Why the ITS is a HORRIBLE Idea (at least in its current iteration)

[Ultimate Steve]

Yes, the ITS has its problems. But there are solutions to most of them and I agree that a revision of the design is necessary.

Heat shield - yeah, that's quite a bit of risk. Not so much at Mars due to the amount of atmosphere, but at Earth, yes. Especially coming back from Mars. Fortunately, the heat shield should be able to be inspected en route using EVA's or maybe a camera robot or something. And with 100 ton cargo capacity, they would probably have something to fix small parts of the heat shield in the event of an impact. This is not entirely an ITS only problem, though. Any spacecraft flying the same mission profile will be exposed to the same conditions (Except the bigger you go, the higher chance of an impact).

 

Abort system - If you fire all 9 Raptors at once the TWR is sufficient (iirc, read it somewhere). The vacuum engines will have the wrong nozzle length but will still produce a good deal of thrust. But I do agree, the current abort plan is sketchy at best. My personal solution would be to make the interstage a separate unit that can detach from both S1 and S2 and pack it full of solid rocket boosters. During a nominal launch, it would stay connected to the first stage and land with it. During an abort situation it would separate from S1 and stay with the spaceship and ignite its motors. At burnout the abort ring would separate and the spaceship would land. Also, another improvement would be to make the crew portion of the spaceship separate from the fuel section of the spaceship in the event of an even worse emergency, like an engine section explosion. During the Challenger disaster, it is believed that the explosion did not directly kill the crew and the cabin was blasted away in roughly one piece. The top of the ITS spaceship would have parachutes in the event of this separation.

 

I'm pretty sure that the ITS does not use helium for pressurization, but I don't have the reference link so I can't prove it.

 

As far as the whole tipping thing, yeah, three legs does not offer redundancy. However, neither does four. Five will, but at a very narrow angle. The landing legs extending to provide a wider footprint has already been pointed out. In the event of a tip over on Mars I suspect most of the crew would be alive, provided they were wearing pressure suits, which the first missions undoubtedly will. Ideally for the first crewed mission, another ITS will have already landed and the astronauts would likely be able to use it to get home.

 

As far as launch failure with 100 people on board, the first ones will probably have less than a dozen. In a perfect world, ejection seats that blast upwards. By the time that SpaceX ramps up to 100 people per launch, they will probably have switched from sending them all up at once to sending them up in groups of 12 or so using a smaller vehicle (yet to be developed, but they probably will at some point. They will eventually want a smaller vehicle for satellite launches, because if Falcon 9 pricing gets down to 10 million optimistically ITS will be cheaper and overkill for a sat launch).

 

Even though the ITS has been criticized a lot, there are still solutions to most of the problems. They might take significant time and cost to find, but they're there. Even though it may be dangerous and sketchy, at the current point in time it is the only method to land on Mars that people are taking seriously and actually developing. NASA does not have a plan to land humans on Mars, their current plans culminate in a flyby. China wants to do it eventually, but we know nothing of their plans. The ITS is actually being developed and hardware is being built.

Hopefully, NASA will realize this and partner with SpaceX on the mission. Maybe ULA as well, because they may know a thing or two about reliability. Given the combined effort of the NASA, ULA, and SpaceX engineers, and the combined budget of all three, I think that Mars is feasibly reachable within the next two decades.

 

 

(Also, YAY! The reflight was successful!)

[mikegarrison]

1 minute ago, Elthy said:

The expanded feets of the IPS seem realy wide. Imagine how far you have to till the spacecraft until it would fall over, even if you assume the whole wheight to be on the top. At that angle you are not landing anyway...

Dont forget there are many people who are quite bored with their everyday job and life. Yeah, mars would be a excrementston of work and not quite confortable, but compared to some remote place you have clean water/air/food and are working wiht hightech. Just because you dont want to live on Mars doesnt mean there are no others. This is more than just an adventure, its a source for a purpose, which is often lacking in the current society after basic needs have been fulfilled and religion fails to appeal the more logical thinking people...

Religion could be useful as a motivating factor. "You want your religion to spread to Mars? Better sign up some colonists!"

