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#1 2019-08-25 16:25:27

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Space X 2024 Human Mission - realistic target?

I'm an optimist as a rule but I am beginning to think the 2024 target for a human mission to Mars is probably unrealistic.  I base that conclusion on:

1. The absence of any indication of recruitment for a Mars Mission crew squad. We are only 5 years from 2024.  I doubt that any crew selection process is going to be acheived in much under 5 years. The fact is that we have not had an inkling of recruitment for a Mars Mission.

2. The absence of a credible and detailed plan of settlement in particular addressing landing issues (plus Starship maintenance and return launch), cargo unload, habitat and propellant production facility.

3.  The narrow window available for test flights and test landing e.g. to the Moon.

4.  The absence of sponsorship deal announcements.  I think once Space X have their "ducks in a row", as we say in the UK, sponsorship announcements will follow. I may be wrong on that - Space X have not sought out sponsorship on their other projects so far.

I do feel that if the 2024 target is missed, Space X will nevertheless be able to meet a revised target date of 2026. That seems very achievable to me, based on the rate of development of the Starship and Super Heavy.

Last edited by louis (2019-08-25 17:13:46)


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

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#2 2019-08-25 17:02:11

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,820

Re: Space X 2024 Human Mission - realistic target?

Space x BFR could have a first flight to LEO by 2024 as that does not seem unreasonable.

Crew selection for mars will come from the moons plus LEO crews with lots of training for those of the highest caliber.

Starship landing tests could be done with the moon to gain credible pad dimensioning for mars.

2026 looks likely for a mars trip cargo landed or crewed flyby with possible visit to the moons.

All of the launch vehicle companies spend based off from Space contracts not from advertising which we know can be a money maker as nascar has shown for decades now but companies are formed by people and we are hard to change force of habit. Or the attitude that we have always done it that way response...

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#3 2019-08-25 17:39:07

kbd512
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Registered: 2015-01-02
Posts: 7,413

Re: Space X 2024 Human Mission - realistic target?

Louis,

All of us would like to see a mission to Mars as soon as possible, but there are a significant number of technologies and operational procedures that haven't even been developed yet, much less tested and proven to work.

1. Perhaps 5 years from now, we'll see a crew selection process take place for our first deep space missions.  5 years after that, a Mars mission crew selection process could begin.

2. There's no Mars settlement plan because we haven't figured out how to get there and back yet.  After we figure that out, then we have to figure out how to live on Mars for years at a time.

3. Proper testing is the very first step after initial development work has been completed.  Setting arbitrary dates to complete development and testing by is an utter waste of time.  It's a great PR stunt, but devoid of substance.

4. Apart from NASA / ESA / ROSCOSMOS, nobody else will be "sponsoring" a Mars exploration mission.  SpaceX generates revenue from commercial satellite launch services contracts, not advertisements.  Coca Cola and Pepsi will not be footing the bill for a Mars exploration mission.

I admire your optimistic attitude, but nobody will be going to Mars in 2026.  At the current pace of development and testing, no magic will happen after another 2 years passes by.  All those other events that aren't happening that you listed off would be the evidence for that.  I believe it takes at least 2 years to provide basic training to an astronaut.  Thereafter, several more years of training are required to do something useful aboard ISS.  I would expect a deep space mission crew to require at least 4 years of training.  Obviously training and R&D can and do happen in parallel, but there's no point in training someone for an undefined mission using undefined hardware at an undefined point in time in the future.

Once we can get a ship to and from Mars, also known as a fly-by mission, then we can do orbital missions, followed by landings.  A realistic first mission would be a free-return trajectory mission that proves Starship can gracefully handle long duration space flight.  It should be an unmanned test flight with "man in a can" simulators.  Think of that as an all-up shake-down mission.  If we did that 4 years from now, that's as fast as I think we could realistically extend our reach using existing technology.  If that works well enough, then a follow-up mission two years later would be a surface cargo mission carrying water and a LOX/LCH4 plant to prove sub-scale return propellant demonstration.  Both of those missions are based on extremely aggressive, and perhaps moderately unrealistic, timelines.

Any colonization missions will require proper spaceships with artificial gravity, ion and chemical propulsion systems, and convoy style operations to prevent stricken ships from killing everyone aboard.

