totm dec 2023 Artemis Discussion Thread

[sevenperforce]

1 hour ago, jinnantonix said:

I am not so concerned with re-usability, I am assuming for the 2024 mission, the lander will be expendable.  I am more concerned about how to deliver the craft to NRHO with currently available launch vehicles (or expected to be available in 2024).  I am assuming here that there is no fuel transfer, that NASA really does not have the ability in the short-term to develop that capability for the HLS.  I am assuming simplicity -  the lander inner tanks are fixed, and only the outer tanks are dropped.

Below is my simulation under development in RSS.  Mass of total craft at launch is just under 32 tons , with the mass of the craft divided near equally between the lunar descent/ascent craft (15t) , and the two drop tanks with fuel for the transit from TLI to NRHO to LLO ( 17t). 

The lunar ascent module, less engine, had a dry mass of 2.1 tonnes and a wet mass of 4.6 tonnes. The descent module's dry mass, less engine, was 1.9 tonnes and its wet mass was 10.2 tonnes. If you assume conservatively that tank and structure mass ratio on the descent and ascent stages was similar (4.37:1), then that says the lunar ascent module's tanks were 572 kg. So the actual core of the ascent module was just 1.5 tonnes. Even with mass growth, 15 tonnes for the descent/ascent stage seems high.

How much descent dV is your module producing and what's the dry mass?

1 hour ago, jinnantonix said:

Launching the fully fueled two stage Dynetics lander craft to LEO is beyond the single launch capability of the Vulcan Centaur Heavy (max payload to LEO = 27.2 tons).  Only SLS Cargo and Falcon Heavy can lift the assembled craft to LEO.

Options:

1. Multiple Vulcan launches ( two or three) with assembly adding drop tanks in LEO and docking with a Centaur second stage for TLI -  high risk, cost and complexity. 
2. Single launch of the fully integrated craft on a SpaceX Falcon Heavy to LEO, dock with separate launch of Falcon 9 or Vulcan Centaur second stage for TLI.   Simpler LEO docking?  
3. SLS Block 1B Cargo, single launch to NRHO.  EUS?  Too expensive?  Available in 2024?

Option 1, but it's really not that bad. Using your numbers, send the 15-tonne core to LEO on pretty much anything. Send one of your 8.5-tonne drop tanks to LEO on pretty much anything, and do a docking to extract. Then, send Vulcan Centaur Heavy up with the second drop tank, dock, and perform TLI.

1 hour ago, jinnantonix said:

Looks very good!!

[kerbiloid]

https://www.reuters.com/article/us-space-exploration-moon-mining-exclusi/exclusive-trump-administration-drafting-artemis-accords-pact-for-moon-mining-sources-idUSKBN22H2SB

So,
1. BDArmory should be in stock.
2. Those KSP players, who start building a Mun/Duna/whatever base from fortification and fire positions (like me), we just have a realistic picture of extraterrestrial colonisation.

P.S.
And stupid me had a doubt if the anti-tank self-aiming submunition with dynamically formed impactor should have a vacuum version with a retrorocket instead of drogue chute, when the instincts were shouting "yez!"...

Edited May 6, 2020 by kerbiloid

[jinnantonix]

1 hour ago, sevenperforce said:

The lunar ascent module, less engine, had a dry mass of 2.1 tonnes and a wet mass of 4.6 tonnes. The descent module's dry mass, less engine, was 1.9 tonnes and its wet mass was 10.2 tonnes. If you assume conservatively that tank and structure mass ratio on the descent and ascent stages was similar (4.37:1), then that says the lunar ascent module's tanks were 572 kg. So the actual core of the ascent module was just 1.5 tonnes. Even with mass growth, 15 tonnes for the descent/ascent stage seems high.

Here is a breakdown of the craft components by mass:

Component	Unit	Qty	Total
Lander Can +	1.21	1	1.21
Payload (human and science)	1.00	1	1.00
Frame *	0.81	2	1.62
Monopropellant	0.21	1	0.21
Solar panels	0.30	2	0.60
Engines	0.14	8	1.10
Inner fuel tank	0.50	2	1.00
Subtotal			6.74
Inner tank fuel only	4.00	2	8.00
Outer tank + fuel	8.58	2	17.16
Total			31.90
+ includes payload bay, lander legs, ladder, comms equipment
* Includes can mount, tank frame, decouplers and thrusters

I am happy to be guided on which assumptions I have wrong, but I actually think I may be underestimating the base craft mass.

