When NASA had a sample of Bennu obtained from the Osiris Rex mission, it also had to decide what to do with the valuable and still operational spacecraft. Now that decision has been made, it confirms a long-term plan to target a more famous asteroid that crosses the Earth, 99942 Apophis, with an adjustment to the mission name.
Apophis was named after the Greek word for the potential threat to the Earth because the great serpent god of Egypt sought to devour the sun and destroy the world. When first observed, it appears that the asteroid will hit the Earth several times in the near future. Although more details about its orbit allow astronomers to rule out the possibility of a collision in the next century, there is nothing to guarantee beyond that.
In fact, if we don't take steps to intervene, the chances of Apophis eventually hitting Earth are even greater than that – the only option is to move it in close proximity to a completely different orbit. Even then, its orbit will be extended by 100 days, while still allowing for more close contact with Earth.
Apophis wasn't enough to be the "dinosaur killer" that caused the mass extinction, but you certainly wouldn't want to go where it struck, maybe even on the same continent. When the time comes, learning more about it can be crucial.
In addition, the Osiris-Apex, as it is now known, will observe Apophis as it passes through the orbit of a geostationary satellite just 32,000 kilometers (20,000 miles) from Earth. For humans in the right position, the passage will be visible to the naked eye even under moderate light pollution.
It is thought that an asteroid of this magnitude only passes so close once every 7,500 years. Earth's greater gravitational pull could have an effect on Apophis, and as in an exaggerated disaster movie, Osiris-Apex will ** the whole process.
Dr. Amy Simon of NASA's Goddard Space Flight Center said in a statement: "Osiris-Apex will study Apophis immediately after it passes, allowing us to see how its surface changes through interaction with Earth's gravity." ”
After such a close proximity to Earth, an object of this size could change the length of Apophis' day – currently 306 earth hours. NASA also believes that it could trigger Apophis**, revealing the substance currently hidden inside.
Dr. Dani Mendoza Dellagiustina, principal investigator at the University of Arizona at the University of Arizona in Tucson, said: "This approach to proximity is a great natural experiment. We know that tidal forces and the accumulation of material from gravel piles are fundamental processes that may play a role in planet formation. They can tell us how to go from fragments of the early solar system to full-fledged planets. ”
There is a more immediate reason for studying Apophis. This is an S-shaped asteroid, which means it has a lot of silicon in its spectrum. With the exception of Apophis, arguably the most threatening space rock known, most of the other known threats come from S-type asteroids.
Proper asteroid defense mechanisms can vary depending on the asteroid type, so it may be a good idea to understand common mechanisms.
Osiris-Apex still has a long way to go before it can catch up with Apophis, and it needs to pass the Sun six times and the Earth three times before it can properly adjust its orbit. Therefore, it will not arrive until April 2029, shortly before the Earth's passage on April 13 of Apophis. Thereafter, it will continue to observe for 18 months, and unlike Earth-based telescopes, its field of view will not be overwhelmed by sunlight at some of the most critical moments.
Osiris-Apex lacks the ability to take samples again, but it will do the next best thing — get within 5 meters (16 feet) of the surface, activate the thrusters, and see how much dust is blown away. In order to avoid affecting natural experiments, this will only happen after a close pass from Earth.