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Almost all challenges are caused by tight mass budgets--the maximum mass that we can get to the lunar surface. Symmetrically, almost all problems can be solved

Almost all challenges are caused by tight mass budgets--the maximum mass that we can get to the lunar surface. Symmetrically, almost all problems can be solved by increasing the mass budget: more fuel to loiter longer, redundant systems, etc. The advantage of SpaceX's Starship--and the reason NASA chose it for the first HLS--is that it has an insane mass budget. It's literally designed to land 100 people on the surface of Mars (TBD whether it will ever meet that goal, but that's the design point). Starship is so hilariously large that there's enough mass budget to solve almost any problem.

LarsDu88 3y ago
What if it tips over?
Workaccount2 3y ago
Didn't the Saturn 5 have a similar mass budget as the Starship? I am guessing there is some major caveat to it.
- bryanlarsen 3y ago
  They might be comparable without refueling, but Starship utilizes refueling to massively increase it's deep space mass budget.
  - pavon 3y ago
    This is the huge difference. Apollo missions used two launches of the Saturn V - one for the crew capsule and one for the lunar lander, which rendezvoused in orbit. Artemis is planning on using one SLS launch for the crew capsule, and an estimated 8-16 Starship launches for the lunar lander and refueling.
    - saratogacx 3y ago
      That isn't how the Apollo missions worked. They put the command module, service module and the LEM on a single Saturn 5[1]. Once in space, the command+service module would need to turn around and dock with the LEM before heading off to the moon. https://www.nasa.gov/history/diagrams/apollo.html https://www.nasa.gov/history/diagrams/apollo.html 1: https://www.nasa.gov/wp-content/uploads/static/history/diagrams/ad003.gif https://www.nasa.gov/wp-content/uploads/static/history/diagr...
    - DarmokJalad1701 3y ago
      > Apollo missions used two launches of the Saturn V - one for the crew capsule and one for the lunar lander, which rendezvoused in orbit. That was a concept called "Earth Orbit Rendezvous" which was discarded early on during the Apollo program in favor of "Lunar Orbit Rendezvous" where the Command and Service Module (CSM) and the Lunar Module (LM) was launched on a single Saturn V. You can see this in the movie Apollo 13.
    - tekla 3y ago
      > Apollo missions used two launches of the Saturn V - one for the crew capsule and one for the lunar lander, What? Have you watched any Apollo mission media ever? Watch Apollo 13 the movie at least and get the most basics of facts straight.
  - nativeit 3y ago
    Starship might utilize refueling. So far it hasn’t done anything of the sort.
    - avhon1 3y ago
      Starship must utilize refueling. It can't get to, land on, and return from the moon without it.
- GMoromisato 3y ago
  No, it did not. Starship gets refueled in orbit (by a fleet of Saturn V-class rockets). A Saturn V could put about 8 metric tons on the lunar surface. With refueling, Starship can land 100 metric tons on the moon.
  - sixothree 3y ago
    How many fuel launches are required for that?
    - agar 3y ago
      That's a matter of some debate. Somewhere between 6 and 12, I believe, is the range. SpaceX plans to stretch the second stage to increase fuel carrying capacity for tanker flights, so the actual number is TBD until both the revised Starship and its engines (Raptor 3) are built and tested.
      - datadrivenangel 3y ago
        It might take up to 20... NASA doesn't actually know / admit that it knows.
    - imtringued 3y ago
      It depends on how many Starships you can launch simultaneously, because the time the fuel depot spends in orbit determines how much fuel is lost to boil-off. If you have a serial launch architecture, assuming reusability, refuling and relaunching, then the upper bound is around 20 launches. Even with expendable Starships, this is still cheaper than SLS, but not by much... This is why reusability is critical to the mission.
      - sixothree 3y ago
        I guess that means boil off would affect missions to the moon and mars as well.
- giantrobot 3y ago
  The Saturn V could get a lot of mass to LEO but most of that mass was fuel to get from LEO to the surface of the Moon. A design caveat of SpaceX Starship (a design feature that's yet to be demonstrated/proven) is refueling in LEO. So the Starship gets a bunch of payload mass to LEO, refuels, and then heads to the Moon. For Mars it would need to refuel on Mars to get back to Earth. It's the refueling that potentially gets a huge usable payload to the Moon. A second Starship whose only payload is fuel would launch with the first and they'd rendezvous and transfer fuel. Ostensibly if something went wrong with the refuel rendezvous the payload (or personnel) carrier would still be able to abort back to Earth.
kunai 3y ago
That's incorrect -- the reason NASA chose Starship is because it was the most capable lander for the lowest possible projected upfront cost. Government contracts always attempt to maximize economic utility while meeting objectives -- any other advantages are ancillary to this. > Symmetrically, almost all problems can be solved by increasing the mass budget: more fuel to loiter longer, redundant systems, etc...Starship is so hilariously large that there's enough mass budget to solve almost any problem. Also incorrect. Mass budget does not change fundamental Newtonian physics, nor does it alter the issue of instability caused by a high center of mass. The engineers at SpaceX are very smart and I'm sure they're hard at work trying to engineer out this solution, but it's a bit like saying that you can prevent a car from rolling over if you make it heavy and powerful enough. Sure, but that causes problems and challenges of its own. It would have been easier to engineer the car to have a lower center of mass, i.e. it would be easier to land on the moon with a lander that had its mass spread out over a larger surface area and didn't have an angular moment of inertia significant enough to where topple was a concern -- like the Dynetics or BO proposals.
- mr_toad 3y ago
  > Also incorrect. Mass budget does not change fundamental Newtonian physics, nor does it alter the issue of instability caused by a high center of mass. The size of the ship solves some problems. Illustrations depict landing gear taller than a person, which means small rocks and holes are less of an issue.
  - kevin_thibedeau 3y ago
    Landing on a sloped surface will be an issue. Apollo 15 was close to disaster on its tilted landing and Apollo 12 had a bobble when setting down. Starship is unlikely to survive the same.
    - wongarsu 3y ago
      Starship will have spare fuel and relightable engines. It could just take off when it starts tipping and go for a second landing attempt on a more even surface. The low gravity is a real pain for landing, but it makes it really easy to abort a landing too, even after touch down.
jojobas 3y ago
This high mass budget comes with some insane quantity of refueling launches (nobody can tell precisely how many, but more than 5 per mission).
imtringued 3y ago
You mean it wasn't because Kathy Lueders had a heavy bias towards SpaceX (she now works at SpaceX) to the point where she forgot to select a second commercial partner for the Artemis missions? When Blue Origin was suing NASA, they were primarily pointing out Kathy Lueders' gross incompetence during the procurement process. It's kind of weird that someone would select a launch architecture that is meant to go to Mars and whose company CEO thinks the moon is a waste of time for a moon mission. Yeah sure, SpaceX is going to Mars, but are they going to the moon? Considering the massive delays at SpaceX, their Starship will turn into another SLS type boondoggle. At the current rate of development, it is not obvious that the schedule of Artemis 3 is going to be meaningfully ahead of Artemis 5. If it takes Blue Origin 2-3 years to launch their New Glenn rocket, then all they have to do is build the lander and they are pretty much set, because it only takes 3 New Glenn rockets, which could launch simultaneously to minimize time in orbit and thereby reduce boil off. Reusability is a nice to have cost optimization for Blue Origin. When it comes to the Artemis 3 architecture, it is impossible to stay under $1 billion per launch without some form of reusability.
- dotnet00 3y ago
  They hadn't selected a second commercial option at the time because they were barely given enough funding for one lander, and all the other proposals wanted a ton more money. They only chose the second option when Congress finally allocated more funding for the program. Congress effectively made Starship the most appealing choice and then complained when their MIC masters didn't get chosen for their 60s era designs. Also, it's ironic you're saying that BO could do it faster, their lander is basically just a Hydrogen fueled Starship.
- deleted 3y ago
  [deleted]

