SpaceX just sent three space weather probes to the final frontier.

A Falcon 9 rocket lifted off from NASA's Kennedy Space Center in Florida today (Sept. 24) at 7:30 a.m. EDT (1130 GMT), carrying NASA's IMAP mission and and two other spacecraft.

Each probe has its own objectives, but all three will work toward the same larger goal: help scientists better understand space weather and its effects on Earth.

They're also all headed to the same place — the sun-Earth Lagrange Point 1, a gravitationally stable spot about 930,000 miles (1.5 million kilometers) from Earth, in the direction of our star.

IMAP (short for "Interstellar Mapping and Acceleration Probe") is the primary payload on today's flight. The roughly $600 million spacecraft carries 10 different science instruments, which it will use to monitor solar activity as well as study interstellar dust and the solar wind, the stream of charged particles flowing continuously from our sun.

The mission's data will also help scientists map the outer boundary of the heliosphere, the vast bubble around our solar system that's dominated by the sun's solar wind and magnetic field.

IMAP will also provide radiation warnings for astronauts — for example, those with NASA's Artemis program, which aims to establish a sustained human presence on and around the moon over the next decade or so.

"Radiation exposure is a real threat to our astronauts traveling to the moon and beyond," Nicky Fox, associate administrator of NASA's Science Mission Directorate, said during a news conference on Sunday (Sept. 21).

"Humanity has only ever existed inside our protective magnetosphere, and as we travel beyond that protective shield, whether it be to the moon or to Mars, the actionable information from missions like IMAP will keep our astronauts safe," she added.

The other two spacecraft that went up today are NASA's Carruthers Geocorona Observatory (CGO) and the U.S. National Oceanic and Atmospheric Administration's Space Weather Follow-on (SWFO-L1) spacecraft.

CGO will investigate the exosphere, the wispy outermost reaches of Earth's atmosphere. The small satellite "will image the faint glow of ultraviolet light from this region, called the geocorona, to better understand how space weather impacts our planet," NASA officials said in a mission description. "The Carruthers mission continues the legacy of the Apollo era, expanding on measurements first taken during Apollo 16."

SWFO-L1 will track solar storms, providing an early warning system for space weather, which can pose a threat to satellites, astronauts in orbit and some infrastructure on the ground, such as power grids.

All went according to plan on today's launch. The Falcon 9's upper stage deployed IMAP into an interplanetary transfer orbit about 84 minutes after launch. SWFO-L1 and CGO followed suit about 6.5 minutes and 13 minutes after that, respectively.

And the rocket's first stage came back to Earth on schedule, landing a little less than nine minutes after liftoff on the SpaceX droneship "Just Read the Instructions," which was stationed in the Atlantic Ocean. It was the second flight for this particular booster, according to a SpaceX mission description.

Today's launch was the 120th Falcon 9 flight of 2025 already. Most of these missions — more than 70% of them — have been dedicated to building out SpaceX's Starlink satellite-internet constellation in low Earth orbit.

Editor's note: This story was updated at 10:55 a.m. ET on Sept. 24 with news of successful spacecraft deployment.

SpaceX will launch NASA's ambitious IMAP mission and two other space weather probes early Wednesday morning (Sept. 24), and you can watch the action live.

A Falcon 9 rocket is scheduled to lift off from NASA's Kennedy Space Center in Florida on Wednesday at 7:30 a.m. EDT (1130 GMT), carrying IMAP and two rideshare spacecraft deep into the final frontier.

You can watch it live here at Space.com, courtesy of NASA, or directly via the space agency. Coverage is expected to will begin around 6:40 a.m. EDT (1040 GMT).

The primary payload is IMAP, whose name is short for "Interstellar Mapping and Acceleration Probe."

IMAP "will study how the sun's energy and particles interact with the heliosphere — an enormous protective bubble of space around our solar system — to enhance our understanding of space weather, cosmic radiation, and their impacts on Earth and human and robotic space explorers," NASA officials wrote in a mission description.

Launching with IMAP are NASA's Carruthers Geocorona Observatory (CGO) and the Space Weather Follow-on (SWFO-L1) spacecraft, which will be operated by the U.S. National Oceanic and Atmospheric Administration (NOAA).

