Jeff Findley wrote:

In article . com,
says...

The argument was that the newer components would be lighter than Apollo
era modules. I pointed out that Orion was much heavier than the Apollo
CM (which is comparing oranges to oranges). I have no idea of the
service module weight since I don't even know if what is being built by
ESA right now would be usable for a replay of Apollo (Orion + Lander)
and a new SM might be needed.


The Orion "command module" is physically bigger than the Apollo Command
Module. But if you did a simple web search, you'd know that:

https://www.quora.com/Why-does-Orion...se-of-lighter-
materials-and-other-advances-to-reduce-weight-still-weigh-3-tons-more-
than-Apollo

Take a look at the picture on the above web page.


I've told him that at least twice. I don't think facts penetrate
Mayfly very well once he gets a bone in his teeth.


If the stack (Lander, SM, Orion) is heavier than Apollo era stack,
wouldn't the Moon orbit insertion/exit end up requiring more thrust?
Unless engine efficiency more than doubled since Apollo, that would
require more fuel than Apollo, woudln't it?


No, the engine used on the Orion service module is not twice as
efficient as the Apollo service module engine. From Reddit (check this
fact yourself if you doubt it):

Orion will have 1340m/s of delta-v, compared to the Apollo one
which had 2800m/s.

So, Orion will have less than half the delta-V of Apollo CSM. So it's
actually half as capable when it comes to propulsion!


I don't think that figure is correct. Wikipedia credits Orion with
1800 m/s delta-v vice the 1340 m/s that you give, which makes it about
64% of Apollo.


The extended mission LM
weighed a bit over 16 tonnes. The Altair lander would have weighed
around 46 tonnes.

I had been told that Saturn V had been the most powerfull rocket ever.
Yet, now I am told that Ares could have carriued a lander that was 30
tonnes heavier when during apollo era, they were concerned with every
gram of mass on the lander.

I'm pretty sure that Altair would not have been launched with the CEV.
That's one huge difference between Apollo/Saturn and Ares/CEV/Altair.
Altair would go up on Ares V while the CEV was to go up on Ares I,
remember? Multiple launches means more capability than a single launch.


But it also involves a rendezvous of the two vehicles in LEO before
the upper stage of Ares V puts the whole works into a TLI orbit.


I honestly don't know exactly the TLI capabilities of the various SLS
"designs" (they've not flown one yet). But, multiple launches solves
the weight issue for any "beyond LEO" plan. Even Deep Space Gateway
will take multiple launches to "build".


The numbers are out there, but plans change. DSG consumes EM-2
through EM-10. Two of those are logistics and resupply missions and
one of them is a long duration stay test mission, so the plan is six
launches to build it.


But the current thing is a diversion from going to Mars since NASA is
developping stuff that won't be of use to Mars, and hasn't yet
developped a plan to get to Mars, and hence can't begin to implement
that plan.

I'm still not convinced NASA is going back to the moon. SLS hasn't been
canceled yet to free up the funding to design and build a lander.


What good is a lander if they cancel the rocket that is supposed to
get them there?


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw