Did you know that our planet is surrounded by giant,
donut-shaped clouds of radiation?
Here’s what you need to know.
1. The radiation
belts are a side effect of Earth’s magnetic field
The Van Allen radiation belts exist because fast-moving charged
particles get trapped inside Earth’s natural magnetic field, forming two
concentric donut-shaped clouds of radiation. Other planets with global magnetic
fields, like
Jupiter, also have radiation belts.
2. The radiation
belts were one of our first Space Age discoveries
Earth’s radiation belts were first
identified in 1958 by Explorer 1, the first U.S. satellite. The
inner belt, composed predominantly of protons, and the outer belt, mostly
electrons, would come to be named the Van Allen Belts, after James Van Allen,
the scientist who led the charge designing the instruments and studying the
radiation data from Explorer 1.
3. The Van Allen
Probes have spent six years exploring the radiation belts
In 2012, we launched the twin Van Allen Probes to
study the radiation belts. Over the past six years, these spacecraft have
orbited in and out of the belts, providing brand-new data about how the
radiation belts shift and change in response to solar activity and other
factors.
4. Surprise! Sometimes
there are three radiation belts
Shortly after launch, the Van Allen Probes detected a
previously-unknown third
radiation belt, created by a bout of strong solar activity. All the
extra energy directed towards Earth meant that some particles trapped in our
planet’s magnetic field were swept out into the usually relatively empty region
between the two Van Allen Belts, creating an additional radiation belt.
5. Swan song for the
Van Allen Probes
Originally designed for a two-year mission, the Van Allen
Probes have spent more than six years collecting data in the harsh radiation
environment of the Van Allen Belts. In spring 2019, we’re changing their orbit to bring the perigee — the part of the
orbit where the spacecraft are closest to Earth — about 190 miles lower. This
ensures that the spacecraft will eventually burn up in Earth’s atmosphere,
instead of orbiting forever and becoming space junk.
Because the Van Allen Probes have proven to be so hardy,
they’ll continue collecting data throughout the final months of the mission
until they run out of fuel. As they skim through the outer reaches of Earth’s
atmosphere, scientists and engineers will also learn more about how atmospheric
oxygen can degrade satellite measurements — information that can help build
better satellites in the future.
After seven years of studying the radiation around Earth, the Van Allen Probes spacecraft have retired.
Originally slated for a two-year mission, these two spacecraft studied Earth’s radiation belts — giant, donut-shaped clouds of particles surrounding Earth — for nearly seven years. The mission team used the last of their propellant this year to place the spacecraft into a lower orbit that will eventually decay, allowing the Van Allen Probes to re-enter and burn up in Earth’s atmosphere.
Earth’s radiation belts exist because energized charged particles from the Sun and other sources in space become trapped in our planet’s huge magnetic field, creating vast regions around Earth that teem with radiation. This is one of the harshest environments in space — and the Van Allen Probes survived more than three times longer than planned orbiting through this intense region.
The shape, size and intensity of the radiation belts change, meaning that satellites — like those used for telecommunications and GPS — can be bombarded with a sudden influx of radiation. The Van Allen Probes shed new light on what invisible forces drive these changes — like waves of charged particles and electromagnetic fields driven by the Sun, called space weather.
Here are a few scientific highlights from the Van Allen Probes — from the early days of the mission to earlier this year:
The Van Allen belts were first discovered in 1958, and for decades, scientists thought there were only two concentric belts. But, days after the Van Allen Probes launched, scientists discovered that during times of intense solar activity, a third belt can form.
The belts are composed of charged particles and electromagnetic fields and can be energized by different types of plasma waves. One type, called electrostatic double layers, appear as short blips of enhanced electric field. During one observing period, Probe B saw 7,000 such blips repeatedly pass over the spacecraft in a single minute!
During big space weather storms, which are ultimately caused by activity on the Sun, ions — electrically charged atoms or molecules — can be pushed deep into Earth’s magnetosphere. These particles carry electromagnetic currents that circle around the planet and can dramatically distort Earth’s magnetic field.
Across space, fluctuating electric and magnetic fields can create what are known as plasma waves. These waves intensify during space weather storms and can accelerate particles to incredible speeds. The Van Allen Probes found that one type of plasma wave known as hiss can contribute greatly to the loss of electrons from the belts.
The Van Allen belts are composed of electrons and ions with a range of energies. In 2015, research from the Van Allen Probes found that, unlike the outer belt, there were no electrons with energies greater than a million electron volts in the inner belt.
Plasma waves known as whistler chorus waves are also common in our near-Earth environment. These waves can travel parallel or at an angle to the local magnetic field. The Van Allen Probes demonstrated the two types of waves cannot be present simultaneously, resulting in greater radiation belt particle scattering in certain areas.