LarsDu88 3y ago

What if it tips over?

Workaccount2 3y ago

Didn't the Saturn 5 have a similar mass budget as the Starship? I am guessing there is some major caveat to it.

bryanlarsen 3y ago
They might be comparable without refueling, but Starship utilizes refueling to massively increase it's deep space mass budget.
- pavon 3y ago
  This is the huge difference. Apollo missions used two launches of the Saturn V - one for the crew capsule and one for the lunar lander, which rendezvoused in orbit. Artemis is planning on using one SLS launch for the crew capsule, and an estimated 8-16 Starship launches for the lunar lander and refueling.
  - saratogacx 3y ago
    That isn't how the Apollo missions worked. They put the command module, service module and the LEM on a single Saturn 5[1]. Once in space, the command+service module would need to turn around and dock with the LEM before heading off to the moon. https://www.nasa.gov/history/diagrams/apollo.html https://www.nasa.gov/history/diagrams/apollo.html 1: https://www.nasa.gov/wp-content/uploads/static/history/diagrams/ad003.gif https://www.nasa.gov/wp-content/uploads/static/history/diagr...
  - DarmokJalad1701 3y ago
    > Apollo missions used two launches of the Saturn V - one for the crew capsule and one for the lunar lander, which rendezvoused in orbit. That was a concept called "Earth Orbit Rendezvous" which was discarded early on during the Apollo program in favor of "Lunar Orbit Rendezvous" where the Command and Service Module (CSM) and the Lunar Module (LM) was launched on a single Saturn V. You can see this in the movie Apollo 13.
  - tekla 3y ago
    > Apollo missions used two launches of the Saturn V - one for the crew capsule and one for the lunar lander, What? Have you watched any Apollo mission media ever? Watch Apollo 13 the movie at least and get the most basics of facts straight.
- nativeit 3y ago
  Starship might utilize refueling. So far it hasn’t done anything of the sort.
  - avhon1 3y ago
    Starship must utilize refueling. It can't get to, land on, and return from the moon without it.
GMoromisato 3y ago
No, it did not. Starship gets refueled in orbit (by a fleet of Saturn V-class rockets). A Saturn V could put about 8 metric tons on the lunar surface. With refueling, Starship can land 100 metric tons on the moon.
- sixothree 3y ago
  How many fuel launches are required for that?
  - agar 3y ago
    That's a matter of some debate. Somewhere between 6 and 12, I believe, is the range. SpaceX plans to stretch the second stage to increase fuel carrying capacity for tanker flights, so the actual number is TBD until both the revised Starship and its engines (Raptor 3) are built and tested.
    - datadrivenangel 3y ago
      It might take up to 20... NASA doesn't actually know / admit that it knows.
  - imtringued 3y ago
    It depends on how many Starships you can launch simultaneously, because the time the fuel depot spends in orbit determines how much fuel is lost to boil-off. If you have a serial launch architecture, assuming reusability, refuling and relaunching, then the upper bound is around 20 launches. Even with expendable Starships, this is still cheaper than SLS, but not by much... This is why reusability is critical to the mission.
    - sixothree 3y ago
      I guess that means boil off would affect missions to the moon and mars as well.
giantrobot 3y ago
The Saturn V could get a lot of mass to LEO but most of that mass was fuel to get from LEO to the surface of the Moon. A design caveat of SpaceX Starship (a design feature that's yet to be demonstrated/proven) is refueling in LEO. So the Starship gets a bunch of payload mass to LEO, refuels, and then heads to the Moon. For Mars it would need to refuel on Mars to get back to Earth. It's the refueling that potentially gets a huge usable payload to the Moon. A second Starship whose only payload is fuel would launch with the first and they'd rendezvous and transfer fuel. Ostensibly if something went wrong with the refuel rendezvous the payload (or personnel) carrier would still be able to abort back to Earth.