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#4 2019-08-26 14:05:26

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

kbd512 wrote:

Louis,

All of us would like to see a mission to Mars as soon as possible, but there are a significant number of technologies and operational procedures that haven't even been developed yet, much less tested and proven to work.

Maybe all of us here would like to see a mission to Mars as soon as possible...possibly. But never underestimate the combined power of  professional jealousy and vested interest.

1. Perhaps 5 years from now, we'll see a crew selection process take place for our first deep space missions.  5 years after that, a Mars mission crew selection process could begin.

So you're saying a Mars landing is probably 15 years away? I think that is too pessimistic.


2. There's no Mars settlement plan because we haven't figured out how to get there and back yet.  After we figure that out, then we have to figure out how to live on Mars for years at a time.

I think we have a game plan for getting there and back.  The Starship-Superheavy system should be able to get us there with about 40 launches over a couple of years. To get back, we have the means to create a propellant production facility which will produce enough propellant/fuel for a single Starship return journey.  How to live on Mars for years at a time is well established. It's simply a matter of applying technologies developed since the days of Apollo and perfected on the ISS.

3. Proper testing is the very first step after initial development work has been completed.  Setting arbitrary dates to complete development and testing by is an utter waste of time.  It's a great PR stunt, but devoid of substance.

So Kennedy's "by the end of this decade" target had no positive effects on the USA's manned lunar programme? Really??

4. Apart from NASA / ESA / ROSCOSMOS, nobody else will be "sponsoring" a Mars exploration mission.  SpaceX generates revenue from commercial satellite launch services contracts, not advertisements.  Coca Cola and Pepsi will not be footing the bill for a Mars exploration mission.

A rocket launch of a satellite gets maybe 30 secs max on a news bulletin. It is absurd to think that a human mission to Mars won't create huge and abiding interest with regular news updates and dedicated programmes over a period of years. Its only point of comparison is the Olympics which generates billions of dollars of sponsorship.

I can see Musk might forgo commercial sponsorship if his revenue streams are big enough from other sources but he wouldn't forgo a Mars Mission to maintain some bogus mission "purity".

I admire your optimistic attitude, but nobody will be going to Mars in 2026.  At the current pace of development and testing, no magic will happen after another 2 years passes by.  All those other events that aren't happening that you listed off would be the evidence for that.  I believe it takes at least 2 years to provide basic training to an astronaut.  Thereafter, several more years of training are required to do something useful aboard ISS.  I would expect a deep space mission crew to require at least 4 years of training.  Obviously training and R&D can and do happen in parallel, but there's no point in training someone for an undefined mission using undefined hardware at an undefined point in time in the future.

Well Space X will definitely have need of astronaut crew for their own Dragon Missions and lunar tourism. So there is no reason why training should not start very soon. It may be that Musk intends to cherry pick the best of experienced (but somewhat younger) ISS crew from all around the world. That would certainly give Space X a head start.

Once we can get a ship to and from Mars, also known as a fly-by mission, then we can do orbital missions, followed by landings.  A realistic first mission would be a free-return trajectory mission that proves Starship can gracefully handle long duration space flight.  It should be an unmanned test flight with "man in a can" simulators.  Think of that as an all-up shake-down mission.  If we did that 4 years from now, that's as fast as I think we could realistically extend our reach using existing technology.  If that works well enough, then a follow-up mission two years later would be a surface cargo mission carrying water and a LOX/LCH4 plant to prove sub-scale return propellant demonstration.  Both of those missions are based on extremely aggressive, and perhaps moderately unrealistic, timelines.

I don't think there is any necessity for a fly-by mission .The robot cargo mission to Mars, which will precede the human landings, is proof of concept. If the cargo Starship lands safely, that is your green light.

What is probably required is some long-term missions - 6 months to one year in Earth and lunar orbit with, ideally, a lunar landing and testing of habs etc there. Of course the gravitational differences mean the testing regime will be incomplete. But the same could be said of tests in the Arizona desert of lunar landers.

Any colonization missions will require proper spaceships with artificial gravity, ion and chemical propulsion systems, and convoy style operations to prevent stricken ships from killing everyone aboard.

I am less optimistic than Musk about the scope for mass colonisation of Mars going forward. It seems to me that for several decades at least Mars colonisation is going to be a process involving highly educated, highly trained, highly skilled, and highly motivated individuals with extremely strong mental resilience as well as top one percentile health factors.

But I think the opportunity to create a permanent Mars base or series of bases with a transitory population in the thousands, maybe 10,000, within 30-50 years is certainly there.

Last edited by louis (2019-08-27 17:23:59)


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

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#5 2019-08-26 19:42:35

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,377

Re: Space X 2024 Human Mission - realistic target?

Greetings to Louis, after a long layoff due to website technical reasons. I somehow can't believe there will be a manned Mars landing in 2014, just too many imponderables remain. I can see an experimental landing of maybe 2 or 3 Starship cargo versions; these will not be required to return to Earth immediately, and can be somewhat stripped down, one way landers, testing how well they can land without toppling over. These will be experimental birds, but could carry construction materials, 3D Printers, tractors, and massive quantities of long-term storable food, such as dried beans, peas, powdered milk, rice, soy protein, etc. The prototype fuel manufacturing plant could be included on one, and a Moxie on another. Maybe by that time, several Bigelow habitats and lots of laboratory equipment? This is something which will require intensive foresight and expert planners. I recall seeing a cartoon back in the 1990's about some people in their backyard bomb shelter, with the man berating his wife:"All these canned goods--and no can opener?"

Last edited by Oldfart1939 (2019-08-27 07:49:14)

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#6 2019-08-26 21:16:35

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,413

Re: Space X 2024 Human Mission - realistic target?

Oldfart1939,

Welcome back, Hoss!

Louis,

I sincerely hope your optimism is rewarded.  However, I also think some acceptance of current limitations while we retire risks would temper optimism with pragmatism.  A healthy amount of pragmatism must be infused into expectations to stave off bitter disappointment when something doesn't happen as fast as we'd like it to.  I've always been optimistic about a more interesting and exciting future being in the works, but the timeline for that is not set in stone.  Unwavering resolve, however difficult that is to maintain, will ultimately prevail, as it always does.

During the Apollo program, we did our homework, made pragmatic choices in the interest of moving forward- nobody cared if vendors were happy with the choices made and the vendors understood that their job was to support the program no matter what happened, we did our testing- which didn't always go according to plan, and then we used tested procedures to achieve the objective.  It's a proven formula for success, but it doesn't always happen as fast as we'd like it to.  There were a number of points in the program where all involved thought the endeavor was doomed to failure, but they put their doubts in the back of their minds and pressed forward, with stunning results.

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#7 2019-08-27 08:27:43

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,453
Website

Re: Space X 2024 Human Mission - realistic target?

Welcome back,  Oldfart1939!

My 2 cents worth on a Mars mission. 

There are two huge differences between that and Apollo-to-the-moon.  One is travel time -- you can not ignore the consequences of microgravity and radiation exposures the way you could with Apollo.  The travel time is 1 to 3 years,  not 2-3 weeks.

The other is isolation due to the distance -- there is no possibility of outside help (not until we have a Star Trek-like "warp drive" of some kind).  There at least was the theoretical possibility of sending another Apollo-Saturn to the moon (however dim that hope really was),  just like there was the theoretical possibility of sending another space shuttle to LEO.  Any rescue on a Mars mission must be self-rescue.  Which is another reason why a Mars mission architecture and vehicle designs can look NOTHING like Apollo-to-the-moon.

My 2 cents worth on Spacex:  Musk has always done what he says he will do.  He just takes twice-or-more-as-long as he says to get it done.  That's the track record.  Getting a manned Starship to Mars at any time in the 2020's is a dim prospect at best.  That being said,  he has a better chance of putting a man on Mars by the 2030's than NASA,  far better indeed.  Nothing NASA has been doing addresses proper radiation sheltering,  or AG to protect against microgravity diseases.

That last still isn't on Musk's radar screen.  He is betting that 38% gee on Mars is "therapeutic enough".  It may or may not be.  We will learn whether it is true "the hard way" once he sends people there. 