Very low frequency chorus waves, another variety of plasma waves, can pump up the energy of electrons to millions of electronvolts. During storm conditions, the Van Allen Probes found these waves can hugely increase the energy of particles in the belts in just a few hours.
Scientists often use computer simulation models to understand the physics behind certain phenomena. A model simulating particles in the Van Allen belts helped scientists understand how particles can be lost, replenished and trapped by Earth’s magnetic field.
The Van Allen Probes observed several cases of extremely energetic ions speeding toward Earth. Research found that these ions’ acceleration was connected to their electric charge and not to their mass.
The Sun emits faster and slower gusts of charged particles called the solar wind. Since the Sun rotates, these gusts — the fast wind — reach Earth periodically. Changes in these gusts cause the extent of the region of cold ionized gas around Earth — the plasmasphere — to shrink. Data from the Van Allen Probes showed that such changes in the plasmasphere fluctuated at the same rate as the solar rotation — every 27 days.
Though the mission has ended, scientists will use data from the Van Allen Probes for years to come. See the latest Van Allen Probes science at nasa.gov/vanallen.
The total solar eclipse is coming! Here’s your chance to ask an eclipse scientist your questions!
Have questions about the upcoming total solar eclipse on August 21? Join our Tumblr Answer Time session on Thursday, August 17 from 3:00 – 4:00 p.m. EDT/12:00 - 1:00 p.m. PDT. here on NASA’s Tumblr, where space physics researcher Alexa Halford will answer them. Make sure to ask your questions now by visiting: https://nasa.tumblr.com/ask!
Alexa Halford is a space physics researcher at our Goddard Space Flight Center and Dartmouth College. She started researching waves in Earth’s magnetosphere as an undergraduate at Augsburg College with Mark Engebretson using ground based magnetometers in the Arctic and Antarctic. She moved away from waves to focus on geomagnetic storms and substorms during her masters at the University of Colorado Boulder with Dan Baker but returned once more to waves with her PhD at University of Newcastle NSW Australia. Her PhD thesis was on Electromagnetic Ion Cyclotron (EMIC) waves during the CRRES mission and their relationship to the plasmasphere and radiation belts.
Since 2011, our Juno spacecraft has been heading towards Jupiter, where it will study the gas giant’s atmosphere, aurora, gravity and magnetic field. Along the way, Juno has had to deal with the radiation that permeates space.
All of space is filled with particles, and when these particles get moving at high speeds, they’re called radiation. We study space radiation to better protect spacecraft as they travel through space, as well as to understand how this space environment influences planetary evolution. Once at Jupiter, Juno will have a chance to study one of the most intense radiation environments in our solar system.
Near worlds with magnetic fields – like Earth and Jupiter – these fast-moving particles can get trapped inside the magnetic fields, creating donut-shaped swaths of radiation called radiation belts.
Jupiter’s radiation belts – the glowing areas in the animation below – are especially intense, with particles so energetic that they zip up and down the belts at nearly the speed of light.
Earth also has radiation belts, but they aren’t nearly as intense as Jupiter’s – why? First, Jupiter’s magnetic field is much stronger than Earth’s, meaning that it traps and accelerates faster particles.
Second, while both Earth’s and Jupiter’s radiation belts are populated with particles from space, Jupiter also has a second source of particles – its volcanically active moon Io. Io’s volcanoes constantly release plumes of particles that are energized by Jupiter’s magnetic field. These fast particles get trapped in Jupiter’s radiation belts, making the belts that much stronger and more intense.
In addition to studying this vast space environment, Juno engineers had to take this intense radiation into consideration when building the spacecraft. The radiation can cause instruments to degrade, interfere with measurements, and can even give the spacecraft itself an electric charge – not good for something with so many sensitive electronics.
Since we know Jupiter is a harsh radiation environment, we designed Juno with protections in place to keep it safe. Most of Juno’s electronics live inside a half-inch-thick titanium vault, where most of the radiation can’t reach them. We also planned Juno’s orbit to swoop in very close to Jupiter’s surface, underneath the most intense pockets of radiation in Jupiter’s radiation belts.
Juno arrives at Jupiter on July 4th. Throughout its time orbiting the planet, it will send back data on Jupiter’s magnetic field and energetic particles, helping us understand this intense radiation environment better than ever before.
Secrets lie deep within Jupiter, shrouded in the solar system’s strongest magnetic field and most lethal radiation belts. On July 4, 2016, our Juno spacecraft will plunge into uncharted territory, entering orbit around the gas giant and passing closer than any spacecraft before. Juno will see Jupiter for what it really is, but first it must pass the trial of orbit insertion. For more information: http://www.nasa.gov/juno and http://missionjuno.swri.edu.
