Tuesday, 23 March 2021

[UPDATED] Reentry predictions for the Falcon 9 RB 2021-017BN

click diagram to enlarge

In my previous post, I discussed 2021-017BN, the Falcon 9 upper stage from the March 4 Starlink launch that should have been deorbitted after 1.5 revolutions on March 4th, but didn't.

It is still on orbit. At the moment of writing, 23 March 2021 at 11:00 UT, it is in a 217 x 200 km orbit according to the latest available elements from CSpOC, and it will stay on orbit for a couple of days to come. But the end is near: the orbital altitude of the rocket stage is quickly decaying, as can be seen in the diagram below:

click diagram to enlarge

My current reentry prediction (see diagram in top of post and table below) is that it will come down in the early hours of March 26 (2021). My prediction, based on modelling in GMAT R2020a using the MSISE90 model atmosphere, appears to be well in line with the TIP from CSpOC so far.

[UPDATE: my final post-cast predicted reentry at 26 Mar 04:34 UT, which is some 35 minutes too late. It is based on a 2/3rd maximum drag surface value. Interstingly, using the maximum drag surface leads to a reenrty at 3:56 Ut, within minutes f the actual time]

Revisit this post for prediction updates in the coming days.

orbit epoch     pred. date     reentry time (UT)
21081.600725    26 Mar 2021    02:33 +- 16.8 hr
21081.922054    26 mar 2021    03:36 +- 15.5 hr
21082.113317    26 Mar 2021    03:59 +- 14.7 hr
21082.216601    26 Mar 2021    03:40 +- 14.1 hr
21082.278149    26 Mar 2021    03:43 +- 13.8 hr
21082.462749    26 Mar 2021    05:29 +- 13.3 hr
21082.585776    26 Mar 2021    05:29 +- 12.7 hr
21082.708770    26 Mar 2021    05:37 +- 12.1 hr
21082.954651    26 Mar 2021    06:13 +- 11.1 hr
21083.138960    26 Mar 2021    05:03 +-  9.9 hr
21083.261785    26 Mar 2021    05:15 +-  9.4 hr
21083.296296    26 Mar 2021    05:20 +-  9.2 hr
21083.507296    26 Mar 2021    05:28 +-  8.3 hr
21083.875164    26 Mar 2021    05:26 +-  6.5 hr
21084.120127    26 Mar 2021    05:59 +-  5.4 hr
21084.181325    26 Mar 2021    05:20 +-  5.0 hr
21084.486963    26 Mar 2021    05:00 +-  3.5 hr
21084.548018    26 Mar 2021    03:19 +-  2.8 hr
21084.974688    26 Mar 2021    04:46 +-  1.1 hr * post-cast
21085.095602    26 Mar 2021    04:34 +-  0.5 hr * final post-cast


UPDATE  26 March 2021  12:30 UT:

The reentry happened last night, over North America, and was widely seen from the US States Washington and Oregon, near 4:00 UT (March 26 UT: that is 9 pm on March 25 local time for that area).

CSpOC's final TIP places the reentry at 03:58 +- 1 min UT. This time matches the reports from Washington and Oregon well, and based on the last orbit it would indeed place the rocket stage near the NW United States coast.

The listed geographic position in the TIP, 24.5 N, 151 W, does however not match well (it is further down the track, near Hawaii, corresponding to the Falcon 9 position about 6 minutes prior to the observed reentry). We have  noted such discrepancies more often in recent TIP messages. In this case, I half suspect the position was that given by their reentry model, and they forgot to update it when the SBIRS detection of the actual reentry fireball came in.

click map to enlarge

My own final "post-cast" places reentry some 35 minutes after the actual reentry.

Here are some of the reentry sightings as reported on Twitter:

 

UPDATE 2 April 2021 23:00 UT:

Debris has been recovered from this reentry. In Grant Country, Washington, a Composite Overwrapped Pressure Vessel (COPV) was found on farmland.


 

 

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6 comments:

  1. Jig26/3/21 07:02

    thanks! excellent work as always.

    ReplyDelete
  2. Florian26/3/21 09:07

    I wonder why this is not covered by other media? An uncontrolled reentry with some debris to be likely to reach the ground would usually catch their attention. Or is it clear that no debris will survive the reentry?

    ReplyDelete
  3. jim oberg28/3/21 22:22

    I'm collecting widespread consistent reports of a rumble heard simo with the overflight -- physically impossible for acoustic sound generated 60+ km high. Are we getting indications of a powerful electrophonic ['meteor sound'] event? The reports come from rural areas with very low ambient background noise.

    ReplyDelete
  4. jim oberg28/3/21 22:24

    Here's a story I did on that phenomenon during the much more powerful Chelyabinsk bolide:
    http://www.astronomy.com/magazine/2013/04/the-whispering-bolide

    ReplyDelete
  5. jim oberg28/3/21 22:25

    My reply email is jamesEoberg@comcast.net, not the 'gmail' address.

    ReplyDelete
  6. SatTrackCam Leiden29/3/21 14:59

    Hi Jim,
    Interesting! I once heard electrophonic sound from a meteor, so I know it exists.

    ReplyDelete

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