[fredinno]

13 minutes ago, Elthy said:

The expanded feets of the IPS seem realy wide. Imagine how far you have to till the spacecraft until it would fall over, even if you assume the whole wheight to be on the top. At that angle you are not landing anyway...

Dont forget there are many people who are quite bored with their everyday job and life. Yeah, mars would be a excrementston of work and not quite confortable, but compared to some remote place you have clean water/air/food and are working wiht hightech. Just because you dont want to live on Mars doesnt mean there are no others. This is more than just an adventure, its a source for a purpose, which is often lacking in the current society after basic needs have been fulfilled and religion fails to appeal the more logical thinking people...

Yes, and what benefit is given to those people over Antarctica, Siberia, Greenland, the Open Sea, or even LEO?

 

Mars is the very limit of human travel at the moment- and thus, it will be very costly for the foreseeable future.

[fredinno]

14 minutes ago, Ultimate Steve said:

Yes, the ITS has its problems. But there are solutions to most of them and I agree that a revision of the design is necessary.

Heat shield - yeah, that's quite a bit of risk. Not so much at Mars due to the amount of atmosphere, but at Earth, yes. Especially coming back from Mars. Fortunately, the heat shield should be able to be inspected en route using EVA's or maybe a camera robot or something. And with 100 ton cargo capacity, they would probably have something to fix small parts of the heat shield in the event of an impact. This is not entirely an ITS only problem, though. Any spacecraft flying the same mission profile will be exposed to the same conditions (Except the bigger you go, the higher chance of an impact).

 

Abort system - If you fire all 9 Raptors at once the TWR is sufficient (iirc, read it somewhere). The vacuum engines will have the wrong nozzle length but will still produce a good deal of thrust. But I do agree, the current abort plan is sketchy at best. My personal solution would be to make the interstage a separate unit that can detach from both S1 and S2 and pack it full of solid rocket boosters. During a nominal launch, it would stay connected to the first stage and land with it. During an abort situation it would separate from S1 and stay with the spaceship and ignite its motors. At burnout the abort ring would separate and the spaceship would land. Also, another improvement would be to make the crew portion of the spaceship separate from the fuel section of the spaceship in the event of an even worse emergency, like an engine section explosion. During the Challenger disaster, it is believed that the explosion did not directly kill the crew and the cabin was blasted away in roughly one piece. The top of the ITS spaceship would have parachutes in the event of this separation.

 

I'm pretty sure that the ITS does not use helium for pressurization, but I don't have the reference link so I can't prove it.

 

As far as the whole tipping thing, yeah, three legs does not offer redundancy. However, neither does four. Five will, but at a very narrow angle. The landing legs extending to provide a wider footprint has already been pointed out. In the event of a tip over on Mars I suspect most of the crew would be alive, provided they were wearing pressure suits, which the first missions undoubtedly will. Ideally for the first crewed mission, another ITS will have already landed and the astronauts would likely be able to use it to get home.

 

As far as launch failure with 100 people on board, the first ones will probably have less than a dozen. In a perfect world, ejection seats that blast upwards. By the time that SpaceX ramps up to 100 people per launch, they will probably have switched from sending them all up at once to sending them up in groups of 12 or so using a smaller vehicle (yet to be developed, but they probably will at some point. They will eventually want a smaller vehicle for satellite launches, because if Falcon 9 pricing gets down to 10 million optimistically ITS will be cheaper and overkill for a sat launch).

 

Even though the ITS has been criticized a lot, there are still solutions to most of the problems. They might take significant time and cost to find, but they're there. Even though it may be dangerous and sketchy, at the current point in time it is the only method to land on Mars that people are taking seriously and actually developing. NASA does not have a plan to land humans on Mars, their current plans culminate in a flyby. China wants to do it eventually, but we know nothing of their plans. The ITS is actually being developed and hardware is being built.

Hopefully, NASA will realize this and partner with SpaceX on the mission. Maybe ULA as well, because they may know a thing or two about reliability. Given the combined effort of the NASA, ULA, and SpaceX engineers, and the combined budget of all three, I think that Mars is feasibly reachable within the next two decades.

