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Jonathan McDowell Profile picture
@planet4589
Aug 28, 2021 • 7 tweets • 2 min read • Read on X
Scrolly
Astra rocket - looks like a problem at Max Q. Something fell off and then "Terminate Sent".
Launch failure confirmed. Fatal problem happened at 33 km altitude at 22:37:32 UTC, 2.5 min into flight. But amazing it got that far after the initial sideways skid at launch
Launch:
T+4s: oh, that doesn't look good
T+6 s: vertical again, but motion is all sideways...
T+18s, still sideways, but starting to climb. Are you kidding me?
T+22s: almost complete recovery, motion now vertical. Medal for most impressive save (albeit only temporary)

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More from @planet4589

Jonathan McDowell Profile picture
May 29, 2023
The planned trajectory of the North Korean satellite launch, as estimated by me based on debris warning areas, passes 500 km above the Okinawa region - higher than the International Space Station. The only landmass it goes directly over is the uninhabited island of Irisuna-jima. Image
It is possible that the second stage could shut down early, or that the yaw manuever prior to stage 2 ignition could go off course, so it is not completely *impossible* for debris from the launch to hit the Okinawa region. But it is very, very unlikely.
Thus, I consider Japanese goverment hyperventilation about the launch to be rather excessive.
Read 4 tweets
Jonathan McDowell Profile picture
May 29, 2023
Thanks to a tip from @martyn_williams I took a look at the warning areas for the upcoming (NET May 31) North Korean recon sat launch.
The map below shows the launch site, polygonal warning areas and (orange lines) my fit to the trajectories. (1/n)... Image
@martyn_williams I think the first and second warning areas correspond to first stage and nose fairing impact zones, and correspond to a -5650 x 150 km x 93.9 deg (sub)orbit (apogee not well constrained).
@martyn_williams Then the second stage makes a 'dog leg' yaw change to head southeast, firing at 1st stage apogee to a -5240 x 500 km x 75.7 deg orbit with impact east of the Phillipines. This trajectory has an apogee over 127.1E 26.1N.
Read 5 tweets
Jonathan McDowell Profile picture
Jan 8, 2023
On Tuesday at 2pm I'll be in room 205 for the "Space as an Environment" splinter session which will include an update on the issue of satellite constellations affecting ground based astronomy
That topic will be continued on Wed at 10am, room 201/202, for the "Space as an Environment" open house, where I'll be tabling and available for informal discussion about the satcon and other space env issues #AAS241
On Wed at 12.45 at the AAS reg desk I invite alumni of the SAO Astronomy Summer REU to join me for our traditional networking lunch expedition, actual eating venue still TBD #AAS241
Read 4 tweets
Jonathan McDowell Profile picture
Jan 6, 2023
The Japanese space agency JAXA is preparing to deploy 3 cubesats from the ISS.
The cubesats are stored in the J-SSOD #24 deployer, which was brought to ISS on Dragon CRS-26 and transferred internally to the Kibo module.
The Japanese JRMS robot arm has extracted J-SSOD #24 from the Kibo airlock and is now holding the deployer out against the direction of ISS motion so that the ejected sats will not recontact ISS.
The first sat to be ejected will be the 1U test satellite SS-1 (SuryaSat) from Surya University in Jakarta.
Read 5 tweets
Jonathan McDowell Profile picture
Dec 19, 2022
OK, it's Sunday night and I'm going to get technical on you.
You may be familiar with the Lagrange Points - specifically Sun-Earth L1 and L2 (SEL1 and SEL2), which are 1.5 million km towards noon and towards midnight respectively.
As the Earth goes round the Sun, L1 and L2 travel with it. So if you define a coordinate system which rotates around the Sun with the Earth, the L1 and L2 points are fixed in that system. One such system is GSE: Geocentric Solar Ecliptic.
Read 15 tweets
Jonathan McDowell Profile picture
Dec 16, 2022
LAUNCH of Falcon 9 at 2248 UTC Dec 16 from Cape Canaveral LC40 with two O3b-mPOWER communications satellites
20 first-gen O3b satellites were launched to 8000 km equatorial orbits in 2013 to 2019. They had a mass of 700 kg.
The new O3b mPOWER sats are Boeing 702X satellites with a . mass of 1700 kg each. I believe their size is around 1.5 x 3.0 x 3.0 m with about 27m solar panel span
Correction, O3b-mPOWER mass may be 2050 kg each, based on info in @SpaceflightNow 's coverage
Read 6 tweets

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