A model of Explorer 1 is held by (left to right) JPL Director William Pickering, University of Iowa physicist James Van Allen and Wernher von Braun from the Army Ballistic Missile Agency.

In the News

This month marks the 60th anniversary of the launch of America’s first satellite, Explorer 1. The small, pencil-shaped satellite did more than launch the U.S. into the Space Age. With its collection of instruments, or scientific tools, it turned space into not just a new frontier, but also a place of boundless scientific exploration that could eventually unveil secrets of new worlds – as well as the mysteries of our own planet.

Poster highlighting the main characteristics of Explorer 1 and the Jupiter C rocket.

A poster highlights the main characteristics of Explorer 1 and the Jupiter C rocket that launched it into space. Image credit: NASA

How They Did It

At the height of competition for access to space, the U.S. and the Soviet Union were both building satellites that would ride atop rockets in a quest to orbit Earth. The Soviets launched Sputnik 1 on October 4, 1957. Shortly thereafter, on January 31, 1958, the U.S. launched Explorer 1, the satellite that would begin a new age of scientific space exploration.

Using rockets to do science from orbit was a brand-new option in the late 1950s. Before this time, rockets had only been used for military operations and atmospheric research. Still, rockets of that era weren’t very reliable and none had been powerful enough to place an object into Earth orbit.

Rocket Lessons from NASA/JPL Edu

Rocket Activities

Explore our collection of standards-aligned lessons for grades K-9.

In order to lift Explorer 1 to its destination in Earth orbit, an existing U.S. Army rocket, the Jupiter C, was fitted with a fourth stage, provided by the Jet Propulsion Laboratory in Pasadena, California. For this stage, a rocket motor was integrated into the satellite itself. The new, four-stage rocket was called “Juno 1.”

Prior to these first orbiting observatories, everything we knew about space and Earth came from Earth-based observation platforms – sensors and telescopes – and a few atmospheric sounding rockets. With the success of Explorer 1 and the subsequent development of more powerful rockets, we have been able to send satellites beyond Earth orbit to explore planets, moons, asteroids and even our Sun. With a space-based view of Earth, we are able to gain a global perspective and acquire a wide variety and amount of data at a rapid pace.

Why It’s Important

scientific instruments mounted inside Explorer 1

This photograph shows the scientific instruments mounted inside Explorer 1 alongside its outer case. Image Credit: James A. Van Allen Papers (RG 99.0142), University Archives, The University of Iowa Libraries

Graphic showing the components and science instruments aboard Explorer 1.

This graphic shows the various components and science instruments aboard Explorer 1, including its primary science instrument, a cosmic ray detector. Image credit: NASA/JPL-Caltech

Graphic showing the Van Allen Belts and the locations of Earth-orbiting spacecraft

This graphic shows a cutaway diagram of the Van Allen belts along with the locations of a few Earth-orbiting spacecraft, including the Van Allen Probes. Image credit: NASA

The primary science instrument on Explorer 1 was a cosmic ray detector designed to measure the radiation environment in Earth orbit – in part, to understand what hazards future spacecraft (or space-faring humans) might face. Once in space, this experiment, provided by James Van Allen of the University of Iowa, revealed a much lower cosmic ray count than expected. Van Allen theorized that the instrument might have been saturated by very strong radiation from a belt of charged particles trapped in space by Earth's magnetic field. The existence of the radiation belts was confirmed over the next few months by Explorer 3, Pioneer 3 and Explorer 4. The belts became known as the Van Allen radiation belts in honor of their discoverer.

Although we discovered and learned a bit about the Van Allen belts with the Explorer missions, they remain a source of scientific interest. The radiation belts are two (or more) donut-shaped regions encircling Earth, where high-energy particles, mostly electrons and ions, are trapped by Earth's magnetic field. The belts shrink and swell in size in response to incoming radiation from the Sun. They protect Earth from incoming high-energy particles, but this trapped radiation can affect the performance and reliability of our technologies, such as cellphone communication, and pose a threat to astronauts and spacecraft. It’s not safe to spend a lot of time inside the Van Allen radiation belts.

Most spacecraft are not designed to withstand high levels of particle radiation and wouldn’t last a day in the Van Allen belts. As a result, most spacecraft travel quickly through the belts toward their destinations, and non-essential instruments are turned off for protection during this brief time.

To conquer the challenge of extreme radiation in the belts while continuing the science begun by Explorer 1, NASA launched a pair of radiation-shielded satellites, the Van Allen Probes, in 2012. (The rocket that carried the Van Allen Probes into space was more than twice as tall as the rocket that carried Explorer 1 to orbit!)

The Van Allen Probes carry identical instruments and orbit Earth, following one another in highly elliptical, nearly identical orbits. These orbits bring the probes as close as about 300 miles (500 kilometers) above Earth’s surface, and take them as far out as about 19,420 miles (31,250 kilometers), traveling through diverse areas of the belts. By comparing observations from both spacecraft, scientists can distinguish between events that occur simultaneously throughout the belts, those that happen at only a single point in space, and those that move from one point to another over time.