The quadruplet spacecraft of the Magnetospheric Multiscale mission have just returned from their first adventure into the solar wind — sailing through the most intense winds of their journey so far.
These spacecraft were designed to study Earth’s giant magnetic system, which shields our planet from the majority of the Sun’s constant outflow of material — what we call the solar wind.
Usually, the Magnetospheric Multiscale spacecraft — MMS for short — take their measurements from inside Earth’s protective magnetic environment, the magnetosphere. But in February and March, the MMS spacecraft ventured beyond this magnetic barrier to measure that solar wind directly — a feat that meant they had to change up how they fly in a whole new way.
Outside of Earth’s protective magnetic field, the spacecraft were completely immersed in the particles and magnetic fields of the solar wind. As they flew through the stream of material, the spacecraft traced out a wake behind each instrument, just like a boat in a river. To avoid measuring that wake, each spacecraft was tilted into the wind so the instruments could take clean measurements of the pristine solar wind, unaffected by the wake.
Within the magnetosphere, the MMS spacecraft fly in a pyramid-shaped formation that allows them to study magnetic fields in 3D. But to study the solar wind, the mission team aligned spacecraft in a straight line at oddly spaced intervals. This string-of-pearls formation gave MMS a better look at how much the solar wind varies over different scales.
Because the four spacecraft fly so close together, MMS relies on super-accurate navigation from GPS satellites. This venture into the solar wind took the spacecraft even farther from Earth than before, so MMS broke its own world record for highest-ever GPS fix. The spacecraft were over 116,000 miles above Earth — about halfway to the Moon — and still using GPS!
Now, just in time for the 1,000th orbit of their mission — which adds up to 163 million miles flown! — the spacecraft are back in Earth’s magnetosphere, flying in their usual formation to study fundamental processes within our planet’s magnetic field.
This winter, our scientists and engineers traveled to the
world’s northernmost civilian town to launch rockets equipped with cutting-edge
scientific instruments.
This is the beginning of a 14-month-long campaign to study a particular
region of Earth’s magnetic field — which means launching near the poles. What’s
it like to launch a science rocket in these extreme conditions?
Our planet is protected by a natural magnetic field that
deflects most of the particles that flow out from the Sun — the solar wind —
away from our atmosphere. But near the north and south poles, two oddities in
Earth’s magnetic field funnel these solar particles directly into our
atmosphere. These regions are the polar cusps, and it turns out they’re the
ideal spot for studying how our atmosphere interacts with space.
The scientists of the Grand Challenge Initiative — Cusp are
using sounding rockets to do their research. Sounding
rockets are suborbital rockets that launch to a few hundred miles in altitude,
spending a few minutes in space before falling back to Earth. That means
sounding rockets can carry sensitive instruments above our atmosphere to study
the Sun, other stars and even distant galaxies.
They also fly directly through some of the most interesting
regions of Earth’s atmosphere, and that’s what scientists are taking advantage
of for their Grand Challenge experiments.
One of the ideal rocket ranges for cusp science is in
Ny-Ålesund, Svalbard, off the coast of Norway and within the Arctic circle.
Because of its far northward position, each morning Svalbard passes directly
under Earth’s magnetic cusp.
But launching in this extreme, remote environment puts another
set of challenges on the mission teams. These launches need to happen during
the winter, when Svalbard experiences 24/7 darkness because of Earth’s axial
tilt. The launch teams can go months without seeing the Sun.
Like for all rocket launches, the science teams have to wait
for the right weather conditions to launch. Because they’re studying upper
atmospheric processes, some of these teams also have to wait for other science
conditions, like active auroras. Auroras are created when charged particles
collide with Earth’s atmosphere — often triggered by solar storms or changes in
the solar wind — and they’re related to many of the upper-atmospheric processes
that scientists want to study near the magnetic cusp.
But even before launch, the extreme conditions make
launching rockets a tricky business — it’s so cold that the rockets must be
encased in styrofoam before launch to protect them from the low temperatures
and potential precipitation.
When all is finally ready, an alarm sounds throughout the
town of Ny-Ålesund to alert residents to the impending launch. And then it’s
up, up and away! This photo shows the launch of the twin VISIONS-2 sounding rockets on Dec.
7, 2018 from Ny-Ålesund.
These rockets are designed to break up during flight — so
after launch comes clean-up. The launch teams track where debris lands so that
they can retrieve the pieces later.
