Once more, the #PDC2025 hypothetical impact scenario was only a test.

#PDC2025 also had multiple comments about "planetary defense" as a term being confusing, as well as far too military.

And that would be why I personally prefer to simply talk about the impact hazard.

#PDC2025 wraps up with a question-and-answer session.

Question: "What about SpaceX?"

Answer: SpaceX has no plans for doing anything beyond Earth orbit. It just sells rockets to the agencies that do.

The 1963 August 3 airburst over the southern ocean was the largest impact after Tunguska and before Chelyabinsk: https://aquarid.physics.uwo.ca/infra_pub/Estimates_of_metereoid_kin_e_from_ovserv_of_infrasonicwaves.pdf

But nobody was there, so it was not a problem.

#PDC2025

For anyone wondering:

The #PDC2025 asteroid impact hypothetical scenario progresses with the possibility of a partial deflection; moving the asteroid south to airburst harmlessly over the southern ocean.

Compare to what actually happened on 1963 August 3: https://link.springer.com/article/10.1007/s11038-007-9173-3.

#PDC2025 continues today with discussion of the importance of providing accurate information about the impact hazard: https://iaa.4hdt.ro/event/1/contributions/57/ .

From things like real images of actual asteroids to "don't immediately run to the window to see what that flash was" if there is another Chelyabinsk.

#PDC2025 features a few talks about having small satellites left on orbit to fly past any asteroids that may require investigation.

Precedents here are Comet Interceptor and also Chang'e 2 flying by Toutatis in 2012; although it was not designed for that.

Occultation data suggests that Dimorphos is considerably less dense than Didymos, or at least was before the #DARTMission impact.

Need more data; for which the #HeraMission is on the way.

#PDC2025

Steve Chesley describes the heliocentric orbit change for Didymos from the #DARTMission impact, rather that the orbit change of Dimorphos about Didymos.

~12 microns/second, measured by occultation timing.

Lots of science from chasing shadows.

#PDC2025

#PDC2025 resumes with @schmemela leading discussion of different asteroid deflection methods; including both the #DARTMission & other work on kinetic impact deflection and things like gravity tractor deflection.

Thobekile Sandra Ngwane, University of Cape Town:

"The Rapid-Response Fully-Automated NEA Follow-Up Program with the SAAO's 1-m Lesedi Telescope" - https://iaa.4hdt.ro/event/1/contributions/99/

#PDC2025

. @asrivkin et al. at #PDC2025 : "JWST As a Tool for Early Characterization of Potential Impactors" - https://iaa.4hdt.ro/event/1/contributions/131/

Considering #2024YR4 and other objects.

Direct attention to all of the other reasons letting companies unilaterally make a mess of low orbit is a bad idea.

Like how the Starlinks are disrupting the operations of weather satellites in LEO.

QT Michael Busch @michael_w_busch
2025 May 7

#PDC2025 reviews the impact of satellite streaks on the asteroid discovery surveys.

They continue to be a nuisance; but are manageable. And they remain concentrated into twilight data where detections were already tricky.
https://mastodon.online/@michael_w_busch/114465581586839589

#PDC2025 reviews the impact of satellite streaks on the asteroid discovery surveys.

They continue to be a nuisance; but are manageable. And they remain concentrated into twilight data where detections were already tricky.

Krisztián Sárneczky, discoverer of 3 very small asteroids before they impacted Earth, discusses his current project from the Piszkéstető Station observatory outside of Budapest.

Featuring Peter Jenniskens from the @setiinstitute running over to look for meteorites after Dr. Sárneczky says where the bolides will be.

#PDC2025

Day 3 of #PDC2025 begins with status reports on asteroid discovery surveys; both the current ones and upcoming new surveys like those by @VRubinObs and NEO Surveyor.

How to find all the asteroids.

Marta Ceccaroni has analyzed the effect of the #Apophis flyby in 2029 on debris in the graveyard orbits past geosynch.

Collision avoidance planning may need to take the perturbations into account - up to ~10 m in months after the flyby.

#PDC2025

#TeamRadar presentations at #PDC2025, continued:

Pupillo et al., "Radar Observation of Asteroids 2005 LW3 and 2006 WB with European Radio Telescopes" - https://iaa.4hdt.ro/event/1/contributions/111/ .

Venditti et al., "The potentially hazardous binary asteroid (285263) 1998 QE2" - https://iaa.4hdt.ro/event/1/contributions/150/

#TeamRadar presentations at #PDC2025 :

Benner et al., "Status of Near-Earth Asteroid Radar Observations at Goldstone" https://iaa.4hdt.ro/event/1/contributions/140/

Brozovic et al., "3D shape model and spin state of 99942 Apophis estimated from 2013 radar and lightcurve data" https://iaa.4hdt.ro/event/1/contributions/9/

Calves et al., "Radar and optical tracking of Near-Earth Objects at the University of Tasmania" https://iaa.4hdt.ro/event/1/contributions/105/

Horiuchi et al., "Southern Hemisphere Asteroid Radar Program (SHARP)" https://iaa.4hdt.ro/event/1/contributions/17/

Leviticus Lewis, now formerly of FEMA, reminds everyone at #PDC2025 about the importance of establishing and maintaining effective disaster-response organizations.

For all natural disasters and hazards. Not just rocks falling from the sky.