But there is an "out":  sending two Starships at once,  docked tail-to-tail,  just like during refueling in LEO.  Spin them end over end.  Starship is about 48 m long,  at least as depicted now.  In the manned spaces,  that's about 40 m from the spin center at the dock point.  At 4 rpm (known to be tolerable long term),  that near 0.7 gee in those spaces. 

GW


GW Johnson
McGregor,  Texas

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

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#8 2019-08-27 08:36:13

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,377

Re: Space X 2024 Human Mission - realistic target?

Thanks, kbd512! As Mark Twain said, "The rumors of my death were greatly exaggerated."
The only game in town with any chance at a Mars landing by 2024 is without a doubt, SpaceX. That's why I started a new thread about Starhopper. That is the beginning of history, as far as the Starship program is concerned. A lot depends on the new Raptor engine, and this will be the most challenging demonstration of it's capabilities yet. Maybe the 150 meter altitude limit doesn't seem all that fantastic, but a controlled retro-propulsive landing of a 9 meter diameter "flying water tank" should be significant. Tim Dodd, the "Everyday Astronaut," did a great job when he covered the first untethered flight about 3 weeks ago. Not sure what time his coverage begins, but guessing the live broadcast will be around 14:30 Mountain Time, 13:30 Central. He may start before then. Elon "The Man himself," was spotted at Boca Chica, TX yesterday. This is a critical test! Don't miss it!

Last edited by Oldfart1939 (2019-08-27 15:08:54)

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#9 2019-08-27 17:37:08

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

Good to hear from you again Oldfart! smile

Yes Musk missed the 2014 deadline! lol

As I understand Space X's outline mission, there is no requirement at all for robot cargo Starships to return to Earth.

I think the cargo Starships can take all the stuff you suggest. But I see no reason if they can and they land successfully we shouldn't follow up with an immediate (plus 2 years) human mission.

I really don't think Mars hab design is that big an issue.  I am sure we can create "safe places" for humans on Mars.

The biggest problems I think are post landing maintenance of Starships (for a human return), water sourcing and return launch (is it that easy to launch off a granite surface as opposed to a NASA Cape Canaveral facility? Maybe - Apollo had no probs launching off the Moon - so let's be optimistic).

When thinking of a Mars Mission I often refer back to WW2 when sometimes revolutionary airplane designs would go from drawing board to mass production within six months.  We have to remember you can do a lot with a lot of money, a lot of ingenuity and a lot of willpower.

NASA is no longer relevant - purely a "talk-down" organisation.

I think Musk will do it i.e. get humans to Mars.

Oldfart1939 wrote:

Greetings to Louis, after a long layoff due to website technical reasons. I somehow can't believe there will be a manned Mars landing in 2014, just too many imponderables remain. I can see an experimental landing of maybe 2 or 3 Starship cargo versions; these will not be required to return to Earth immediately, and can be somewhat stripped down, one way landers, testing how well they can land without toppling over. These will be experimental birds, but could carry construction materials, 3D Printers, tractors, and massive quantities of long-term storable food, such as dried beans, peas, powdered milk, rice, soy protein, etc. The prototype fuel manufacturing plant could be included on one, and a Moxie on another. Maybe by that time, several Bigelow habitats and lots of laboratory equipment? This is something which will require intensive foresight and expert planners. I recall seeing a cartoon back in the 1990's about some people in their backyard bomb shelter, with the man berating his wife:"All these canned goods--and no can opener?"


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

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#10 2019-08-27 17:54:59

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

I think (from previous discussions) that an average there-and-back travel time of between just under 1 year and 1 year and 4 months could be expected. 

Things have moved on. Basically we now know how to stop bone and muscle loss in zero G. That is a HUGE advance.  You don't need a Mars therapeutic phase to deal with muscle and bone loss.  It also obviates the need for spin AG in flight.

Yes, we do need a failsafe approach to Mars Mission One. But it's a lot easier. Mission One really only needs to get there and get back. In that sense, it is similar to Apollo 11. 

