Mars mission with current rockets.

[Cloakedwand72]

Since starship “might” go bankrupt can the worlds space agency’s do a mars mission with current rockets? And what was the best short term mars mission design that also had artificial gravity in mind?
 

[DDE]

2 hours ago, Cloakedwand72 said:

And what was the best short term mars mission design that also had artificial gravity in mind?

This, probably overemphasized, criterion immediately makes the mind jump to Zubrin's Mars Direct. SLS is human-rated, and the combination of a pre-placed MAV and a single-launch outbound vehicle can tolerate the abysmal launch cadence - as opposed to the many missions with on-orbit assembly.

[Vanamonde]

Thread moved to Spaceflight, since that's what it's about. 

[JoeSchmuckatelli]

3 hours ago, Cloakedwand72 said:

Since starship “might” go bankrupt can the worlds space agency’s do a mars mission with current rockets? And what was the best short term mars mission design that also had artificial gravity in mind?
 

There is no artificial gravity.

Sci-fi likes to paint that as a potential - but if it is, it's a LOOOOOOOONG way in the future.

Centrifugal force capsules might be buildable... but there's nothing in the works - and they'd likely have to be built in space.

 

Now - we actually do Mars Missions all the time (or rather, with some frequency) but if you are talking about a Mars Colony?  SX is the only one seriously working towards that.

[SunlitZelkova]

15 minutes ago, JoeSchmuckatelli said:

Centrifugal force capsules might be buildable... but there's nothing in the works - and they'd likely have to be built in space.

To expand upon at @DDE's reply, Mars Direct actually does have such a feature. It would look like this, but with the TMI booster tethered in place of the Apollo CSM variant-

Source of the image- http://spaceflighthistory.blogspot.com/2019/01/apollo-to-mars-venus-north-american.html

16 minutes ago, JoeSchmuckatelli said:

Now - we actually do Mars Missions all the time (or rather, with some frequency) but if you are talking about a Mars Colony?  SX is the only one seriously working towards that.

I think he means crewed expedition, neither robotic exploration nor full scale permanent habitation.

[JoeSchmuckatelli]

5 minutes ago, SunlitZelkova said:

To expand upon at @DDE's reply, Mars Direct actually does have such a feature. It would look like this, but with the TMI booster tethered in place of the Apollo CSM variant-

Source of the image- http://spaceflighthistory.blogspot.com/2019/01/apollo-to-mars-venus-north-american.html

I think he means crewed expedition, neither robotic exploration nor full scale permanent habitation.

@Spacescifi should look at this graphic: that would make the toilets work!

Which brings up a whole host of 'interior reshuffling' that would have to happen.  Example: The seats used for launch  would be oriented so that in the 'artificial G' config, you'd have to lay back in them - so they'll need swivels for the space ride to be useable.  or just fold out into a bed.

[FleshJeb]

This is NASA's Design Reference Architecture 5.0 for manned Mars missions (July 2009):

https://www.nasa.gov/pdf/373665main_NASA-SP-2009-566.pdf (No mention of centrifuge. See PDF page 35 for Transportation)

Addendum 1 (July 2009):

https://www.nasa.gov/pdf/373667main_NASA-SP-2009-566-ADD.pdf (Centrifuge mentioned in passing. See PDF page 190 for Transportation)

Addendum 2 (March 2014):

https://www.nasa.gov/sites/default/files/files/NASA-SP-2009-566-ADD2.pdf (search for "centrifug" = 51 matches) This is the best document of the three.

[sevenperforce]

An extensible tethered hab (a la Stowaway) is the lowest-mass and most readily-realizable solution for artificial gravity during the transfer to Mars. It would need to be tested extensively in LEO and possibly cislunar space as well, probably using a modified Dragon or Starliner to start and then upgrading. The transfer coast will, of course, require a larger hab, built up with successive launches in LEO like the ISS, containing several rigid pressurized modules and several expandable modules. That hab would subsequently be rigorously tested with the tethered artificial gravity solution.