 

Quote

How much descent dV is your module producing and what's the dry mass?

Stage 1 has 2495 m/s, and this completes TLI to NRHO to LLO to near lunar surface
Stage 2 has 3025 m/s, and this completes landing with hover, surface to LLO to NRHO.
 

Quote

Option 1, but it's really not that bad. Using your numbers, send the 15-tonne core to LEO on pretty much anything. Send one of your 8.5-tonne drop tanks to LEO on pretty much anything, and do a docking to extract. Then, send Vulcan Centaur Heavy up with the second drop tank, dock, and perform TLI.

Seems complicated to me, at least compared to option 2.

Option 2 also has the advantage that the Centaur TLI booster can dock with the existing docking port on the top of the lander can, which saves weight  and complexity in the lander design.

 

Quote

Looks very good!!

Thanks

Edited May 6, 2020 by jinnantonix

[tater]

PPE and NG hab module to be integrated and launched at the same time (possibly FH):

 

[EchoLima]

To scale, assuming HALO has the same diameter as Cygnus.

 

[RealKerbal3x]

3 minutes ago, EchoLima said:

To scale, assuming HALO has the same diameter as Cygnus.

 

Do we know how massive it is? Will FH have to expend all three first-stage boosters to get it to Gateway?

Edited May 6, 2020 by RealKerbal3x

[EchoLima]

46 minutes ago, RealKerbal3x said:

Do we know how massive it is? Will FH have to expend all three first-stage boosters to get it to Gateway?

This NASA paper (p3) lists the "Small stack" gateway configuration as 7 tonnes. On the other hand, the PPE is supposedly 5000kg and Cygnus 6,600 kg (3,400kg dry mass), = 8.4 to 11.6 tonnes.

Assuming a C3 of -2.2 to -1.5 (p119) is needed for a direct transfer, then based on this calculator:

	c3 = -1.7	c3 = -1.5
Reusable	7010kg	6975kg
Expendable	15515kg	15460kg

 

(It won't let me go lower than -1.7.)

500 m/s is required for orbital insertion.

This is riddled with assumptions, but a reusable FH can just barely lift the first configuration (7t) but not the second (8.4t+).

I got a little carried away doing this...

 

Edited May 6, 2020 by EchoLima

[RealKerbal3x]

3 minutes ago, EchoLima said:

This NASA paper (p3) lists the "Small stack" gateway configuration as 7 tonnes. On the other hand, the PPE is supposedly 5000kg and Cygnus 6,600 kg (3,400kg dry mass), = 8.4 to 11.6 tonnes.

Assuming a C3 of -2.2 to -1.5 (p119) is needed for a direct transfer, then based on this calculator:

 

	c3 = -1.7	c3 = -1.5
Reusable	7010kg	6975kg
Expendable	15515kg	15460kg

 

(It won't let me go lower than -1.7.)

This is riddled with assumptions, but a reusable FH can just barely lift the first configuration (7t) but not the second.

I got a little carried away doing this...

 

If a fully reusable FH can just about do it, then a partially reusable configuration with the centre core expended and the boosters landing on droneships would give it a bit more margin.

[tater]

 

[jinnantonix]

11 hours ago, tater said:

PPE and NG hab module to be integrated and launched at the same time (possibly FH):

""We assured ourselves that it could be done with the Falcon Heavy," Loverro said. "We haven't selected the launch vehicle yet, but we had to assure ourselves that there would be at least one vehicle for it. "

There is another launch vehicle that can do this?  I don't think so. NASA is pretending that SpaceX doesn't have a monopoly on the bid?

[tater]

9 minutes ago, jinnantonix said:

There is another launch vehicle that can do this?  I don't think so. NASA is pretending that SpaceX doesn't have a monopoly on the bid?

Could NG do it if it was operational?

[jinnantonix]

Just now, tater said:

Could NG do it if it was operational?

Probably, but it isn't available for a 2023 launch.

10 hours ago, EchoLima said:

To scale, assuming HALO has the same diameter as Cygnus.

 

I don't believe it is practical for the Falcon second stage nor PPE ion drive to complete NRHO insertion.  I think there will need to be a small transit vehicle included (eg Cygnus SM?).  This would certainly push the payload beyond the limits of FH recoverable.

