The Artemis 1 mission management team is currently working through flight readiness analysis cycles, calculating lunar launch opportunities and vehicle performance margins. Currently, the first launch period available for an NET late-November 2021 readiness date is Launch Period 15, which opens on November 23 and runs through December 10. Following that, Launch Period 16 is December 21 through January 3, 2022, with Launch Period 17 running January 17 through January 30.
If they wanted to launch with an ecliptic inclination as low as possible (around 5 degrees) on the 22nd of November 2021, that would occur at about 0710 UTC by my calculations. Although, I've heard there are advantages for lunar missions to not doing that. But I've done it in Orbiter 2016 with the SLS Block 1 and gotten to the Moon (performed a TLI) that way with total delta-V (post-LEO) of around 2.35 km/s
Quote from: CreponChris on 08/10/2021 04:57 pmIf they wanted to launch with an ecliptic inclination as low as possible (around 5 degrees) on the 22nd of November 2021, that would occur at about 0710 UTC by my calculations. Although, I've heard there are advantages for lunar missions to not doing that. But I've done it in Orbiter 2016 with the SLS Block 1 and gotten to the Moon (performed a TLI) that way with total delta-V (post-LEO) of around 2.35 km/sThere are restrictions on the SLS trajectory that you probably violated to do that. SLS propulsion elements provide more performance than Orion and some parts of SLS hardware can allow. I've posted about this before, but it has been a long time.
Well, that is interesting. Thanks. There are a couple PDF's I've found related to the Artemis I, https://ntrs.nasa.gov/api/citations/20205005150/downloads/AAS20649_Artemis1_Trajectory_Design_Optimization.pdf that one I think being the most relevant. I'll have a look at the article already linked to in this thread and if you ever want to point me toward threads you've already contributed to that would be appreciated. Don't want to hijack this one :]
Does anyone know whether the Artemis 1 mission will have a launch window, or whether it can launch at any time (subject to range constraints,, etc., etc.)
A couple of things I noted:The video says there are two daily launch windows. The linked paper says there is one. I think that is because one of the daily launch windows is not feasible to reach from the launch site and have the spacecraft arrive at the right time for the TLI burn. The spaceship needs to circularize the orbit before the TLI burn, & this time & geography constraint mean the only meaningful launch window is the one on the opposite side of the earth from the launch site on the day of launch.
Why would the daily windows be at night?
Great post, slobberg1. I have a follow up question, you mention that Apollo went for morning lighting for landing, which makes sense since they had to see topography to avoid boulder fields and such. The Artemis landings are targeting locations at the South Pole, would lighting conditions there always be "morning like" since the sun is at a low angle? Or is there any precession/seasonality that would give slightly better lighting conditions at certain times of the month or year?
Finally, to try and keep this post at least somewhat related to the original topic of the thread, which was Artemis I Launch Windows, I wanted to remind readers that Artemis I (and I believe Artemis II) are performing an insertion into a Distant Retrograde Orbit at moon arrival (not a lunar landing), and therefore any Artemis lunar landing timing constraints would not seem to be applicable to the launch window for these two missions.
Artemis II won't be going into DRO. It will do a Lunar flyby around the Moon, ...
...since nearly all the delta-V of Orion will be used to complete TLI.
Quote from: Steven Pietrobon on 09/29/2021 07:48 amArtemis II won't be going into DRO. It will do a Lunar flyby around the Moon, ...So Artemis I will enter a DRO, but Artemis II won't.Quote from: Steven Pietrobon on 09/29/2021 07:48 am...since nearly all the delta-V of Orion will be used to complete TLI.Because its payload will be greater than Artemis I's?And what about Artemis III? It enters lunar orbit. Is it that its NRHO is an easier destination than a DRO?