They'd need the hab for both directions of the journey, and it would be far too large to aerocapture, so it would need to bring propellant for a Martian capture burn. It would also need to bring propellant for the return. That's 4.6 km/s round-trip, so if we are using storables then you're looking at a transfer hab that is 77% propellant after trans-martian injection (slightly less if you use drop tanks, but not by much). Orion is capable of handling entry from an interplanetary transfer so they'd have an Orion docked underneath it for the final entry at Earth, but the hab would probably end up being single-use. A shame.

So you use orbital assembly for the hab, orbital assembly for the upgraded tether system, orbital assembly to add hypergolic propellants for the trip, a single Falcon Heavy launch to add an unmanned Orion, a Falcon 9 Crew Dragon launch to send up the crew, and then an SLS launch of a naked, stretched EUS to perform the TMI burn. But you'd need to stretch it a good bit.

And that gets you on the way to Mars, but that's not enough. Unless you were looking at a truly minimalist flags-and-footprints mission, you'd want a pre-emplaced hab on the surface. So that would need to be done well in advance, using a series of Falcon Heavy or even SLS launches. You also need a way of getting down to the surface and back up. They would probably use an Orion-based framework for an EDL vehicle that would be launched on Falcon Heavy and aerocapture with a heat shield into low Martian orbit for rendezvous with the transfer hab. Of course they would need to test it unmanned at least once. For the ascent vehicle, they would have to design something completely from scratch, with an expandable heat shield and enough fuel for the landing and ascent but only enough oxidizer for the landing, and a disposable oxygen separator that would use solar or RTG power to crack and liquefy oxygen out of the Martian atmosphere to refill the oxidizer tanks for the ascent. That would also need to be tested.

[DDE]

6 hours ago, sevenperforce said:

They'd need the hab for both directions of the journey

Depends on your assumptions. While some seek to counter the lack of gravity entirely, others are solely concerned with conditioning the crew for Martian gravity on the outbound leg. Hence Zubrin combining the Earth-to-Mars transit vehicle and Mars surface hab.

6 hours ago, sevenperforce said:

enough fuel for the landing and ascent but only enough oxidizer for the landing, and a disposable oxygen separator that would use solar or RTG power to crack and liquefy oxygen out of the Martian atmosphere to refill the oxidizer tanks for the ascent

Or you could just go brute-force with milspec UDMH-IRFNA.

[kerbiloid]

Klingons would just take twin bros, send one on Mars in a boat-sized capsule to film the TV live, then present another one for public three years later as returned.

But humans don't seek easy ways.

[RCgothic]

Re-entry element selection:

Ok, so Orion is totally the wrong capsule to take along for this ride. For every 1t that makes the round trip though TMI, MI and then TEI, that requires about 30t of storable propellant.

Orion is enormously overweight. The combined Orion ESM weighs 26.5t. On this mission it will never fly free. The only thing it's needed for is is heat shield. Ideally we'd come up with something like Soyuz descent element, but that's a bit small for a crew of 5-6 and I suspect a conical capsule is better for re-entry from interplanetary speeds. That leaves Dragon 2, which weighs 12t wet. It has previously been mooted with an uprated heat shield, so that's if not quite ideal, probably the best we've got without designing a bespoke ultra-lightweight re-entry vehicle.

At 14.5t lighter than Orion, that's something like 435t saved on the round trip.

Launch Vehicle Selection:

Similarly, SLS will not be useful in this mission (even if it were a currently operational rocket, which it's not). The amount of mass to Mars is well over 1000t. EUS can't push that much out of Earth's gravity well even with refuelling, which it doesn't support. We're going to have to use storable hypergolics and do orbital construction. That's going to take a *lot* of missions, and a lot of missions will cost a lot.

What's the most cost effective launcher with the highest flight rate?

Falcon 9.

