It’s finally here. After the first paper in February, the two linked papers are now in the new, next (April) issue of J Astronaut Sci. They’re all part of a special collection (a virtual “issue”), “Navigating Asteroid Impact Hazards: Astronautics Strategies for Planetary Defense”:
link.springer.com/collections/didcicgjgf
First, in vol. 73 #1, Feb 2026:
Micheli, M. Devogèle, M. Denneau, L. et al. Astrometric Follow-up of Near-Earth Asteroid
2024 YR4 During a Torino Scale Level 3 Alert 8 s40295-025-00541-3
Followed this April (vol. 73 #2) by:
Farnocchia, D., Fenucci, M. Bernardi, F. et al. The impact hazard assessment for near-Earth asteroid 2024 YR4 28 s40295-026-00576-0
Devogèle, M., Hainaut, O. R. Micheli, M. et al. Rapid-response characterization of near-Earth asteroid 2024 YR4 during a Torino scale level 3 alert 31 s40295-025-00550-2
… then see also (same issue):
Atchison, J. A. Cascioli, G. Pedros-Faura, A. et al. Operational Mass Measurement for Flyby Reconnaissance Missions of Potentially Hazardous Asteroids 29 s40295-026-00574-2
Gramigna, E. Park, R. S. Riedel, J. E. et al. High-Accuracy Mass Estimation of Small
Asteroids for Planetary Defense Using the Gravity Imaging Radio Observ… 25 s40295-025-00568-6
Wilmer, A. P. Atchison, J. A. Holzinger, M.J. et al. Rapid-Response Reconnaissance
Architecture Design for Planetary Defense with Nested Trajectory Optimi… 23 s40295-025-00561-z
That first trilogy I list concerns our brief Torino entry, 2024 YR4. Upon initial detection, orbit determination, and possible Earth-intersect solutions, the alert was sounded per IAWN protocol. Telescopes around the world then mobilized to refine the orbit solution, and assess both impact probability, and resulting danger. But don’t take my word, read the papers.
The next three papers in the special issue are more general takes on hazardous asteroids. Atchison et al. is a fairly straightforward description of a threat assessment probe making a flyby, except it uses a sub-probe. Deploying a smallsat to act as a test mass is a new, (supposedly) better way to gauge the mass (and therefore destructive power) of the asteroid. But the details make the mission: not just any old CubeSat can be slapped on to do the experiment.
Wilmer et al. take a step back: what would a rapid-response, pre-emplaced threat assessor asset look like? The Comet Interceptor mission will build a craft, then have it ‘lurk’ at the Earth-Sun L2 point for a nice comet. Is this same scheme a wise use of planetary-defense resources? Surprisingly, not really. Having a probe and rocket lurk near the launch pad is at least as good.
Finally, Gramigna et al. consider their GIRO (Gravity Imaging Radio Observer) program as a planetary defense asset. The stated goal of GIRO is, well, gravity measurement. But a passing asteroid is a gravity disturbance, and might be measurable. Can GIRO (if built and flown) help out as asteroid assessment? Don’t take my word, read Granmiga et al.