The predicted close approach on Oct 16 involves a Soviet Parus navigation satellite and a Chinese rocket stage. Here is the Parus. It's a big satellite, about 800 kg, 2 metres in dia and it has a 17 metre long gravity gradient boom.
The Parus satellite was designed by ISS Reshetnev in Zheleznogorzk and built by PO Polyot in Omsk. Images from kik-sssr.ru
The CZ-4C third stage is about 7.5m long and 2.9m diameter. I don't have a good mass for it but it is probably of order a tonne. Here is art of the stage from the specific launch in question with the payload still attached at right
Here's my own visualization of the encounter. Kosmos-2004 (red) is heading south towards the pole, CZ-4C-Y4 (purple) is heading north towards the Falklands
Parus (Kosmos-2004) is in a 970 x 1013 km x 83.0 deg polar orbit. CZ-4C-Y4 Stage 3 is in a 970 x1203 km x 100.4 deg retrograde orbit.
By the way, the Parus satellite carried a communications relay package and a navigation payload using Doppler beacons - basically a Soviet copy of the @JHUAPL/US Navy Transit navigation system

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More from @planet4589

14 Oct
A TsSKB-Progress Soyuz-2-1a rocket stands on the pad at Baykonur's Area 31, ready to launch an RKK Energiya Soyuz-MS spaceship.(Confusingly 'Soyuz' can refer to either the rocket or the spaceship on top.)
The Soyuz 2-1a rocket has taken over human spaceflight launch duties from the now-retired Soyuz-FG rocket. Today's rocket is serial Kh 15000-045 and is the 41st Soyuz-2-1a to be launched.
There is a further upgraded version, the Soyuz-2-1b, with a newer third stage engine - apparently they don't trust this for piloted missions. The Soyuz-2-1a and 2-1b use a lower stage design derived from the original 1957 R-7 ICBM and 8K71PS Sputnik launch vehicle.
Read 16 tweets
26 Sep
Here are all the actual satellites in orbit in this range of heights and inclinations (green = working, red = dead). See how they are almost all right on the magenta SSO line. They are also almost all below 1000 km. The rest of the diagram is really empty of satellites!
Now let's add in orbital debris. Generic orbital debris in black; debris from the 2007 Chinese antisatellite test in blue. You couldn't have picked a much worse region of orbital parameter space to make a big debris cloud.
Finally, here is a zoom in on the busiest part of SSO, omitting the debris
Read 12 tweets
25 Sep
A nice cache of declassified documents on the Soviet E-8 lunar program has been released to commemorate the anniversary of Luna-16: roscosmos.ru/29219/
One thing I hadn't registered before is that Lunokhod is referred to as L-2, in the sequence between L-1 (Zond) and L-3 (human landing missions). I guess @historyasif already knew this though.
@historyasif The documents also include official contemporary reports noting the payload fairing failure on the first Lunokhod launch (Feb 69) and the Blok-D ignition failure on the first E-8-5 sample return attempt (Jun 69).
Read 4 tweets
22 Sep
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.
Read 5 tweets
17 Sep
I've just written about the Starlink reentries in JSR latest.html, but I'll repeat my comments here. After 63 years of orbital spaceflight this is a qualtiatively new kind of orbital decay (hi @orbital_decay !)
(1/n)
@orbital_decay it's not a normal deorbit and not a
normal orbital decay, but something inbetween. The Starlink satellites are, apparently, retired by continuously lowering their orbit with electric propulsion.
@orbital_decay Reentry occurs in a way similar to uncontrolled reentry - eventually the satellite is low enough and the ambient density is high enough that the vehicle heats, breaks up and is destroyed.
Read 6 tweets
15 Sep
China launched a Chang Zheng 11 at 0123 UTC, placing 9 satellites in sun-sync orbit. The satellites are all in Changuang Satellite Tech's Jilin-1 constellation: three video sats (Jilin-1 GaoFen 03C 01 to 03 xing) and six pushbroom imager sats (Jilin-1 GaoFen 03B 01 to 06 xing)
The CZ-11 was launched from a barge called 德渤三号 (Debo-3), which sailed from the new Shandong Eastern Spaceport at Haiyang.
This is the second CZ-11 sea launch; the previous flight in 2019 was a test using a different barge, the Tai Rui, before the Eastern Spaceport was opened.
Read 5 tweets

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