New Mars Forums

Official discussion forum of The Mars Society and MarsNews.com

You are not logged in.

Announcement

Announcement: We've recently made changes to our user database and have removed inactive and spam users. If you can not login, please re-register.

#1 2017-08-07 16:28:52

louis
Member
From: UK
Registered: 2008-03-24
Posts: 2,299

Space X - getting ready for Mars.

http://www.dailymail.co.uk/sciencetech/ … aunch.html

I see no signs of a rethink by Musk from this article.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

Offline

#2 2017-08-07 18:54:00

RobS
Member
From: South Bend, IN
Registered: 2002-01-15
Posts: 1,665
Website

Re: Space X - getting ready for Mars.

It is still not clear Falcon Heavy has ANYTHING to do with the Mars effort, except for being a step toward building the boosters he really wants. The media often makes a link to the Mars effort that is not accurate.

It appears Musk is redesigning the booster and the MCT, though; apparently the booster will be 9 meters in diameter instead of 12 and therefore a bit more than half as powerful. But a 9 meter booster is more likely to be used for other purposes and thus pay for itself.

Space X has also hinted about going to the moon first. Again, that really does make sense if NASA will pay. Space X's prices are low enough so we could afford both (otherwise, NASA cannot).

Offline

#3 2017-08-07 20:20:01

Oldfart1939
Member
Registered: 2016-11-26
Posts: 826

Re: Space X - getting ready for Mars.

The Original Post was pretty much a rehash of what's been on the SpaceX website for over a year. Nothing new.

RobS-Where did you get the data about the 9 meter diameter rocket?

Offline

#4 2017-08-08 07:17:45

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 10,075

Re: Space X - getting ready for Mars.

Offline

#5 2017-08-08 07:48:52

Oldfart1939
Member
Registered: 2016-11-26
Posts: 826

Re: Space X - getting ready for Mars.

OK, in other words, this is a re-run of the older Falcon XX, skipping the Falcon X. Still...a big step forward. I can find no actual reference from Elon in what I read, just some secondary speculations.

Even if this does come to pass, I have my gut feeling that it's too big a jump from Falcon 9, and Falcon X should be an intermediate step for proof of concept. Many of the biggest disasters I've seen in the chemical industry were a result of an overly ambitious scale-up. Any time one works with highly exothermic systems, and rocket motors fit that description, dealing with too much energy without steps taken to mediate the results can have appalling consequences.

On the other hand, the 9 meter concept fits nicely with the Zubrin/Baker model.

Added as an afterthought, in edit: Has anyone calculated how big an explosion would/could result from one of the BFRs would make? The amount of highly energetic material would have a near mini-nuke explosive result! I'm withholding judgment on the proposed 9 meter design. That's roughly a 6x scale up from Falcon 9 v.1.2. The intermediate case will be a Falcon Heavy, a ~3x scale up of Falcon 9. The previously proposed Falcon X was roughly the same level as Falcon Heavy without the separate boosters, and Falcon X Heavy would accomplish roughly the same as Falcon XX.

Last edited by Oldfart1939 (2017-08-08 08:02:46)

Offline

#6 2017-08-08 10:19:09

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 2,543
Website

Re: Space X - getting ready for Mars.

Falcon-Heavy supposedly can fling a payload equivalent to a loaded Dragon to Mars for a one-way direct landing.  The "best" way to do this with widest windows for a burn is to stop in LEO before trans-Mars injection. 

So,  why not assemble what you need for Mars in LEO and "launch" it from there?  What do you need a bigger rocket for anyway? 

We already know how to put together 15-ton items.  Falcon-Heavy flown expendibly can put 50-60 ton items to LEO.  Probably 30-40 ton items recoverably. 

Just asking.

GW

Last edited by GW Johnson (2017-08-08 10:20:00)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

Offline

#7 2017-08-08 10:36:28

RobertDyck
Member
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 4,872
Website

Re: Space X - getting ready for Mars.

In Should SpaceX consider using SRBs on Falcon 9?, my response was SpaceX should consider upgrading Falcon Heavy by replacing the central core stage with a new stage exactly the same size, but with LCH4/LOX and Raptor engines. And replace the upper stage with one that uses a subscale vacuum Raptor. They already tested a subscale Raptor with 1/3 the thrust of a full-size Raptor. The subscale raptor produced a tiny bit more than double the thrust of Merlin 1D, so this is a major upgrade. I said the core stage could use 9 subscale Raptors using the same octaweb they currently use (8 engines around a central engine), or 3 full-size Raptors.

Falcon 9 v1.2 (aka Full Thrust or FT) uses Merlin 1D+. That means all the upgrades as of now. Merlin 1D produced 650 kN thrust at sea level, or 720 kN in vacuum. Merlin 1D Vacuum produces 934 kN in vacuum. In May 2016 they announced their intention to upgrade Merlin 1D to 845 kN at sea level, and 914 kN in vacuum. I assume this is what they mean by "1D+".

