Dragon Direct.

Oldfart1939 · 2017-04-28 09:12:43

We've all been spouting our proposals for a new Mars mission architecture for a long time. Everything has been based (by some!) on the now middle aged Mars Direct proposal made by Dr. Robert Zubrin back in 1990. That "tuna can"concept is now 27 years old, and we've all been making suggestions for an update.

Everyone here should order up Dr. Zubrin's latest small book "Mars Direct." In it, he discusses the recent state of NASA and it's political failings. He thoroughly analyzes the VASIMR concept and refers to it as "the VASIMR Hoax." But most importantly, he exhibits his knowledge and enthusiasm for SpaceX and introduces what he has named "Dragon Direct." He briefly outlines the new Mars mission made possible using the Falcon Heavy and incorporates many of the ideas expounded here on our website. Too much to reiterate here, so I suggest we support Dr. Zubrin by buying the book. Available on Amazon in Kindle format for about the price of a sixpack of decent beer. I guess that this isn't the latest word, so to speak, since the falcon Heavy payload to LEO has increased by 11 metric tonnes since it was written. This proposal incorporates 3 Falcon Heavy launches and sends a crew of 2 to Mars for an 18 month stay.

Last edited by Oldfart1939 (2017-04-28 09:15:01)

RobS · 2017-04-28 15:46:54

Can you give us a link?

Oldfart1939 · 2017-04-28 16:01:12

Link to Zubrin's Mars Direct. This is the Kindle format.

https://www.amazon.com/Mars-Direct-Expl … ert+zubrin

SpaceNut · 2017-04-28 18:49:38

One of the biggest challenges for the effective exploration and exploitation of space has been the high cost of space access.

Colonizing Mars: A Critique of the SpaceX ITS by Robert Zubrin

http://www.thenewatlantis.com/publicati … izing-mars

“Elon is a Hero” Says Mars Society President, Robert Zubrin

The race to Mars: here's how SpaceX ranks against the competition Who will get to the Red Planet first?

A transorbital railroad to Mars

SpaceX Wants to Go to Mars. Here’s Why Humans Aren’t There Yet.

RobS · 2017-04-29 14:01:07

I'm inclined to think Musk has thought through his plan a lot more thoroughly than Zubrin thinks. Musk is thinking much farther ahead than Zubrin, and Zubrin is still mired in some of his assumptions. Zubrin wants to leave the interplanetary transport on Mars as a habitat; Muskl considers that a waste of $100 million because its cheaper to build housing on Mars (that's his assumption) and he wants to fly the habitat home.

Oldfart1939 · 2017-04-29 16:47:58

RobS-

I think we have something of a disconnect here, since Zubrin is talking a Mars mission ASAP. No doubt there ill be rapid expansion and upgrades to said mission; a second mission will undoubtedly be much larger. Getting human on the planetary surface is important, no matter the mission architecture.
That said, I can understand why Musk would want his $100,000,000 spaceship home.
Realistically there should be some sort of intermediate design as upgraded proof of concept by SpaceX. In my mind, that should have a crew of 10 to 12.

Tom Kalbfus · 2017-04-29 19:40:58

Problem is, if you give up your spaceship to have a house on Mars, you have to build a brand new spaceship to launch the next group of colonists, if you reuse that spaceship, then you don't have to build a brand new spaceship to get that next bunch of colonists over to Mars, the amortize the cost of the spaceship (all of its reusable stages and components) over the total number of trips it can make, if you sacrifice the spaceship so the colonists have a home on Mars, you make the trip that much more expensive as you are forcing the colonists to buy the whole spaceship in order to get to Mars instead of just one trip on that spaceship. I think Zubrin is still operating on the throwaway mindset.

RobertDyck · 2017-04-30 05:59:07

Just finished reading Robert Zubin's book "Mars Direct". It was published 2013, so a little out of date already. It goes on a tirade about the Obama administration, both space related and not, others have recommended against buying that book for that reason. Frankly, I skipped the last half of that chapter. And it's really small, not a full book like his other books, this is just a pocket book: 4" x 6" and 100 pages. But the reason Oldfart1939 wanted us to read it is the new mission plan.

