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Jonathan McDowell

@planet4589.bsky.social

Astrophysicist

19,755 Followers  |  2,015 Following  |  3,673 Posts  |  Joined: 12.05.2023
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Posts by Jonathan McDowell (@planet4589.bsky.social)

I'm going to be in Bromley, just a bit south of Greenwich

06.03.2026 13:38 — 👍 0    🔁 0    💬 0    📌 0

You'll just have to come to London instead. I'm in Boston still for the next couple of months though probably

06.03.2026 13:38 — 👍 1    🔁 0    💬 1    📌 0

Yes. I remember when retirees could keep their email addresses with no issue, but there's a ridiculous sense in management now that this is costly...

06.03.2026 04:42 — 👍 10    🔁 0    💬 2    📌 0
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A reentry observed at 0255 UTC over Calgary was likely Starlink-1723 (object 46333)

06.03.2026 04:30 — 👍 42    🔁 9    💬 0    📌 1

I'm now the orbital police full time, since before I was doing that in my downtime from the day job.

06.03.2026 04:29 — 👍 9    🔁 0    💬 1    📌 0

Thanks to my retirement from the Center for Astrophysics, my old email address jcm@cfa.harvard.edu no longer works. I had that email address for 38 years!! Before that I was JBVAD::JCM, CAVAD::JCM, and (1978) UK.AC.CAM.PHX::JCM4. I don't recall what my id was on the ICL machine at RGO in 1977.

06.03.2026 04:09 — 👍 114    🔁 10    💬 5    📌 0

BITNET and EARN!

06.03.2026 04:00 — 👍 3    🔁 0    💬 1    📌 0

LAUNCH of Rocket Lab Electron from Mahia at 2353 UTC Mar 5 carrying a BlackSky Global Gen3 imaging satellite

06.03.2026 00:29 — 👍 35    🔁 2    💬 1    📌 0

Apparent FAILURE of Kairos during first stage flight, for the third time in a row
Failure appeared to be about 1 min into flight.

05.03.2026 02:14 — 👍 64    🔁 5    💬 3    📌 3

LAUNCH at 0210 UTC Mar 5 of Kairos rocket flight 3 from Kii spaceport, Japan

05.03.2026 02:10 — 👍 27    🔁 0    💬 0    📌 0

That's the plan.

04.03.2026 23:03 — 👍 2    🔁 0    💬 0    📌 0

Sorry, I don't right now...

04.03.2026 20:05 — 👍 3    🔁 0    💬 2    📌 0
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Encouraged to see the provisions in the Senate's NASA authorization bill (reported out of ctee today) supporting Chandra: #saveChandra

04.03.2026 19:32 — 👍 68    🔁 9    💬 5    📌 0

Yes, or so I understand. There is a protocol in place.
(in any case Russia and China presumably watch the NOTAMs too...)
And warning systems will quickly spot that the missile is headed for Kwaj as usual - the place on Earth that's been attacked by more ICBMs than anywhere except Kura in Kamchatka

04.03.2026 16:21 — 👍 2    🔁 0    💬 0    📌 0

The way these work is that they pull a missile and its crew out of a silo in, e.g., Montana, fly them to Vandenberg, put on an instrumentation front end instead of the nukes, and see how close they can hit the target spot, usually in the Kwaj atoll's lagoon which is strewn with location sensors

04.03.2026 16:15 — 👍 26    🔁 3    💬 1    📌 0

Here's Marco's usual excellent map of the nav warnings associated with today's Minuteman test launch.

