Yet another Mars architecture

RobS · 2014-03-02 12:06:13

Thanks, Robert Dyck and GW Johnson, for your replies. Robert, I remember reading that posting of yours earlier. But even then I was wondering what masses you had in mind, and I still wonder what volumes we're talking about.

To give a concrete example: I have been playing around with a design I call the "gryphon." The capsule part has 3 levels and 45 cubic meters; bigger than Dragon, smaller than Zubrin's ERV. It would be for three crew and would have an inflatable ITV that provided another 150 cubic meters, and which would stay in a high Mars orbit, attached to the trans-Earth injection stage. The gryphon would go to the surface and return to orbit; I figure it needs a delta-v of about 5.2 km/sec and a mass ratio of 4.1, so if it massed 9 tonnes for everything on ascent, it'd need 30 or so tonnes of methane/oxygen, which is doable even with solar panels. The gryphon would have a fair amount of mass; on the way out it'd have all the consumables and on the way back, all the consumables and other mass stored in the ITV. So the astronauts would sleep in the capsule where there is maximum radiation protection. The inflatable would have a large common room for eating and socializing and space for exercise and greenery. Some work would be done in the capsule, some in the inflatable, but the latter would be the higher radiation environment. I don't know what the mass of the ITV would be; it could be pretty light and might draw off the life support equipment in the capsule. The mass for trans-Earth injection might be around 14 or 15 tonnes, so the total propellant needed would be about half that, and couls be supplied initially from Earth and left in a highly elliptical 24.6 hour 1-sol orbit. The gryphon has a heat shield, so it could aerobrake at Earth arrival. If the trans-Earth injection stage were essentially a gryphon propulsion module with the ITV attached, it could aerobrake the ITV.

RobS · 2014-03-02 12:33:29

Robert, we posted about simultaneously. I take, then, you're talking about four people in a total volume of about 125 cubic meters. The 8-meter in diameter hab provides 50 square meters of floor space and if the ceiling is 2.5 meters, that's 125 cubic meters. That's helpful. Now, masses: what's the mass of the ISS module you're talking about? How much mass do you need to throw to Mars from LEO? How much from a high Mars orbit?

RobertDyck · 2014-03-02 13:10:29

The US habitation module was designed to be 28 feet long, by 14 feet diameter. Compare to a motorhome, they usually include engine and driver's seat for total vehicle length, but vehicles are 8 feet wide to fit on a road. So that's about the size of a 30-foot motorhome with slide-outs. Good enough?

RobS · 2014-03-02 13:19:06

Another point I would like to make: there are applications in low Earth orbit and the moon that should be kept in mind when developing a Mars transportation architecture. A vehicle with a delta-v of 5.5 km/sec (sorry, that's a correction; that's the delta-v from the Martian surface to an elliptical 1-sol orbit) has a lot of other potential uses. For example, a 45 cubic meter cabin attached to a 35-tonne propulsion stage could be launched into low earth orbit using a first stage of about the size of a Falcon. It'd serve as its own second stage and could transport quite a few tourists to a low earth orbit hotel; at 1.5 cubic meters per person, it could carry 30 passengers. Launched on top of a Falcon Heavy so that its 35 tonne propulsion stage is still full, 5.2 km/sec can get it to low lunar orbit. If orbital refueling is developed and it could refuel in low lunar orbit, 5.2 km/second could take the vehicle to the lunar surface, then back to Earth. The same amount of fuel could move the vehicle to an L1 Gateway Station (delta-v, I think, 3.3 km/sec) with an ITV, where it could refuel and go straight to the Martian surface (though without much cargo or hydrogen feedstock; that would work after the Martian base has water). Spreading out the development cost of such a vehicle among multiple uses will save the Mars system a lot of money and will allow the vehicle to acquire experience. Improvements would also be spread among several potential users.

RobS · 2014-03-02 13:23:14

The US habitation module, then, is about 114 cubic meters.

Quaoar · 2014-03-02 15:37:39

To Robert Dycke:

This NASA study is proposes a very lightweight (3 Kg/m) graphite-epoxy coilable boom for artificial gravity, that can fit very well with your mission architecture.

http://www.artificial-gravity.com/NASA-JSC-EX-02-50.pdf

There is also an apparently similar commercial product of ATK ( http://www.atk.com/products-services/co … m-systems/ ): it is projected for light loads but I think they can build a sturdy version hor high loads on demand.

