Minimal Manned Mars Mission - 2*Briz = doable! + a NEA

[DBowman]

I found a nice 'low' re-entry speed, short, low initial deltaV trajectory - the PLAD510: 3742 m/s, 510 days: I haven't quite 'got it' but I can see it's there so I plugged 510 days into my mass spreadsheet, mocked up the vehicles, and hacked together some pics with hyper edit.

An Inter Planetary Module: a docking port leads to about 4 m³ pressurized space with food, water, fecal bags, etc etc. O₂ & N₂, electrics, comms, thermal control, and Cygnus solar cells are bolted on. The whole thing is bolted to a Briz which can throw it into a 3100 m/s elliptical orbit with enough fuel left over in the Briz core to do the fly by.

A Soyuz with beefed up heat shield:  It has standard 30 man days of LS on board to cover rendezvous with the IPM. It first rendezvous with a boost Briz which has enough delta V to match orbit with the IPM at Pe. I allowed an extra marshaling orbit of LS for fine tuning and fiddling about. The Briz verniers can make adjustments down to 0.006 m/s, probably finer with the Soyuz RCS. The whole stack has about 100 m/s 'excess' - so on the border of the possible, but 'easy' with another Briz of propulsion.

At Venus Pe:  There is a radiator on the other side of the IPM. The stack that does the interplanetary injection is low thrust and has just one docking joint. I need RVE or something to 'make clouds' for Venus.

 Mars approach:  I think this is pretty much what it would look like; a half Mars, and then skimming the dark side at 150 km.

Mars departure:  the trajectory is not hyperbolic like it should be so it wouldn't look like this but Valles Marineris is so stunning.

Edited November 4, 2016 by DBowman
add images

[DDE]

Care to plug in Vostochny's latitude and an Angara-A5, as well as to try using Block D in place of the Briz? Sure, it's kerolox, but the original iteration was built for Lunar orbit injection.

[DBowman]

@DDE thanks - I hadn't thought of Vostochny; it's inclination is better for this flight, the Angara-A5 lifts a couple ton more than Proton, and the Block-D has more deltaV than Briz. The PLAD510 flyby is in August 2023 so Vostochny should be up and running fully by then but Angara-A5 will still be a couple of years from commercial availability - maybe for something like this they would make an exception since it will be flying military loads by then.

It reads like Block-D is only 'good' for a few hours due to LOX boil-off. The ideal vehicle could lift 10 ton IPM+Soyuz and a cryonic stage that can give the payload 3750 m/s from LEO - A5+Block-D is about 1400 m/s short. Without such a vehicle the Venus Mars stack will need to use storable propellant to do the Trans Venus Injection; A5+Block-D lifting IPM+BrizCore (with just the TVI fuel) is about 100 m/s short of being able to lift it to the marshaling orbit - so you could use it but there is no advantage and more complexity + inflexibility.

A5 is intended to use Briz-M also, I calced it up and it would buy 500-1000 kg more mass for the IPM which I could easily spend:

1. 546 kg switch from 'have to develop and probably complex / breakable' Carbon Dioxide Removal System like ISS to heritage dumb foolproof radiation sheltering LiOH
2. 150 kg add some O₂ redundancy - more O₂, in more tanks, with more redundant valves

So Vostochny A5 + Briz would be great and could either make the mission safer or move it from 'not quite enough deltaV' to 'well enough deltaV'. 

Edited November 6, 2016 by DBowman

[DDE]

13 hours ago, DBowman said:

It reads like Block-D is only 'good' for a few hours due to LOX boil-off.

Well, as I said,

On ‎05‎.‎11‎.‎2016 at 0:03 AM, DDE said:

Sure, it's kerolox, but the original iteration was built for Lunar orbit injection.

So for about a hundred extra kilos you get three days or so. This can be fully compensated if you find someone to synthesize Syntin for you - or are crazy enough to use Flox-30.

Besides, who knows, maybe the KVTK will finally get out of Development Hell.