I simulated this in the first part of this video: 

 

[jinnantonix]

15 hours ago, EchoLima said:

This NASA paper (p3) lists the "Small stack" gateway configuration as 7 tonnes. On the other hand, the PPE is supposedly 5000kg and Cygnus 6,600 kg (3,400kg dry mass), = 8.4 to 11.6 tonnes.

Assuming a C3 of -2.2 to -1.5 (p119) is needed for a direct transfer, then based on this calculator:

	c3 = -1.7	c3 = -1.5
Reusable	7010kg	6975kg
Expendable	15515kg	15460kg

 

(It won't let me go lower than -1.7.)

500 m/s is required for orbital insertion.

This is riddled with assumptions, but a reusable FH can just barely lift the first configuration (7t) but not the second (8.4t+).

I got a little carried away doing this...

 

The LOPG wiki states that the PPE has an intended mass of 8 - 9 tons, and the Cygnus wiki suggests a launch mass of 6.6t (including payload and fueled Cygnus SM).  The SM will require addition fuel and a suitable main engine (something like a SuperDraco-L).  This is well within the capability of the Falcon Heavy expendable.  NASA would need to do some trimming to go FH re-usable.

The craft should fit just inside the F9 fairing. The below 16 ton mock-up has a delta-V of 450 m/s which should be sufficient for NRHO insertion from TLI.


 

Edited May 7, 2020 by jinnantonix

[Flavio hc16]

58 minutes ago, jinnantonix said:

The LOPG wiki states that the PPE has an intended mass of 8 - 9 tons, and the Cygnus wiki suggests a launch mass of 6.6t (including payload and fueled Cygnus SM).  The SM will require addition fuel and a suitable main engine (something like a SuperDraco-L).  This is well within the capability of the Falcon Heavy expendable.  NASA would need to do some trimming to go FH re-usable.

The craft should fit just inside the F9 fairing. The below 16 ton mock-up has a delta-V of 450 m/s which should be sufficient for NRHO insertion from TLI.


 

i think that they will try their best to do a "boosters on droneships, 1st stage expended" kind of launch, like the next Air force launches on falcon heavy, as from Musk statement you have only  a 10% payload penalty from this configuration vs fully expendable ( so around 65 tons to LEO and 12.5 tons to NRHO )

p.s: you have also to take into consideration the new enlarged fairing for the Falcons

Edited May 7, 2020 by Flavio hc16

[jinnantonix]

Assuming ULA completes ACES by 2024, the Dynetics Lander can be launched fully integrated to NRHO by two options:

1.  SpaceX Falcon Heavy re-usable to TLI, thence lander burns to NRHO (requires additional 5 tons of fuel in the lander outer tanks)
2.  ULA: Two Vulcan Heavy (6 SRB) launches:

• (a) Launch  to LEO
• (b) Launch a naked ACES second stage, dock with craft in LEO, thence TLI and NRHO insertion.

Question for the bean counters.  Which option is cheaper?  SpaceX or ULA?

 

ULA ACES docked with Dynetics lander, on TLI burn.

[RCgothic]

Is F9US direct NRHO insertion completely out of the question? Would 3 days' endurance not be an easier stage upgrade than an EOR?

[jinnantonix]

40 minutes ago, RCgothic said:

Is F9US direct NRHO insertion completely out of the question? Would 3 days' endurance not be an easier stage upgrade than an EOR?

Not out of the question entirely, but hydrogen boil off is going to be a big problem.  But note that the SpaceX option does not involve an EOR,.  With that option the lander simply carries an additional 5 tons of fuel and completes burn from TLI to NRHO.  There is no orbital rendezvous required until docking with the Orion in NRHO.

With the ULA Vulcan / ACES option there are two launches and an EOR.  It is more complex and risky.  But is it cheaper?

Edited May 7, 2020 by jinnantonix

[RCgothic]

23 minutes ago, jinnantonix said:

Not out of the question entirely, but hydrogen boil off is going to be a big problem.  But note that the SpaceX option does not involve an EOR,.  With that option the lander simply carries an additional 5 tons of fuel and completes burn from TLI to NRHO.  There is no orbital rendezvous required until docking with the Orion in NRHO.

With the ULA Vulcan / ACES option there are two launches and an EOR.  It is more complex and risky.  But is it cheaper?

I mean, the lander doesn't need to be designed to carry extra fuel if FH US could complete the NRHO insertion after 3 days with an endurance upgrade. It's Kerolox, so no boil off?

[jinnantonix]

4 minutes ago, RCgothic said:

I mean, the lander doesn't need to be designed to carry extra fuel if FH US could complete the NRHO insertion after 3 days with an endurance upgrade. It's Kerolox, so no boil off?