Falcon 9 can do about 15.6t reusably, so that's the module limit. 5m class fairing isn't ideal, but payload will be mostly propellant drop tanks.

Note: all current DIVH, Atlas and Arianne 5 launches are spoken for and Vulcan, New Glenn and Arianne6 aren't current launchers either.

That really doesn't leave much choice in the medium-heavy lift categories. There's Falcon Heavy, of course, but most of its payload is propellant residuals that won't be useful as storeables and we really don't know at this point that any member of the Falcon family can lift more than 15.6t actual payload to LEO. There's the Russian Angara or Proton of you want to throw the Russians a bone politically. Or there's the Chinese Long March series, for a properly international mission.

Martian Hab:

A Mars mission is going to be in the surface a while, probably over a month. It makes sense to pre-position a hab. A 15.6t module on the way to Mars would have about 11t mass budget not counting propellant  That really isn't much for a longish duration stay, but it's probably the minimum baseline.

It would take about 6x 15.6t propulsion modules to send the Hab to Mars, or 7x F9 flights.

Crew Module:

The crew is going to need somewhere a bit more spacious than Dragon to live, plus life support, power and supplies, and possibly a tether for artificial gravity but that's possibly a big  ask given a 15.6t mass budget. Assume anything consumed gets replaced by payload from the Martian surface 

This and Dragon are the only bits that come back to earth. That's about 27.6t, which will take 3x 15.6t propulsion modules for Trans Earth Injection.

Mars Lander:

To land takes ~1km/s to descend and 3.8km/s to get back up.

A single stage lander weighing 15.6t in Martian orbit would weigh just 2.8t with 0.5t of payload. That's probably not enough. Doubling up 31.2t allows an ascent module of 5t with 1.5t payload.

Mass for Mars Insertion:

Crew Module, Dragon, 3 propulsion modules for return, and the 2-stage lander. That's 105.6t.

Mars Insertion takes~ 1440m/s. So that'll take 5x 15.6t propulsion modules. 183.6t total.

Mass for TMI:

TMI takes about 4270m/s. To push 183.6t through TLI would take 62x 15.6t propulsion modules.

That's 62+5+3 propulsion modules.

2 part lander.

Crew module.

Dragon.

7 Flights to pre-position the Hab.

81x Falcon 9 flights.

That's not completely impossible, but it's definitely in the high end of infeasible, all for a pretty lightweight mission with 5-6 crew for 30-40 days on the surface and 1.5 tonnes return payload.

The F9 flights alone would retail for ~$5Bn, which is actually quite reasonable. The multiple common elements would probably be pretty cheap as well. The expensive bits would be the lander, Hab and crew compartment.

Edited December 4, 2021 by RCgothic

[kerbiloid]

13 hours ago, RCgothic said:

a conical capsule is better for re-entry from interplanetary speeds. That leaves Dragon 2

Crew Dragon looks closer to Soyuz than to Apollo in sense of shape.

Of course, as always, we don't know anything concrete about its physical characteristics.

13 hours ago, RCgothic said:

which weighs 12t wet

With thin LEO heat protection and construction strength for 8 km/s air drag.

If it was reinforced, it would become a worse Orion.

13 hours ago, RCgothic said:

What's the most cost effective launcher with the highest flight rate?

Falcon 9.

Falcon 9 can do about 15.6t reusably, so that's the module limit. 

How many dockings (not berthings) has US performed since Canadarm has appeared?

But even how many berthings with humans onboard?

At least one automatic docking ever performed by US?

Anything like Lyappa ever made/used by US?

 

1000 / 15.6 ~= 60 docking procedures.

1. Such enormous docking number would just suddenly lead to a crash.

2. The construction of every module would be overweighted.

3. The construction in whole would be a toy of Kraken, shaking and pulsing at every motion.

Falcon is same nothing for the Mars mission as Dragon.

 

13 hours ago, RCgothic said:

A 15.6t module on the way to Mars would have about 11t mass budget not counting propellant 

Currently just two ~2 t rovers have ever been landed. And several smaller ones.

A 15.6 t module would deliver a tent for two, not a habitat.

Nothing to do with Falcon here.

13 hours ago, RCgothic said:

and possibly a tether for artificial gravity but that's possibly a big  ask given a 15.6t mass budget.

15.6 t is Salyut, appropriate for 3 months on LEO. Absolutely inappropriate for 3 year long ride.

Nothing to do with Falcon here.

 

13 hours ago, RCgothic said:

81x Falcon 9 flights.

If extraterrestrial invaders are going to occupy the Earth and it's the last human hope to foud a rebel base on Mars to revenge.

SpaceX is nothing even close to what's needed for Mars.

[RCgothic]

Dragon was originally going to be used for moon missions. Obviously I'm assuming that upgrade path still exists, because otherwise we're designing a new capsule from scratch. Don't like that? Fine. Then there are no suitable capsules for current rockets. Boring answer, sorry.

Want a bigger hab with more space? Fine. Add additional modules and then more fuel. Or count both SLS and Superheavy as current rockets, ignore SLS, and build something with Superheavy. But I think that breaks the rules of the topic.

And again, yes, I know it's a lot of dockings between modules full of hypergolic fuel. If you don't like dockings, add another launch to add a CanadaArm to perform the berthings. Don't like that many modules? Fine. I've already agreed it's the high end of infeasible. Enjoy the boring answer.

Still don't like it? Well then it just can't be done with current rockets. They all lack the payload, flight rate, and a low enough cost point to raise enough storeable propellant for a Mars mission. Enjoy the boring answer.

 

Ultimately, Starship is absolutely the way to do this properly. It's definitely not being done by any other current rocket, or by SLS.

Edited December 5, 2021 by RCgothic

[kerbiloid]

16 minutes ago, RCgothic said:

Dragon was originally going to be used for moon missions.

Dragon was originally for Moon, Mars, Mars habitat, rocket landing, and whatever,

Irl it just had been splashing from LEO and never tested at 11.2 km/s, like, say, the Soyuz (Zond) capsule was..

Its engines are heavy but puny things useless for both lunar flight and landing at lunar speed. but making itheavier, so worse for aerobraking and adding more stress in the hull.

And as we can see, all claims about Dragons have been flushed down by SpaceX itself long ago in the name of Starship.
Currently only talks about the lunar tourists are seen, for years and it's doubtful if they ever will get real.

Say, the brutal Soviet rocketeers have launched several Zonds to the Moon and back before putting a brave cosmonaut inside.
But where is at least one crewless lunar Dragon flight?
Will a (US? JP?) billionaire be an equivalent of the Soviet lunar tortoises to test the capsule?
Talks are cheap.

25 minutes ago, RCgothic said:

And again, yes, I know it's a lot of dockings between modules full of hypergolic fuel.

Where?

I don't talk about the hypergoilcs fear, it's all about the dockings themselves?

Gemini/Apollo/Shuttle were docking manually.

Cargo Dragons and Cygnuses are captured manually.

Just several dockings of the lightweight Crew Dragon?

27 minutes ago, RCgothic said:

Want a bigger hab with more space? Fine. Add additional modules and then more fuel

Tens of docking ports and dockings to assemble a ship in orbit is a very optimistic way,

The only two orbital assemblies ever assembled in orbit without hands are Mir (6 modules) and the Russian ISS segment (also ~6 modules), others were assembled manually.
And even after the automatic docking, the integration required EVA.

30 minutes ago, RCgothic said:

add another launch to add a CanadaArm to perform the berthings.

80 ?

Has the Canadarm-2 provided this number in all its life?
Was it ever working without a human onboard?

31 minutes ago, RCgothic said:

Ultimately, Starship is absolutely the way to do this properly.

Currently it's as absolutely the way as N-1, Nova, Convair Nexus, Rombus, Sea Dragon, and a hundred of others were.