GW Johnson · 2014-03-02 18:44:40

Quaoar:

Thanks, I had never seen that NASA report before. Amazing how they came to the same conclusions I did: 4 rpm, 1 full gee, and an end-over-end spinning baton as both stable and (at least a bit) maneuverable while spinning.

The truss they used is an artifact of the nuclear-electric propulsion they assumed. There's not a plethora of propellant tanks, but you need connecting structure to make the baton shape.

If instead you use chemical propulsion, then you have a plethora of propellant tanks, and that stack of tanks can serve the function of the truss, without a need for any truss at all. If you are clever with your stack-up of those tanks, you can stage-off empties and still maintain overall length, just at reduced mass and (to a much lesser extent) mass moment of inertia.

This kind of thing just does not integrate hardly at all with direct-landing or aerocapture designs. Unfortunately. But, I think it solves so many other problems, that it's worth the extra propellant. Just my opinion.

GW

RobertDyck · 2014-03-02 22:30:16

It's a long time since I worked out masses. Energia with it's upper stage can throw 35,680kg to C3=0 (TLI), or 31,091kg to C3=10, or 17,446kg to C3=50, or 8,006kg to C3=100. Interpolating, it should throw 29,090kg to C3=15 (TMI). Since it's interpolated, round off to 29 metric tonnes. So that's what I considered the budget for launch mass from Earth for the MAV. Same for the lab and pressurized rover, pre-landed. The US hab would have been launched by Shuttle, I don't know launch weight, but the Shuttle could carry 16,050kg to ISS. Dragon CRS (cargo version) has a dry mass of 4.2kg plus 1.227kg of propellant, the trunk with solar panels 681kg, so 6.108kg plus furniture and life support. ADEPT heat shield for aerocapture. Mars Direct estimated the heat shield mass as 5.26 metric tonnes. That's for atmospheric entry, not just aerocapture, but let's use that mass anyway. So as a very rough estimate, 27.418 metric tonne from Mars orbit, not including TEI stage. From Earth orbit, add something for lander and unpressurized rover.

Slide 6 for ADEPT has a little graphic to land on Mars, with 4 options to land 40 MT (assume metric tonnes) landed payload.
#1: 23m umbrella heat shield during aerocapture, then expand to 44m at transition between hyper- & supersonic, then subsonic retro-thrust. Finally terminal descent and landing. Total mass before entry: 90mT
#2: 33m aerocapture, remain 33m during hyper- & supersonic, begin retro-thrust at transition between super- & subsonic. Terminal descent and landing. Total mass: 87mT
#3: 23m aerocapture, remain 23m hyper- & supersonic, supersonic retrothrust. Terminal descent and landing. Total mass: 81mT
#4: 23m aerocapture, parachute opens supersonic, subsonic retrothrust. Terminal descent and landing. Total mass: 78mT

A lander with hab and one unpressurized rover would have landed mass of 19.4 metric tonnes. Using option #4, that would require 37.83 metric tonnes to Mars. So roughly 65.25 metric tonnes depart LEO, not including TMI stage.

That involves 2 heat shields. One fabric heat shield for aerocapture, then a separate heat shield for the lander to enter Mars atmosphere. This shows aerocapture at Mars will require almost three times the mass of aerocapture at Earth. But Earth has more gravity, and the vehicle will have fallen toward the Sun during transit from Mars, so greater velocity. I guess that's Ok. And the entry heat shield will not experience aerocapture, just entry, so less load. But for simplicity I'll stick with the same mass figure.

Last edited by RobertDyck (2014-03-03 12:21:47)

RobertDyck · 2014-03-02 22:48:04

One interesting option to reduce launch cost: self launching. Falcon 9 can launch the ITV as payload, but you could design the upper stage of Falcon 5 to be self-launching. The only customer for Falcon 5 has stopped work, so it's cancelled. The last announcement for Falcon 5 was a design change from a dedicated vehicle to Falcon 9 with 4 of the first stage engines removed. So the upper stage of Falcon 9, designed as a hab module like the Skylab workshop.

Falcon 9 upper stage tanks: 3.9m (12.8 feet) long, 3.66m (12.0 feet) diameter. Would require a custom stage. Standard payload fairing is 5 metres (16.4 feet) wide. Oh, stick with standard Falcon 9. Cost saving for launch vehicle would be less than additional cost for a custom upper stage.