Two more ideas I've had are

• simply ditching the Soyuz service engine if it's giving us that much trouble - the "coarse" RCS thrusters do its job well on the Progress, and, from what info I can piece together from random sources, Soyuz already has them in the right place;
• and possibly cooking up something based around Fregat, which is ultimately just the Ye-8 lunar probe minus the probe; I don't like the idea of using an underfuelled Briz and Wikipedia's listed characteristics for Fregat 2 suggest it's around the required category. It has listed orbital life of 2 days, but that's because it carries its own guidance kit and power supply.

Edited November 6, 2016 by DDE

[DBowman]

9 hours ago, DDE said:

So for about a hundred extra kilos you get three days or so.

I'm not sure what yo mean here. 100kg of insulation to buy three days of LOX storability? that would be long enough to rendezvous with a Soyuz.

9 hours ago, DDE said:

ditching the Soyuz service engine if it's giving us that much trouble

You mean the service section or just the engine? to save mass? I was thinking to use some deltav there for:

1. the Briz boosted Soyuz to rendezvous with the Briz boosted IPM - do the rough velocity matching with the Briz, fine & close approach with Soyuz main, then dock as usual.
2. bail out from the marshaling orbit
3. any trajectory tuning in the first 240 days before Soyuz propulsion is 'dead'.

9 hours ago, DDE said:

cooking up something based around Fregat

Fregat looks real nice, better mass ratio than Briz and 25 restarts! that would make the pilot feel safer. The Briz approach would have 4 restarts after TVI and then it would be left with just it's high pressure ullage motors with maybe 25 m/s left in them (should be enough to ensure a re-entry 'somewhere'). Fregat is too small to lift itself + IPM and have enough deltaV to make the TVI. I cacled A5 lift to LEO, Block-D (under-fueled) lift Fregat(under-fueled)+IPM direct to the marshaling orbit - it works out about the same as the Proton+Briz+IPM but with more restarts & maneuver propellant left over. If only Fregat had bigger drop tanks and could substitute for the Briz. It looks like to use Fregat you'd have to go to 3 launches, so if the Briz solution blew out past 2 (e.g. need more IPM mass) or was just unworkable (insufficient maneuver contingency) then Fregat would be a good choice.

[DDE]

7 hours ago, DBowman said:

I'm not sure what yo mean here. 100kg of insulation to buy three days of LOX storability? that would be long enough to rendezvous with a Soyuz.

Yep. The more precise info is 7 refires and 7 days of operability. I can't find a dead number, but Astronautix gives 3500 kg for Blok D as found in N1-L3 (hence with the insulation) and Zak gives 3420 kg for the stripped-down, 9-hour Blok DM (including 1090 kg separated before firing).

7 hours ago, DBowman said:

any trajectory tuning in the first 240 days before Soyuz propulsion is 'dead'.

From what I've heard of H2O2, it's not going to "die"; it's going to explode.

Quote

But (as is usual in the propellant business, there were lots of "buts") the freezing point of 100 percent H2O2 was only half a degree below
that of water. (Of course, 85 or 90 percent stuff, which was the best available in the 40's, had a better freezing point, but diluting a propellant
with an inert, just to improve its freezing point, is not a process that appeals to men interested in propulsion!) And it was unstable.

Hydrogen peroxide decomposes according to the equation H2O2 —*H2O + 1ZiO2, with the evolution of heat. Of course, WFNA also decomposed,
but not exothermically. The difference is crucial: It meant that peroxide decomposition is self-accelerating. Say that you have a tank
of peroxide, with no efficient means of sucking heat out of it. Your peroxide starts to decompose for some reason or other. This decomposition produces heat, which warms up the rest of the peroxide, which naturally then starts to decompose faster — producing more heat. And so the faster it goes the faster it goes until the whole thing goes up in a magnificent whoosh or bang as the case may be, spreading superheated steam and hot oxygen all over the landscape. And a disconcerting number of things could start the decomposition in the first place: most of the transition metals (Fe, Cu, Ag, Co, etc.) and their compounds; many organic compounds (a splash of peroxide on a wool suit can turn the wearer into a flaming torch, suitable for decorating Nero's gardens); ordinary dirt, of ambiguous composition, and universal provenance; OH ions. Name a substance at random, and there's a 50-50 chance (or better) that it will catalyze peroxide decomposition. There were certain substances, stannates and phosphates, for instance, that could be added to peroxide in trace quantities and would stabilize it a bit by taking certain transition metal ions out of circulation, but their usefulness and potency was strictly limited; and they made trouble when you wanted to decompose the stuff catalytically. The only thing to do was to keep the peroxide in a tank made of something that didn't catalyze its decomposition (very pure aluminum was best) and to keep it clean.