The plan in this book uses Falcon Heavy to launch Dragon. Based on Mars Semi-Direct, but reduced for only 2 crew members. One launch would send a Dragon spacecraft with an inflatable habitat extension: 6 meter diameter x 8 meter long, 2 deck. This would be sent with a propulsion stage that uses LCH4/LOX, and park in high Mars orbit. Mars Semi-Direct calls this the Interplanetary Transit Vehicle (ITV) but in this book Robert Zubrin calls it ERV. Then send another vehicle to be used as MAV, only intended to launch from Mars surface to the ERV in high Mars orbit. It would bring a full LCH4 tank from Earth, but make LOX on Mars from the atmosphere. It would require a 10 kWe power supply, either solar or nuclear. The MAV would not use Dragon, instead Zubrin proposes a vehicle that would have the same dry mass as the ascent stage of the Apollo LM: 2 tonne (metric ton). The MAV would include 3 tonnes of surface exploration gear. Once both of these are in place, a third Falcon Heavy would launch crew. The crew would ride in another Dragon spacecraft, with another inflatable, again 6m diameter x 8m long, 2 deck. Artificial gravity during transit to Mars with a tether connecting this Dragon+inflatable to the spent upper stage. He claims it can carry 2,500kg of consumables, including food and life support supplies. He claims this is so much that the crew vehicle can include a light ground vehicle and several hundred kilograms of surface science instruments. He also states that the inflatable is so light that if the in-space inflatable can't be collapsed for landing, then a second inflatable could be carried as surface hab.

I have concerns with this. First it's only 2 crew. And this plan abandons ISPP, only producing LOX in-situ for the MAV. And I question his estimate of the mass of the inflatables. TransHab or Bigelow habs use multiple layers for micrometeoroid shield. They have a firm outer fabric, then a foam spacer, then ballistic Kevlar similar to a bullet-proof vest. The outer fabric causes micrometeoroids to break up, the spacer allows them to separate, then the Kevlar stops them. This sandwich is duplicated 3 times. Then there's the Kevlar pressure bladder, 3 bladders for redundancy, a restraint layer around the bladder to hold it in shape, and an inner "scuff" layer to ensure astronauts don't puncture the pressure bladder. And outside there's a thermal blanket. All this has mass, it's significant.

This plan includes both a surface rendezvous, and orbital rendezvous. His criticism of my plan is that it includes the same two rendezvous. My plan would use a reusable vehicle to transit from Earth orbit to Mars orbit and back to Earth orbit. It's less expensive for multiple missions because you don't need to replace that hardware. And we've seen with Apollo that missions using expendable hardware are very easy for politicians to cancel, while Shuttle demonstrated reusable hardware is difficult to cancel.

Last edited by RobertDyck (2017-05-06 11:38:31)

Tom Kalbfus · 2017-04-30 07:13:50

These two vehicles have much in common. They are both reusable. Von Braun relied on gliders to return his stages on his proposed vehicles in 1956, the ITS relies on landing rockets. The early mission Von Braun proposed as before he abandoned the idea of reusability as impractical, but reusability lowers costs of transportation into space if done right and allows for much grander mission proposals.

louis · 2017-04-30 08:14:51

I like a lot of the elements of the Zubrin plan. However, doesn't sound like it makes extensive use of pre-landing in a zone marked by transponders. I like the idea of a separate Apollo-style MAV. It could perhaps be reusable.

A two person mission sounds unnecessarily risky to me. One person gets ill, breaks a leg, or suffers a serious burn, then you have a major problem with the whole mission viability. I see no reason why we can't run with 6 in 2 x 3 approach.

Not a fan of the tethered AG. Imagine how long NASA would take to design and test that!

I agree with you on the merits of a reusable transit vehicle.

RobertDyck wrote:

Just finished reading Robert Zubin's book "Mars Direct". It was published 2013, so a little out of date already. It goes on a tirade about the Obama administration, both space related and not, others have recommended against buying that book for that reason. Frankly, I skipped the last half of that chapter. And it's really small, not a full book like his other books, this is just a pocket book: 4" x 6" and 100 pages. But a the reason Oldfart1939 wanted us to read it is the new mission plan.
The plan in this book uses Falcon Heavy to launch Dragon. Based on Mars Semi-Direct, but reduced for only 2 crew members. One launch would send a Dragon spacecraft with an inflatable habitat extension: 6 meter diameter x 8 meter long, 2 deck. This would be sent with a propulsion stage that uses LCH4/LOX, and park in high Mars orbit. Mars Semi-Direct calls this the Interplanetary Transit Vehicle (ITV) but in this book Robert Zubrin calls it ERV. Then send another vehicle to be used as MAV, only intended to launch from Mars surface to the ERV in high Mars orbit. It would bring a full LCH4 tank from Earth, but make LOX on Mars from the atmosphere. It would require a 10 kWe power supply, either solar or nuclear. The MAV would not use Dragon, instead Zubrin proposes a vehicle that would have the same dry mass as the ascent stage of the Apollo LM: 2 tonne (metric ton). The MAV would include 3 tonnes of surface exploration gear. Once both of these are in place, a third Falcon Heavy would launch crew. The crew would ride in another Dragon spacecraft, with another inflatable, again 6m diameter x 8m long, 2 deck. Artificial gravity during transit to Mars with a tether connecting this Dragon+inflatable to the spent upper stage. He claims it can carry 2,500kg of consumables, including food and life support supplies. He claims this is so much that the crew vehicle can including a light ground vehicle and several hundred kilograms of surface science instruments. He also states that the inflatable is so light that if the in-space inflatable can't be collapsed for landing, then a second inflatable could be carried as surface hab.
I have concerns with this. First it's only 2 crew. And this plan abandons ISPP, only producing LOX in-situ for the MAV. And I question his estimate of the mass of the inflatables. TransHab or Bigelow habs use multiple layers for micrometeoroid shield. They have a firm outer fabric, then a foam spacer, then ballistic Kevlar similar to a bullet-proof vest. The outer fabric causes micrometeoroids to break up, the spacer allows them to separate, then the Kevlar stops them. This sandwich is duplicated 3 times. Then there's the Kevlar pressure bladder, 3 bladders for redundancy, an restraint layer around the bladder to hold it in shape, and an inner "scuff" layer to ensure astronauts don't puncture the pressure bladder. All this has mass, it's significant. And outside there's a thermal blanket.
https://upload.wikimedia.org/wikipedia/commons/thumb/5/53/TransHab_shell_cutaway.jpg/170px-TransHab_shell_cutaway.jpg
This plan includes both a surface rendezvous, and orbital rendezvous. His criticism of my plan is that it includes the same two rendezvous. My plan would use a reusable vehicle to transit from Earth orbit to Mars orbit and back to Earth orbit. It's less expensive for multiple missions because you don't need to replace that hardware. And we've seen with Apollo that missions using expendable hardware are very easy for politicians to cancel, while Shuttle demonstrated reusable hardware is difficult to cancel.

Oldfart1939 · 2017-04-30 08:48:31

Based on more recent estimates by SpaceX, the Falcon Heavy can now deliver 63.8 Metric Tonnes to LEO, nearly an 11 Tonne increase. This makes the Zubrin plan seem more realistic, but the architecture I offered on another thread seems to have been a modification of this latest Mars Direct plan. I strongly disagree with a 2 person mission, since it's only a slight improvement from a one way suicide mission. I agree with Louis about the potential for illness, accident, or some sort of mishap dooming the undertaking. That 11 Tonne payload increase should be utilized for more food, and a third (if not a fourth) crew member. I also thought that the crew quarters should be integral with the spaceship.

RobertDyck · 2017-04-30 11:26:29

Oldfart1939 wrote:

Based on more recent estimates by SpaceX, the Falcon Heavy can now deliver 63.8 Metric Tonnes to LEO, nearly an 11 Tonne increase.

Be very careful about these numbers. Remember that's when Falcon Heavy is all expendable. Mass for landing legs and propellant reserve for landing will significantly reduce launch mass. And the US standard is 185km orbit @ 28º inclination.

Oldfart1939 · 2017-04-30 12:40:39

Robert-

The 63.8 metric Tonnes is directly from the SpaceX website, which was the source listed for the earlier 53 Tonnes. SpaceX plans include use of previously flown Falcon 9 rockets as the 2 booster stages this coming July. We never know exactly what SpaceX is capable of doing until the present us with astounding results.

SpaceNut · 2017-04-30 14:06:57

I see several issues for the dragon inflateable not only from the stand point that dragon will need hugh modification but also for the inflateable as well since the ends are the hatch location and not its sides as we would use to enter and exit via.

Falcon heavy full up not reuseable mass to orbit includes a second stage mass with fuel, the interchange collar, the truck plus capsule fully fueled and then the roughly 5mT payload mass.

https://en.wikipedia.org/wiki/Bigelow_E … ity_Module

It was inflated from its packed dimensions of 2.16 m (7.1 ft) long and 2.36 m (7.7 ft) in diameter to its pressurized dimensions of 4.01 m (13.2 ft) long and 3.23 m (10.6 ft) in diameter. The module has a mass of 1,413.0 kg (3,115.1 lb), and its interior pressure is 14.7 pounds per square inch (1 atm), the same as inside of the ISS. Or in english BEAM is expanded from its packed dimensions of 5.7 feet long and just under 7.75 feet in diameter to its pressurized dimensions of 13 feet long and 10.5 feet in diameter. .

https://blogs.nasa.gov/spacestation/201 … full-size/

NASA Astronaut Jeff Williams and the NASA and Bigelow Aerospace teams working at Mission Control Center at NASA’s Johnson Space Center spent more than seven hours on operations to fill the BEAM with air to cause it to expand. Williams opened the valve 25 times today for a total time of 2 minutes and 27 seconds to add air to the module in short bursts as flight controllers carefully monitored the module’s internal pressure. Time in between bursts allowed the module to stabilize and expand.