RobertDyck · 2014-03-02 23:15:54

GW Johnson wrote:

If instead you use chemical propulsion, then you have a plethora of propellant tanks, and that stack of tanks can serve the function of the truss, without a need for any truss at all.

Not a good idea. We need to reduce number of launches in order to reduce cost. My mission plan:

First mission:
· 1 SLS Block 2 for MAV
· 1 SLS Block 2 for lab & pressurized rover
· 1 Falcon 9 for ITV
· 1 SLS Block 1 for TMI stage
· 1 Falcon 9 for lander & unpressurized rover
· 1 Falcon 9 for Dragon
· 1 Atlas V 402 for Dream Chaser (return crew from ISS)

Second mission:
· 1 SLS Block 2 for MAV
· 1 SLS Block 2 for lab & pressurized rover
· 1 SLS Block 1 for TMI stage
· 1 Falcon 9 for lander & unpressurized rover
· 1 Atlas V 402 for Dream Chaser

Third mission:
· 1 SLS Block 2 for MAV
· 1 SLS Block 1 for TMI stage
· 1 Falcon 9 for lander & unpressurized rover
· 1 Atlas V 402 for Dream Chaser

When I say "SLS Block 2" that includes the full size upper stage, but could use 5-segment SRBs instead of advanced boosters.
If you use the Dragon to return crew from ISS, then delete the Atlas V 402 and DreamChaser from each mission, but add 1 Falcon 9 and Dragon for missions 2 & 3.

To compare number of launches with Mars Direct, delete the separate lab and SLS to launch it. My mission plan pre-lands the lab with a backup food supply. If everything goes well, the hab will provide life support to the lab. If the hab fails, then the pressurized rover can supply the lab. This makes the lab a backup hab. You would have to remove all lab equipment to use it as a hab, and the pressurized rover couldn't go anywhere, but that is an option. An extra layer of backup. And landing each mission at the same spot means the third mission will have 2 labs, 3 habs, 2 pressurized rovers, and 3 unpressurized rovers.

Last edited by RobertDyck (2014-03-02 23:38:19)

Quaoar · 2014-03-03 05:01:46

GW Johnson wrote:

Quaoar:
Thanks, I had never seen that NASA report before. Amazing how they came to the same conclusions I did: 4 rpm, 1 full gee, and an end-over-end spinning baton as both stable and (at least a bit) maneuverable while spinning.
The truss they used is an artifact of the nuclear-electric propulsion they assumed. There's not a plethora of propellant tanks, but you need connecting structure to make the baton shape.
If instead you use chemical propulsion, then you have a plethora of propellant tanks, and that stack of tanks can serve the function of the truss, without a need for any truss at all. If you are clever with your stack-up of those tanks, you can stage-off empties and still maintain overall length, just at reduced mass and (to a much lesser extent) mass moment of inertia.
This kind of thing just does not integrate hardly at all with direct-landing or aerocapture designs. Unfortunately. But, I think it solves so many other problems, that it's worth the extra propellant. Just my opinion.
GW

Why not send every module of your ship in Earth-Moon L2, by a solar-electric space-tug?
It's almost a year spiral trip with two 40 meter diameter 790 KW mega-flex solar array and 50 km/s electric propulsion (all the tug can be stoved in a 5 x 25 m cylindrical module). When your ship is assembled, the crew can reach it with an Orion or a Dragon Rider: starting from L2, the inserction in a Mars trasfer orbit is less than 1 km/s of delta-V.

Another option may be to protect the belly of every module and reinforce the docking joints to support aerobraking: starting from L2 your ship is shorter (it's also possible to have one full gee with 35 m radius and 5 rpm: not very comfortable but astronauts can adapt) and I think it's factible. Protecting the belly will add almost 14% of mass but it will save a much more propellant.

Last edited by Quaoar (2014-03-03 05:15:14)

Tom Kalbfus · 2014-03-03 16:40:53

RobertDyck wrote:

It's a long time since I worked out masses. Energia with it's upper stage can throw 35,680kg to C3=0 (TLI), or 31,091kg to C3=10, or 17,446kg to C3=50, or 8,006kg to C3=100. Interpolating, it should throw 29,090kg to C3=15 (TMI). Since it's interpolated, round off to 29 metric tonnes. So that's what I considered the budget for launch mass from Earth for the MAV. Same for the lab and pressurized rover, pre-landed. The US hab would have been launched by Shuttle, I don't know launch weight, but the Shuttle could carry 16,050kg to ISS. Dragon CRS (cargo version) has a dry mass of 4.2kg plus 1.227kg of propellant, the trunk with solar panels 681kg, so 6.108kg plus furniture and life support. ADEPT heat shield for aerocapture. Mars Direct estimated the heat shield mass as 5.26 metric tonnes. That's for atmospheric entry, not just aerocapture, but let's use that mass anyway. So as a very rough estimate, 27.418 metric tonne from Mars orbit, not including TEI stage. From Earth orbit, add something for lander and unpressurized rover.

Working with Russia is a little problematic, as Putin seems more intent on conquering land on Earth than in conquering space. Russians have been operating in space for a while, seems a pity that they are an imperialist expansionist power. Not the Russian Cosmonauts fault of course. Remember the Movie 2010 A Space Odyssey? I wonder what's going on in the ISS at this very moment as the powers on Earth clash.
Even more unfortunate if there were to be a Ukrainian crew member!

RobertDyck · 2014-03-03 17:57:52

Yea, I've been watching the news. There's a very large Ukrainian community here in Winnipeg. Many of their ancestors came here when Stalin invaded. Not sure what to say. Could a Canadian offer about space exploration convince him to give up on Ukraine? Probably not. Small potatoes. Russia has a major navy base in Crimea. All pipelines but one that deliver Russian natural gas to Europe go though Ukraine. One does go through Belarus and Poland to east Germany. One CBC business reporter suggested the pipelines are why Europe is so interested. This really screws up any plan to use Energia.

I would like them to get along; remember the liquid boosters for Energia are manufactured in Ukraine. They were a major part of Soviet Union's aerospace industry. Antonov made many Soviet air force planes. The Antonov An-225 Mriya was built there, used to deliver tanks for Energia's core stage to Kazahkstan. The tanks were made at the same factory that makes Soyuz rockets. I'm sure Putin is determined to ensure Ukraine remains in Russia's sphere. He's probably worried about another Georgia debacle.

::Edit:: Before An-225 was built, they transported Energia fuel tanks with a modified bomber: Myasishchev VM-T (Vladimir Myasishchev – Transport), based on the M-4 bomber. According to Wikipedia, two were built, Russia still has them. The aircraft factory is in Reutov, near Moscow. But I'm sure Russia would prefer to use the An-225.

Last edited by RobertDyck (2014-03-04 01:59:05)

Tom Kalbfus · 2014-03-04 07:27:45

I wonder how many people they could send to Mars for the cost of conquering Ukraine. As I recall Russia sold Alaska to the United States, they were always more interested in conquering their neighbors than in settling distant lands or planets. The Soviet space program was always designed to generate propaganda for the purpose of taking over the Earth, more so than conquering space. Russia could have landed men on the Moon after the Apollo Program ended, but didn't. I guess the important thing to them was beating the United States, rather than colonizing the Moon. it was cheaper for them to orbit space stations.

Terraformer · 2014-03-04 09:30:35

Don't forget, that was the US plan as well...

RobertDyck · 2014-03-04 09:38:10

The vast majority of citizens of the United States lost interest after Apollo 11. By Apollo 13 it didn't get much coverage. Only the disaster got people watching again. They landed an unmanned rover in 1970. The lander Luna 17 landed rover Lunokhod 1. I didn't know about it until recently. And I watched live on TV the last two missions of Mercury, all of Gemini, and all of Apollo through Apollo 17, Skylab, and Apollo-Soyuz. It operated from November 10, 1970, through September 14, 1971. That endurance record stood until Spirit & Opportunity. After they lost the race to the Moon, they wanted to put humans on Mars. But their first unmanned probes failed. So they decided to build space stations first, to develop long duration space technology before going to Mars. Good idea, but they lost interest, never did proceed on to Mars.

