NASA launched its billion-dollar Lucy probe into space on Saturday with a predawn launch, beginning a 12-year, 4-billion-mile mission to make close flybys of eight asteroids that may represent the origins of our solar system.
Launched from Cape Canaveral, a spacecraft is heading toward the Sun’s atmosphere to investigate “the fossils.”
As Lucy travels through Jupiter’s orbit, it will study two swarms of asteroids that are ahead of and behind the giant.
The objects are thought to be leftovers from the formation of planets, according to scientists at the US space agency (NASA).
Due to this, these Trojans, as they are known, can provide valuable information regarding the early evolution of the Solar System.
At 05:34 EDT (09:34 GMT; 10:34 BST), the liftoff of an Atlas-V rocket from Cape Canaveral Space Force Station in Florida went ahead on schedule.
Asteroids known as Trojans orbit the sun beyond the main belt of rocky debris between Mars and Jupiter. As if in a swarm, they are grouped together in two directions, one group 60 degrees ahead of the giant planet and one group 60 degrees behind.
As part of NASA’s Lucy mission, the probe was launched on a trajectory that planned three Earth flybys in order to send it first past an asteroid in the main belt between Mars and Jupiter and then past five asteroids in one Trojan swarm and two in the other.
The United Launch Alliance Atlas 5 rocket launches NASA’s space probe Lucy into orbit from Cape Canaveral Space Force Station (left). An extended exposure (right) captures a dramatic view of the rocket arcing towards the east.
Hal Levison, a principal investigator at Southwest Research Institute, believes that Trojan asteroids lead or follow Jupiter’s orbit by about sixty degrees, “If you put something there early in the history of the solar system, it will be steady forever because of the gravitational effect of Jupiter and the sun.”
Essentially, these things are the fossil remains of what planets form from. Planets formed after these things hit each other and grew, and these are the remnants of that. So if you want to understand where the solar system originated, you have to look at these small bodies.”
On a picture-perfect launch from Cape Canaveral Space Force Station on Saturday morning, Lucy’s mission launched with a rocket from United Launch Alliance. With a stunning pre-dawn show of flaming exhaust, the rocket lit up the sky miles away as it rocketed away from pad 41.
A 23-day window opened during which Earth and the eight target asteroids were in the most favorable position for the eight planned flybys.
It will take Lucy two Earth flybys, in 2022 and 2024, to reach the first Trojan swarm, using Earth’s gravity to increase her velocity and send her outward toward the “L4” swarm.
Due to her convoluted trajectory, Lucy will have to go close to Earth twice to reach the Trojan swarm (left) and once more to reach the other cluster (right).
In 2025, the probe will fly by an asteroid named after Donald Johanson, the paleoanthropologist who discovered the Lucy fossils, the oldest known human ancestor, in 1974.
The L4 swarm and the flybys of the Trojan asteroid Eurybates and its small moon Queta will follow in August 2027, followed by Polymele in September 2027, Leucus in April 2028, and Orus in November 2028.
When Lucy leaves the L4 group in 2033, she will return to the inner solar system for another gravity assistance to send her on to the L5 Trojan swarm beyond Jupiter’s orbit and a flyby of the unusual twin asteroids Patroclus and Menoetus.
One thing that really surprised Levison about the Trojans was how different they looked from one another, especially in terms of their colors, “Gray, red and yellow are just a few. … We think the color indicates different locations during planet formation. These things were all thrown together during the last phase of planet formation.”
Therefore, if we want to be able to understand what this population is telling us about how planets form, we have to understand its diversity. And that’s what Lucy intends to do. And this we accomplish through this very exciting trajectory that combines science, art, and luck.
Because the project team did not realize Lucy would have the opportunity to observe the L5 binary pair, Patroclus and Menoetius, when the trajectory was designed, Lucy ultimately starts to figure into the plot. In the years that followed, researchers discovered the spacecraft would pass near two asteroids in 2033.
In addition to her four primary instruments, Lucy also comes equipped with a steerable platform.
From a distance of more than 600 miles away, Lucy Long Range Reconnaissance Imager, or L’LORRI, can be used to detect flies on the other side of a football field or a crater as wide as 229 feet.
The camera built by Johns Hopkins University Applied Physics Laboratory is a modified version of the device aboard the New Horizons probe, which captured spectacular photos of Pluto during its flyby in 2015.
Hal Weaver, APL’s principal investigator of the camera, anticipates that L’LORRI will provide detail up to eight yards across. The tiny distance between these objects will be amazing to be able to see them at that kind of resolution. “It’ll be the same as a first down in football. What will we see? Are there mountains, valleys, pits, mesas? Who knows? I’m sure we will be surprised.”
The Lucy spacecraft is equipped with a multi-spectral visible light and infrared spectrometer, called L’RALPH, developed by NASA’s Goddard Space Flight Center, that maps asteroids’ surfaces for organic compounds and other chemical signatures.
The Lucy Thermal Emission Spectrometer, or L’TES, is another instrument that has been developed by Arizona State University. This remote thermometer will help determine an asteroid’s physical properties by measuring the surface’s temperature.
With the T2CAM, Lucy will be able to detect the shapes of the asteroids that pass by her over the course of a long journey, taking wide-angle images of them to help determine the exact location and shape of the asteroids.
In addition to those data, researchers will be able to determine the asteroid’s density and mass by analyzing subtle changes in the spacecraft’s radio signals as asteroid gravity affects its velocity.
