The Jet Propulsion Laboratory (JPL) was building spacecraft before NASA even existed, and today it's the space agency's go-to center for the robotic exploration of worlds beyond Earth.

Technicians at NASA's Jet Propulsion Laboratory work on the Mars Science Laboratory rover Curiosity in May 2011. The rover is upside-down, and its six wheels are off (they rest on a table, at far right of the photo).
Technicians at NASA's Jet Propulsion Laboratory work on the Mars Science Laboratory rover Curiosity in May 2011. The rover is upside-down, and its six wheels are off (they rest on a table, at far right of the photo).
Credit: Mike Wall

JPL leads the $2.5 billion Mars Science Laboratory mission, which dropped the 1-ton Curiosity rover on the Red Planet's surface in 2012. The center also runs the Saturn-studying Cassini mission, the Voyager probes nearing the edge of the solar system and many other well-known unmanned exploration efforts.

JPL is based in Pasadena, Calif., and is managed for NASA by the California Institute of Technology (Caltech). Here's a brief rundown of the lab, which employs about 5,000 people and has an annual budget of $1.6 billion.

JPL's roots go back to 1936, when a group of researchers at Caltech's Guggenheim Aeronautical Laboratory performed a series of rocket experiments in a dry canyon wash known as Arroyo Seco. They moved out to the valley after an accidental explosion on campus.

"They weren't going to mess anything up out here," Jia-Rui Cook told Cook works with JPL's media relations.

The success of those trials attracted the attention of the United States military, which gave the Caltech team money to develop strap-on rockets to help Army planes take off from short runways — a concept called "jet-assisted takeoff," or JATO. [10 Military Aircraft that Never Made it Past the Test Phase]

In 1943, several of the researchers formed the Aerojet Corporation — which remains in business today — to manufacture JATO motors. That same year, the Caltech team began referring to their research organization as the Jet Propulsion Laboratory.

In the early years, JPL was funded by the U.S. Army to develop missile technology. By 1945, the lab employed nearly 300 people and had begun to launch test vehicles to an altitude of 37 miles (60 kilometers) from White Sands, N.M.

Just two years later, JPL first launched Corporal, a guided missile viewed as an answer to Germany's famous V-2 rocket. Corporal missiles were deployed in the U.S. and Europe from 1954 to 1964.

JPL then branched out, applying the skills gained from its missile efforts to nonmilitary research missions. The lab began developing Explorer 1, the United States' first successful satellite, in November 1957 and launched it to orbit on Jan. 31, 1958.

Before the end of the year, JPL had been transferred from military to civilian jurisdiction. Congress created NASA in October 1958, and the space agency took charge of JPL two months later. [NASA's 10 Greatest Science Missions]

The lab soon began setting its sights beyond Earth orbit. In 1962, for example, JPL's Mariner 2 spacecraft flew by Venus, becoming the first probe ever to observe another planet up close.

The Mariner 9 spacecraft.
The Mariner 9 spacecraft.
Credit: NASA


Mariner 4 performed a Mars flyby in 1964, and Mariner 9 became the first spacecraft to circle another planet when it settled into orbit around the Red Planet in 1971.

JPL efforts also helped pave the way for NASA's manned Apollo moon missions. In 1964 and 1965, the Ranger 7, 8 and 9 spacecraft took photos of Earth's nearest neighbor before intentionally crashing into the lunar surface. And from 1966 to 1968, Surveyor 1, 3, 5, 6 and 7 made soft landings on the moon.

Mariner 10, launched in 1973, was another pioneering effort. The JPL spacecraft swung by Mercury after getting a boost from Venus — the first time a probe ever employed this planetary "gravity-assist" strategy, which allows robotic explorers to maximize the distance they travel while minimizing fuel use.

Curiosity may be the most ambitious and most capable rover ever launched, but it's far from JPL's first Red Planet foray. The lab has helped send a phalanx of robotic explorers to Mars over the last four decades. [History of Robotic Mars Missions (Infographic)]

In 1975, NASA launched the Viking mission, the agency's first attempt to look for life on the Red Planet. Viking delivered two orbiters and two landers to Mars, eventually returning intriguing but equivocal evidence of possible biological activity. JPL built the orbiters and eventually assumed responsibility for management of the mission.

JPL also led the Mars Pathfinder mission, which placed a rover and a lander on the Red Planet in 1997, and Mars Global Surveyor, which studied the planet from orbit from 1997 through 2006. The lab's Mars Odyssey orbiter launched in 2001 and remains operational today.

Further, JPL manages the Mars Exploration Rover mission, which landed the twin rovers Spirit and Opportunity on Mars in January 2004. Spirit stopped communicating with Earth in 2010, but Opportunity is still going strong.

