Besides eight planets, our solar system has a huge number of smaller astronomical bodies, mainly asteroids, but also comets and dwarf planets. They are collectively called Minor Planets, and data about their properties are collected by the Minor Planet Center in a database. At the time of writing this blog, the monumental database contains 1,478,907 objects, with new discoveries added daily. Most objects are asteroids in the main belt between Mars and Jupiter, but there is an important subcategory, the Near-Earth Objects (NEO), that come close to Earth. Their number in the MPC database is now 40,146, also daily increasing. When asteroids in this category have orbits that cross the orbit of Earth, and are large enough to cause substantial damage in case of a collision, they are called Potentially Hazardous Asteroids (PHA). At the moment, their number is ~2500, with an estimated ~2000 not yet discovered.
This beautiful image, published by NASA in 2013, show the orbits of the ~1400 PHA’s, known at that time.
On 19 June 2004, the Pitt Peak National Observatory discovered a “new” asteroid. It got a provisional designation 2004MN4 in the MPC database. In a recent blog, I explained the coding used by MPC. The M stands for the 2nd half of June, the N for the number 13, and the 4 means 4×25. This asteroid was the 13 + 4 x 25 = 113th asteroid, discovered in the second half of June 2004.
But 2004MN4 was not an ordinary asteroid. After its orbit was calculated, it became clear that it was a NEO and even a PHA, with a small probability (2.7%) that it would hit Earth on 13 April 2029. More accurate calculations of its orbit showed that it would not hit Earth, although it would come very close, and there remained a possibility that it might hit Earth exactly 7 years later, on 13 April 2036.’ The asteroid got a permanent number in the MPC database (99942) and was given the name Apophis, the Egyptian god of the underworld, the enemy of the sun god Ra.
The possibility of a hit in 2036 remained a matter of concern, and in December 2009 I read in the Guardian about a Russian proposal to send a spacecraft to Apophis and modify its course away from Earth. The newspaper had this impressive artist’s impression of what could happen if Apophis were to hit Earth. Click on the image for a link to the Guardian article.
This was the first time I read about Apophis, and I was curious to know more. I had just started blogging, and in January 2010 I published my first post: Will the Earth be hit by Apophis in 2036? I got a few comments from readers and published a second post a few weeks later: Again Apophis, with more details and an explanation why in 2036 it would be again on 13 April.
In the following years, accurate calculations of Apophis’ orbit showed that also in 2036 the asteroid would not hit Earth, not even in the next 100 years. Actually, none of the known PHA’s will hit Earth in the next century!
But on 13 April 2029, less than 4 years from now, Apophis will pass Earth within about 30,000 km. That is closer than the orbits of the geostationary satellites. An asteroid crossing our own backyard, what a unique opportunity!
In July 2024, the European Space Agency (ESA) proposed a mission to Apophis. It got the name Ramses (Rapid Apophis Mission for Space Safety), to be launched between mid April and mid May 2028 and to arrive at Apophis in February 2029 . It would then measure properties of Apophis before, during and after the flyby. It would also deploy two so-called CubeSats, miniature spacecrafts. One of them might try to land on Apophis. Here is an artist’s impression of RAMSES, the two CubeSats and Apophis, about 30,000 km above the surface of Earth.
Preparations for the mission started in July 2024 with partial funding by ESA. In August 2025 JAXA, the Japanese Space Agency, decided to collaborate with ESA and received funding from the Japanese government. RAMSES will be launched on one of their rockets.
Would RAMSES receive full funding by the European Union? Those decisions are made by the ESA Council meeting at Ministerial level, this year held in Bremen, 27 November. The result:
The largest contributions in the history of the European Space Agency, €22.1 bn
Three missions have been approved. So It means green light for RAMSES, which now has to be built on a very tight schedule, within two and a half years! But it makes sense, because RAMSES is part of ESA’s Planetary Defense System. Apophis is not dangerous, but another asteroid might be in the future, and inthat case fast action is critical. It explains the “Rapid” in the name of the mission.
This will be the first post about RAMSES, just to celebrate that it has been funded.