This is what it looks like once we have people in it...

RobS · 2017-05-05 16:26:23

I just got my copy of Zubrin's little book "Mars Direct." Don't bother to buy it. 90% of it has been published on the web before, including his proposal to use 3 Falcon Heavy launches to send two people to Mars. It's an old proposal. The heavier payload of the Falcon Heavy does help, but Zubrin also called for use of a hydrogen stage to push everything to Mars and that doesn't exist. If you used kerosene and LOX you'd probably be right back to the 17.5 tonnes Zubrin used as his baseline. Maybe you could stick a Centaur stage on top, though?

The rest of the book consists of a collection of Zubrin's known and also already published rants against VASIMR, NASA, etc. His calculations about the "worth" of an astronaut in calculating risk is interesting.

It is too bad that Musk is skipping a small, initial form of his Mars plan and aiming to start with a huge booster. Risky; if you can't raise the money to build the thing, everything fails. And if the big booster were to blow up on launch and take out a nearby neighborhood, you'd have a huge, fatal problem.

Oldfart1939 · 2017-05-05 16:43:29

RobS-

I've stated on this forum that there needs be an intermediate step beyond the Red Dragon mission, simply as a "proof of concept." That said, Musk does NOT think small. My mission architecture calls for a scaled up falcon 9 Main stage which is 5 meters diameter and has an additional 7 Merlin 1-D engines, combined with 4 previously-flown Falcon 9s a boosters. My calculation would put 116 metric tonnes into LEO, and go from there.

Terraformer · 2017-05-06 04:10:40

I wonder if Musk is thinking about ocean launch for the MCT rocket? The rocket most similar in payload that has previously been proposed is Sea Dragon, which would have used an ocean launch. On the other hand, the animations released show it taking off from the ground and landing back on the ground.

I think there will be deep space human missions flown by Falcon Heavy (well, we *know* there'll be at least one, planned for next year), but it might not be Mars. If SpaceX puts together a plan for a Lunar base, they might be able to sell it to the United States, and use that to gain some deep space experience (funded by NASA) in preparation for a Mars mission?

Oldfart1939 · 2017-05-06 10:25:24

Just "wondering out loud," but Musk earlier proposed a 6 meter diameter Falcon X vehicle which essentially embodied parts of my proposal. Did SpaceX really abandon that concept, or are they holding their cards close to the vest? There's a small upgrade possible for the Falcon Heavy by means of a different propellant for the 2nd stage: UDMH and LOX. That would have better Isp than simply using RP-1, in addition to better freezing resistance. If UDMH is used in all stages, the performance upgrade is about 6%.

Terraformer- I suspect no ocean departure is planned by SpaceX, since they've spent lots of $$$ leasing and refurbishing SLC 39 & 40.

Last edited by Oldfart1939 (2017-05-06 11:08:59)

SpaceNut · 2017-05-06 20:28:45

For a mars landing and ascent vehicle that could be reuseable why not go for a larger diameter as that would make that first step from the top of the capsule to the ground a bit lower for sure. Since being a skinny diameter makes the stage very tall....

Right now for mars we have zero methane engines for the Insitu propelant manufacturing to make use of, granted the raptor is but its not even in production or use yet. All other long term fuels we are not making on mars from insitu so we are left initially as throw away when it comes to a mars lander.....

Oldfart1939 · 2017-05-07 16:06:42

SpaceNut-

One of the recent architecture suggestions includes abandoning the Methane ISRU on Mars, but replenishment of the LOX by means of the Moxie system. LOX accounts for 75% of the propellant mass for the MAV. Using one of the several Hydrazine variants would work well: UDMH, MMH, Aerozine 50, and there's also a 25% UDMH-Hydrazine mixtures. None of these are troubled by boil off issues.

SpaceNut · 2017-05-07 20:15:53

So lets assume that we are landing the newly designed compensated Dragon for the fuels. Were is the ascent hydrazine variants coming from as we did not have that kind of down mass in a dragon plus any crew, so we must be in payload preload again just to make a single trip possible. The distance to where the fuel and the tanks to be reloaded are, then Next will be the fuel transfering process in that its something we have not been doing with this type of fuels.

