Uncertainty is central to planetary defense decision-making. Decisions to address potentially hazardous near-Earth objects (NEOs) must often be made years in advance, long before accurate information about an asteroid’s orbit, mass, or composition are known. Balancing the risk of inaction - waiting until too late to be able to execute an effective deflection campaign - against the cost of premature action - spending valuable resources when the object will ultimately not impact the Earth - is a daunting challenge.
The recently discovered asteroid 2024 YR4, which has a possible impact in 2032, highlights this dilemma. Its highly elliptical orbit and small size (57 m diameter) make it difficult to observe for most of its orbit. Waiting until its next close approach in 2028 to confirm a potential future impact may not leave enough time to act. With limited data, decisions about whether and when to mount a deflection mission are fraught with uncertainty.
While the decision whether or not to mount a deflection campaign is one of the most momentous in planetary defense, it is one of many needed to to address a high probability impact event. Many of these decisions will require technical solutions to reduce associated uncertainties, but many also require legal, policy and economic solutions. Beyond this, there are also uncertainties as to how governments and the public will respond to the knowledge of such an event.
Current Uncertainties in Planetary Defense
Below you will find a series of questions that address the uncertainties encountered across various fields. To learn more of how planetary defense impacts each broad topic, click the title links.
- How can scientific models account for uncertainties in asteroid detection, such as incomplete datasets or observational gaps, to improve prediction accuracy?
- What engineering challenges must be addressed to design deflection technologies capable of functioning effectively despite uncertainties in asteroid composition and behavior?
- Under what circumstances would disruption of an asteroid be an appropriate mitigation versus when would it be more likely to increase risk to the Earth?
- How can international agreements account for incomplete or evolving scientific data on asteroid risks while ensuring timely and effective action?
- What strategies can be implemented to build trust and foster collaboration among nations with differing priorities, resources, and levels of risk exposure?
- How should policymakers balance the costs and benefits of immediate asteroid defense measures against long-term uncertainties in risk prediction?
- What strategies can be developed to communicate asteroid risks effectively to a global audience with varying levels of scientific literacy?
- How should information about a potential impact be communicated to the public to minimize panic and misinformation?
- Can the existing emergency response infrastructure adequately handle an asteroid impact evacuation?
Social and Ethical Considerations
- How should decision-makers address the ethical implications of prioritizing certain asteroid threats over others, especially when uncertainty exists about which will cause the greatest harm (ex. predicted to hit London vs. the Sahara Desert)?
- What responsibility does humanity have to future generations in preparing for asteroid risks, even when those risks may not materialize for centuries?
- Who is responsible for the rebuilding efforts for affected populations?
- How should liability for asteroid impacts or failed mitigation efforts be determined when there is uncertainty about causation or responsible parties?
- What economic models can fund planetary defense efforts sustainably while accommodating the unpredictability of asteroid threats?
- How can insurance systems be designed to manage financial risks associated with asteroid impacts or mitigation failures, given the inherent uncertainties?
Current Solutions That Help Reduce Uncertainties in Planetary Defense
- State-of-the-Art Surveys: The Vera C. Rubin Observatory features the largest camera ever built, enabling earlier identification of potential asteroid threats. Vera Rubin
- Advanced Computational Tools: The ADAM platform developed by the Asteroid Institute analyzes large datasets to enhance the discovery and confirmation of hazardous objects. Asteroid Institute
- Infrared Telescopes: NASA’s NEOWISE provides critical data on asteroid mass, size, and composition, reducing uncertainties in risk assessments. NEOWISE Overview
- Alternate Planetary Defense Methods: The Gravity Tractor uses spacecraft gravitational pull to alter an asteroid’s trajectory, guiding it away from potential "keyholes" after deflection. NASA Gravity Tractors
- Observer Spacecrafts: Missions like ESA’s Hera provide detailed pre- and post-deflection data on asteroid mass, composition, and debris fields. Hera Mission
- Global Warning Networks: The International Warning Network (IWAN) establishes global protocols for sharing information about asteroid threats with governments and organizations, ensuring coordinated responses. IWAN Overview
- Coordinating Efforts Between International Partners: The Planetary Defense Coordination Office (PDCO) tracks and communicates asteroid risks while facilitating partnerships globally. NASA PDCO
- Education Initiatives: Asteroid Day Awareness Campaigns promote public understanding of asteroid risks and planetary defense efforts. Asteroid Day
- Legal & Policy Impact Worldwide: The United Nations COPUOS facilitates international collaboration on planetary defense missions and publishes guidelines addressing legal and policy uncertainties. UN COPUOS