The "Madcap Musk" meme is really based on the Falcon 9H experience. There he did go down the wrong road...trying to strap three rockets together was always going to be problematic. He succeeded in the end but I think he learned from the experience....the KISS priniciple has been reinstated. I love the way they are putting together the Starships in full view out in the open. smile


GW Johnson wrote:

Welcome back,  Oldfart1939!

My 2 cents worth on a Mars mission. 

There are two huge differences between that and Apollo-to-the-moon.  One is travel time -- you can not ignore the consequences of microgravity and radiation exposures the way you could with Apollo.  The travel time is 1 to 3 years,  not 2-3 weeks.

The other is isolation due to the distance -- there is no possibility of outside help (not until we have a Star Trek-like "warp drive" of some kind).  There at least was the theoretical possibility of sending another Apollo-Saturn to the moon (however dim that hope really was),  just like there was the theoretical possibility of sending another space shuttle to LEO.  Any rescue on a Mars mission must be self-rescue.  Which is another reason why a Mars mission architecture and vehicle designs can look NOTHING like Apollo-to-the-moon.

My 2 cents worth on Spacex:  Musk has always done what he says he will do.  He just takes twice-or-more-as-long as he says to get it done.  That's the track record.  Getting a manned Starship to Mars at any time in the 2020's is a dim prospect at best.  That being said,  he has a better chance of putting a man on Mars by the 2030's than NASA,  far better indeed.  Nothing NASA has been doing addresses proper radiation sheltering,  or AG to protect against microgravity diseases.

That last still isn't on Musk's radar screen.  He is betting that 38% gee on Mars is "therapeutic enough".  It may or may not be.  We will learn whether it is true "the hard way" once he sends people there. 

But there is an "out":  sending two Starships at once,  docked tail-to-tail,  just like during refueling in LEO.  Spin them end over end.  Starship is about 48 m long,  at least as depicted now.  In the manned spaces,  that's about 40 m from the spin center at the dock point.  At 4 rpm (known to be tolerable long term),  that near 0.7 gee in those spaces. 

GW


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

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#11 2019-08-27 18:21:10

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,820

Re: Space X 2024 Human Mission - realistic target?

I dare say the issue for BFR starship missions to mars is the refueling on orbit which for a 3 ship going to mars is going to take another feul tanker ship 18 additional launches just to provide the needed fuels to leave LEO.

If that were such a good idea we would see a Dragon falcon 9 launching keep its second stage engine to LEO and try a refueling just to prove out that concept by doing it repeatedly so as to make use of the same senario for going to the moon. Or do the same with a Falcon 9 Heavy in the same manner.

https://en.wikipedia.org/wiki/Falcon_9
payloads of up to 22,800 kilograms (50,300 lb) to low Earth orbit


https://en.wikipedia.org/wiki/Falcon_Heavy
payloads of up to 64,000 kilograms (141,000 lb) to low earth orbit

Second stage mass empty 4,000 kg (8,800 lb)  and fully fueled 111,500 kg (245,800 lb)

Maybe GW will flesh out the numbers or others will give it a try.

I was glad that Oldfart1939 could return as he was missed....

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#12 2019-08-28 05:44:58

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

According to the link below, the principal Mars development engineer for Space X, Paul Wooster, told a recent Human to Mars Summit (June 2019) that:

"An estimated five Starship launches are required to refuel a single Mars-bound Starship in low-Earth orbit, and this would involve the transfer of hundreds of tons of methane and liquid oxygen."

https://arstechnica.com/science/2019/06 … fely-back/

So that would seem to be 15 fuelling launches for a three ship mission.

Space X's stated plan involves a total of 6 Starships landing on Mars, so that would be 6 plus 30 fuelling launches, making a total of 36 launches spread over two years.  That seems doable to me, though very demanding.


SpaceNut wrote:

I dare say the issue for BFR starship missions to mars is the refueling on orbit which for a 3 ship going to mars is going to take another feul tanker ship 18 additional launches just to provide the needed fuels to leave LEO.