If this was the newly altered Falcon 9 for this fuel what would we need to alter?

So mars sized falcon 9 is 32.5 m tall for a dragon plus truck of 8.1 m with a first stage 17.7 m with fuel/oxidizer of 30 t with a second stage that is 6.7 m tall and fueled with 18.8 t of which we would need to land with the second stage empty and a bit large fuel fill for the first stage for th combined landing attempt.

Seems like we could make this a single stage to orbit with the 9 vacuum engines. 3.7 m diameter to the more practical 10 m to make the stages shorter as well.

With this long post we can see that for mars we are only landing a stackup of no more than the hieght of the current stage Falcon 9 for the entire mars lander. Which is a small 40 m tall at the 3.7 m diameter but if we go to the 10 m diameter then we are looking at something under 15 m tall. That said 4 engines for a complete single stage to orbit would seem to be correct.

Oldfart1939 · 2017-05-12 17:17:29

Everyone should recall that in the original Mars Direct architecture, there was a reservoir of 2 metric tonnes of Hydrogen brought to Mars to facilitate the Sabatier synthesis of Methane. My architecture essentially lands some additional mass of a Hydrazine fuel and only requires Oxygen manufacture by the Moxie unit. The fuel required is for Mars orbit and not a Hohmann transfer back to Earth; an additionally fueled booster awaits in orbit. This architecture returns the spacecraft back to LEO for possible reuse.

Doing some additional literature searching yielded the information that Aerozine-50 is stable enough to allow it's use in regeneratively cooled rocket engines.

Last edited by Oldfart1939 (2017-05-12 17:36:26)

louis · 2017-05-12 17:22:18

I agree - we need to think in terms of a short hop to LMO, not a direct flight back.

Oldfart1939 wrote:

Everyone should recall that in the original mars Direct architecture, there was a reservoir of 2 metric tonnes of Hydrogen brought to Mars to facilitate the Sabatier synthesis of Methane. My architecture essentially lands some additional mass of a Hydrazine fuel and only requires Oxygen manufacture by the Moxie unit. The fuel required is for Mars orbit and not a Hohmann transfer back to Earth; an additionally fueled booster awaits in orbit. This architecture returns the spacecraft back to LEO for possible reuse.

SpaceNut · 2018-11-25 17:33:24

We could land with the Red Dragon but it would be a one way mission from GW's numbers.
So could we build a booster stage for one on mars from space parts?

SpaceNut · 2018-11-27 20:53:27

We are going to know very soon if the crewed dragon will be up to the task....

The next space x flight is schedueled for Jan. 7 date set for first SpaceX unmanned capsule to International Space Station This is the Crew Dragon's commercial flight will be known as Demo-1 or DM-1 only with no one on board.

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#1 2017-04-28 09:12:43

Dragon Direct.

#2 2017-04-28 15:46:54

Re: Dragon Direct.

#3 2017-04-28 16:01:12

Re: Dragon Direct.

#4 2017-04-28 18:49:38

Re: Dragon Direct.

#5 2017-04-29 14:01:07

Re: Dragon Direct.

#6 2017-04-29 16:47:58

Re: Dragon Direct.

#7 2017-04-29 19:40:58

Re: Dragon Direct.

#8 2017-04-30 05:59:07

Re: Dragon Direct.

#9 2017-04-30 07:13:50

Re: Dragon Direct.

#10 2017-04-30 08:14:51

Re: Dragon Direct.

#11 2017-04-30 08:48:31

Re: Dragon Direct.

#12 2017-04-30 11:26:29

Re: Dragon Direct.

#13 2017-04-30 12:40:39

Re: Dragon Direct.

#14 2017-04-30 14:06:57

Re: Dragon Direct.

#15 2017-05-05 16:26:23

Re: Dragon Direct.

#16 2017-05-05 16:43:29

Re: Dragon Direct.

#17 2017-05-06 04:10:40

Re: Dragon Direct.

#18 2017-05-06 10:25:24

Re: Dragon Direct.

#19 2017-05-06 20:28:45

Re: Dragon Direct.

#20 2017-05-07 16:06:42

Re: Dragon Direct.

#21 2017-05-07 20:15:53

Re: Dragon Direct.

#22 2017-05-12 17:17:29

Re: Dragon Direct.

#23 2017-05-12 17:22:18

Re: Dragon Direct.

#24 2018-11-25 17:33:24

Re: Dragon Direct.

#25 2018-11-27 20:53:27

Re: Dragon Direct.

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