Soyuz Lunar Mission

[N_Molson]

A quick calculation I just made about the Dv given by a TMA/DM2 stack :

Dv = Velocity Exhaust x ln (m0/m1)

(m0 = mass before burn, m1 = mass after burn).

DM2 gross mass = 19500 kg
DM2 RCS propellant mass = 200 kg
DM2 main (LOX/Kero) propellant mass = 17000 kg
DM2 empty mass = 2300 kg

I'm assuming the SoyuzTMA has burn some of it's fuel to dock the blockDM2 and has a mass of 7000kg. I add 500kg to the DM2 for the "docking module". The Soyuz remaining fuel is not use. I add 200kg for the DM2 RCS (it gives us a little margin).

Dv = 3453.12 * ln (2300 + 200 + 500 + 7000 + 17000/2300 + 200 + 500 + 7000)

Dv = 3453.12 * ln (26500/10000)

Dv ~= 3365.27 m/s

From that source, a lunar pass requires a Dv of 4100 m/s from LEO... :hmm:

 

[Urwumpe]

Yes, without modifications, it will be tough...

 

[N_Molson]

Keeping the same numbers, we need 6500 extra kilograms of propellant to reach the required Dv :

Dv = 3453.12 * ln (33000/10000)
Dv ~= 4122.76 m/s

Which means we need a blockDM2 with an extended tank holding 23,500 kg of propellant.

Now my question would be : is that technically possible ?

 

[DanM]

A quick calculation I just made about the Dv given by a TMA/DM2 stack :

Dv = Velocity Exhaust x ln (m0/m1)

(m0 = mass before burn, m1 = mass after burn).

DM2 gross mass = 19500 kg
DM2 RCS propellant mass = 200 kg
DM2 main (LOX/Kero) propellant mass = 17000 kg
DM2 empty mass = 2300 kg

I'm assuming the SoyuzTMA has burn some of it's fuel to dock the blockDM2 and has a mass of 7000kg. I add 500kg to the DM2 for the "docking module". The Soyuz remaining fuel is not use. I add 200kg for the DM2 RCS (it gives us a little margin).

Dv = 3453.12 * ln (2300 + 200 + 500 + 7000 + 17000/2300 + 200 + 500 + 7000)

Dv = 3453.12 * ln (26500/10000)

Dv ~= 3365.27 m/s

From that source, a lunar pass requires a Dv of 4100 m/s from LEO... :hmm:

There are other existing boosters, such as the IUS, Delta-K, and Centaur. I'm not sure which of these provides enough Dv for a soyuz, but the Centaur could probably send one all the way to Jupiter Orbit.

 

[Thorton]

Could you make calculations for Soyuz/Fregat/DM2 stack?
Fregat: m0=1050 kg, m_fuel = 5435 kg

 

[N_Molson]

In which order do you want to fire them ?

The DM2 then the Fregat ?

 

[Thorton]

Yep, Fregat should be launched atop of DM

 

[DanM]

I just ran a calculation for the centaur (which has the more Dv than the DM or Breeze-M, and has a higher specific impulse), with a soyuz it is about 3779 m/s, which I think is enough for a circumlunar trajectory. 3220 m/s is what's needed from LEO to Earth Escape Velocity, and a free return trajectory requires launching into a highly elliptical orbit, which would require less Dv than escape velocity, I think. If an orbit is to be established, another booster or stronger soyuz main engine would be needed.

 

[N_Molson]

Could you make calculations for Soyuz/Fregat/DM2 stack?
Fregat: m0=1050 kg, m_fuel = 5435 kg

Excellent news :

Block-DM2 Velocity Exhaust : 3453.12 m/s
Fregat Velocity Exhaust : 3207.87 m/s

I assume that the Fregat is attached to the docking mechanism (in order to allow the Soyuz to dock). So I add 500 kilograms to the Fregat.

The stack is made of :

1st Stage : BlockDM2 : m0 = 2,500 ; m1 = 19,500
2nd Stage : Fregat : m0 = 6,985 ; m1 = 1,550
Payload : SoyuzTMA : m = 7,000

Let's fire the Block-DM2 :

Dv1 = 3453.12 * ln (33,485/16,485)
Dv1 ~= 2447.0421 m/s

We discard the empty DM2, the Fregat and the Soyuz have gained a velocity of 2447.0421 m/s. It's not enough to reach the Moon.

Let's fire the Fregat :

Dv2 = 3207.87 * ln (13,985/8,550)
Dv2 ~= 1578.4454 m/s

We discard the Fregat, our SoyuzTMA has gained an additional velocity of 1578.4454 m/s. Is that enough to reach the Moon ?

DvT = Dv1 + Dv2
DvT = 2447.0421 + 1578.4454
DvT = 4025.4875 m/s

The SoyuzTMA has gained a total of 4025 m/s. We needed about 4100 m/s. That should be OK !

The fuel that remains in the SoyuzTMA (roughly 500 kg) can be used for stack orientation & small trajectory corrections.

---------- Post added at 10:34 PM ---------- Previous post was at 09:43 PM ----------

And here's what it would look like :

 

[T.Neo]

If I may put my limited and potentially useless proposal on the table;

Soyuz spacecraft, all-up mass of maybe 7 250 kilograms.