If that were such a good idea we would see a Dragon falcon 9 launching keep its second stage engine to LEO and try a refueling just to prove out that concept by doing it repeatedly so as to make use of the same senario for going to the moon. Or do the same with a Falcon 9 Heavy in the same manner.

https://en.wikipedia.org/wiki/Falcon_9
payloads of up to 22,800 kilograms (50,300 lb) to low Earth orbit


https://en.wikipedia.org/wiki/Falcon_Heavy
payloads of up to 64,000 kilograms (141,000 lb) to low earth orbit

Second stage mass empty 4,000 kg (8,800 lb)  and fully fueled 111,500 kg (245,800 lb)

Maybe GW will flesh out the numbers or others will give it a try.

I was glad that Oldfart1939 could return as he was missed....


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

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#13 2019-08-28 17:28:54

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,820

Re: Space X 2024 Human Mission - realistic target?

Thats not accounting for boiloff between the initial fuel to getting a full fuel tank as they will not be capable of a launching a tanker for refueling the starship at a rate of 1 per day or even every other day.
Remember that we only get a month or 2 for a launch window to go to mars...

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#14 2019-08-28 18:15:04

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

It's supposed to be what Wooster told the seminar...and he is the chief development engineer! Maybe the Starship doesn't need all that propellant to get to Mars from a "standing start". Maybe the full tank is required for return to Earth? So maybe that gives some leeway on boil-off while in LEO.

SpaceNut wrote:

Thats not accounting for boiloff between the initial fuel to getting a full fuel tank as they will not be capable of a launching a tanker for refueling the starship at a rate of 1 per day or even every other day.
Remember that we only get a month or 2 for a launch window to go to mars...


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

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#15 2019-08-28 18:15:36

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,012

Re: Space X 2024 Human Mission - realistic target?

For SpaceNut re #13 ... Your observation about the risk of boiloff of liquid fuel is interesting, and it may be a problem that needs to be addressed.

However, I am under the impression that space is ** really ** cold, in the absence of sunlight.  Please look to see if anyone has experimented with storing liquid oxygen or liquid hydrogen (as proof cases) in space, by providing shade.

I found what appears to be a paper published in 1997 at this site:
https://www.permanent.com/space-transpo … lants.html

The paper appears to show that liquid oxygen could be stored in space at the Earth's distance from the Sun.  However, the site did not come up properly on my machine, so I couldn't be sure.

My guess is that boiloff is only a problem if the Sun is allowed to deliver heat to the storage container.

Your research (were you to be successful) would answer the question one way or the other.

(th)

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#16 2019-08-28 19:18:38

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,820

Re: Space X 2024 Human Mission - realistic target?

A brief search of Human and Interplanetary for key word Bioloff returned 4 pages where we talk about it. The many are for when using LH2 and Lox but its noted that 10% of the centura stage for apollo occured and that was a 3 day trip once leave earth orbit.
While in earth orbit the temperature is cycling from hot boiling to icy cold at the rate or the orbital duration as you are parked waiting between each fueling.

The one topic that is On Orbit fuel depot is a platform that is shaded for holding the fuel in a tank farm with the use of active cooling to try to drive it towards a zero boiloff.

Space is only cold in the shade....

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#17 2019-08-29 04:46:09

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,012

Re: Space X 2024 Human Mission - realistic target?

For SpaceNut re #16 and topic "On Orbit fuel depot".

Thanks for the reprise of that thread, which started in 2007 or so, and continued to recently.  I was impressed by the ambitious concepts reported, and by the successful DARPA test mission to perform on-orbit refueling.

I expect that Elon's team is likely to be thinking about ways to mitigate boil-off.  Your reminder of the issue is helpful (for me at least).

(th)

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#18 2019-08-29 06:42:03

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

Indeed I can't believe that Wooster or the rest of the Space X team are unaware of the issue. I am sure technology has moved on since the 1960s and we are talking about a difference propellant for the Starship.

Unless there is evidence to the contrary, I think we have to assume that Space X have done the calculations correctly and it's 5 launches for fuelling of each Mars-bound Spaceship.


tahanson43206 wrote:

For SpaceNut re #16 and topic "On Orbit fuel depot".

Thanks for the reprise of that thread, which started in 2007 or so, and continued to recently.  I was impressed by the ambitious concepts reported, and by the successful DARPA test mission to perform on-orbit refueling.

I expect that Elon's team is likely to be thinking about ways to mitigate boil-off.  Your reminder of the issue is helpful (for me at least).