CGO will study Earth's exosphere — the atmosphere's wispiest outer reaches — to help scientists better understand how space weather affects our planet. SWFO-L1 will monitor and track solar storms, "serving as an early warning beacon for potentially disruptive space weather, helping safeguard Earth’s critical infrastructure and technological-dependent industries," NASA officials wrote in the mission description.

The trio will do this work at the Earth-sun Lagrange Point-1 (L1), a gravitationally stable spot that lies 930,000 miles (1.5 million kilometers) from our planet. Several other spacecraft operate at L1, including India's Aditya-L1 solar probe and the Solar and Heliospheric Observatory (SOHO), a joint effort of NASA and the European Space Agency.

If all goes according to plan on Wednesday, the Falcon 9's upper stage will deploy IMAP, CGO and SWFO-L1 into interplanetary transfer orbit during a 13-minute stretch that begins about 83 minutes after liftoff. The three spacecraft will then make their way out to L1.

Editor's note: This story was updated at 4:25 p.m. ET on Sept. 22 with the new target launch date of Sept. 24.

SpaceX is preparing to launch three spacecraft on a first-of-its-kind mission to study the sun's influence throughout the solar system, from Earth's atmosphere to the edge of interstellar space.

A Falcon 9 rocket is scheduled to lift off from Launch Complex-39A, at NASA's Kennedy Space Center in Florida, on Sept. 23 at 7:32 a.m. EDT (1132 GMT). Stowed inside Falcon's payload fairing are NASA's Interstellar Mapping and Acceleration Probe (IMAP), the Space Weather Follow-on (SWFO-L1) spacecraft from the U.S. National Oceanic and Atmospheric Administration (NOAA), and NASA's Carruthers Geocorona Observatory.

The satellite trio is bound for the Earth-sun Lagrange Point-1 (L1), an orbitally stable location in permanent sunlight that lies 930,000 miles (1.5 million kilometers) from Earth. Though each mission has its own distinct objectives, their combined science is designed to build a more complete picture of the Earth-sun relationship.

IMAP is the first spacecraft dedicated to mapping the outer boundary of the heliosphere, the vast magnetic bubble surrounding our solar system that's formed by the solar wind. The satellite's 10 instruments, built by teams across the U.S. and with contributions from 27 international partners, will measure solar wind, interstellar dust and charged particles, while also providing continuous solar weather monitoring.

IMAP and its companions will be the first spacecraft to observe solar activity from their L1 vantage point, and are designed to offer between 30 minutes to an hour of advanced warning of dangerous radiation storms headed for Earth.

This is particularly important for astronaut missions beyond low Earth orbit (LEO), which won't enjoy much radiation protection from Earth's magnetosphere. And NASA aims to launch two such missions soon — the Artemis 2 flight around the moon in 2026 and Artemis 3 lunar landing mission in 2027.

"IMAP will provide warnings beginning with Artemis 2 and Artemis 3 of incoming harmful radiation storms faster than any other spacecraft has done before," Nicky Fox, associate administrator of NASA's Science Mission Directorate, told reporters during a press conference on Sept. 4.

David McComas, principal investigator for the mission, said IMAP data "will help us better understand the fundamental physics of the heliosphere" and how it shields Earth and spacefarers from cosmic rays.

Riding alongside IMAP, NOAA's SWFO-L1 will serve as a dedicated solar alert system, monitoring space weather and energetic particles in real time. Its data will feed directly into NOAA's forecasting models to help safeguard satellites, communications systems and power grids from geomagnetic storms.

NASA's Carruthers Geocorona Observatory — previously known as the Global Lyman-alpha Imagers of the Dynamic Exosphere (GLIDE) — is tasked with studying Earth's exosphere, a thin atmospheric layer that extends nearly halfway to the moon.

"We actually don't know exactly how big it is," said University of Illinois scientist Lara Waldrop, the mission's principal investigator. "We don't know whether it's spherical or oval, how much it changes over time, or even the density of its constituent hydrogen atoms."

Waldrop said what we do know is that the exosphere plays a critical role in Earth's response to geomagnetic storms. L1 sits outside the exosphere, providing mission operators a rare chance to measure it from the outside.

Findings will also improve scientists' understanding of how atomic hydrogen escapes Earth's gravity and inform models of planetary evolution in the search for habitable exoplanets.