Raptor is supposed to produce 3,285 kN at sea level, or 3,050 kN in vacuum. In August 2016 they tested a subscale engine which produced 1MN thrust (1,000 kN). Obviously that was ground level at McGregor, Texas. Presumably a subscale vacuum engine would produce more in vacuum. Currently Falcon 9 v1.2 produces 9 x 845 kN = 7,605 kN at sea level. Just 2 full-size Raptors would produce 2 x 3,285 kN = 6,570 kN at lift-off. That wouldn't be an upgrade, but 3 full-size Raptors would produce 3 x 3,285 kN = 9,855 kN. That would increase thrust at lift-off by 1.295858 times, round off for significant figures to 1.296 times. Would you say "almost 30% increase" or "29½%"?

But more importantly, Elon Musk said their target for Raptor Vacuum is Isp=382s in vacuum. However, according to Wikipedia, expected performance of regular Raptor is Isp=363s in vacuum. Merlin 1D has Isp=282s at sea level, or 311s in vacuum. Merlin 1D Vacuum has Isp=348s in vacuum. The higher Isp of Raptor would allow thrust for a greater time, accumulating greater delta-V.

I think that should be their next step. Falcon X Heavy would be great! That would have 6 metre core diameter, but able to lift payloads with 10 meter diameter. Falcon X Heavy was said to be able to lift 125,000 kg to LEO, making it perfect for the Zubrin/Baker model. But as GW Johnson said, and RobS said before, why not assemble in LEO using Falcon Heavy?

Offline

#8 2017-08-09 03:16:17

louis
Member
From: UK
Registered: 2008-03-24
Posts: 2,299

Re: Space X - getting ready for Mars.

Hi GW - My view entirely...LEO assembly has always been my favoured approach with current technology.

I think we also have to build in the politics of all this...I think Musk is savvy enough to understand he has to tread carefully balancing his statements about his Mars vision with others emphasising the current challenges in developing the technology. He has to keep NASA, the US President, Congress, China and the UN all sweet(ish).

I can't personally believe he doesn't understand the scope for putting together a Mars transit vehicle in LEO.

GW Johnson wrote:

Falcon-Heavy supposedly can fling a payload equivalent to a loaded Dragon to Mars for a one-way direct landing.  The "best" way to do this with widest windows for a burn is to stop in LEO before trans-Mars injection. 

So,  why not assemble what you need for Mars in LEO and "launch" it from there?  What do you need a bigger rocket for anyway? 

We already know how to put together 15-ton items.  Falcon-Heavy flown expendibly can put 50-60 ton items to LEO.  Probably 30-40 ton items recoverably. 

Just asking.

GW


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

Offline

#9 2017-08-09 04:39:53

kbd512
Member
Registered: 2015-01-02
Posts: 1,068

Re: Space X - getting ready for Mars.

1. Why not just use Raptor in an upper stage with the same diameter as the payload shroud?

2. If Raptor can actually be built using existing tooling and tech created for Merlin, then why not evolve Falcon Heavy to use full-flow staged combustion for the boosters and the upper stage?

3. If the composite tank technology can really handle LOX and LCH4 without issue, then why not construct Falcon Heavy stages using that new tech first?

The combination of composite tanks, a lighter upper stage with a higher Isp Raptor engine, and lighter boosters with higher Isp Merlin engines should permit Falcon Heavy to come quite close to the performance of the initial version of SLS.  If Falcon Heavy can deliver 50t to ISS with reusability, then surely NASA can construct a MTV using a SEP powered habitat module and a NTO/MMH chemical propulsion kick stage to leave LEO.  The spiraling time lost to LMO insertion, TEI orbital transfer, and LEO insertion using the SEP module is of little consequence if there are no other affordable alternatives.

* The testing for the high power SEP thruster, MegaFlex and ROSA PV arrays, and CAMRAS and IWP life support equipment is nearly complete.  There have been no showstopper issues identified with any of these key technologies.  All work well and are significantly better than what NASA currently has.

* AJ-10-190 is thoroughly proven technology, so there's no need to develop an entirely new upper stage engine.  There are no boil-off issues to contend with when using NTO/MMH, either.  LOX/LH2 is obviously better, but the RL-10 engine is not man-rated and Centaur upper stages have had a history of problems.

* The ISS Destiny lab module or MPLM module for habitation is also thoroughly proven technology.

* We don't have any alternatives to SEP at this time.  The spiral times will have to be accepted, otherwise the delivered tonnage is too costly.

As far as SpaceX is concerned, I think Mr. Musk received a lane departure warning from his own engineers regarding ITS.  I thought it was crazy cool, but sometimes engineering reality kinda sucks.