The
next launch of the Grand Challenge Initiative is AZURE, launching from Andøya
Space Center in Norway in March 2019.
For even more about what it’s like to launch science rockets
in extreme conditions, check out one scientist’s notes from the field: https://go.nasa.gov/2QzyjR4
For updates on the Grand Challenge Initiative and other
sounding rocket flights, visit nasa.gov/soundingrockets or follow along with NASA Wallops and NASA
heliophysics on Twitter and Facebook.
Currently, six humans are living and working on the International Space Station, which orbits 250 miles above our planet at 17,500mph. Below you will find a real journal entry, written in space, by NASA astronaut Scott Tingle.
The launch went as planned. Our Soyuz spacecraft did a great job getting the three of us to the International Space Station (ISS).
A week later, it all seems like a blur. The bus driver played me a video of my family and friends delivering their good luck messages. After exiting the bus at the launch pad, I was fortunate to have the Soyuz chief designer (Roman) and NASA’s associate administrator for Human Exploration and Operations (Bill Gerstenmaier) walk me to the stairs and elevator that would take us to the top of the rocket for boarding. The temperature at the pad was approximately -17 degrees centigrade, and we were wearing the Russian Polar Bear suits over our spacesuits in order to stay warm. Walking in these suits is a little hard, and I was happy to have Roman and Bill helping me.
We walked into the fog created by the systems around the rocket, climbed the ladder, and waved goodbye. My last words before launch were to Bill, “Boiler Up!”. Bill is a fellow and very well-known Boilermaker. We strapped in, and the launch and docking were nominal. But I will add that the second stage cutoff and separation, and ignition of the third stage was very exciting. We were under approximately 4 Gs when the engine cutoff, which gave us a good jolt forward during the deceleration and then a good jolt back into the seat after the third stage ignited. I looked at Anton and we both began to giggle like school children.
We spent two days in orbit as our phase angle aligned with ISS. Surprisingly, I did not feel sick. I even got 4 hours of sleep the first night and nearly 6 hours the second night. Having not been able to use my diaper while sitting in the fetal position during launch, it was nice to get out of our seats and use the ACY (Russian toilet). Docking was amazing. I compared it to rendezvousing on a tanker in a fighter jet, except the rendezvous with ISS happened over a much larger distance. As a test pilot, it was very interesting to watch the vehicle capture and maintain the centerline of ISS’s MRM-1 docking port as well as capturing and maintaining the required speed profile.
Just like landing at the ship, I could feel the vehicle’s control system (thrusters) making smaller and faster corrections and recorrections. In the flight test world, this is where the “gains” increase rapidly and where any weaknesses in the control system will be exposed. It was amazing to see the huge solar arrays and tons of equipment go by my window during final approach. What an engineering marvel the ISS is. Smooth sailing right into the docking port we went!
About an hour later, after equalizing pressures between the station and Soyuz, we opened the hatch and greeted our friends already onboard. My first view of the inside of the space station looked pretty close to the simulators we have been training in for the last several years. My first words were, “Hey, what are you guys doing at Building 9?”. Then we tackled each other with celebratory hugs!
Ten years ago, on March 6, 2009, a rocket lifted off a launch pad at Cape Canaveral Air Force Station in Florida. It carried a passenger that would revolutionize our understanding of our place in the cosmos–NASA’s first planet hunter, the Kepler space telescope. The spacecraft spent more than nine years in orbit around the Sun, collecting an unprecedented dataset for science that revealed our galaxy is teeming with planets. It found planets that are in some ways similar to Earth, raising the prospects for life elsewhere in the cosmos, and stunned the world with many other first-of-a-kind discoveries. Here are five facts about the Kepler space telescope that will blow you away:
Kepler observed more than a half million stars looking for planets beyond our solar system.
It discovered more than 2,600 new worlds…
…many of which could be promising places for life.
Kepler’s survey revealed there are more planets than stars in our galaxy.
The spacecraft is now drifting around the Sun more than 94 million miles away from Earth in a safe orbit.
Kjell N. Lindgren was selected by NASA in 2009. Born in Taiwan
while his family was stationed overseas, he spent most of his childhood abroad and returned to the U.S. to complete his education and earn a Doctorate of Medicine from the University of Colorado. He is board certified in emergency and aerospace medicine. After serving as the Deputy Crew Surgeon for Space Shuttle mission STS‐130 and Expedition 24, he was selected to join our astronaut corps. Dr. Lindgren flew on the International Space Station from July 2015 to December 2015 and logged 141 days in space. He participated in two spacewalks and in more than a hundred different scientific experiments. In his free time, Dr. Lindgren enjoys spending time with his family, running, reading, movies, photography and amateur astronomy.
