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To clarify, youíre saying you think itís dumb if the landed starship is also the return vehicle, correct?

How do you think this changes if there is no intention for the landed starship to take off again? (i.e. the payload is a MAV?)

Hadn't thought about landing a Starship with a MAV.  That might work, especially since it would allow the MAV to be 6-7.5m long, and up to 2m wide.

The MAV could sit horizontally on the garage deck, and be rotated into launch position (i.e., pointed out the hatch).  The issue would be how you launch the silly thing.  It's possible that you can catapult it out of of the garage's hatch.  It'll be ~37m in the air, so as long as the SRM can fire and gimbal to keep it from hitting the ground, that might work.  This would make the landed Starship's tilt tolerances quite critical, though.  It might require some sort of leveling mechanism to overcome worst-case tilt on landing.  It also might require some kind of opposite-side leg bracing to counteract the recoil from catapulting it out of the hatch.

This isn't that different from how the plan-of-record MAV is intended to be launched.  However, since this MAV could be substantially larger, all of the mass margin problems would go away.

Figure an expendable landed Starship, nearly no prop at landing, and a payload (elevator, fetch rover / helicopter(s), and MAV) of 4t.  Total waist thruster thrust would be ~530kN.  This would take about 350t of prop from LEO, which would be maybe 260t of prop via tankers--two launches.

However, now you really need either the ERO or a second StarKicker in LMO.

Note that none of this obviates the need for Cat II clearance for a landing site close enough to Perseverance and/or Three Forks.

If possible, I would skip the elevator and go back to the idea of cargo pods between the engines.
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They also reserved eight Atlas V LVs, which are presumably ready to go as needed starting now. The fact that they are not using them points to issues with the satellites or satellite production rather than launcher availability.
{snip}

Given satellite production seems to be limiting factor maybe now is not good time to book more LVs.
This is equivalent to saying that Kuiper will not make the July 2026 deadline to launch 1616 satellites. That in turn means they must plan to get a waiver from the FCC. But I suspect that just about everybody in the industry, not just SpaceX, will oppose that.

How many Kuiper satellites would represent a Minimum Viable Product?
That might be enough so that at least one satellite is visible from any place in the USA (Hawaii & Alaska excepted). If they haven't even got to that by the July 2026 deadline, ISTM it would make their application to the FCC for an extension even more problematical
If your LEO constellation can continuously serve any one point at a certain latitude, it can serve every point at that latitude (assuming a ground station or ISL) so no advantage to skipping Hawaii. You can skip Alaska but only by skipping Canada, Nordic countries, Russia,and Antarctica.
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ULA - Delta, Atlas, Vulcan / Re: Potential sale of ULA
« Last post by Jim on Today at 10:32 pm »
For a company headed by an "oNeilian", the obsession with the Karman line is pathetic.  VG, I understand.  But BO? Their heads should be far far beyond this by now.

BO didn't make the quote. ULA did.  The reporter sees something that isn't there.
Did ULA ever make that call out before?  Before the potential sale to BO came up?  I can't remember.
Doesn't matter.  there is no linkage.  BO had no influence on this launch
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Advanced Concepts / Re: Spinlaunch on the Moon
« Last post by Exastro on Today at 10:24 pm »


Exactly this, but if the rotation is always co-axial with the main shaft (which again is probably desirable, because it keeps all motion "horizontal" within the extreme rotating hyper-gravity field) you need a minimum of two masses that rotate around the main shaft.
So something like this, I guess.

I think I'm finally go for a large motor, about 500 hp, and a higher mass payload.  The problem of the smaller payload is that the mass fraction of the control and propulsion unit is much higher for a small payload than for a larger one.  The controls and valves remain the same for a small or a large payload, but the percentage of overall mass goes down significantly for a large payload.

You'll want to taper the launch arm (so it gets thinner toward the fast end) because the part near the end is supporting mostly the payload while the part near the rotation axis is supporting the centrifugal force produced by the whole arm plus the payload.  The taper should be more or less straightforward to calculate by keeping the material stress constant, but you'll have to solve a differential equation.

The tapering will reduce the mass of the arm and the energy needed to spin it up.
I agree.  That equation has been solved and it's on the Wikipedia page for tethers.  But at this point in the design, I just used a cheap pyramid to get about the right value.  My main issue has to do with the dynamics of releasing a mass at a relatively high RPM on a long arm, ideally without releasing a counterweight or requiring complex actuators.
the other issue is a question of optimization of transportation: Is it better to capture the payload in low orbit after circularization, so a smart Payload, or to have a stronger system and launch it all the way to one of the L-points where a smart catcher takes it in?  How smart does the payload need to be?
Returning a complex payload unit has a big impact of economical feasibility.

At the risk of being pedantic: The equation will not be the same as for the tether case because the acceleration varies with distance from the anchor point as 1/r for the spinner vs. 1/r2 for the tether.

Totally agree wrt the dynamics: that's the hard part of this problem, I suspect.  You can get all kinds of unwanted forces on the arm at release time if you're not careful.  Releasing the counterweight for the payload simultaneously with the payload should in principle get rid of everything except the elastic rebound (the arm length shrinks like a spring with part of the tension released) and the resulting Coriolis forces, which will induce transverse waves.  I haven't done the calculation, but I suspect that might still be a problem.

In general, I think you'll have to have some kind of damping setup to suppress transverse waves on the arm, and probably other things.

As for the payload propulsion to raise the perigee above the surface: Have you considered wrapping the payload in an ablative shell and hitting it with a pulsed laser to give it a kick near apogee?  Just a thought.

Another probably dumb idea: a catcher in LLO could intercept the payload (which would be moving a bit slower than the catcher) close to apogee and raise its perigee. If your spinner is at a lunar pole, the catcher could be in the right position every couple hours.  A ring of catchers could be deployed to allow more frequent launches.
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This is equivalent to saying that Kuiper will not make the July 2026 deadline to launch 1616 satellites. That in turn means they must plan to get a waiver from the FCC. But I suspect that just about everybody in the industry, not just SpaceX, will oppose that.

I wouldn't be so sure that many others will oppose a short waiver.  SpaceX probably will not, because its operations could be impacted the most in the future with any negative precedent.
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ULA - Delta, Atlas, Vulcan / Re: Potential sale of ULA
« Last post by meekGee on Today at 10:11 pm »
For a company headed by an "oNeilian", the obsession with the Karman line is pathetic.  VG, I understand.  But BO? Their heads should be far far beyond this by now.

BO didn't make the quote. ULA did.  The reporter sees something that isn't there.
Did ULA ever make that call out before?  Before the potential sale to BO came up?  I can't remember.
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Here is a video of the Commission meeting.  Starts at ~ 2:58:00.

https://cal-span.org/meeting/ccc_20240410/

The discussion is disappointing, but at least the Space Force can put the breaks on singling out particular companies/individuals for political reasons.

It seems that SpaceX's activities are just not very impactful, now that they have adjusted operations to evening launches.
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