Offline

#10 2017-08-09 08:20:09

Oldfart1939
Member
Registered: 2016-11-26
Posts: 826

Re: Space X - getting ready for Mars.

IMHO.
I believe that Elon Musk is having an internal struggle--with himself. His dream is HUGE, but it's now being subjected to tempering with a combination of engineering and economic realities. That said, he's a very rational dreamer, so I'm just speculating that he to will see the advantages of  building even a handful of Falcon Xs, if for no other reason than the orbital satellite business, coupled with the return to Moon concepts. Then there is time. Building the BFR (as the ITS was called by the engineers working on it) cannot be done in anything less than 10 years. Musk is still pretty young (at least by comparison with THIS group!). If he wants to go to Mars himself, his aging will encourage his change of plans to something less grandiose and faster to get accomplished.

Offline

#11 2017-08-09 09:13:21

RobertDyck
Member
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 4,872
Website

Re: Space X - getting ready for Mars.

kbd512 wrote:

* AJ-10-190 is thoroughly proven technology, so there's no need to develop an entirely new upper stage engine.  There are no boil-off issues to contend with when using NTO/MMH, either.  LOX/LH2 is obviously better, but the RL-10 engine is not man-rated and Centaur upper stages have had a history of problems.

Be very careful. I would not make that claim at all. Remember, NASA engine engineers wanted to develop a new engine for Ares V based on SSME but 50% more powerful. NASA executives said no, use the existing engine. Then Boeing sales reps sold them on RS-68; it already provided 50% more thrust, and was optimized to be expendable. They designed it to not have some features of SSME so RS-68 would have lower manufacturing cost, but lower Isp. That required more propellant, but the additional cost of propellant plus tank was less than the cost savings for the engine, so total cost of the stage was minimized. Great! NASA bought it. But the engine guys wanted to develop a new engine, so they made the accusation that RS-68 was not man rated. NASA executives gave them the task of man rating it, but what they did had nothing to do with man rating. What they did is add all those features of SSME that RS-68 was designed without, features that increased Isp and had nothing what so ever to do with man rating. This was their scam to design the new engine they always wanted. That work dramatically slowed development of Ares V, and dramatically increased cost. Again, this meant they were developing a new engine, not man rating an existing one. Delays and cost increases postponed Constellation so long that President George W.'s term was over, and President Obama cancelled Constellation entirely. There was several reasons for delays, but this engine scam was a major one.

kbd512 wrote:

* The ISS Destiny lab module or MPLM module for habitation is also thoroughly proven technology.

Again, you're falling into scams of "Old Space" contractors. Boeing came up with a design for a Deep Space Habitat, intended for the Asteroid Redirect Mission. Their design was simply ISS modules linked together. That DSH would be heavy, clumsy, and require multiple launches. It's just an excuse to create manifest for SLS. But we don't want to arbitrarily increase cost. The goal is to keep cost down so we can do more missions. If each mission required multiple launches of SLS, then we won't get a single mission. Destiny lab was designed to fit in Shuttle's cargo bay, and designed for zero-G. You can use the hull technology, but a complete redesign is necessary for Mars.

kbd512 wrote:

* We don't have any alternatives to SEP at this time.  The spiral times will have to be accepted, otherwise the delivered tonnage is too costly.

SEP could be used for cargo, but not for crew. It's way too slow. Spiral times are not acceptable.

kbd512 wrote:

As far as SpaceX is concerned, I think Mr. Musk received a lane departure warning from his own engineers regarding ITS.  I thought it was crazy cool, but sometimes engineering reality kinda sucks.

That's possible. First stage of the Soviet N1 used 30 engines: 24 in an outer ring, 6 inner engines. They had major problems. Their greatest problem is one Soviet politician who didn't believe in space took away funding for the test stand for that stage, used the money for something that had nothing to do with space. So the first test of the stage was launching the full-stack rocket. First two launch failures were engine failure. Third was a control system failure, uncontrolled roll. The fourth was due to "hammering" propellant feed lines causing rupture when attempting to stage. From Wikipedia...

Wikipedia wrote:

An investigation revealed that the abrupt shutdown of the engines led to fluctuations in the fluid columns of the feeder pipes which ruptured and spilled fuel and oxidizer onto the shut down, but still hot, engines. A failure of the #4 engine turbopump was also suspected. It was believed that the launch could have been salvaged had ground controllers sent a manual command to jettison the first stage and begin second stage burn early.

Cited reference is: Harford, James (1997). Korolev : how one man masterminded the Soviet drive to beat America to the moon. New York; Chichester: Wiley. p. 300. ISBN 9780471327219.

Designing ITS with a similar number of engines risks similar problems.

Last edited by RobertDyck (2017-08-09 16:13:55)

Offline

#12 2017-08-09 09:46:16

RobertDyck
Member
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 4,872
Website

Re: Space X - getting ready for Mars.

