Author Topic: Fly Me to the Moon on an SLS Block II  (Read 20618 times)

Offline Patchouli

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Re: Fly Me to the Moon on an SLS Block II
« Reply #60 on: 09/05/2017 01:50 AM »
Michel Lamontagne from Canada has been doing some fantastic work on providing artwork of the launch and landing sequence. Here's some preliminary artwork to whet your appetite.

I always thought it might be a good idea to use the EUS as a crasher esp if IVF technology from the ACES upper stage was applied to it.

Another option you could get a large cargo lander by adding legs to the EUS like this proposal with the S-IVB.

https://www.wired.com/2012/11/skylab-on-the-moon-1966/

Though it should be a lot easier with the SLS upper stage since the RL-10 can be made to throttle as seen on the DCX maybe even replace two or all four of the engines with the CECE.
« Last Edit: 09/05/2017 01:52 AM by Patchouli »

Offline Steven Pietrobon

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Re: Fly Me to the Moon on an SLS Block II
« Reply #61 on: 09/05/2017 05:37 AM »

Another option you could get a large cargo lander by adding legs to the EUS like this proposal with the S-IVB.

https://www.wired.com/2012/11/skylab-on-the-moon-1966/

Interesting! I think a better solution would have been to use a standard S-IVB (modified to reduced the boiloff rate) do 75% of the landing burn followed by a custom built habitat using storable propellants for the remaining 25% of the landing. This way the payload fairing can be ejected after entering LEO and then doing TLI. Going straight to TLI is difficult since any small mistiming will cause very large miss distances to the Moon. This allows a larger habitat to be landed that is easily reached by the astronauts, instead having to climb the 18 m high S-IVB!
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Nibb31

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Re: Fly Me to the Moon on an SLS Block II
« Reply #62 on: 09/05/2017 12:40 PM »
Isn't using crasher stages a bit dangerous for base building ? You have the risk of debris from the impact hitting your base.

Online Welsh Dragon

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Re: Fly Me to the Moon on an SLS Block II
« Reply #63 on: 09/05/2017 03:28 PM »
Depends on how early you stage. Because you do more braking after you dump your crasher stage, it will always overshoot the base. The overshoot distance depends on staging time and trajectory. You can imagine a number of trajectories (see attachment). The ballistic trajectory is what crasher stage and lander are on prior to final descent. It is also roughly the trajectory the crasher stage will take following staging, whilst the lander does more braking and targets the base. In this case, the distance between crasher stage impact and base is a function of trajectory and timing of staging.

There are a number of other possibilities. You could make the stage do a modest divert burn after staging to get the impact area further away from the base. Without the lander to push, you'd need only a short burn to get a decent bit of delta-v. The logical extension of this is the 'uncrasher' trajectory (by our own Jonathan Goff), where the crasher stage sans lander has enough delta-V left to take itself back into orbit for refueling.

Offline TrevorMonty

Re: Fly Me to the Moon on an SLS Block II
« Reply #64 on: 09/05/2017 06:03 PM »
The uncrasher stage can have very low dry mass as there is no need for redundant systems. If there is propulsion failure on descent, lander separates and returns EML1. This allows a single BE3 to be used while Xeus needs redundant engines.

Offline Patchouli

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Re: Fly Me to the Moon on an SLS Block II
« Reply #65 on: 09/13/2017 01:44 AM »
[quote author=Steven Pietrobon link=topic=38069.msg1719356#msg1719356

Interesting! I think a better solution would have been to use a standard S-IVB (modified to reduced the boiloff rate) do 75% of the landing burn followed by a custom built habitat using storable propellants for the remaining 25% of the landing. This way the payload fairing can be ejected after entering LEO and then doing TLI. Going straight to TLI is difficult since any small mistiming will cause very large miss distances to the Moon. This allows a larger habitat to be landed that is easily reached by the astronauts, instead having to climb the 18 m high S-IVB!
[/quote]

The S-IVB was part of the payload as it would be converted into a hab.

The uncrasher stage can have very low dry mass as there is no need for redundant systems. If there is propulsion failure on descent, lander separates and returns EML1. This allows a single BE3 to be used while Xeus needs redundant engines.

I wonder could a NTR engine be used on one as the high ISP would allow for some interesting mission profiles.
Though even something like a J-2X or a couple of RL-10s probably would have enough performance for it to make it back to orbit and maybe even to L1.
« Last Edit: 09/13/2017 01:55 AM by Patchouli »

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