Meet Ramses, ESA’s Mission to Asteroid Apophis

Today, ESA’s Space Safety Programme is taking another step towards answering this question. The programme has been given permission to begin preparatory work for the next planetary defence mission – the Rapid Apophis Space Safety Mission (RAMSES).

Ramses will meet and accompany asteroid 99942 Apophis during its safe but extremely close flyby of Earth in 2029. Researchers will study the asteroid as Earth’s gravity changes its physical properties. Their findings will improve our ability to defend our planet from any similar object that might be on a collision course in the future.

Apophis

Apophis is about 375 meters in diameter, about the size of a cruise ship, and will pass within 32,000 kilometers of Earth’s surface on April 13, 2029. For a short time, it will be visible to the naked eye in clear, dark skies to about 2 billion people across much of Europe, Africa and parts of Asia.

Apophis won’t pass Earth: Astronomers have ruled out any chance of the asteroid hitting our planet for at least the next 100 years. But Apophis’s close approach to Earth in April 2029 would be an extremely rare natural phenomenon.

By analyzing the sizes and orbits of all known asteroids, astronomers believe that an object this size comes close to Earth only once every 5,000 to 10,000 years. For comparison, a total solar eclipse occurs somewhere on Earth about once every 18 months, and Halley’s Comet returns to Earth’s skies every 76 years.

The flyby of Apophis in 2029 will capture the world’s attention and represent a unique opportunity for science, planetary defense, and public engagement.

Ramses

ESA’s Ramses spacecraft will meet Apophis before it passes close to Earth and will accompany the asteroid during the flyby to observe how it is deflected and changed by our planet’s gravity.

Patrick Michel, Research Director at French National Center for Scientific Research At the Côte d’Azur Observatory in Nice, he commented: “There is still a lot to learn about asteroids, but until now, we have had to travel deep into the solar system to study them and carry out experiments ourselves to interact with their surfaces.”

“For the first time ever, nature has brought us one and done the experiment itself. All we need to do is watch Apophis as it stretches and compresses under powerful tidal forces that could trigger landslides and other disturbances and expose new material from beneath the surface.”

Ramses is due to launch in April 2028 to allow access to Apophis in February 2029, two months before its closest approach. To meet this deadline, ESA has requested permission to begin mission preparatory work as soon as possible using available resources. The Space Safety Programme Board has granted this permission. A decision on full commitment to the mission will be taken at the ESA Council of Ministers meeting in November 2025.

Using a suite of scientific instruments, the spacecraft will conduct a comprehensive survey before and after impact with the asteroid, surveying its surface shape, orbit, rotation, and orientation. By analyzing how Apophis changes during the flyby, scientists will learn much about the asteroid’s response to external forces, as well as its composition, internal structure, cohesion, mass, density, and porosity.

All of these characteristics are crucial to assessing how best to keep a dangerous asteroid off its collision course with Earth. And since asteroids are also time capsules that formed more than four billion years ago, the data from the Ramses Observatory will also provide new scientific insights into the formation and evolution of the solar system.

Meanwhile, NASA has redirected the OSIRIS-REx spacecraft toward Apophis. Due to the limits of orbital mechanics, the newly renamed spacecraft Osiris-Apex The probe will reach Apophis about a month after the asteroid passes close to Earth.

Researchers expect that tidal forces on Earth will change the asteroid’s spin and possibly trigger earthquakes and landslides. Having Ramses there in advance will provide a detailed “before and after” view of how Apophis has changed due to its close proximity. Later, having two highly efficient spacecraft at Apophis after the flyby will allow for additional scientific investigations and longer-term impact measurements.

Rapid Reconnaissance: The Cornerstone of Planetary Defense

The international collaboration between NASA’s DART probe and ESA’s Hera probe demonstrates that humans are in principle capable of redirecting an asteroid if necessary. But to respond to a real threat, we need to be able to mount and deploy a rapid response.

“The RAMSES mission will demonstrate that humanity is capable of sending a reconnaissance mission to encounter an incoming asteroid within just a few years,” said Richard Moisel, head of ESA’s Planetary Defence Office. “This type of mission is a cornerstone of humanity’s response to a dangerous asteroid. A reconnaissance mission will first be launched to analyse the orbit and structure of the incoming asteroid. The results will be used to determine the best ways to redirect the asteroid or rule out the possibility of a non-impact before developing an expensive deflection mission.”

“The Ramses mission concept reuses much of the technology, expertise, industrial and scientific communities that were developed for the Hera mission,” adds Paolo Martino, who leads ESA’s Ramses programme efforts. “Hera has shown how ESA and European industry can meet tight deadlines, and Ramses will follow its example.”