Just those were spending mostly paper, while Starship and N-1 also metal.

***

The only two rockets who ever could with great efforts were Saturn-V and Energy.

Currently maybe SLS, as it uses tested equipment.

[RCgothic]

None of Energia, Saturn V, SLS or N1 were/will be capable of anything other than a flyby. A couple hundred tonnes a year to LEO is nowhere near sufficient.

And a Mars mission at Opposion has a duration of 1.5y, not 3y.

Edited December 5, 2021 by RCgothic

[kerbiloid]

2 hours ago, RCgothic said:

None of Energia, Saturn V, SLS or N1 were/will be capable of anything other than a flyby.

They were able to lift 100+ t and dramatically reduce the number of orbital operations and improve the marsship structural integrity.

Edited December 5, 2021 by kerbiloid

[DDE]

1 hour ago, RCgothic said:

None of Energia, Saturn V, SLS or N1 were/will be capable of anything other than a flyby. A couple hundred tonnes a year to LEO is nowhere near sufficient.

And a Mars mission at Opposion has a duration of 1.5y, not 3y.

Conjunction-class (I think) nuclear-electric mission... granted, a surface stay of 9 days is pretty pathetic.

[SunlitZelkova]

37 minutes ago, DDE said:

Conjunction-class (I think) nuclear-electric mission... granted, a surface stay of 9 days is pretty pathetic.

According to NASA sources, conjunction is the long one, opposition class is 30-90 days or, evidently, even less.

NASA DRA 5.0 had a 500 day stay but the amount of equipment did not feel much more expansive than the proposed opposition class missions with superficially similar design and mass, like the 1969 proposal for the Integrated Program Plan (with the MEM and nuclear shuttle). Would Energia have been able to handle something akin to the Constellation mission?

Although I have only glanced at post-Soviet Russian Mars mission proposals, nearly all of them use nuclear electric propulsion, while the Constellation era profile requires NTRs. In the event the modern day Russian aerospace industry has something against them, an identical profile, at least, wouldn't work.

[kerbiloid]

50 minutes ago, DDE said:

Spoiler

 

[DDE]

28 minutes ago, SunlitZelkova said:

According to NASA sources, conjunction is the long one, opposition class is 30-90 days or, evidently, even less.

NASA DRA 5.0 had a 500 day stay but the amount of equipment did not feel much more expansive than the proposed opposition class missions with superficially similar design and mass, like the 1969 proposal for the Integrated Program Plan (with the MEM and nuclear shuttle). Would Energia have been able to handle something akin to the Constellation mission?

Although I have only glanced at post-Soviet Russian Mars mission proposals, nearly all of them use nuclear electric propulsion, while the Constellation era profile requires NTRs. In the event the modern day Russian aerospace industry has something against them, an identical profile, at least, wouldn't work.

Don't think it has - the various nuclear-electric tugs are the hot stuff right now. That said, the short surface stay is the result of taking a whole lot of time to decelerate into low orbit.

These long times have led to the concept of "podsadka", delivering the crew to a rendezvous with the main craft already in a near-escape orbit. Similarly there's an advantage to dropping the crew off in an ERV and then decelerating the interplanetary ship over a long period of time.

[sevenperforce]

On 12/4/2021 at 12:30 PM, RCgothic said:

Ok, so Orion is totally the wrong capsule to take along for this ride. For every 1t that makes the round trip though TMI, MI and then TEI, that requires about 30t of storable propellant.

Orion is enormously overweight. The combined Orion ESM weighs 26.5t. On this mission it will never fly free. The only thing it's needed for is is heat shield. Ideally we'd come up with something like Soyuz descent element, but that's a bit small for a crew of 5-6 and I suspect a conical capsule is better for re-entry from interplanetary speeds. That leaves Dragon 2, which weighs 12t wet.

But this is NASA we're talking about, so they would want to use their precious Orion. Probably with the tanks largely drained.

