18 August 2022 at 12:50 pm #611999
As the US are due to send the Artemis mission to the Moon soon, does anyone know if TLEs or an ephemeris can be obtained for its position en route? I assume they will have been calculated for its anticipated launch window.
It would be nice to see how close to the Moon it can be tracked with modern amateur OTAs and sensors.
I detected the Israeli Beresheet lunar lander when approx 1/3rd of the way there and have seen the russian Spektr-R mission near apogee, but neither appeared near the Moon, so I am keen to give it a go – cloud permitting.18 August 2022 at 2:15 pm #612002Daryl DobbsParticipant
A few people in America are asking the same question on a NASA forum, a couple of web links were suggested
Apparently the trajectory will be available on this site after launch
People around here are eagerly following our local hero astronaut Shaun the Sheep who is taking a big step for lambkind
18 August 2022 at 7:51 pm #612007
- This reply was modified 1 month, 1 week ago by Daryl Dobbs.
Ah, excellent. I looked and they appear to have a place holder object name in place, so it looks hopeful.
It could be a lot of fun. It looks like it will be taking a while to get there.27 August 2022 at 12:12 pm #612152
It doesn’t look good for us in the UK.
Assuming that the launch goes ahead at the start of the 2 hour window (12:33 UTC on Monday Aug 29) the geometry for the UK is poor with the spacecraft below the horizon at night for the first week. It is above the horizon in a dark sky on Sept 5/6 when it is at declination -27 and due south around 2100 UTC but, by then, it will be a long way away and close to the Moon in the sky (not a surprise really) low in Sgr.
It gets to high northern declinations on the way back but by then it is heading for solar conjunction.
All in all I doubt if anyone will image it from here. A good opportunity to use a remote telescope I think.27 August 2022 at 7:17 pm #612156
At -27 theres not much hope from home for me then as my dome blocks everything below -10 and a nearby hill blocks everything below -15.
Damn.27 August 2022 at 8:51 pm #612157Paul LeylandParticipant
Dec is fine from here in LP but whether the sky is clear is another matter. The rainy season is beginning and there is thick cloud tonight.27 August 2022 at 9:00 pm #612158
Yes, it’s going to be a challenge. The attached plots show the visibility from my observatory in Chelmsford to give some idea. These show the altitude of the Orion spacecraft, the Sun and the Moon at the date shown along the bottom. On the night of the launch Orion is around 12 deg up at nautical twilight and descending. I don’t know how bright it will be but at 20h on the day of launch it will only be 10 deg up from here and it is already 79000 km away. The ISS at this distance would be around 4th mag and Orion is a lot smaller than the ISS.
By the time the circumstances get better it is far away and close to the Moon as you can see from the second plot.
I would love to be proven wrong and would be very impressed if anyone gets this from the UK!
Attachments:29 August 2022 at 1:32 am #612168
Ted Molczan has provided a table of expected magnitudes for the spacecraft (Orion) and the SLS upper stage and spacecraft adaptor (the Interim Cryogenic Propulsion Stage) on seesat:
They indicate that Orion will be 13th mag on the night of launch fading to 17th mag at lunar distances with the ICPS around 1 mag fainter.
The ICPS will be deflected from the spacecraft trajectory by a disposal burn shortly after trans-lunar injection (TLI). This will target a lunar flyby which will put the stage into a heliocentric orbit. The stage will probably do a propellant dump shortly after the disposal burn as part of its passivation procedure. Sadly we are not going to see that from here but it could be an interesting sight for people in the right place. Have a look at Chris Taylor’s description of the equivalent from the Apollo 8 S-IV-B upper stage:
JPL Horizons has an ephemeris for Orion but not the ICPS. It is likely that an ICPS ephemeris will appear here:
Good hunting. Please post any images you get on this website.31 August 2022 at 12:30 pm #612187
An updated ephemeris for the rescheduled Artemis launch time (window opens on Sept 3 at 18:17 UTC) is on JPL Horizons. This has much better visibility for us on the evening of the launch. The spacecraft rises around 20:00 UTC and gets above 40 deg altitude by 21:00. The upper stage separation burn is at T + 2hr 7min so may well be visible from the UK if the sky is clear.
Let’s hope that they now fully understand the LH2 bleed and the RS-25 cryogenic conditioning problems that scrubbed the last launch and that the weather cooperates on both sides of the Atlantic.31 August 2022 at 5:27 pm #612188
That sounds very hopeful. Would love to see the burn…
Of course that means overcast skies plus fog for the next couple of weeks then. 🙂
31 August 2022 at 10:22 pm #612192
- This reply was modified 3 weeks, 3 days ago by Grant Privett.
This document has some useful background information on SLS. In particular it has a timeline including the ICPS disposal burn on page 55:
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