Lander, open-cockpit, minimal mass, hypergolic propellants. Can potentially draw from the LM Langley Light, but save further mass by using modern materials and construction techniques. All-up mass of maybe 4 300 kilograms.

Briz-M stage, equipped with docking and homing systems for Soyuz. Fuel mass 19 800 kilograms, empty mass with extra equipment 2 870 kilograms.

With these masses, I get a dV of 2760 m/s for the Briz-M, insufficient to make the TLI burn, let alone the LOI or TEI burn for the Soyuz.

Removing the lander, we have 3150 m/s of dV. Which is still insufficient, if we want to perform LOI and TEI. So some sort of multistage configuration, as has been discussed, is required... it makes me cringe, but still. But maybe it can include Centaur and then become a multinational operation.

Another cause for concern would then be the open cockpit module. We can extend the length of the EVA by recharging the suit's batteries- and potentially, having the ability to recharge it's other expendables (such as oxygen, potentially by bypassing the in-suit systems and connecting to an umbilical with the lander). Of course the Pirs/Progress orbital module based lander could always be turned into some sort of unmanned direct lander, a lunar shed, where cosmonauts/astronauts could take refuge in a pressursed environment.

 

[diogom]

I don't know if it is this is very important for this thread or not, but here it goes.
Earlier today, after reading this thread, I performed one of my crazy experiments, related to the Soyuz re-entry issue.
I placed a Soyuz TMA (Thorton's) in a 44M x 70.0k orbit, and, after the modules separation, I used Universal Cargo Deck to attach a UMMU re-entry pack to the SA. Surprisingly, the Soyuz survived the 10 km/s re-entry, and didn't burn up.
It descended a little bit, came back up at a speed of 8 km/s, and went for an orbit to the earth (now reduced to ~1M x 65k). It came down again, and that time it went through, performing an almost perfect landing (landed in the Atlantic Ocean).
Maybe it doesn't solve the weak heat shield problem, but it could give some ideas.

 

[Urwumpe]

Well, something from my front - an Briz M rocket stage (without torus tanks) would work perfectly for an ascent propulsion system for a soyuz OM based payload (altogether 2000 kg payload mass). I calculated with 8500 kg at lift-off and 3600 kg dry, results in 2750 m/s dV that is pretty much enough for a good ascent from the moon.

 

[N_Molson]

Well, something from my front - an Briz M rocket stage (without torus tanks) would work perfectly for an ascent propulsion system for a soyuz OM based payload (altogether 2000 kg payload mass). I calculated with 8500 kg at lift-off and 3600 kg dry, results in 2750 m/s dV that is pretty much enough for a good ascent from the moon.

I think I tried that with Velcro Rockets a couple of years ago, if I remember well it works quite well.

 

[DanM]

The thing that turned me off of the Briz-M was that it would require a 17 minute TLI.

 

[Thorton]

The SoyuzTMA has gained a total of 4025 m/s. We needed about 4100 m/s. That should be OK !

By this we will be on translunar trajectory only, but we still need to perforn LOI and TEI burns. Any idea how?

 

[DanM]

I'm trying to calculate Dv budget for a Soyuz Lunar Orbit mission. I can't quite figure out the Dv required at TLI. Hyptothetically, let's say it launches into an HTO of 300 x 384,399 kilometers. If it came out of circular 300 km orbit, then the speed would be 7.73 km/s. The Dv required would be velocity at perigee minus 7.73. This gives a radius (at perigee) of 6671 km, and a semi-major axis of 188,073 km.

From there on I used the Vis-viva equation:

Where:
-v is velocity
-

, the gravitational constant of Earth (9.8 m/s^2)
-r is radius of orbiting object from focus
-a is semi-major axis of orbit
I know this formula applies of all types of orbits. Whenever I run it, though, I get 0.053 m/s at the perigee. What am I doing wrong?

 

[Urwumpe]

The thing that turned me off of the Briz-M was that it would require a 17 minute TLI.

This was for lunar ascent not for TLI.

 

[SiberianTiger]

Which means we need a blockDM2 with an extended tank holding 23,500 kg of propellant.

Now my question would be : is that technically possible ?

Yep, by extending the tank with a cylindrical liner section of necessary length.

 

[Urwumpe]

What am I doing wrong?

You mistake surface gravity acceleration for the standard gravitational parameter of Earth, with is 398600.0 km³/s² (if you use kilometers as unit of distance). It is the product of universal gravity constant with the mass of Earth.

 

[N_Molson]

The SoyuzTMA has gained a total of 4025 m/s. We needed about 4100 m/s. That should be OK !

By this we will be on translunar trajectory only, but we still need to perforn LOI and TEI burns. Any idea how?

It would be ok for a simple circumlunar flight, then (lunar pass).

Another problem : fully loaded and taking into account the docking module, the DM2/Fregat stack has a total mass of 26,495 kg, beyond the LEO capacity of the ProtonM... We need to fire the DM2 for orbit insertion, which diminishes the DeltaV... So I would replace the BlockDM2 by the lighter BlockDM5, or launch the DM2 with not fully loaded tanks.

A N1 would be a valuable asset there ! :lol:

We can launch another BlockDM2 with a RCS attached to it for automatic docking. That BlockDM2 docks the DM5/Fregat stack in LEO, and we send the whole (DM2/DM5/Fregat stack) towards the Moon.

And unless I'm mistaken, there's no available docking port for the SoyuzTMA :hmm: