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Jonathan McDowell Profile picture
@planet4589
Sep 22, 2020 • 5 tweets • 2 min read • Read on X
The debris object that ISS avoided is now available on SpaceTrack as 2018-084CQ, 46477, from the breakup of Japan's H-2A F40 rocket stage. At 2221:07 UTC it passed within a few km of ISS at a relative velocity of 14 6 km/s, 422 km over the Pitcairn Is in the S Pacific Image
Correction: it passed within a few km of the position ISS would have been at if it hadn't manuevered
H2A F40 launched GOSAT-2 in Oct 2018. The stage appears to have made a depletion burn to lower orbit from 597 x 618 km to 598 x 520 km. Nevertheless it underwent a major breakup on 2019 Feb 6.
77 debris objects have been cataloged from the breakup; 5 have reentered so far. This plot shows the locations at conjunction time of the remaining 72 (almost all in one plane) and the pre-maneuver track of ISS for +/- 10 min Image
Most of the debris objects are still at somewhat higher altitudes, but they will eventually decay through the ISS height range Image

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More from @planet4589

Jonathan McDowell Profile picture
Feb 10
WOOHOO! THANK YOU EVERYONE - I HAVE REACHED THE $100K GOAL. Thanks especially to the generous folks at @COMSPOC and to the other large donor who prefers to be anonymous, but also to every single one of you. This will help a LOT.
HOWEVER - I just got back from a week of property-hunting in the UK. Alas, I will not be able to acquire the particular place I had in mind - I got outbid and there would have been planning reg issues anyway. I've found a few other possibilities and am continuing to look.
It will work out, but I am going to continue accepting donations in the hope of making another tier of properties affordable.
Read 6 tweets
Jonathan McDowell Profile picture
Jan 17
Back from an intense week at the American Astronomical Society meeting. Much to report and much still to catch up on, but I'll start tonight with an update on the Starship flight
Starship Flight 7 was launched at 2237 UTC Jan 16 from Starbase, Texas, but failed to reach orbit. I will assign designation 2025-F01 to the launch. Super Heavy Booster 14 reached an apogee of 91 km, performed a boostback burn, and was caught by the launch tower.
Ship 33 separated from Booster 14 at 2m40s. There are three 'center' and three 'outboard' Raptor engines on Ship. At T+7:40 one center engine went out, followed at T+8:02 by a second center one and T+8:04 by the adjacent outboard one.
Read 7 tweets
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

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