Yea, the race to the Moon was a stunt to impress allies. The first satellite was Sputnik, launched on an ICBM. Scientists wanted a satellite, but world leaders saw this as a demonstration that they could drop a nuclear bomb anywhere on the world. It also demonstrated technology prowess. They did win countries to their side. The US tried to compete, but every time the US attempted to achieve anything first, the Soviet Union did it first. The first human in orbit. The first space walk. The first spacecraft with two crew. The first woman in space. The first rendezvous between two spacecraft. JFK said: "We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too." When he said that, he meant it literally. That goal was one that would take so much time, and so hard, that the Soviet Union couldn't just beat them to it. And it worked. Apollo 8 was supposed to be an unmanned flyby of the Moon to test hardware. Apollo 9 would be the manned flyby. But as they were preparing Apollo 8, the Soviet Union prepared to send a single Cosmonaut in a Soyuz launched on a Proton rocket. They had difficulty get their N1 rocket to work, their equivalent to Saturn V, so this flight would send a single Cosmonaut in a Soyuz with no orbital module, and life support that would normally go in the orbital module fitted into the descent module space that would normally have the other two seats. But it would include the full service module, the one intended to fly to lunar orbit and back. American spies learned of this, so NASA asked astronauts for volunteers. They said flying in Apollo 8 would be extremely risky, with untried untested equipment. But the Soviets had beat them to every "first" so far. So they wouldn't select anyone, they wouldn't ask anyone to go on a suicide mission. Absolutely every astronaut volunteered. It worked. Apollo 8 was the first achievement that American did "first".

Before you criticise the Russians, remember that Nixon cancelled Apollo. He was the third candidate. He didn't have the Republican nomination. But he campaigned on a promise that he had a secret plan to end the Vietnam War early. American citizens were so eager to end that war, that they elected him. After elected they saw what his plan was: raid NASA's budget, give the money to the military. That didn't work at all. But NASA was gutted, and never did recover. Nixon considered space to be a ridiculous stunt.

So today, how do we convince Russia to pull out of Ukraine? The CBC anchor man said there is actually very little at stake, that no one wants to take the Russian navy base away from them. Perhaps that's the key. The rest of the world will panic if Russia attempts to annex Crimea. This could get very very bad. But if this is just about the navy base, then just give Putin assurance that no one will take it away. He can have that base, but Ukraine keeps Crimea.

Terraformer · 2014-03-04 12:21:07

To be honest, it's looking like the Crimeans will keep Crimea, and it's up in the air as to whether it will be Ukrainian Crimea, Russian Crimea, or Independent Crimea. This is, from what I can tell, more like the South Ossetian conflict than anything else. Nothing really changed seven years ago, so why would it now?

/treading on eggshells

Be very careful, here. Do we have free chat again?

RobertDyck · 2014-03-04 12:43:43

Um, well, this discussion thread is supposed to be alternate mission plans for Mars. I described mine back on page 2. The mass I gave above in #283 is for Robert Zubrin's Mars Direct hab. Only one unpressurized rover, no pressurized one, no RCS thrusters (done by the ITV), etc. I had moved the lab to a separate lander, replaced aluminum-lithuium alloy with an inflatable, and deleted any micrometeoroid shield from the surface hab. Just use inner pressure membrane(s), Tennara architectural fabric for the outer layer instead of Orthofabric, and thermal insulation optimized for the atmosphere of Mars. All that was to fit within the launch mass of Energia. I would have to calculate that mass again. But right now it looks like we won't have access to Energia. If we use SLS instead, then we could use a metal wall hab.

GW Johnson · 2014-03-04 13:48:28

Hmmmm. These hab modules y'all are discussing sound like landers to me, just once down and maybe once back up.

Whether you need the full space allottment per person would depend upon stay length on the surface. But, for around a year, I'd say yes, you need it.

If one uses 90 cu.m per person and a crew of 4, that's 360 cu.m of unobstructed pressurized space. Assuming such space is 25% obstructed with equipment or propellants, that's about 500 cu.m of vehicle. Assuming a cylinder of L/D=2, that's a vehicle 7 m in diameter and 14 m long. Plus its propulsion, or a separate ascent vehicle. That's awfully big.

What if you built a smaller lander and brought a big inflatable with you for surface use? I know multiple payloads might be landed at the same site, if you have working homing capability during the hypersonics, and during the descent after hypersonics are over (not really available with chutes, but these things are too big for chutes anyway). Missing the target, collisions, and rocket blast damage are all serious issues with multiple vehicles to be landed at a single site.

This notion of landing direct does put some serious constraints on what you design, if you intend to meet the living space criteria we were discussing here earlier. If you do not meet them, you have well-known health concerns to address. This can get quite serious.

GW

RobertDyck · 2014-03-04 14:18:53

I already addressed that. Any number is plucked out of thin air (pun intended). So I ignore numbers for cubic metres per person. What is important, is private space, communal space, etc. That has already been addressed.

"Too big for chutes"? Not at all. As I said in #283 above, the NASA paper for ADEPT already worked out total mass for landing systems, for 40 metric tonne landed payload. My design required half that landed mass. If you want to argue further, read the ADEPT paper. It has a simple graphic with mass for each entry, descent, and landing method. I summarized in #283.

Landing separate modules that have to be brought together? Rocket blast is a valid concern. That's why Mars Direct lands its hab walking distance from the ERV. Its inflatable greenhouse is brought with the hab, erected after landing. My design split the hab: lab and hab. One reason for using inflatables is they can be moved before erecting/inflating. So the lander with crew and hab can land farther from the lab. Even with a hard wall hab, then we could leave the lab deflated/folded so it can be dragged over before erecting.

The lab provides another level of redundancy. The lab could be used as a hab. The lab wouldn't have separate life support, but the pressurized rover would. How big with a pressurized rover have to be for recycling life support? What range would that give?

Last edited by RobertDyck (2014-03-06 13:18:14)

SpaceNut · 2014-03-05 20:16:18

The different ISS modules all stacked to make up the Mars Lander reminds me of The Space X GrassHopper....

Grasshopper was announced in 2011 and began low-altitude, low-velocity hover/landing testing in 2012. The initial Grasshopper test vehicle—the 106 ft (32 m) -tall Grasshopper v1.0—made eight successful test flights in 2012 and 2013 before being retired.

RobertDyck · 2014-03-16 13:05:15

As I write this, Crimea is voting for the referendum to join Russia. Looks like cooperation with Russia isn't an option. So Energia is not available.

Some here have raised concern that SLS is expected to be expensive. So what's the alternative? My mission cannot really be split into pieces small enough to fit on Falcon Heavy (aka Falcon 9 Heavy), so what else? This article talks about proposals for Falcon X Heavy and Falcon XX. While Falcon 9 uses Merlin 1D engines, with 9 engines per core, Falcon X would use Merlin 2 engines, 3 per core. Falcon X Heavy would have 3 cores. And Falcon XX would have a single core, but much bigger with 6 Merlin 2 engines. This would give Falcon X Heavy 125 metric tonne lift to LEO, and Falcon XX would have 140 tonne. Instead of SLS, my mission plan could use either Falcon X Heavy or Falcon XX.

Note: This is from 2010. Falcon 9 Heavy today is able to lift 53 tonnes to LEO, or 13.2 tonnes to trans-Mars trajectory. According to the SpaceX website. The reason is Falcon 9 now has a taller core, so larger fuel tank.

Using mass ratio for landing using ADEPT for aerocapture, parachute, subsonic retrothrust, terminal descent and landing, a single Falcon 9 Heavy could land 6.77 metric tonnes on Mars.

Last edited by RobertDyck (2014-03-16 14:02:38)

RobS · 2014-03-16 13:33:10

I think Musk agrees with you, Robert: he wants to settle Mars and Falcon Heavy isn't big enough. He said he'd develop the bigger rocket if there was demand. Sounds like there might be, based on his success. The launch of the first Falcon Heavy is delayed because they can't produce and launch Falcons fast enough to meet demand! They are planning to double production in the next year and will open another spaceport--probably Brownsville, Texas--in a few years, so they can launch from three spaceports. If they can reuse 2 of the 3 cores of the Falcon Heavy, which may be possible in a year or two, that will reduce the cost of launching Falcon Heavys even more and increase their sales further.

Quaoar · 2014-03-18 02:12:39

RobertDyck wrote:

The reason is Falcon 9 now has a taller core, so larger fuel tank.
Using mass ratio for landing using ADEPT for aerocapture, parachute, subsonic retrothrust, terminal descent and landing, a single Falcon 9 Heavy could land 6.77 metric tonnes on Mars.

Using Falcon H the only possibility is using orbital docking to build a bigger spaceship: a surface hab has to be 5 x 13 meters and has to dock with the ADEPT and with the TMI stage before leaving. The same for the ERV.

Another possibility is using belly lander slander body biconc vehicles.