At nearly 15,000 miles per hour, we’re flying near the targets, but the gravitational pull from the Trojan asteroids will slightly alter our velocity, according to Southwest Research Institute deputy principal investigator Cathy Olkin. “As we fly by, we will be able to detect … the change in Doppler frequency (of the radio signal). That’s how we’ll know the mass of the Trojan asteroids.”
A Trojan asteroid orbits about five times further away from the sun than Earth. Lucy’s solar arrays measure 24 feet across on either side of its body, which unfold like Chinese fans to collect solar energy when Lucy is 530 million miles from the sun and the arrays collect enough solar energy to power Lucy’s instruments when it is 530 million miles from the sun.
It is the first spacecraft at that distance to operate with solar power, instead of nuclear generators, and is orbiting Jupiter currently. Lucy is also expected to travel farther from the sun as it passes through the Trojan swarms on its path to the sun than Juno.
In low Earth orbit, those wings generate about 18,000 watts of power, which is equivalent to powering up my house and those of my neighbors, said Katie Oakman, an engineer at Lockheed Martin Space.
We only have about 500 watts of power when we fly out to Jupiter Trojan asteroid, which would only light up a few light bulbs in my living room. However, our instruments only need about 82 watts to work during the encounter.
NASA has allocated $981 million (£720 million) for the mission over 12 years. The Lucy probe will visit seven Trojans during this time.
Our understanding of human origins and evolution has been changed by the Lucy fossil skeleton.
The Lucy fossil is a famous human fossil from Africa that taught us a lot about where our species originated. NASA’s new mission takes direct inspiration from that origins story – and even takes its name from it – but this spacecraft is searching for fossils hundreds of millions of kilometers away from Earth, circling the Sun in formation with Jupiter.
In Jupiter’s orbit, Trojan asteroids follow Jupiter by approximately 60 degrees, said Hal Levison, Lucy’s principal investigator at the Southwest Research Institute (SwRI), which is located in Boulder.
He told reporters that the objects were held there by Jupiter and the Sun, and if you put them there early in the Solar System’s history, they would have stayed there forever. They’re fossils of the stuff from which planets are made.
In addition to Lucy, Nasa has launched missions to investigate asteroids throughout the Solar System.
A city-sized (and even more massive) object will be studied using Lucy’s instrumentation, which will analyze its shape, structure, surface features, composition and temperature.
Considering that the trojans were formed from the same types of materials as Jupiter’s moons, it means that they were formed at around the same distance from the Sun as it. This has not been predicted, however.
Dr Carly Howett, mission scientist for SwRI, says that if they’re composed of the sort of things we see far out in the Kuiper Belt, it indicates they formed out there and then were pulled inward later.
This mission is a test of models. We have a theory that there was a big rebalancing of objects early in Solar System history when some got thrown away and some came in. We’ll be able to test that theory now,” she told BBC News.
Several extraordinary navigation calculations were used to develop the mission plan.
Researchers have worked out that if the probe periodically returns to make a flyby of Earth, it can use the slingshot effect to visit both trojan swarms.
The launch on Saturday will bring Lucy to the leading group of Trojans in 2027/2028, followed by a tour through the trailing cluster in 2033. A total of about 6 billion kilometers (4 billion miles) will be covered.
Leading swarm:
- Eurybates and Queta (moon) – August 2027
- Polymele– September 2027
- Leucus– April 2028
- Orus– November, 2028
Trailing swarm:
- Patroclus and Menoetius – March 2033
Main-belt asteroid:
- Donald Johanson– April 2025
Choosing this trajectory is an amazing decision, since we can continue to do loops through the swarm, as long as the spacecraft is in good condition, said Coralie Adam of KinetX Aerospace, which is providing navigation support for the mission.
Lucy will also visit another type of asteroid en route to Jupiter’s orbit, an object called Donald Johanson, after the palaeoanthropologist who found an Ethiopian fossil human skeleton in 1974.
For its 1.5-ton spacecraft, Lucy has an initial funding agreement of 12 years
This new spacecraft shares many engineering similarities with the New Horizons mission that flew by Pluto for the first time in 2015.
Lucy is equipped with a new version of one of New Horizon’s main instruments.
One of the biggest differences between the two is the power source. The solar panels on Lucy’s spacecraft are arranged, unlike Pluto’s nuclear power system, in the form of a fan.
Those “wings” are huge, measuring over 7 meters across. It will be necessary for them to be so large to generate enough electricity to power the systems of the spacecraft in Jupiter’s orbit.
During close approach to Earth, Lockheed Martin spokesperson Katie Oakman says the wings produce 18000 watts. “Having access to this energy is the equivalent of having all my neighbors’ homes powered”, she said. “The only problem is that Lucy would only have about 500 watts of power when she is on the trojan asteroids. A few bulbs would be able to be lit, and my microwave wouldn’t be able to heat up my coffee.”
Lucy’s instruments require only 82 watts of power to perform their duties.
NASA is now in the midst of an era of great asteroid study, and Lucy marks the next step in that process.
As of this morning, NASA’s Osiris-Rex spacecraft has reached Earth after delivering samples from Bennu, a distant object in the solar system.
Nasa will launch the Psyche spacecraft to a metal asteroid, also called Psyche, next year.
“Asteroids deserve our attention, and I expect to learn a great deal about them,” said Dr Thomas Zurbuchen, the director of the associate administrator for science office. “Taking multiple measurements of an asteroids population is necessary to understand any population of asteroids. That is exactly what we do.”
“Asteroids can threaten the Earth, and in November we’ll launch an experiment called Dart and follow it up with Europe’s Hera mission to see if we can impart momentum to an incoming asteroid”, he further told BBC News.