Ah yes, of course, its LOX + RP-1.  So that is an option.  

[sevenperforce]

4 hours ago, jinnantonix said:

Question for the bean counters.  Which option is cheaper?  SpaceX or ULA?

Always SpaceX.

According to Bruno at the original Vulcan announcement, baseline Vulcan is half the $164 tag of the baseline Atlas V. So if you are going to be using two of them, the price will vastly exceed one FHe.

4 hours ago, RCgothic said:

Is F9US direct NRHO insertion completely out of the question? Would 3 days' endurance not be an easier stage upgrade than an EOR?

FH expendable can send 16.8 tonnes to Mars, which is at least 3.93 km/s beyond LEO. TLI is 3.2 km/s and NRHO injection is 430 m/s, so a total of 3.63 km/s. Assuming a dry FHUS mass of 4.1 tonnes and backing out the 3.93 km/s gives 45.26 tonnes of props in LEO. Getting 3.63 km/s at 348 s isp requires 65.5% of your m₀ to be propellant, so a little math gives an estimated payload to NRHO of 19.74 tonnes. Probably a little lower given a heavier FHUS, boiloff, and more expensive LEO insertion. If it flies with only an expended core then probably closer to 17 tonnes.

Edited May 7, 2020 by sevenperforce
typo brain

[tater]

Not sure where he gets his numbers, plus paywall...

[sevenperforce]

2 hours ago, tater said:

Not sure where he gets his numbers, plus paywall...

FH with side-core reuse can deliver 15 tonnes direct to NRHO in a week.

Fully reusable FH can't even send 8 tonnes to TLI.

But he is correct that there are very low-dV trajectories to get to NRHO if you have plenty of time. 

[jinnantonix]

11 hours ago, sevenperforce said:

FH with side-core reuse can deliver 15 tonnes direct to NRHO in a week.

Fully reusable FH can't even send 8 tonnes to TLI.

But he is correct that there are very low-dV trajectories to get to NRHO if you have plenty of time. 

Gateway (PPE + HALO) == ~15 tons.  LV = FH side core re-use.  

Dynetics Lander = ~ 27 tons.  2 launches needed (a) FH (side-core re-usable?) to LEO (b) either naked FH re-usable or naked Vulcan with ERO to go to NRHO.

The question is the degree of re-usability of the Falcon Heavy in the above scenarios.

Edited May 8, 2020 by jinnantonix

[sevenperforce]

9 hours ago, jinnantonix said:

Gateway (PPE + HALO) == ~15 tons.  LV = FH side core re-use.  

Dynetics Lander = ~ 27 tons.  2 launches needed (a) FH (side-core re-usable?) to LEO (b) either naked FH re-usable or naked Vulcan with ERO to go to NRHO.

The question is the degree of re-usability of the Falcon Heavy in the above scenarios.

According to Musk, recovering the side boosters on droneships is only a 10% payload penalty from full-expendable. Even if he is exaggerating and the penalty is more like 15%, that suggests more than 54 tonnes to LEO with side-core reuse. So the Dynetics lander is easy AF if you expend the center core.

With triple-core recovery FH can send 8 tonnes to GTO, which is 2.27 km/s. With a 4.1-tonne FHUS, that means it reaches LEO with prop residuals of at least 11.4 tonnes and a total mass of 23.5 tonnes. So it can probably send at least 19.4 tonnes to LEO with a burn to MRS. That checks out generally because an expendable F9 sends just slightly more to orbit than a triple-core-reuse FH, and F9's expendable LEO payload is 22.8 tonnes. NOt quite enough for the Dynetics lander.

What about the TLI burn, if FH launches naked with triple-core reuse? We know that it reaches LEO with at least 11.4 tonnes of propellant carrying an 8-tonne payload, so it will have around 20 tonnes of propellant (probably a little more) if it launches naked. If you mate a 27-tonne payload to it, that's just shy of 1.7 km/s, which is not enough for GTO, let alone TLI.

But there's another solution. Use FH with triple-core-recovery to send only the lander and inboard tanks to LEO, then use FH with an expended center core to send the drop tanks to LEO. The lander can do transposition, docking & extraction with the first drop tank, then rotate and dock with the second drop tank, which can remain fixed to the FHUS for TLI, which it can do easily. 

 

 

[RCgothic]

The VAB is getting some new paint: