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Have there been any updates or reported trajectories for the F9 upper stage? It 'should' have made a perilune pass approximately the same time IM-1 performed LOI....

Yes, Bill Gray at Project Pluto is maintaining an orbit for both IM-1 and the F9 upper stage here:

https://projectpluto.com/pluto/mpecs/24030a.htm
https://projectpluto.com/pluto/mpecs/24030b.htm

Of course the orbit for IM-1 will soon be obsolete after its LOI maneuver.  He mentions that the orbit for the upper stage should be useful for some time, especially after new optical observations are available post-perilune.

If I'm playing the game right the simulator currently predicts a return to the Earth-Moon vicinity in May.
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and SpaceX being SpaceX...

Here is a map of the North and South (Exuma) 53° booster trajectories for comparison. From SLC-40, the North ASDS is 618km downrange, while Exuma is 613km.
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If you are saying the engines themselves would mass too much, I'm not seeing it, at least not for a VASIMR type design. Electric propulsion historically can't do stuff like this because of the specific power (kW/kg) of the power source. If that constraint is removed...

If you can deploy very large areas of very thin film solar in space, you just don't *need* nuclear propulsion for the Inner Solar System. If you want a problem set where these kinds of things *do* make sense, humans to Titan / Enceladus or something would fit better.

Specific power of solar arrays is nearly constant as you scale up their total power.  That's not true for nukes:  specific power rises as total power increases.  At some point, the nuke will outperform the solar array, even when burdened with the required heat rejection.

I crunched some numbers from the VASIMR paper here.  From what they have, it's hard to separate the pure power supply from the thrusters, but here's a quick roll-up:

90-day transit time: 12MW system, power+propulsion+thermal = 58t, so 207W/kg.
39-day transit time: 200MW system, power+propulsion+thermal = 154t, so 1299W/kg.

Last I checked, space solar arrays are getting close to a specific power of 350W/kg (at 1AU).  I'm willing to believe that specific power will triple over the next 20 years.  So let's say 1050W/kg.  But the arrays will be operating at an average distance of 1.26AU, which takes them down to 660W/kg.

I'm willing to believe that the thrusters and thruster-specific heat rejection scale substantially sub-linearly.  (The 200MW description didn't break them out.)  Let's say that they only increase from 21t in the 12MW case to 40t in the 200MW case.  That makes the whole system 583W/kg, which is less than half the specific power of the nuke.

Continuous low thrust systems are incredibly sensitive to specific power.  I conclude from this that SEP is probably a loser for an architecture like this.  You need the big nuke.

PS:  Don't get me wrong:  the big nuke and scaling up VASIMR is probably 0.1% of the engineering cost of getting an exploding inside-out boosted fission propulsion system to work.  If you really need to get people to Mars in one month, this is probably the best option.  But getting spin gravity and decent shielding to work for a 4-month trip is probably 1% of the engineering cost of getting the big nuke to work.  And it's about 0.005% of the political cost.
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https://twitter.com/wapodavenport/status/1760434944239620510
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FWIW the media credentialing site lists April 22 as the launch date.
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According to this, 1 of the C-5C "outsized payload" birds (68-0216 ) flew from the Cape to California today.

https://globe.adsbexchange.com/?icao=ae051d



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Space Science Coverage / Re: IM-1 Odysseus lunar lander
« Last post by catdlr on Today at 10:23 pm »
https://twitter.com/Int_Machines/status/1760442834329473383

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Flight controllers analyzed the post-Lunar Orbit Insertion engine burn data and updated the anticipated flight maneuver timing, including an expected 1630 CST landing opportunity on Thursday. The landing opportunity will be Odysseus’ hardest challenge yet. The lander continues to be in excellent health, orbiting approximately 92 km above the lunar surface.
(21FEB2024 1645 CST)

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https://twitter.com/VickiCocks15/status/1760401679512457670

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and this image from @rocketjunkie94 has a close up taken from an old @RGVaerialphotosimage, above a clipped image from the @LabPadre snap above. The new socket definitely looks closer to the right of the mounting bracket now.
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Commercial Space Flight General / Re: Intuitive Machines
« Last post by theinternetftw on Today at 10:18 pm »
I know you found it, but for the future reference of anyone coming across this thread, all IM-1 mission updates are occurring in its mission thread.
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https://twitter.com/VickiCocks15/status/1760401676337320160

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So the stabilizer pin socket that got removed...
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Saw two C-5s at the Skid Strip.  I bet the payload was delivered.

Would delivery of a presumably high cost DoD payload 1 month before launch be historically typical?
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