kunai 3y ago

That's incorrect -- the reason NASA chose Starship is because it was the most capable lander for the lowest possible projected upfront cost. Government contracts always attempt to maximize economic utility while meeting objectives -- any other advantages are ancillary to this. > Symmetrically, almost all problems can be solved by increasing the mass budget: more fuel to loiter longer, redundant systems, etc...Starship is so hilariously large that there's enough mass budget to solve almost any problem. Also incorrect. Mass budget does not change fundamental Newtonian physics, nor does it alter the issue of instability caused by a high center of mass. The engineers at SpaceX are very smart and I'm sure they're hard at work trying to engineer out this solution, but it's a bit like saying that you can prevent a car from rolling over if you make it heavy and powerful enough. Sure, but that causes problems and challenges of its own. It would have been easier to engineer the car to have a lower center of mass, i.e. it would be easier to land on the moon with a lander that had its mass spread out over a larger surface area and didn't have an angular moment of inertia significant enough to where topple was a concern -- like the Dynetics or BO proposals.

mr_toad 3y ago
> Also incorrect. Mass budget does not change fundamental Newtonian physics, nor does it alter the issue of instability caused by a high center of mass. The size of the ship solves some problems. Illustrations depict landing gear taller than a person, which means small rocks and holes are less of an issue.
- kevin_thibedeau 3y ago
  Landing on a sloped surface will be an issue. Apollo 15 was close to disaster on its tilted landing and Apollo 12 had a bobble when setting down. Starship is unlikely to survive the same.
  - wongarsu 3y ago
    Starship will have spare fuel and relightable engines. It could just take off when it starts tipping and go for a second landing attempt on a more even surface. The low gravity is a real pain for landing, but it makes it really easy to abort a landing too, even after touch down.

jojobas 3y ago

This high mass budget comes with some insane quantity of refueling launches (nobody can tell precisely how many, but more than 5 per mission).

imtringued 3y ago

You mean it wasn't because Kathy Lueders had a heavy bias towards SpaceX (she now works at SpaceX) to the point where she forgot to select a second commercial partner for the Artemis missions? When Blue Origin was suing NASA, they were primarily pointing out Kathy Lueders' gross incompetence during the procurement process. It's kind of weird that someone would select a launch architecture that is meant to go to Mars and whose company CEO thinks the moon is a waste of time for a moon mission. Yeah sure, SpaceX is going to Mars, but are they going to the moon? Considering the massive delays at SpaceX, their Starship will turn into another SLS type boondoggle. At the current rate of development, it is not obvious that the schedule of Artemis 3 is going to be meaningfully ahead of Artemis 5. If it takes Blue Origin 2-3 years to launch their New Glenn rocket, then all they have to do is build the lander and they are pretty much set, because it only takes 3 New Glenn rockets, which could launch simultaneously to minimize time in orbit and thereby reduce boil off. Reusability is a nice to have cost optimization for Blue Origin. When it comes to the Artemis 3 architecture, it is impossible to stay under $1 billion per launch without some form of reusability.

dotnet00 3y ago
They hadn't selected a second commercial option at the time because they were barely given enough funding for one lander, and all the other proposals wanted a ton more money. They only chose the second option when Congress finally allocated more funding for the program. Congress effectively made Starship the most appealing choice and then complained when their MIC masters didn't get chosen for their 60s era designs. Also, it's ironic you're saying that BO could do it faster, their lander is basically just a Hydrogen fueled Starship.
deleted 3y ago
[deleted]