SUMMARY

SUMMARY

UPDATE (05 June 2026): Let's look at total fall mass from this event. I recently heard from colleagues who independently decided that this was an iron meteorite fall based on completely separate data from what I presented in the previous Update. So we shall assume that this was an iron meteorite fall. Meteorite falls are highly destructive to the parent asteroid or meteoroid, with ~1-5% of "stony" meteorite mass surviving the fireball and ~10-20% of iron meteorites surviving to land as meteorites. The Cape Cod Bay event came in at a steep angle (~73 degrees below horizontal). Steep infall is more destructive than shallow entry angles, so let's be conservative and assume 10% of the meteoroid survived to land as meteorites. NASA Meteoroid Environment Office estimates the mass of the meteoroid at 5600 kg (5.6 metric tons), so simple math says 10% of that value gives a total fall mass of ~560 kg, or about half a metric ton of iron meteorites. This serves as a first-pass estimate of the total mass of all the meteorites that fell into Cape Cod Bay.

The Jormungandr2 dark flight model estimates that of the total fall mass of 560 kg, 129.8 kg is larger than 1g in mass.  This is the "findable" total - meteorites large enough for recovery when searching visually. Of the meteorites actually observed on radar, they span a mass range between 5.9g and 2105g (2.1kg). The radar signature with 2.1kg meteorites contains approximately 34 meteorites of that size. Other signatures contain ~4 430g, ~58 102g, 200 23g, 670 5.9g, and 199 228g meteorites. These counts are approximate, and only count up meteorites seen in the radar sweeps. Additional meteorites certainly slipped past the slow-turning radars. This gives an estimate of how many meteorites are lying on the Cape Cod Bay floor, and we have a good idea of where they landed from the Jormungandr2 flight model results. Additional data from sonar methods would be useful for narrowing down their actual landing sites.

UPDATE (03 June 2026):  Calculations using the radar data have turned up some unusual features of this fall:
- Very high altitude terminus (~50 km, as opposed to the more typical ~25 km). This may be due to high-ish infall velocity (>18 km/s) and steep entry angle?
- Very short total appearance time on radar of about 2 minutes as opposed to the more typical 8-10 minutes. This suggests that very few small pieces were produced.
- The size vs. number of meteorites observed on radar has a slope higher than any other radar-detected fall to date. This indicates a meteoroid with high mechanical strength.
- Jormungandr2's meteorite density calculation (which is still experimental at this stage) gives a value of about 8000 kg/m3, consistent with an iron meteorite.
This was a fairly fast-moving, steeply inclined meteoroid that broke up high in the atmosphere. It is evidently very mechanically strong, however, and produced very few small pieces. The meteorites produced appear to be concentrated in the 100s of grams to kg range, as opposed to the typical 1-100g range. These factors, along with the experimental density measurement suggests it is an iron meteorite. It is not clear if the overall radar reflectivity is consistent with an iron meteorite however. 

UPDATE (01 June 2026): The fall has been modeled using the Jormungandr2 dark flight model, which uses the physics of falling objects and actual NOAA weather balloon data to accurately model the landing sites of meteorites from the fall. Evidence suggests this fall entered the Earth's atmosphere at a steep angle and fragmented at relatively high altitude (~50 km) as discerned by the NASA Meteoroid Environment Office at Marshall Space Flight Center. Radar data predominantly shows larger meteorites ranging from 40g to multiple kilograms. This is unusual for a meteorite fall, where 1-10g meteorites usually predominate. It is not immediately clear why this is, although the stormy weather at the time and place of the fall may have driven the NOAA radars to adjust their sensitivity settings. Meteorites landed in Cape Cod Bay at an area near the lat/long coordinates provided here.

This was a daytime bolide seen over a wide area of the U.S. northeast, with viewership limited by weather.  

Signatures of falling meteorites are clearly indicated data from four radars: KBOX (Boston, MA), TBOS (Boston Logan airport radar), KOKX (Long Island, NY), and KENX (Albany NY). Another small signature from KGYX (Portland, ME) might be related.

This was a daytime bolide that produced a meteorite fall right in the middle of Cape Cod Bay. This fall into water is techically called a "fishy squisher" in uber-serious scientific terms. 

While all the meteorites from this fall landed in water, the water depth at the fall site is 34m (100'). Most meteorites are strongly attracted to a magnet, and these ones are within reach of a 100' length of rope dangled off of a boat. In case anyone is interested in such factoids.