For example, with three launch of Falcon H, we can put an ERV in low Mars orbit:

1) biconic ERV, 12 tons of dry mass and 40 tons of N2O4-MMH (pressur feed rockets 3.175 km/s Vex like Astrium Aestus) delta-V = 4.6 km/s
2) reusable I stage: 2 tons of dry mass 50 tons of N2O2-MMH
3) reusable II stage: 2 tons of dry mass 50 tons of N2O2-MMH

1) ERV, I and II stages dock in LEO
2) I stage fire, insert ERV and II stage in a 5000 km apogee elliptical orbit (delta-V = 1 km/s), detatch and return in LEO via aerobraking
3) II stage fire and isert ERV in a 100000 km apogee HEO (delta-V = 2 km/s), detatch and return in LEO via aerobraking
4) ERV fire and isert in a MTO (delta-V = 1 km/s), aerobrake and insert in LMO.

Last edited by Quaoar (2014-03-18 07:41:03)

RobS · 2014-03-19 06:54:18

An interesting new article about NASA's SLS: http://www.space-travel.com/reports/Spa … t_999.html

I'll paste it below. Note last three paragraphs in particular about the politics of the SLS:

Space Launch System - Who Needs It
by Staff Writers
Bethesda MD (SPX) Mar 19, 2014

File image.
NASA's Space Launch System (SLS) is a Space Shuttle - derived heavy launch vehicle developed for future human space exploration. Launchspace engineers think of it as the Phoenix of cancelled Constellation Program launch concepts. As you will recall, retirement of the Space Shuttle coincided with a replacement family of two launch vehicles, the Ares I and the Ares V.

The Ares I development got as far as a single demonstration launch of the SRB-based first stage with a dummy second stage. This was known as the Ares I-X launched on October 28, 2009. However, the Ares I design was plagued with a number of serious flaws that had been aired by NASA, Launchspace and others.

Design challenges included excessive longitudinal vibrational amplitudes, extreme structural sensitivities to transverse loads during ascent, stability and control complications and significant redesign of the Shuttle's Solid Rocket Boosters (SRBs) to fit the Ares I First Stage mission requirements.

All this and the additional complications of huge cost overruns and the required in-orbit rendezvous with a cargo ship (Ares V) for missions beyond low earth orbit (LEO). In summary, it proved to be an unmitigated engineering and economic disaster.

Mercifully, President Obama cancelled the Constellation Program and signed the NASA Authorization Act of 2010 which transformed the Ares I and Ares V vehicle designs into a single launch vehicle that would be usable for both crew and cargo launches. The embodiment of the single launcher is the SLS.

The early version (Block I) will not carry an upper stage, but is projected to lift up to 70 metric tons to LEO. Block II is intended to include an integrated upper Earth Departure Stage (EDS) with a lifting capacity of at least 130 metric tons to LEO. This is 12 metric tons more than the Saturn V could carry. Thus, if SLS Block II is built it will represent the most capable launch vehicle ever built.

The SLS with the EDS would be capable of lifting astronauts and hardware beyond LEO to other near-Earth destinations such as asteroids, the Moon, Mars and Earth's Lagrangian points. SLS could also support trips to the International Space Station (ISS), but such missions are expected to be fulfilled by commercial space operators, such as Orbital Sciences and SpaceX.

The SLS program does not include the crew quarters. However, NASA is separately developing the Orion Crew and Service Module which will be integrated with the SLS at the launch site. Astronauts will return to earth in a capsule-shaped, four-person crew module. SLS will operate out of NASA's Kennedy Space Center, Florida. The first flight-test of the Block I SLS is scheduled for 2017.

There has been a great of push back from several groups, claiming the SLS and human spaceflight beyond ISS are not needed and cannot be justified. However, as one space industry publication puts it: As long as Sen. Richard Shelby is alive, NASA will build the SLS, because the space agency needs the Alabama Republican, (ranking member of his party on the Senate Appropriations Committee) and Shelby needs the SLS to keep his constituents at the Marshall Space Flight Center (MSFC) happy.

Thus, SLS funding will continue at an annual level of about $1.3 billion, with some added advanced-technology money.

In the meantime, MSFC is pursuing ways to broaden its constituent base, but so far has not announced any good news. To further weaken the SLS case a recent analysis by the Air Force and National Reconnaissance Office (NRO) offered no mission requirements for a Saturn V-class launch vehicle. Given the expected costs of using the SLS and the limited justification for such a capability, it is difficult to be optimistic about its future.

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