 

 

(Also, YAY! The reflight was successful!)

The Heat Shield is not a issue on, for example, Mars Direct- which covers its shield. And how effective any repair would be is highly questionable.

 

You need to attach the rockets onto the crew capsule in some way- otherwise, it's pointless. Also, when did the ITS 2nd stage have 9 Raptors? Wasn't it 4?

 

Is a 50m drop from Mars gravity survivable? (the length of ITS)

 

Ejection seats aren't very useful for rockets. It's a good thing Gemini never blew. 12 is still 7 more than Columbia. And that killed the Shuttle. 12 is still enough to scare Congress into nationalizing the space industry. The Russians just did it.

 

NASA has a plan. It's called DRM 5.0- and the SLS modified versions of it.

The ITS is fundamentally flawed in its design. After everything is modified to fix it, (like with the Hyperloop), it won't be the ITS any more.

It will also become out of reach for SpaceX cost-wise.

 

NASA + ULA will never join SpaceX. ULA has no profit motive, and NASA has its own rocket (SLS) and plans (let's face it, a SLS Moon Mission will happen BEFORE SpaceX ITS Mars).

NASA might offer expertise and payloads, but that's about it. They don't have the money even if they wanted to.

 

To me, SpaceX's Mars plans are about as phantom as the #JourneytoMars.

A cheap publicity stunt that's a bad idea, and the "getting there" plan is so sketchy and problematic, it was doomed from the start.

[DerekL1963]

42 minutes ago, Elthy said:

Dont forget there are many people who are quite bored with their everyday job and life. Yeah, mars would be a excrementston of work and not quite confortable, but compared to some remote place you have clean water/air/food and are working wiht hightech.

Working with high tech really isn't different than working with low tech - it's still work.  (And not much at all like Star Trek.)  And high tech or low, most of the work on Mars is going to be painstaking and repetitive and not much excitement to be had.
 

48 minutes ago, Elthy said:

This is more than just an adventure

It's not an adventure in any way, shape, or form.  It's work, a metric crapload of it, and a return to cramped living quarters at the end of the day and almost certainly extremely boring and largely repetitive food and canned entertainment.

With the exception of the food, which was actually pretty good, BTDT four times underneath the Atlantic.  You couldn't pay me to do it on Mars.  The people who think they want to are clueless as to what they're actually getting involved in.

[Raven Industries]

11 minutes ago, DerekL1963 said:

Working with high tech really isn't different than working with low tech - it's still work.  (And not much at all like Star Trek.)  And high tech or low, most of the work on Mars is going to be painstaking and repetitive and not much excitement to be had.
 

It's not an adventure in any way, shape, or form.  It's work, a metric crapload of it, and a return to cramped living quarters at the end of the day and almost certainly extremely boring and largely repetitive food and canned entertainment.

With the exception of the food, which was actually pretty good, BTDT four times underneath the Atlantic.  You couldn't pay me to do it on Mars.  The people who think they want to are clueless as to what they're actually getting involved in.

There are always people who would sacrifice everything for a cause they believe in, and with enough searching you could probably find some who's cause is the colonization of Mars.

 

@fredinno

I just checked, second stage of ITS does have 9 engines, 6 vacuum and 3 atmospheric.

Edited March 31, 2017 by KerbalSaver

[Mad Rocket Scientist]

37 minutes ago, fredinno said:

 

You need to attach the rockets onto the crew capsule in some way- otherwise, it's pointless. Also, when did the ITS 2nd stage have 9 Raptors? Wasn't it 4?

There are nine. Six vacuum and three sealevel:

[Robotengineer]

4 hours ago, fredinno said:

The Falcon 9's relative simplicity and lack of (yes, it's not innovative- everything on the rocket has been done before, fight me) innovation has cut costs to unprecedented levels.

Yes, successfully landing a first stage capable of delivering a payload to orbit has been done so many times before! And so many rockets have flown twice! Show me another first stage with grid fins and landing legs (New Shepard doesn't count).

4 hours ago, fredinno said:

I've been wanting to make this thread for a while. But now that SpaceX fanboyism has probably cooled down, maybe people will actually listen to my concerns.