04.03.2026 16:14 — 👍 24    🔁 2    💬 1    📌 1
Text (screenshot) of Navigational Warnings NAVAREA XII/26 and HYDROPAC 582/26 defining five exclusion zones between California and Kwajalein

Text (screenshot) of Navigational Warnings NAVAREA XII/26 and HYDROPAC 582/26 defining five exclusion zones between California and Kwajalein

The five exclusion zones from Navigational Warnings NAVAREA XII/26 and HYDROPAC 582/26 plotte don a map of the Pacific, with a fitted ballistic trajectory

The five exclusion zones from Navigational Warnings NAVAREA XII/26 and HYDROPAC 582/26 plotte don a map of the Pacific, with a fitted ballistic trajectory

Navigational Warnings have appeared that point to the test #launch of an unarmed #Minuteman-III #ICBM from Vandenberg to the Ronald Reagan test range in Kwajalein, March 4-5.
@planet4589.bsky.social @nukestrat.bsky.social @m514ever.bsky.social

27.02.2026 12:29 — 👍 30    🔁 4    💬 2    📌 4

Launch was from either silo LF09 or silo LF10. Unfortunately DoD has not released which silo was used for the last couple of launches.

04.03.2026 15:56 — 👍 19    🔁 1    💬 0    📌 0

Exactly. There is never a time where there is nothing problematic going on in the world that people will try and associate with a launch.

04.03.2026 15:51 — 👍 4    🔁 0    💬 0    📌 0

As scheduled, suborbital LAUNCH of Minuteman 3 ICBM operational test flight GT255GM ( with dummy warhead) from Vandenberg to Kwajalein at 0701 UTC Mar 4.
To head off the usual uninformed comments: these GT test launches are planned long in advance, are not related to current events.

04.03.2026 15:41 — 👍 52    🔁 7    💬 3    📌 1

LAUNCH at 1052 UTC Mar 4 of Starlink Group 10-40 from Canaveral

04.03.2026 15:39 — 👍 14    🔁 0    💬 0    📌 0
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No.
1030pm Mar 2 MST = 0530 UTC Mar 3; this was the reentry of Starlink-1294

04.03.2026 02:55 — 👍 1    🔁 0    💬 0    📌 0

SJ-12 was an inspector satellite, which carried out a series of rendezvous experiments with the SJ-6/3A and SJ-6/4A satellites. It seems to have ended its mission in 2010 Dec.

04.03.2026 01:14 — 👍 2    🔁 0    💬 1    📌 0

Actually increased X-ray flux heating the upper atmosphere

04.03.2026 00:24 — 👍 3    🔁 0    💬 1    📌 0

It's drag from the Earth's outer atmosphere that slowly makes the orbits shrink until they reenter.

03.03.2026 21:45 — 👍 4    🔁 0    💬 1    📌 0
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We've been seeing a lot of old Soviet Tselina-D/Ikar sigint satellites reenter lately. 68 were launched from 1970 to 1992.
The plot shows their orbital altitude vs time, with approximate dates of solar maxima overlaid in red. You can see how reentry dates are grouped near the maxima.

03.03.2026 21:35 — 👍 91    🔁 17    💬 5    📌 2
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Starlink-1651 reentered over Aruba at 0108 UTC Mar 3 and its breakup was observed by Marcos Bislip of Aruba Astro Research:

03.03.2026 21:16 — 👍 47    🔁 10    💬 1    📌 0

Graphs for each individual sat can be found at e.g. www.planet4589.org/space/con/st... by clicking through from the main page at www.planet4589.org/space/con/st...

03.03.2026 20:30 — 👍 0    🔁 0    💬 0    📌 0

No, there were additional Star 48 boost motors strapped on the back of the Voyagers and jettisoned later.

02.03.2026 21:00 — 👍 3    🔁 0    💬 0    📌 0

Pioneer 10 Centaur was left in a low perigee elliptical Earth orbit and reentered in Aug 1972.
Pioneer 11 Centaur similar, reentered Nov 1974
Voyager 2 Centaur in 1.0 x 3.0 AU orbit
Voyager 1 Centaur in 1.0 x 3.4 AU orbit
NH Centaur in 0.98 x 3.03 AU orbit

02.03.2026 20:44 — 👍 7    🔁 0    💬 1    📌 0