1-2 hours from when they are visible, to when they set. A photo from the same location can look completely different just an hour later!

Using a tripod will help you hold your camera steady while taking longer exposures. If you don’t have a tripod, brace your camera against something – a tree, a fence, or a car can all serve as a tripod for a several-second exposure.

The crescent Moon will pass near Jupiter and Saturn a few days before the conjunction. Take advantage of it in your composition!

Get more tips HERE.

Still have questions about the Great Conjunction?

Our NASA expert answered questions from social media on an episode of NASA Science Live on Thursday, Dec. 17. Watch the recording HERE.

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You don't necessarily need fancy equipment to watch one of the sky's most awesome shows: a solar eclipse. With just a few simple supplies, you can make a pinhole camera that allows you to view the event safely and easily. Before you get started, remember: You should never look at the Sun directly without equipment that's specifically designed for solar viewing. Do not use standard binoculars or telescopes to watch the eclipse, as the light could severely damage your eyes. Sunglasses also do NOT count as protection when attempting to look directly at the Sun. Stay safe and still enjoy the Sun's stellar show by creating your very own pinhole camera. It's easy! 

See another pinhole camera tutorial at https://www.jpl.nasa.gov/edu/learn/project/how-to-make-a-pinhole-camera/

Watch this and other eclipse videos on our YouTube channel:  https://youtu.be/vWMf5rYDgpc?list=PL_8hVmWnP_O2oVpjXjd_5De4EalioxAUi

A pinhole camera is just one of many viewing options. Learn more at https://eclipse2017.nasa.gov/safety 

Music credit: Apple of My Eye by Frederik Wiedmann

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Seeing the Invisible Universe

This computer-simulated image shows a supermassive black hole at the core of a galaxy. The black region in the center represents the black hole’s event horizon, beyond which no light can escape the massive object’s gravitational grip. The black hole’s powerful gravity distorts space around it like a funhouse mirror. Light from background stars is stretched and smeared as it skims by the black hole. You might wonder — if this Tumblr post is about invisible things, what’s with all the pictures? Even though we can’t see these things with our eyes or even our telescopes, we can still learn about them by studying how they affect their surroundings. Then, we can use what we know to make visualizations that represent our understanding.

When you think of the invisible, you might first picture something fantastical like a magic Ring or Wonder Woman’s airplane, but invisible things surround us every day. Read on to learn about seven of our favorite invisible things in the universe!

1. Black Holes

This animation illustrates what happens when an unlucky star strays too close to a monster black hole. Gravitational forces create intense tides that break the star apart into a stream of gas. The trailing part of the stream escapes the system, while the leading part swings back around, surrounding the black hole with a disk of debris. A powerful jet can also form. This cataclysmic phenomenon is called a tidal disruption event.

You know ‘em, and we love ‘em. Black holes are balls of matter packed so tight that their gravity allows nothing — not even light — to escape. Most black holes form when heavy stars collapse under their own weight, crushing their mass to a theoretical singular point of infinite density.

Although they don’t reflect or emit light, we know black holes exist because they influence the environment around them — like tugging on star orbits. Black holes distort space-time, warping the path light travels through, so scientists can also identify black holes by noticing tiny changes in star brightness or position.

2. Dark Matter

A simulation of dark matter forming large-scale structure due to gravity.

What do you call something that doesn’t interact with light, has a gravitational pull, and outnumbers all the visible stuff in the universe by five times? Scientists went with “dark matter,” and they think it's the backbone of our universe’s large-scale structure. We don’t know what dark matter is — we just know it's nothing we already understand.

We know about dark matter because of its gravitational effects on galaxies and galaxy clusters — observations of how they move tell us there must be something there that we can’t see. Like black holes, we can also see light bend as dark matter’s mass warps space-time.

3. Dark Energy

Animation showing a graph of the universe’s expansion over time. While cosmic expansion slowed following the end of inflation, it began picking up the pace around 5 billion years ago. Scientists still aren’t sure why.

No one knows what dark energy is either — just that it’s pushing our universe to expand faster and faster. Some potential theories include an ever-present energy, a defect in the universe’s fabric, or a flaw in our understanding of gravity.

Scientists previously thought that all the universe’s mass would gravitationally attract, slowing its expansion over time. But when they noticed distant galaxies moving away from us faster than expected, researchers knew something was beating gravity on cosmic scales. After further investigation, scientists found traces of dark energy’s influence everywhere — from large-scale structure to the background radiation that permeates the universe.