(th)


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

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#19 2019-08-29 17:05:42

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,820

Re: Space X 2024 Human Mission - realistic target?

The boiloff is being controlled by using a centaur tank design common bulk head with in the much larger centaura design. The smaller inner tanks are used for the landing in mars. Boiloff is vented into the near empty larger tanks in hopes that radiant energy will not get passed through to the inner tanks. That would imply that these are very heavy mass tanks for thicker walls to be able to do this.
Meaning no light weight composite tanks.

Liquid oxygen is not that much colder than liquid methane so the wall thickness must also assure that we are not super chilling or freezing the methane in the design.

To liquefy 860 metric tons of oxygen gas for one BFR minimum energy Earth return mission to be mixed with 200 metric tons of methane is a hugh order.

https://www.reddit.com/r/spacex/comment … e_transit/

Its not a video...sorry Loius...

29343905184_04284af1e2_o.0.0.jpg

This was the ITS from 2016 ish time frame

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#20 2019-08-30 10:24:09

tahanson43206
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Registered: 2018-04-27
Posts: 17,012

Re: Space X 2024 Human Mission - realistic target?

For SpaceNut re the problem of avoiding boiloff of liquified gaseous fuel and oxidizer ...

Today the local news feed contained articles about progress assembling the James Webb telescope.

In the middle of one of the articles I found a link to an article about how the telescope will be kept cool despite constant Solar radiation.

The performance specifications make this system attractive for a fuel depot:

https://jwst.nasa.gov/content/observato … hield.html

(th)

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#21 2019-08-30 18:02:58

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,820

Re: Space X 2024 Human Mission - realistic target?

A sunshield is a reflective umbrella that is to keep the heat from getting to the object that it is trying to keep cool but it does not work when its solar panels are shaded such that we have no power.

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#22 2019-08-31 07:58:06

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

Seems like Elon is thinking in terms of an 18 metre diameter for the next generation Starship 2.0

https://www.youtube.com/watch?v=t5kj1Bx1YrQ

Production going to be 500 Raptor engines per year.

Think the presenter is forgetting the need for additional vehicles to fuel the Mars-bound craft (maybe x2 or x3 the number of Mars-bound craft).


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

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#23 2019-08-31 08:06:31

louis
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From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

Full assembly of a  Starship one month away. Orbital flight end of Nov to early Dec.


https://www.youtube.com/watch?v=4hUk1KLMW9U

Super-Heavy development not that far away, according to this presenter as it is simply a matter of writing the code to co-ordinate the 30 plus Raptor engines.


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

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#24 2019-08-31 15:45:30

Oldfart1939
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Registered: 2016-11-26
Posts: 2,377

Re: Space X 2024 Human Mission - realistic target?

The Starship development is actually proceeding on "Elon time!" Major problem is lack of supporting infrastructure to support a human mission; need to partner with Bigelow for habitat design and have Tesla battery powered and tracked Bobcat-type vehicles available. Spacesuits appropriate for doing physical labor, and not NASA style "balloon suits," but use mechanical counterpressure. Come up with some creative ways to mitigate against solar flare events, and attenuate GCR. Need a Tesla Rover for travel on surface. Need to orbit several GPS and radio relay satellites for surface navigation and communication. No magnetic field means not compasses.

Last edited by Oldfart1939 (2019-08-31 15:47:26)

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#25 2019-08-31 16:22:37

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Space X 2024 Human Mission - realistic target?

Well a lot of activity taking place! More tanks delivered to Boca Chica for the Starship Orbital...

https://www.youtube.com/watch?v=LvJXKFiaGno

Oldfart1939 wrote:

The Starship development is actually proceeding on "Elon time!" Major problem is lack of supporting infrastructure to support a human mission; need to partner with Bigelow for habitat design and have Tesla battery powered and tracked Bobcat-type vehicles available. Spacesuits appropriate for doing physical labor, and not NASA style "balloon suits," but use mechanical counterpressure. Come up with some creative ways to mitigate against solar flare events, and attenuate GCR. Need a Tesla Rover for travel on surface. Need to orbit several GPS and radio relay satellites for surface navigation and communication. No magnetic field means not compasses.


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

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