Undergraduate Rahil Makadia, a NASA Space Technology Graduate Research Opportunity Fellow from the University of Illinois at Urbana-Champaign shared his innovative research. He made a resounding final presentation to the EPSC-DPS2025 Joint Meeting in Helsinki. His work is aimed at figuring out where the safest places would be to redirect these potentially hazardous asteroids. This duty becomes especially important as the threat of asteroid impacts on Earth becomes a harsher reality. The study sheds light on the need to pick deflection tactics strategically. Irresponsible choices might inadvertently put an asteroid on a trajectory that eventually results in it colliding with Earth.
One of the primary takeaways from Makadia’s presentation was the idea of a “gravitational keyhole.” These areas in the cosmos are extraordinarily important. If an asteroid were to be deflected into them, it might eventually be put onto a collision course with the Earth. The difficulty is that you need to make sure that no deflected orbit leads to the asteroid going through such a keyhole. This requires very careful trajectory design and a thorough understanding of the target asteroid’s properties.
Understanding Asteroid Characteristics
Before any deflection mission is attempted, many important aspects about the asteroid need to be carefully considered. These parameters are the asteroid’s 3-dimensional shape, surface topology, rotation and mass. Each of these factors contributes to whether the deflection maneuver is effective and safe.
The geometry of an asteroid is a key first ingredient since its form dictates how the object would behave towards exterior impact pressures. Even irregularly shaped asteroids might need a unique approach versus spherical ones. Equally important, surface topology—which includes the geometry of hills, craters and any geological ridges—needs to be correctly mapped. These types of features could determine where a spacecraft should impact to accomplish the desired deflection, without producing secondary hazards.
The rotation of the asteroid presents serious challenges as well. For instance, an asteroid that spins very quickly could behave in surprising ways when hit, making any deflection attempt much harder. Second, knowing the mass of the asteroid is critical for calculating how much force you’ll need to apply for a successful deflection. Makadia’s research emphasizes that all of these factors need to be accounted for in order to develop a comprehensive, long-term deflection strategy.
The Role of Targeting Uncertainty
Indeed, Makadia’s research includes maps based on a targeting uncertainty of 25m, which would be the case for a kinetic impactor mission. This uncertainty is an important consideration when planning any deflection attempt. The more accurate the impact point, the greater chance it has of successfully altering an asteroid’s course in the event of a collision. This precise targeting stops the asteroid from going towards a gravitational keyhole.
Makadia’s maps mostly feature the asteroid Bennu front and center. It’s no wonder that scientists have declared asteroid Bennu an Earth-destroying menace. The “keyhole probability map” created for Bennu shows best candidate impact locations on its surface. Each crosshair on this map represents places where it is possible to reduce the severity of an impact after deflection. Broader implications of this research in particular, it will provide major assistance to future missions aimed at protecting Earth from possible asteroid hazards.
Case Study: The Didymos System
Makadia further delved into lessons learned from earlier missions with an emphasis on the Didymos system and moonlet Dimorphos. He emphasized that the Didymos system is far too large to attempt to redirect onto a collision course with Earth. This important understanding provided more flexibility in targeting than had been available during DART’s original mission. What’s more, Dimorphos is quite small. This large size meant that the precise impact location was less important than in cases where the asteroid was smaller or more dangerous.
I hope this short case study provides one small lesson. In doing so, it spotlights the ways that mission parameters vary based on the nature of your target asteroid. It underscores the importance of targeting place-based impact. It pushes us to look deeply into the unique dynamics of each asteroid system.