Oldfart1939,

I think you're right. But a few of us have come up with plans to send a mission about the size of Mars Direct, but using existing launch vehicles. I read about Energia from Robert Zubrin's book, in the first years of the Mars Society a lot of people were excited about it, so I came up with a plan (a modification of Mars Direct) that used Energia. RobS encouraged me to change the design to use Falcon Heavy, so I did. It's not 100 people at a time, it's only 4, but it's practical.

Offline

#13 2017-08-09 13:39:05

louis
Member
From: UK
Registered: 2008-03-24
Posts: 2,299

Re: Space X - getting ready for Mars.

But didn't he always plan an intermediate rocket/MTV technology before the ITS? That was my understanding...I think it was just never quite clear what was intended...human-rated Red Dragon or something else.

Oldfart1939 wrote:

IMHO.
I believe that Elon Musk is having an internal struggle--with himself. His dream is HUGE, but it's now being subjected to tempering with a combination of engineering and economic realities. That said, he's a very rational dreamer, so I'm just speculating that he to will see the advantages of  building even a handful of Falcon Xs, if for no other reason than the orbital satellite business, coupled with the return to Moon concepts. Then there is time. Building the BFR (as the ITS was called by the engineers working on it) cannot be done in anything less than 10 years. Musk is still pretty young (at least by comparison with THIS group!). If he wants to go to Mars himself, his aging will encourage his change of plans to something less grandiose and faster to get accomplished.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

Offline

#14 2017-08-09 16:05:24

Oldfart1939
Member
Registered: 2016-11-26
Posts: 826

Re: Space X - getting ready for Mars.

Louis-

To the best of my knowledge, Musk never actively promoted an intermediate vehicle, since the Red Dragon was something of an outgrowth of the Dragon 2 capsule which is planned to be man-rated. SpaceX DID have a series of design concepts they released a number of years ago; they were available on Spaceflight101.com for some time. That's where the Falcon X and Falcon X Heavy come from, and also the Falcon XX.

Robert-

I'm a strong supporter of orbital assembly using Falcon 9 and Falcon Heavy launches to construct a Mars-capable vehicle. Although I consider a crew of 4 as being too small, I would also support sending it instead of wasting another 10 to 15 years waiting around for NASA to procrastinate further. Maybe the Falcon Heavy and lots of orbital assembly isn't "Ideal," it would at least work.

LET'S GET OUR ASSES TO MARS!

Last edited by Oldfart1939 (2017-08-10 08:23:12)

Offline

#15 2017-08-09 18:02:51

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 10,075

Re: Space X - getting ready for Mars.

List of current do ables:
1.) capability to launch using what we have for cargo or modules for subassembly and even man once rated.
2.) completed module design for human occupency for a mars duration

Demonstrator needs:
1.) Artificial gravity and course correction while spinning or tumbling end to end
2.) Retro propulsion of larger mass payload to mars surface and relaunch once on the surface back to orbit eother by proven refueling of depot fuels which were delivered or by insitu refueling.

Offline

#16 2017-08-10 09:07:11

Oldfart1939
Member
Registered: 2016-11-26
Posts: 826

Re: Space X - getting ready for Mars.

SpaceNut-
Some thought needs to be applied to use of fuels other than CH4 and RP-1; using Hydrazine type fuels have nearly identical Isp but are better in Id. The Oxygen ratio for combustion is also more favorable. Optimization by refinement of concept.

Offline

#17 2017-08-13 18:55:42

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 10,075

Re: Space X - getting ready for Mars.

Yes to other fuels as we need to be able to make them early in order to get better performance sooner.

Here is a run down of 40th Falcon 9 mission and 11th rocket this year.Elon Musk Is Getting SpaceX Closer to Mars, One Rocket at a Time

Offline

#18 2017-08-15 12:47:53

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 2,543
Website

Re: Space X - getting ready for Mars.

Well,  Spacex was successful again.  Falcon-9 Dragon toward ISS,  first stage landed back at the Cape.  Congrats.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

Offline

#19 2017-08-16 15:46:37

Oldfart1939
Member
Registered: 2016-11-26
Posts: 826

Re: Space X - getting ready for Mars.

Capture of the latest Dragon capsule was accomplished earlier this afternoon. This marks successful completion of the first 12 mission contract with SpaceX.

Offline

#20 2017-08-16 17:22:37

louis
Member
From: UK
Registered: 2008-03-24
Posts: 2,299

Re: Space X - getting ready for Mars.

Great news...more cash in the coffers for the Mars effort which remains Musk's prime focus! smile I am buoyed up as well to hear how well the latest Tesla launch went - must translate into more cash available for the Mars effort one way or the other.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

Offline

Board footer

Powered by FluxBB