Unlikely given SpaceX just flew, then landed a used booster.

4 hours ago, fredinno said:

2. Too tall for landing.

It's height-to-width ratio is comparable to the F9 1st stage (WHEN THE LEGS ARE SPREAD OUT), more than anything else that lands today. That is fine for an unmanned system, worse case scenario, you're going to lose a stage.

 

But something that's fairly unstable in design is not a good idea when landing with humans on another body.

Huh? IIRC, that F9 leg would have failed regardless of height. It's also landing at sea, last time I checked Mars didn't have any. I'm not sure why you are saying it is unstable. Also I'm fairly certain the engines and mounting hardware will be massive enough to pull the center of gravity down far enough for it to not be at too much risk of falling over, and if it would the design would change. The ITS as it is now is a first draft.

4 hours ago, fredinno said:

1. NO ABORT SYSTEM

Yes, it has a 2nd stage that 'can' be used as an abort stage, but that's a horrible idea. The 2nd stage is the stage that has to do the MOST IMPORTANT burns in the mission. The ones for landing, for example, that can't be aborted.

It has to fire multiple times and do course adjustments. It's already under massive stress from constant re-firing.

 

Worse, it's vulnerable ITSELF to failure. Remember that one time when the Helium tank in the 2nd stage blew?

 

Thus, if the 2nd stage fails, you're screwed. No one else uses the 2nd stage for an abort system, because the entire point of an abort system is to be separate from the rest of the rocket system.

 

There's also the fact that it may not have enough thrust in a pad explosion to get out quickly.

Ok, and an abort system couldn't fail? Obviously high TWR SRB based abort systems (like Soyuz) are more reliable due to their simplicity, but there's no reason the ITS second stage couldn't be engineered for reliability. The helium tank in the second stage blew due to fueling IIRC, not a fault in the tank itself.

4 hours ago, fredinno said:

3. (BONUS !(lol)) The Heat Shield

As we all know, this is a major issue. Sure, the Shuttle survived 4 times when it reentered from Earth's atmosphere when it's shield was holed up- but it failed that one time. It was a pretty unlucky hit, that foam strike.

 

And you're going to be in deep space for at least 12 months, minimum. A strike of some sorts is an inevitability... And that shield needs to be used 3 times during a mission- none of which can be aborted.

 

You could fix this with a covering, but that one covers the first 6 months TO Mars. What about the final aerobrake to Earth?

It's more dangerous than anything else, since Earth's atmosphere is so much more dense, and it's coming it at MUCH faster speeds than Columbia in 2003. A hole that might have not been a big issue for the Shuttle could become a major failure point for the ITS on that essential final brake.

SpaceX has been developing better heat shield material for use on Dragon. Again, this is an engineering problem that can be solved. We can never make any endeavor perfectly safe, but we can make accidents extremely rare.

Like I said earlier, this version of ITS is a first draft. I'm sure SpaceX will go through many iterations of the ITS before it is ready to launch. None of the problems you list would be a reason to completely scrap the design and start over.

[Kerbart]

2 hours ago, mikegarrison said:

Elon Musk likely does not have a bag of money big enough to send a manned mission to Mars. That's why he needs to raise enough interest to get other investors.

I was talking about the amount of money required to have congress vote for whatever you need it to vote for. Those dudes are a lot cheaper than a mission to Mars and well within Musk range.

2 hours ago, fredinno said:

There IS NO BETTER LIFE ON MARS. (at least not any time soon). This is something that people need to realize.

The only people who will go are the skilled professionals and rich tourists that build up the first colony. And none of them will go.

 

The people wanting to "have a new life" are going to go to Siberia, Greenland, or West Antarctica when they melt- or maybe even an floating ocean colony.

Those places have much more immediate potential for a low-level worker with few prospects.

If you believe people make rational decisions based on carefully unbiased selected data, then we need to talk about that bridge in Brooklyn that I want to sell to you...

Seriously, filling those ships with volunteers to go to live on FRIGGIN' MARS will be at the very, very bottom of things Musk needs to worry about. 

[Frybert]

Closed as there is already a thread for discussing matters of SpaceX.