The cleanliness required was not merely surgical —it was levitical. Merely preparing an aluminum tank to hold peroxide was a project, a diverting ceremonial that could take days. Scrubbing, alkaline washes, acid washes, flushing, passivation with dilute peroxide —it went on and on. And even when it was successfully completed, the peroxide would still decompose slowly; not enough to start a runaway chain reaction, but enough to build up an oxygen pressure in a sealed tank, and make packaging impossible. And it is a nerve-wracking experience to put your ear against a propellant tank and hear it go "glub" —long pause — "glub" and so on. After such an experience many people, myself (particularly) included, tended to look dubiously at peroxide and to pass it by on the other side.

7 hours ago, DBowman said:

If only Fregat had bigger drop tanks

Which Fregat variant did you use?

Edited November 7, 2016 by DDE

[DBowman]

7 hours ago, DDE said:

Which Fregat variant did you use?

I did some calcs with 'vanilla', M, MT, SB, & 2 - it's a nice stage, just not big enough on it's own.

I liked the H2O2 quote, I guess the Soyuz guys are levitical  as far as I can tell the H2O2 is used to drive the turbos for the main engine and it slowly decomposes until sometime after 240 days the big engine wont light. The 'use by' date used to be less but they improved something about the H2O2 storage or preparation. Possibly the Soyus RCS is enough for any 'final approach' adjustments, but I'd prefer to have a storable propellant stage to be sure - Fregat with 25 restarts would be good in that respect.

[Kryten]

H2O2 turbopumps are used on the Soyuz rocket, the usage on the Soyuz spacecraft is in monoprop RCS on the return capsule.

[DBowman]

@Kryten thanks I think I'd conflated early Soyuz spacecraft H₂O₂ use for RCS (e.g. though I originally read it somewhere else) with the turbo thing.

As you say currently H₂O₂ is used only for descent attitude control of the descent module - so that's good, there will be usable deltaV in the Soyuz for tweaks and final approach, over 100 m/s probably (well enough). This says the critical limiter on the SS use by is the H₂O₂ for descent orientation, I'll have to look into the 'certain avionics systems' issue. This harrowing sounding near disaster descent of Soyuz 5 in 1966 shows that even without attitude control the re-entry is survivable but not accurate. This shows they already have contingency plans for reentries without attitude control, 50% greater G force, and the decomposition state of the H₂O₂ can be monitored.

Edited November 7, 2016 by DBowman

[DBowman]

It lives!

 

I made a spreadsheet, and checked it twice. A two Briz mission plan will flyby Venus and Mars with 680 kg propellant margin in the Briz and a full propellant load in the Soyuz! that's 480 to 510 m/s (2/3 on Soyuz main).

 

My spreadsheet includes: 

• Computed everything from a 200 km LEO but under-fueled the Brizs using mass info from the Proton mission planning handbook. I think this is conservative because it would be better (but harder for me to compute) to under-fuel the third stage and dump the more dry mass early. I did this for:
  • inclination change
  • circularisation burns
• Used the conservative choice where there were multiple source values for mass or ISP
• Ullage burns out of 205 kg high pressure propellant budget
• Used a detailed burn schedule, computing ullage, combined, main, tune regimes
• Full mass Soyuz (missing passengers & H2O2 = extra thermal protection)
• Used baseline InterPlanetary Module mass per my consumables calcs etc for 510 days + 26 days marshaling
• Added mass for solar cells etc on Briz

 

Trajectory is courtesy of PLADs Flyby Finder:

Depart 25 Aug 2023 02:24, inclination 62.8 degrees 3742 m/s (almost perfect for Baikonur, spooky)

Venus @ D + 164 days 13.6 hours, 21 Aug 2024 @ 8054 km altitude

Mars @ V + 197 days 12 hours @ 145 km altitude

Earth @ M + 147 days 19.4 hours, 15 Jan 2025 reentry @ 12.4 km/s

 

Flight plan uses a Marshaling Orbit Rendezvous strategy (LEO + 3150 m/s abut 13 day period):

- Launch Proton + Briz + InterPanetary Module containing consumables and Soyuz supplementary services

- Two Pe kicks from Auxiliary Propellant Tank & stage it (saving restarts, 3 might be ok)

- One Briz core Pe kick into marshaling orbit

- 'later'

- launch Proton + Briz with dock welded on into IPM plane

- launch Soyuz to rendezvous with dock-able Briz

- Soyuz closes and docks

- Three Pe kicks from APT and stage it

- One core Pe kick to LEO + 2925 m/s / MO - 225 m/s

- Soyuz rendezvous with IPM at Pe with a two minute burn

- about 13 days to Trans Venus Injection

- Soyuz closes and docks to IPM using as far as possible the 1200 kg of residual Briz propellant

- up to this point the mission can scrub and return safe

- TVI burn 592 m/s in 6:40 seconds 

- fall for 510 days, no deltaV required for the flyby, just tweaks to make sure the gravity assists are accurate

- should be ample deltaV for setting up reentry timing (location) and Pe

 

Things I couldn't compute:

• How much deltaV the Soyuz would use in rendezvous with IPM - cannot be much since the Briz that lifts the Soyuz has 300 m/s & 3 restarts margin and there is plenty of time as long as the 'matching manoeuvre' is okay.
• Briz attitude control propellant usage. It comes from the high pressure system the ullage motors use. There is lots of time to get oriented right so it should be very low.
• Briz usable propellant vs propellant capacity. I saw 2% residual used by a Mars Heavy Transport Architecture, I'm not sure how reliable it is. That would eat 400 kg of the 680 kg margin.
• Re-entry: 12.4 km/s is less than the record set by Stardust (12.9 km/s & 34 g) and the human g record on a rocket sled is 46 g (not for long I bet). You have to trade off g against peak and total heating - so who knows but could be doable. Lunar reentry is 11 km/s & there were plans to use Soyuz for that, so 'its only 13% faster'... (but the heating isn't linear)

Edited November 27, 2016 by DBowman
oops spelling & marshaling time

[DBowman]

I wondered if the basic mission 'architecture' could reach anywhere else interesting - yes! as long as small rocks are interesting. Turns out there is one Near Earth Asteroid, 2000 SG344, with a 3550 m/s 370 day trip leaving 2027-2031. If you could dock a full Briz core under the baseline stack that would open up another 70 objects ( NASA NHATS ), all with trip times under 450 days and stay times 8-16 days.

changes from baseline:

• less consumables => 'free mass', an extra Briz core can mean a lot more free mass.
• there is no EVA without either undocking the Soyuz or adding another hatch in the Orbital Module (I know which I'd pick)
• EVAs mean more N2 budget
• take science mass for on the spot work and swap in samples for the return

The 'architecture' doesn't seem to get anywhere else.

[DDE]

On 12/1/2016 at 6:17 AM, DBowman said:

there is no EVA without either undocking the Soyuz or adding another hatch in the Orbital Module (I know which I'd pick)

Got back to this thread from an unrelated discussion.

The Soyuz orbital module ingress and EVA hatch is completely separate from the SSVP docking system up front. It dates back to the old L3-era mechanical grapple and crew transfer via EVA.

 

[DBowman]

cool thanks @DDE like https://www.quora.com/How-do-astronauts-get-inside-the-Soyuz-spacecraft I guess do closest approach outside! selfie time...

[tater]

That Soyuz concept looks like torture to live in for so long.

[kerbiloid]

Spoiler

5 hours ago, tater said:

That Soyuz concept looks like torture to live in for so long.

Xbox. Time just flies.