Lagrange points, or Lagrangian points, are locations in space where objects can stay in position relative to another, larger body. 

They are made possible by the balance of gravitational and centripetal forces — for example, between Earth and the sun, or between Earth and the moon, NASA explains. 

Because Lagrange points are easy to reach, many spacecraft are sent to perform their observations from these locations.

Related: How Lagrange points solved one of physics' biggest problems 

Lagrange point FAQs

How many Lagrange points are there?

Each pair of gravitational bodies has five Lagrange points. Let's take Earth and the sun as an example. The first Lagrange point, L1, is between Earth and the sun. The second Lagrange point, L2, is on the opposite side of Earth from the sun. Because the sun is partially blocked by Earth, L2 provides a dark, unhindered vantage point for space telescopes such as the James Webb Space Telescope (JWST) to view the universe, according to NASA.

L3 is located on the opposite side of the sun to Earth, so we cannot see it. L4 and L5 are positioned 60 degrees in front of and 60 degrees behind Earth in its orbit and are where the Trojan asteroids cluster.

These five points are mirrored in other pairs of bodies. For example, the Earth-moon system has its own set of Lagrange points. L1 is between Earth and the moon, L2 is on the far side of the moon, L3 is on the opposite side of Earth to the moon, and L4 and L5 are 60 degrees in front of and behind the moon on its orbit around Earth.

Who discovered the Lagrange points?

The history of the Lagrange points goes back to the mid-to-late 18th century, long before there were rockets or spacecraft. Much of the legwork had been done in the previous century, with Johannes Kepler's three laws of planetary motion and Isaac Newton's laws of gravitation, which together describe how the moon orbits Earth, and how Earth and the other planets orbit the sun.

The first three Lagrange points were initially proposed by the great mathematician Leonhard Euler in 1760 while he was studying the inward and outward forces acting on a large body orbiting another object, such as the sun. Later, in the early 1770s, Joseph-Louis Lagrange, who was Euler's student, discovered L4 and L5 and corroborated Euler's earlier work. 

How do Lagrange points work?

A spacecraft at a Lagrange point feels a balance between the gravitational pull of two large bodies — such as Earth and the sun, or Earth and the moon — on a smaller object, and the centripetal force needed for that smaller object to move in time with them and thus appear to remain in a specific location relative to them, NASA explains. Such a location is a Lagrange point.

For example, at the L1 point, which lies between Earth and the sun, the sun's gravity will pull a spacecraft around it faster than Earth orbits the sun. (Kepler's second law of planetary motion tells us that the closer an object is to the sun, the faster it will orbit.) However, Earth's gravity can pull back on a spacecraft, slowing it down. At L1, all of these forces are in balance, and a spacecraft at L1 would be moving slow enough to maintain its position, at least temporarily.

The situation is reversed for L2, which is a little farther from the sun than Earth is. Here, spacecraft should orbit the sun a little more slowly than our planet does, but Earth's gravity can pull them along and balance the forces.

The European Space Agency (ESA) describes L1, L2 and L3 as "meta-stable," meaning that, over longer periods of time, spacecraft or asteroids will drift out of them. L4 and L5 are permanently stable over billions of years, which is why the Trojan asteroids can remain there.

What are the distances to the Lagrange points?

The distance to the Earth-sun Lagrange point 1 is about 932,000 miles (1.5 million kilometers) from Earth. Lagrange Point 2 is the same distance in the opposite direction. Lagrange Point 3 is about 186 million miles (300 million km) from us. Both L4 and L5 are about 19 million miles (30 million km) from Earth.

Given the relatively short distances to the Earth-sun L1 and L2 points, they can be easily accessed by spacecraft. Because the Earth-moon Lagrange points are much closer to us, all of them can be reached.

What spacecraft are currently at the Lagrange points?

Several spacecraft are found at the Earth-sun L1 point. These include the joint ESA-NASA Solar and Heliospheric Observatory and NASA's Advanced Composition Explorer and Wind missions, which study the solar wind. In September 2023, the Indian Space Research Organisation launched Aditya-L1, a solar mission to L1. Meanwhile, the National Oceanic and Atmospheric Administration's Deep Space Climate Observatory is at L1, looking back at Earth.

