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When a cruise ship-sized asteroid comes within 19,883 miles (32,000 kilometers) of Earth on April 13, 2029, it won’t be alone.
The European Space Agency has announced that its new Ramses spacecraft could accompany Earth before and after a safe, yet very close, flyby of the asteroid Apophis.
The 1,230-foot (375-meter) diameter space rock will get closer to Earth in orbit than any satellite and 10 times closer than the Moon. Apophis will get so close to Earth that it can be seen by the naked eye by about 2 billion people in Europe, Africa, and parts of Asia.
To reach Apophis in February 2029, Ramses must be launched in April 2028. According to ESA, preparatory work for the mission using existing resources has already begun to achieve this ambitious goal. However, the final decision on the implementation of the mission will be taken at the ESA Ministerial Council meeting in November 2025.
First discovered in 2004, Apophis is named after the Egyptian god of chaos and darkness and is thought to be shaped like a peanut. Initially, astronomers were concerned that the space rock might collide with Earth in 2029 and 2068, but subsequent observations have suggested that it may be the closest thing to Earth to Earth. Eliminate any risk According to NASA’s Center for Near Earth Object Studies, Apophis could pose a threat to Earth for the next century.
Scientists at the center use radar and telescopes to study near-Earth objects to understand the danger they pose to our planet. They track asteroids on close orbits and compile a list of asteroids that come close enough to pose a potential collision concern.
Apophis currently poses no danger, but the flyby will be a rare occasion: astronomers believe that an asteroid this large only comes this close to Earth once every 5,000 to 10,000 years.
ESA and NASA plan to take advantage of this unique space phenomenon to study Apophis from as close a perspective as possible and improve our understanding of what happens when space rocks interact with Earth’s gravity. Each agency will send a spacecraft to fly close to the asteroid and track it.
“There’s still a lot we don’t know about asteroids, and until now we’ve had to travel deep into the solar system to study them, experiment on them ourselves, and interact with their surfaces,” Patrick Michel, an astrophysicist and research director at the French National Center for Scientific Research, said in a statement. “For the first time in history, nature has brought an asteroid to us and is conducting an experiment on itself.”
Apophis is interesting because it’s an S-type, or stony, asteroid, which means it’s different from other space rocks visited by NASA missions, such as Bennu, which is a C-type, or carbonaceous, asteroid.
NSF/AUI/GBO/JPL-Caltech/NASA
These images represent radar observations of Apophis on March 8, 9, and 10, 2021, during its final close encounter before impacting Earth in 2029. The data ruled out an Earth impact for at least a century.
C-type asteroids are made of clay and silicate rocks, while S-types are made of silicate material and nickel-iron.
Stony asteroids are among the most common class of potentially hazardous asteroids that pose a threat to Earth, and understanding their composition and other details that can only be obtained by flybys could help space agencies determine how to most effectively deflect such asteroids if they are predicted to be on a collision course with Earth.
The Ramses mission is unique in that it will travel to Apophis before the asteroid passes Earth, then essentially accompany it there afterward. This data could show astronomers how the asteroid is being deformed by Earth’s gravity.
“All we have to do is watch as Apophis gets stretched and compressed by strong tidal forces, causing landslides and other disruptions that bring new material out from beneath the surface,” Michel said.
Forces generated by Earth’s gravity could also cause asteroid quakes.
The probe will carry a suite of instruments to measure the asteroid’s shape, surface, orientation and orbit, and changes observed during the flyby may reveal information about Apophis’ composition, mass, density, porosity and internal structure.
Monitoring Apophis during and after its approach to Earth may tell scientists whether there are any changes in its orbit that could affect its chances of a future collision with Earth, as well as whether there are any changes to the asteroid’s rotation rate or surface.
“Ramses will demonstrate that humanity can deploy a reconnaissance mission to rendezvous with an approaching asteroid in just a few years,” ESA’s Planetary Defence Director Richard Moisle said in a statement. “Mission of this kind will be the linchpin of humanity’s response to hazardous asteroids. The reconnaissance mission will first be launched to analyse the trajectory and structure of the approaching asteroid. The results will be used to determine how best to alter the asteroid’s trajectory and to rule out possible collision avoidance before expensive deflection missions are developed.”
Ramses needs to be designed, built and finally approved by ESA by next year. NASA’s OSIRIS-APEX missionApophis, formerly known as OSIRIS-REx, is on track to catch up with the asteroid shortly after its close approach to Earth. By working together, both spacecraft will be able to collect valuable data that will provide a full picture of how Apophis changes as a result of its close approach to Earth.
As OSIRIS-REx, the spacecraft spent seven years making its round trip to the near-Earth asteroid Bennu, including time spent exploring the space rock, landing, and taking samples.
The mission successfully delivered NASA’s first space-collected asteroid sample to Earth in September and has a new name in honor of its new goal: “Origins, Spectral Interpretation, Resource Identification and Security – Apophis Explorer.”
The spacecraft won’t be able to collect samples from Apophis — its sample-collection head is on board a capsule with the Bennu samples that were delivered to Earth — but OSIRIS-APEX will use gas thrusters to kick up and study dust and rocks above and below Apophis’ surface.
“Apophis is a dual mission between different agencies working together for the best of science and planetary defense, and it’s a great opportunity to show the world the best of international collaboration,” Michel said.
NASA and ESA have collaborated on other asteroid exploration missions in the past.
In September 2022, NASA’s DART mission will intentionally crash a spacecraft into Dimorphos, a moon asteroid orbiting a larger parent asteroid called Didymos. The historic test was a success. Changed the movement of celestial bodies While neither space rock posed a threat to Earth, Dimorphos’ size is comparable to asteroids that could pose a danger to Earth, making the double asteroid system a perfect target to test deflection techniques.
of ESA’s Hera mission The company is set to launch a spacecraft in October on a journey to observe the aftermath of the DART collision, arriving at the pair of asteroids around the end of 2026. Along with two CubeSats, the mission will study Dimorphos’ composition and mass, changes caused by the impact, and determine how much momentum was transferred from the spacecraft to the asteroid.
“The Ramses mission concept reuses much of the technology, expertise, industry and science developed for the Hera mission,” Paolo Martino, Hera spacecraft manager who also worked on the Ramses mission, said in a statement. “Hera demonstrated that ESA and European industry are capable of meeting tight deadlines, and Ramses will follow that example.”