JPL's Mars Reconnaissance Orbiter launched in 2005 and continues to study the Red Planet from above. And in 2008, the Phoenix lander confirmed the presence of water ice just below the Martian surface near the planet's north pole.

Not all of JPL's Mars efforts have been successful. For instance, contact was lost with Mars Observer in 1993, shortly before it was slated to enter orbit. And both the Mars Climate Orbiter and Mars Polar Lander were lost upon arrival at the Red Planet in late 1999.

"Landing on Mars is hard," Cook said.

That's why missions often rely on existing ideas and hardware from previous trips to the red planet. According to Cook, the upcoming Mars2020, for instance, will utilize the a spare heat shield from the Curiosity mission.

"If we've done it successfully already, then we'll build on that," she said.


An artist's illustration of NASA's Voyager 1 spacecraft, the farthest human-built object from Earth, which launched in 1977 and is headed for interstellar space.
An artist's illustration of NASA's Voyager 1 spacecraft, the farthest human-built object from Earth, which launched in 1977 and is headed for interstellar space.
Credit: NASA

JPL has also sent many probes beyond Mars. Two of the most famous are the lab's twin Voyager spacecraft, which launched in 1977 to study Jupiter, Saturn and their moons. The probes achieved their initial goals, then kept on going, checking out Uranus and Neptune on their way toward interstellar space.


Both spacecraft are now observing the strange environment at the edge of the solar system; Voyager 1 is about 11 billion miles (18 billion km) from Earth, and Voyager 2 is 9 billion miles (15 billion km) from home.

JPL's Galileo probe also studied Jupiter, entering orbit around the solar system's largest planet in 1995 and making observations for the next eight years. Cassini, which launched toward the Saturn system in 1997, is still sending data and images home today.

The lab has also led or participated in missions to study comets and asteroids. One such effort was Stardust, which collected particles from the tail of Comet Wild-2 in 2004 and returned them to Earth.

The JPL-managed Deep Impact spacecraft smashed a projectile into Comet Tempel 1 in 2005, then chased down Comet Hartley 2 for an up-close look in 2010. And JPL's Dawn spacecraft orbited Vesta, the second-largest object in the asteroid belt, before heading off to study the belt's biggest body, the dwarf planet Ceres.

JPL also keeps its eyes on Earth. According to Jason Craig, who works on visualization for JPL, nearly a third of the lab's budget is spent studying our own pale blue dot. Satellites large and small monitor Earth's atmosphere, oceans, gravity, and temperature as it orbits the sun. They even track "what's on fire around the Earth," Cook said, thanks to the carbon monoxide in the atmosphere. In addition to wildfires, this allows scientists to track the slash-and-burn tactics prevalent in the rainforests of South America and Africa. All of this information is available to the public through a desktop application known as "Eyes on Earth."

"We collect the data and we hand it over," Craig said. "Everything we do is released to the world."

The Deep Space Network command center keeps track of JPL's far-flung missions.
The Deep Space Network command center keeps track of JPL's far-flung missions.
Credit: Nola Taylor Redd

While JPL is best known for its planetary exploration missions, it has managed or assisted a number of other efforts over the years as well.

For example, the lab manages the Spitzer Space Telescope, which has been scanning the universe in infrared light since its 2003 launch. And JPL's Wide-field Infrared Survey Explorer space telescope, or WISE, found more than 100,000 previously unknown asteroids in the asteroid belt before shutting down in 2011.

JPL also serves as the home of NASA's Near-Earth Objects Program, which coordinates observations of Earth-crossing asteroids and comets.

Further, JPL managed flight project development for the Kepler space telescope, which has spotted more than 2,300 potential alien planets to date. The lab handed control of Kepler's science operations over to NASA's Ames Research Center in Mountain View, Calif., after Kepler's March 2009 launch.

JPL also designed, built and operates NASA's Deep Space Network, a system of antenna stations located in California's Mojave Desert, Spain and Australia. The DSN provides tracking for NASA and international missions to deep space, and it helps image planets and asteroids using radar. Data collected from the outskirts of the solar system streams back to the lab in California, leading some JPL folks to jokingly refer to it as "the center of the universe," according to Jim McClure, who manages Mission Control.

The floor of the DSN's mission control testifies to the nickname. A large inset commemorates the cooperation of JPL with NASA and Caltech, proclaiming the site to be the center of the universe.

"We fly our nerd flags extremely high here at JPL," McClure said. "So high we have had four marriage proposals at the center of the universe."

In addition to its main Pasadena site and the three DSN antenna stations around the world, JPL facilities include an observatory at Table Mountain, Calif., and a launch complex at Florida's Cape Canaveral. The lab's current director is Dr. Michael Watkins, who took control in July 2016. [Infographic: NASA Centers' New Mission

Additional reporting by contributor Nola Taylor Redd. Follow her tour of JPL here.