Watch the video above to learn more about the Van Allen Probes and a discovery they made shortly after starting their mission. Credit: NASA Goddard

The Van Allen Probes carry on the work begun by Explorer 1 and, like all successful space missions, are providing answers as well as provoking more questions. NASA continues to explore Earth and space using spacecraft launched aboard a variety of rockets designed to place these observatories in just the right spots to return data that will answer and inspire questions for years to come.

Teach It

TAGS: Explorer 1, STEM, NASA in the Classroom, Lessons, Activities, Teachable Moments

  • Ota Lutz
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Students plot changes in Earth's gravitational field using data from NASA's GRACE mission.

In the Education Office at NASA’s Jet Propulsion Laboratory, we’re always working to bring exciting scientific content to K-12 classrooms. Educators can access many of these free resources, classroom materials and activities online, and we’re adding more all the time. The inspiration for these products often comes from the work being done at JPL and NASA, but sometimes it’s the teachers we work with whose creative ideas inspire the lessons we share with our community of STEM educators. Our new column, Teacher Feature, is an effort to capture those creative ideas and highlight the teachers behind them.


Classroom Activity: Earth Science Data Visualizations – How to Read a Heat Map

Featured Lesson: How to Read a Heat Map

Students learn to read, interpret and compare “heat maps” representing Earth science data.

LoriAnn Pawlik recently shared her NASA-inspired lesson during a professional development workshop hosted by the agency.

LoriAnn teaches STEM to grades K-5 at Penn Elementary School in Prince William County, Virginia, which focuses on students learning English, as well as those with learning disorders and autism. When she recently came across a lesson on the NASA/JPL Edu website, she saw an opportunity to bring real-world NASA data to her students.

How do you use NASA in the classroom?

Using the lesson “How to Read a Heat Map” as a jumping-off point, LoriAnn had her students first dive into the practice of reading and interpreting graphs. From here, she extended the lesson with an exploration of NASA satellites and the data they collect, focusing on the Gravity Recovery And Climate Experiment, or GRACE mission, to tie in with a community science night on water science.

GRACE was launched in 2002 to track changes in the distribution of liquid water, ice and land masses on Earth by measuring changes in the planet’s gravity field every 30 days. Circling Earth 16 times each day, GRACE spent more than 15 years collecting data – all of which is available online – before its science mission ended last October. The mission provided students the perfect context to study climate and water through authentic NASA data.

Students plot changes in Earth's gravitational field using data from NASA's GRACE mission.
Students plot changes in Earth's gravitational field using data from NASA's GRACE mission.
Students plot changes in Earth's gravitational field using data from NASA's GRACE mission.

LoriAnn's students plotted changes in Earth's gravitational field using data from NASA's GRACE mission.

How did students react to the lesson?

LoriAnn set the stage for her students by explaining to them that they would be providing their data to NASA scientists.

“I told them that I was working on a project for a scientist from NASA-JPL and that we needed their help,” she said via email. “By the time I gave them the background and showed a brief GRACE video, they were all in – excited, eager enthusiastic! It helped that each table, or ‘engineering group,’ was responsible for a different U.S. state.”

As a result, students were able to plot the changes in gravitational fields for multiple locations over several years.

What are other ways you use NASA lessons or resources?

By extending the lesson, LoriAnn gave her students a sense of authentic ownership of the data and practice in real scientific analysis. But it wasn’t her first time uniting NASA science with her school curriculum:

“I'd been working with our second-graders on field studies of habitats,” LoriAnn explained. “We observed, journaled and tracked the migration of monarch butterflies, discussed what happened to habitats of living things since Hurricane Harvey and Hurricane Irma were just going through, and then I used the [NASA Mars Exploration website] to have students extend the findings to space habitats.”


Have a great idea for implementing NASA research in your class or looking to bring NASA science into your classroom? The Educator Professional Development Collaborative, or EPDC, can help. The EPDC at JPL serves educators in the greater Los Angeles area. Contact JPL education specialist Brandon Rodriguez at brandon.rodriguez@jpl.nasa.gov. Note: Due to the popularity of EPDC programs, JPL may not be able to fulfill all requests.

Outside the Southern California area? The EPDC operates in all 50 states. Find an EPDC specialist near you.

The EPDC is managed by Texas State University as part of the NASA Office of Education. A free service for K-12 educators nationwide, the EPDC connects educators with the classroom tools and resources they need to foster students’ passion for careers in STEM and produce the next generation of scientists and engineers.

TAGS: Teaching, K-12, NASA in the Classroom, Graphing, Activities, Science, Earth Science, Climate Change

  • Brandon Rodriguez
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