RE: Inspiration 4 estimated elsets

From: Richard Cole via Seesat-l <seesat-l_at_satobs.org>
Date: Wed, 15 Sep 2021 05:27:26 +0000
The spacex.com mission time timeline shows only one burn of the second stage and an immediate separation of the Dragon which I think implies a low perigee, so the first elset may be the best. Very limited northern hemisphere visibility.

Regards

Richard

-----Original Message-----
From: Seesat-l <seesat-l-bounces+richardc=recole.plus.com_at_satobs.org> On Behalf Of Marco Langbroek via Seesat-l
Sent: 14 September 2021 22:11
To: satelliet lijst (SeeSat) <SeeSat-L_at_satobs.org>
Subject: Inspiration 4 estimated elsets


Hi all,

Below are two possible elsets for the upcoming SpaceX Inspiration 4 crewed Crewdragon commercial mission.

Elsets are for the start of a several hour long launch window: this window opens at 16 Sep 2021, 00:02 UT. If the launch is later, you can use my "TLE from Proxy" software (https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fsoftware.langbroek.org%2F&amp;data=04%7C01%7C%7Cc3dd869329224edbba5f08d977cc9620%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637672542839623251%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=ToW9OFqRJJmQKUq%2BykgDzYylzFfwLYNxE2QWlcQgByk%3D&amp;reserved=0) to adjust the elsets to the correct launch time.

The orbital altitude is not entirely clear to me. In the press conference, an apogee at 540 km was mentioned. At the SpaceX website, and apogee at 575 km is mentioned instead. Confusing!

The 51.6 degree orbital inclination was mentioned in the press conference.

Perigee altitude was not mentioned either in the presco or on the website. I therefore provide four variations:

- one eccentric orbit with a low perigee and 575 km apogee;
- one that assumes that the "540 km" from the press conference was actually
  the perigee, not apogee, and apogee is 575 km;
- a circular orbit for 540 km;
- a circular orbit for 575 km.


202 x 575 km:
INSPIRATION 4                   for launch on 16 Sep 2021 00:02:00 UT
1 70000U 21999A   21259.00138889  .00000000  00000-0  00000-0 0    06
2 70000 051.6000 251.1904 0275366 048.1738 324.5829 15.59651758    08


540 x 575 km
INSPIRATION 4                   for launch on 16 Sep 2021 00:02:00 UT
1 70001U 21999A   21259.00138889  .00000000  00000-0  00000-0 0    07
2 70001 051.6000 251.2367 0025232 048.1463 325.8682 15.03049589    06


539 x 541 km
INSPIRATION 4                   for launch on 16 Sep 2021 00:02:00 UT
1 70002U 21999A   21259.00138889  .00000000  00000-0  00000-0 0    08
2 70002 051.6000 251.2366 0001445 048.1463 325.7387 15.08756327    07

574 x 576 km
INSPIRATION 4                   for launch on 16 Sep 2021 00:02:00 UT
1 70003U 21999A   21259.00138889  .00000000  00000-0  00000-0 0    09
2 70003 051.6000 251.2412 0001438 048.1436 325.9970 14.97378736    03


- Marco


-----
Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.
e-mail: sattrackcam_at_langbroek.org

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Received on Wed Sep 15 2021 - 00:28:59 UTC

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