In just under half a decade, a 1,000-foot (305-meter) wide asteroid named after the Egyptian god of chaos and destruction, Apophis, will pass within 30,000 miles (48,300 kilometers) of Earth. Scientists do not intend for the rare close passage of a space rock of this size to be lost.
On April 13, 2029 – a Friday, no less – when Apophis, formally known as (99942) Apophis, makes its closest approach to Earth, it will become so prominent above our planet that it will be visible to the naked eye. NASA’s OSIRIS-APEX spacecraft (once known as OSIRIS-REx) will be on hand to encounter the near-Earth asteroid (NEA) in person. But if things go well, that NASA mission could be joined by a host of small satellites during its rendezvous.
Under the promising “NEAlight” project, a team from the Julius-Maximilians-Universität Würzburg (JMU) led by aerospace engineer Hakan Kayal has unveiled three concepts for such spacecraft. Each of the proposed satellites will aim to exploit this asteroid passage, as Earth experiences such an event only once a millennium. The target? To collect data that could help scientists better understand the solar system, and perhaps even help develop defense measures against dangerous asteroids.
Related: Asteroid Apophis will swing by Earth in 2029 – could a collision with space rock hit us?
Why is Apophis a suitable target for a planetary defense study? Well, discovered in 2004, the asteroid quickly rose to the top of tables measuring the risk from so-called potentially hazardous asteroids (PHAs), or asteroids with a width of 140 meters or more that fall within 20 lunar distances of Earth.
Both Apophis’ size and how close its orbit comes to Earth kept the asteroid at the top of the “impact risk list” of the European Space Agency’s (ESA) PHAs and NASA’s Sentry Risk Table for 17 years. That was until a quick flyby of the asteroid — a space rock nearly as wide as the Empire State Building is tall — in March 2021 allowed NASA scientists to determine that Apophis won’t hit Earth for another hundred years.
Although we now know that Apophis will not collide with Earth for at least the next century, its scientific impact will still be enormous in 2029, and space agencies from countries around the world will be closely monitoring its trajectory.
Furthermore, as an asteroid that formed from leftover material around the young Sun around the same time as the planets, Apophis also offers researchers a unique opportunity to determine what the chemical composition of the solar system was about 4.6 billion years ago.
Meet the rendezvous candidates
Despite the fact that we are aware of approximately 1.3 million asteroids in the solar system, 2,500 of which are considered potentially hazardous (although none are expected to hit Earth for at least a century), spacecraft missions to study asteroids are relatively rare.
To date, only twenty missions have been deployed to study asteroids in situ, including the aforementioned OSIRIS-REx, Japan’s Hayabusa1 and Hayabusa2 spacecraft, ESA’s Rosetta spacecraft, and NASA’s asteroid-hopping mission Lucy, currently underway. is traveling to the Trojan asteroids that share their orbit with Jupiter. So the JMU team must carefully consider its options when considering a future asteroid-exploring spacecraft.
The team’s first concept is a small satellite that will join Apophis for a period of two months as it approaches Earth in April 2029. The spacecraft will remain with the ‘God of Destruction’ space rock for weeks afterwards, even as it moves away. Over the course of the mission, this German national spacecraft will photograph Apophis and take measurements to document any changes the NEA undergoes during its flight.
This particular mission would be challenging due to its duration, the distance to be covered and the fact that the craft will have to function autonomously for long periods. It should also launch at least a year before Apophis arrives near Earth.
The team’s second concept involves integration with a larger spacecraft planned by the ESA, called RAMSES. This mission will be equipped with smaller satellites, measuring equipment and telescopes. RAMSES, named after the Egyptian pharaoh Ramesses the Great, would travel to Apophis and stay with the asteroid as it passes Earth.
If the second concept becomes reality, one of RAMSES’ small satellites will be designed by the JMU team, with this project requiring less technical effort than the first concept, while promising to gain more scientific knowledge.
However, one of the main problems facing the second concept has to do with getting REMESES off the ground – not literally, but figuratively. Its success will depend on the willingness of ESA partner countries to finance the mission. Here too, a lead time of at least 365 days would be required to guarantee the success of this concept.
Related stories:
— Asteroid Apophis will visit Earth in 2029. Why do scientists want NASA to send a probe there first?
– NASA’s OSIRIS-APEX asteroid probe wakes up after a brief pass by the sun
– NASA can’t wait for its OSIRIS-APEX spacecraft to encounter ‘God of Chaos’ asteroid Apophis in 2029
The third concept involves a small satellite that will fly only briefly past Apophis when the asteroid is closest to Earth, taking images of the asteroid. This concept would require much less effort and the craft would be relatively cheap.
However, the disadvantage of concept 3 is that the observation time would be limited, which would also limit the amount of knowledge that this mission would add to our understanding of asteroids.
On the plus side, the small-scale mission could launch just two days before Apophis’s arrival. Furthermore, if Concept 3 were to successfully observe Apophis, it would demonstrate the capability of small and inexpensive satellites in studying asteroids, perhaps leading to increased interest in in situ asteroid study missions in the future.
The NEAlight project started at the beginning of May 2024; between now and April 30, 2025, JMU scientists will work out the requirements and specifics of the respective missions.
Beyond Apophis’ visit, the three concepts discussed could remain options for future missions to other planets in the solar system, the moon – or perhaps other intriguing NEAs.