He took some time from being a NASA astronaut to answer questions about his life and career! Enjoy:
What is one thing you would take to space that would make life easier?
A real R2 unit, of course! Just kidding, but in the future… Honestly though, life is pretty good on the International Space Station. While it is still a lot like camping (sleeping bags, no running water, rehydrated food) the space station team has really equipped us for success. As you all prepare for YOUR future spaceflight, I would say that the two most useful items I had with me on a daily basis were a pair of scissors and a spoon. The scissors were super useful for cutting plastic wrappers, tape, etc., and opening food packages (much more useful than a knife). And the spoon is the only utensil you need for eating – at least with the food system that we have right now.
Who helped get you to where you are?
Getting this opportunity, becoming an astronaut – that was a team effort for sure. I had so many people walking alongside me on this journey, helping me along the way. My parents set the bit early on – telling me that I could become whatever I wanted through hard work. They really gave me permission to dream big. Teachers and coaches, mentors, co-workers and friends all played a huge part in reaching this goal. Most of all, though, my wife, Kristi and my three kids have been an integral part of this adventure. I would not have this job, and I wouldn’t be successful in it without their love and daily support.
You and your crew mates were the first astronauts to harvest lettuce grown on orbit. How did it taste?
The lettuce tasted like…lettuce, which was a good thing, because if it hadn’t, then it meant we had made a huge mistake. It was so much fun to be a part of that experiment. The payoff, getting to eat fresh grown food on orbit was of course, a lot of fun. But just getting to take care of the lettuce plant, watch it grow in the sterile looking environment of the space station, getting to take care of this living thing on a daily basis, it was good for the soul.
How do you prepare for someone getting hurt or sick in space?
We train at least two crew members on every expedition to be Crew Medical Officers, or CMOs. They spend about 40 – 50 hours learning how to use the medical equipment and procedures on the space station, so that they can essentially serve as an extension of the flight surgeon in mission control. We have equipment and medication to deal with most minor illnesses and injuries. But because we are in low earth orbit, we can evacuate an ill crew member back to Earth in the event of a severe medical issue. This option won’t be available as we push out further from Earth, so we’ll need more rigorous training and a more comprehensive medical system.
How many times did you apply to be an astronaut?
I was very fortunate and got selected on my first try. I have several friends in the office though, who applied 4 or 5 times before being selected. It is amazing to go through the selection process and to meet others who share your dream. Enjoy the experience and keep applying – it is worth it!
How can I improve my chances of being selected to become an astronaut?
I recommend continuing to do things that you enjoy, continue to build experience at work and maybe look for new opportunities in your job that will grow you in your career and grow you as a leader. But choose opportunities because YOU want to do them, not based on what you think NASA is looking for. There is no one path or experience that leads to becoming an astronaut. We have an amazing diversity of experience and background in the astronaut office.
What advice do you have for the newest astronauts?
Enjoy the journey! Spaceflight is amazing, but even as astronauts, most of us spend 95% of our career on the ground. Enjoy every part of the job, supporting missions as a Spacecraft Communicator (CapCom), verifying procedures for a repair or training for a spacewalk. It is amazing to be a part of the team that launches and supports humans living and working in space. It is an amazing thing.
Which is more exciting: spacewalking or skydiving?
Skydiving was pretty amazing. I got to do quite a bit of it as a member of the Air Force Academy parachute team. But there is nothing quite like doing a spacewalk. It is an indescribable experience, putting hundreds of hours of training to work, the physical and mental challenge of operating in that harsh environment. But the view outside the space station, of the Earth, the stars, the structure of the space station – it was a highlight of my time in space and something I will never forget.
What’s the most interesting part about training with the Dragon capsule?
It has been awesome working with the NASA and SpaceX teams as we are preparing to launch in the Crew Dragon capsule. My favorite part of the experience has always been and continues to be the people. Safely sending humans to space and back is one of the most difficult things humanity has ever done. That challenge attracts the best and brightest people from across our country. Getting to work with those folks at NASA and at SpaceX, to experience their enthusiasm, dedication and ingenuity on a daily basis is a gift. It has also been a lot of fun seeing a different approach to human spaceflight. I’m very familiar with how NASA and the Russian Space Agency Roscosmos operate. It has been fun seeing a different perspective and approach.
Can you share your favorite photo or video that you took in space?
Yes! This is my favorite photo of the Milky Way, with a lightning strike illuminating a solar array.
Thanks Dr. Lindgren, and good luck on your next spaceflight!
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Today — June 20, 2024 — is the northern summer solstice. In the Northern Hemisphere, it marks the longest day of the year and the official start to summer.