On 12/4/2021 at 12:30 PM, RCgothic said:

What's the most cost effective launcher with the highest flight rate?

Falcon 9.

Falcon 9 can do about 15.6t reusably, so that's the module limit. 5m class fairing isn't ideal, but payload will be mostly propellant drop tanks.

Note: all current DIVH, Atlas and Arianne 5 launches are spoken for and Vulcan, New Glenn and Arianne6 aren't current launchers either.

That really doesn't leave much choice in the medium-heavy lift categories. There's Falcon Heavy, of course, but most of its payload is propellant residuals that won't be useful as storeables and we really don't know at this point that any member of the Falcon family can lift more than 15.6t actual payload to LEO.

I will point out that SpaceX offers both a 1,575-mm PAF and a 2,624-mm PAF, and for the latter, the Falcon User's Guide explicitly provides for payloads up to 19 tonnes. The User's Guide also says that Falcon can accommodate heavier payloads on request.

Plus, if I recall correctly, Bridenstine talked about Falcon Heavy being able to launch both ICPS and Orion in a single stack, which would come to about 52 tonnes to LEO. Of course that would be flying expendable. But I don't think there is any reason to think Falcon Heavy couldn't do a 21-tonne monolithic payload to LEO (which is about what we would expect it to be capable of given its 8 metric tonne payload to GTO).

On 12/4/2021 at 12:30 PM, RCgothic said:

A Mars mission is going to be in the surface a while, probably over a month. It makes sense to pre-position a hab. A 15.6t module on the way to Mars would have about 11t mass budget not counting propellant  That really isn't much for a longish duration stay, but it's probably the minimum baseline.

It would take about 6x 15.6t propulsion modules to send the Hab to Mars, or 7x F9 flights.

Or Falcon Heavy can send a 16.8-tonne hab module to Mars in a single launch, flying expendable.

Now, a 16.8-tonne hab might not be enough. They might want to do orbital construction of something a little bigger. But even so, a naked Falcon Heavy (either expendable or partially expendable) would be able to dock with it and push it to TLI. You can do a lot with 68 tonnes of residuals.

On 12/5/2021 at 1:50 AM, kerbiloid said:

Crew Dragon looks closer to Soyuz than to Apollo in sense of shape.

Of course, as always, we don't know anything concrete about its physical characteristics.

What physical characteristics of Crew Dragon are you are unfamiliar with?

[kerbiloid]

6 minutes ago, sevenperforce said:

What physical characteristics of Crew Dragon are you are unfamiliar with?

L/D?

[sevenperforce]

9 minutes ago, kerbiloid said:

L/D?

Approximately 0.24. It has a 120-kg ballast sled that can be moved back and forth behind the heatshield to adjust the L/D ratio in realtime.

[kerbiloid]

7 minutes ago, sevenperforce said:

Approximately

This.

But anyway, Apollo/TKS have 0.4

Dragon is something like Soyuz in sense of L/D.

Apollo was withstanding ~-7g on aerobraking from the Moon,
Zond/Soyuz (from different sources) - 8..10 or 10..12, i.e 10+/-

So, 1.5 times greater.

[sevenperforce]

5 minutes ago, kerbiloid said:

This.

But anyway, Apollo/TKS have 0.4

Dragon is something like Soyuz in sense of L/D.

Apollo was withstanding ~-7g on aerobraking from the Moon,
Zond/Soyuz (from different sources) - 8..10 or 10..12, i.e 10+/-

So, 1.5 times greater.

"Approximately" because it could be varied realtime by the ballast sled.

I don't know what L/D ratio TKS had, but Apollo's was around 0.35, not 0.4, and the 7K-L1 Zond only need an L/D of 0.2 for skip entry reducing the gees from 10-15 down to 4-7 (although this was increased to 0.3 to give better landing accuracy).

In any case, an L/D of 0.24 is enough for a skip entry, so it's fine.