4. Gravitational Waves

Two black holes orbit each other and generate space-time ripples called gravitational waves in this animation.

Like the ripples in a pond, the most extreme events in the universe — such as black hole mergers — send waves through the fabric of space-time. All moving masses can create gravitational waves, but they are usually so small and weak that we can only detect those caused by massive collisions.  Even then they only cause infinitesimal changes in space-time by the time they reach us. Scientists use lasers, like the ground-based LIGO (Laser Interferometer Gravitational-Wave Observatory) to detect this precise change. They also watch pulsar timing, like cosmic clocks, to catch tiny timing differences caused by gravitational waves.

This animation shows gamma rays (magenta), the most energetic form of light, and elusive particles called neutrinos (gray) formed in the jet of an active galaxy far, far away. The emission traveled for about 4 billion years before reaching Earth. On Sept. 22, 2017, the IceCube Neutrino Observatory at the South Pole detected the arrival of a single high-energy neutrino. NASA’s Fermi Gamma-ray Space Telescope showed that the source was a black-hole-powered galaxy named TXS 0506+056, which at the time of the detection was producing the strongest gamma-ray activity Fermi had seen from it in a decade of observations.

5. Neutrinos

This animation shows gamma rays (magenta), the most energetic form of light, and elusive particles called neutrinos (gray) formed in the jet of an active galaxy far, far away. The emission traveled for about 4 billion years before reaching Earth. On Sept. 22, 2017, the IceCube Neutrino Observatory at the South Pole detected the arrival of a single high-energy neutrino. NASA’s Fermi Gamma-ray Space Telescope showed that the source was a black-hole-powered galaxy named TXS 0506+056, which at the time of the detection was producing the strongest gamma-ray activity Fermi had seen from it in a decade of observations.

Because only gravity and the weak force affect neutrinos, they don’t easily interact with other matter — hundreds of trillions of these tiny, uncharged particles pass through you every second! Neutrinos come from unstable atom decay all around us, from nuclear reactions in the Sun to exploding stars, black holes, and even bananas.

Scientists theoretically predicted neutrinos, but we know they actually exist because, like black holes, they sometimes influence their surroundings. The National Science Foundation’s IceCube Neutrino Observatory detects when neutrinos interact with other subatomic particles in ice via the weak force.

6. Cosmic Rays

This animation illustrates cosmic ray particles striking Earth's atmosphere and creating showers of particles.

Every day, trillions of cosmic rays pelt Earth’s atmosphere, careening in at nearly light-speed — mostly from outside our solar system. Magnetic fields knock these tiny charged particles around space until we can hardly tell where they came from, but we think high energy events like supernovae can accelerate them. Earth’s atmosphere and magnetic field protect us from cosmic rays, meaning few actually make it to the ground.

Though we don’t see the cosmic rays that make it to the ground, they tamper with equipment, showing up as radiation or as “bright” dots that come and go between pictures on some digital cameras. Cosmic rays can harm astronauts in space, so there are plenty of precautions to protect and monitor them.

7. (Most) Electromagnetic Radiation

The electromagnetic spectrum is the name we use when we talk about different types of light as a group. The parts of the electromagnetic spectrum, arranged from highest to lowest energy are: gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves. All the parts of the electromagnetic spectrum are the same thing — radiation. Radiation is made up of a stream of photons — particles without mass that move in a wave pattern all at the same speed, the speed of light. Each photon contains a certain amount of energy.

The light that we see is a small slice of the electromagnetic spectrum, which spans many wavelengths. We frequently use different wavelengths of light — from radios to airport security scanners and telescopes.

Visible light makes it possible for many of us to perceive the universe every day, but this range of light is just 0.0035 percent of the entire spectrum. With this in mind, it seems that we live in a universe that’s more invisible than not! NASA missions like NASA's Fermi, James Webb, and Nancy Grace Roman  space telescopes will continue to uncloak the cosmos and answer some of science’s most mysterious questions.

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When sending experiments to space, what is the most unexpected thing you have to think about? Like you're probably have to consider things like radiation damage, but what is something that isn't an immediately obvious issue that you have to account for?

Chris Williams

Born in New York City, Chris Williams considers Potomac, Maryland, to be his hometown. A private pilot and Eagle Scout, Williams is a board-certified medical physicist and holds a doctorate in physics from MIT. https://go.nasa.gov/49YJJmf

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