The Earth-sun L2 point has become famous recently as the home of JWST. It is joined at L2 by ESA's Euclid and Gaia missions and a German-Russian high-energy astrophysics mission called Spektr-RG. Past missions at L2 include NASA's Wilkinson Microwave Anisotropy Probe and ESA's Planck mission, both of which studied the cosmic microwave background, and ESA's Herschel Space Observatory. 

Future missions to L2 will include NASA's Nancy Grace Roman Space Telescope, ESA's PLATO and ARIEL exoplanet missions, and the joint ESA-Japan Aerospace Exploration Agency Comet Interceptor spacecraft.

There are no current missions at L3, L4 or L5.

What are Trojan asteroids?

Because L4 and L5 are permanently stable Lagrange points, any objects that exist in them will remain there. As such, asteroids can become trapped at L4 and L5. Astronomers call these objects Trojan asteroids. 

Jupiter has the most Trojan asteroids. More than 10,000 have been detected so far, with more at L5 than at L4. NASA's Lucy mission launched in October 2021 to explore Jupiter's Trojan asteroids and will arrive at its first one in 2027.

Trojans have also been found, in much smaller numbers, at the L4 and L5 points of Venus, Earth, Mars, Uranus and Neptune, which, after Jupiter, has the most, with 31 known Trojans as of the end of 2023.

Additional resources

You can read more about the five Lagrange points in this article by Neil deGrasse Tyson. If you're more mathematically inclined, check out this NASA PDF describing the Lagrange points using equations. For an animated view and description of Lagrange points, watch this NASA video featuring Hal Levison, principal investigator for the Lucy mission.

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NASA's Earth Polychromatic Imaging Camera — or EPIC for short — is living up to its acronym, by producing visually stunning and scientifically fascinating images of Earth.

EPIC lives onboard NASA's Deep Space Climate Observatory (DSCOVR), which orbits the sun about 1 million miles from Earth — a perfect vantage point to take a snapshot of Earth's entire sunlit face every 2 hours. A new video from NASA explains how this location allows EPIC to track features like clouds, particulates in the air or volcanic ash clouds. It will also provide information about the energy budget of the planet — an important piece of information for climate models.

Today (Dec. 14), at the annual meeting of the American Geophysical Union, scientists released new images taken by EPIC, and described some of the science it will facilitate.[See more photos from NASA's Deep Space Climate Observatory]

"We've grown accustomed to seeing images of our planet from space," says the new video produced at the NASA Goddard Spaceflight Center. "But full Earth views […] have actually only been seen by astronauts on their way to the moon, and a handful of retreating probes, like Galileo, as they peered back toward home for the last time." 

As most people are well aware, satellites orbiting the Earth provide "high resolution images of the planet every day," according to the video. But as the video explains, these satellites are too close to the surface of the Earth to capture its entire face at once. Instead, they have to take many pictures as they loop around and around Earth. The pictures are then compiled into a single image. But that means these images don't show changing features, like storms, at the same point in time. EPIC, on the other hand, provides a complete view of the Earth face in each image.

"It’s the only view we have like this where everything is at the exact same instant in time, even though the local times are different," Jay Herman, EPIC instrument lead investigator at Goddard, said in a statement from NASA. With this capability, it's possible for scientists to watch storms or clouds of dust as they move across the planet. "We can see the progression in real time," Herman said.

EPIC will produce gorgeous color images of the Earth, but it also take pictures in ultraviolet and near-infrared light, which are better for tracking some features, the scientists at the AGU meeting said. The science of EPIC is somewhat expansive, and will include helping to measuring Earth's energy balance (which is based partly on how much sunlight is absorbed and reflected by the planet). That information is used in climate models. Scientists are also "analyzing EPIC data to better understand vegetation, aerosols, ozone and other features of Earth and its atmosphere," according to the statement from NASA.

DSCOVR launched on Feb. 11 of this year, aboard a SpaceX Falcon 9 rocket. The location where it orbits the sun is known as the first Lagrange point, or L1, a place where the gravitational pull of the sun and the Earth "balance out," allowing spacecraft to stay relatively stable, the scientists said. It is also carrying instruments that will study the sun, and perhaps provide information that could help scientists predict solar flares and other dangerous space weather events. 

Follow Calla Cofield @callacofield.Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.