New Mars Forums

Dream big, but be prepared to be confronted with reality.  We lack fundamental technologies required for human habitation.  There's no budget to do what the kids from Purdue want to do, either, but that's a minor technical detail.

* CL-ECLSS
* Active Radiation Shielding
* SEP tug
* Interplanetary Transit Vehicle
* HIAD and ADEPT

All other elements of any deep space mission are a question of what you want to do when you get to wherever you want to go.  The five enabling technologies listed above are hard requirements.  If ARM was taken seriously, we'd have CL-ECLSS, a SEP tug, and Interplanetary Transit Vehicle.  We may get a proof-of-concept SEP tug and one deep space test of Orion from ARM.

We're going to need a real HLLV if we want to lift that much tonnage.  If SLS was a 150t capable vehicle by 2022, that works out to roughly 2.5 launches per year between 2022 and 2040.  The current budget would support no more than 1.5 launches per year.  I seriously doubt that SLS will be much more than a 105t capable vehicle in its most capable configuration.  At 115t-125t, SLS is pretty near to the practical limit of what that vehicle's design would be capable of without a complete redesign to add a 5th RS-25 (confirmed by ATK) or liquid boosters (something that there's no infrastructure or even room on the pad to support).

If F9H could be developed into a 100t class vehicle with a significantly larger payload shroud while not simultaneously dramatically increasing launch costs, the launch schedule would be supportable from a budget perspective.  That would mean a redesign of F9H, though.

The flight schedule alone is a bit unrealistic with existing rockets.  Ten years from now, who knows?  Anything's possible.

Start really small.  That means small capsules, small ITV's, and small landers.  We can concern ourselves with colonization and whatnot after we get there.  We have to get there first.  I think we need to stop pushing the master colonization plans until we get there.  That doesn't mean we stop thinking big, but in the near term we must focus on all the incremental technology advancements and test objectives required to realize the dream.

GW,

Nobody here wants to get anyone killed.  Some other ugly little facts have to be faced, though.  There isn't a good solution for every potential problem.  In the same way that missing the runway normally results in death and destruction here on Earth, such is the case on Mars.  You land where you're supposed to or your odds of survival are slim to none.  We've launched over 100 Space Shuttle missions and never lost a single orbiter to pilot error.  You get one and only one chance to get it right, which is why older men and women with thousands of hours of flight time in multiple airframes are the only ones permitted to fly it.  To channel Chris Costa a little, if you're a professional pilot then you practice landing until you can't get it wrong.

Minimum mass missions don't necessarily make the missions more dangerous to the crew if you're intelligent about what you send to Mars.  Even something as simple as the pressure vessel for landing clearly illustrates the problem with all the solutions I've seen from NASA.  Nearly every concept attempts to use some novel technology or combination of novel technologies that demonstrate how clever their engineers are as opposed to designing something simple that works or adapting existing technologies for their purposes.  Obviously it makes the problem more interesting, but is the goal behind the development work to make the solution intriguing to the engineers and scientists or to use simple and workable solutions that function in the real world where cost and complexity are real problems?

In simplest form, a lander (for humans) is a maneuverable pressure vessel with a thermal protection system.  There's no requirement for landing everyone in the same capsule.  That's just defense contractors who want big spending programs to collect as much money as possible from the tax payers.  I don't care about the spending programs if there's unlimited funding available and we don't care how long the solution takes to develop and test.  In the real world, there's no such thing as unlimited funding, so let's pretend for a moment that we have work within the constraints of a rather small budget for the undertaking that NASA says it wants to attempt.

We can make the human EDL solution for Mars as heavy and complicated as is pleasing to us, no doubt producing a whole range of other problems that require solutions of their own, or we can accept that smaller and simpler can and will function just as well as heavier and more complicated in actual operations.

I doubt they'd join up. If Elon Musk can create a system to get people to Mars, why should he use their candidates? He'd choose his own. And if he wanted tv deals, people would come to him; he wouldn't have to chase them down. He's already worth enough money ($10 billion) to get people to Mars all by himself, and he doesn't need to spend it all because he can leverage it with partnerships and loans.

My point about wearout applies to flight vehicles,  for which minimum weight is critical.  Houses are anything but minimum weight,  so comparing houses to flight vehicles is a rather egregious non-sequitur. 

Besides,  not all houses last.  Custom-builts tend to hold up well,  while the crackerboxes they put up as tract homes tend to fall apart in under 2 decades.  Same applies to appliances,  none of which are min weight designs.

Metal structures have a fatigue life that you have to observe.  They say composites do not have fatigue,  but I do not believe that (we haven't had them that long yet,  to have the necessary long-term experience to know).  Fatigue life shows as a negative-slope curve on a log-log plot,  with abscissa number of cycles,  and ordinate cyclic stress level.  If the stress is low enough,  the slope breaks to zero (stresses under that level are OK for "infinite fatigue life").

Few flight vehicles today (air or space) have structures so lightly loaded as to have the "infinite fatigue life".  The last one I know of was the wing structure in the DC-3,  from 1935.  Most of the space technology we discuss here derives from missile heritage,  which was all one-shot stuff.  The low inert weights are achieved by loading the structures to yield and even beyond,  factor 5-10 or even 10+ beyond the "infinite fatigue life" stress levels. 

Aluminum is the worst of all about this effect.  Between yield and ultimate you get to load the thing only a tiny handful of times,  maybe even only once.  That's really short working-life stuff,  defined as cycles of one kind or another (number of landings for airplanes,  usually).  Pressurizations for tankage.  You get the picture. 

Like I said somewhere above,  ISS will be worn out and endangering its crews by about 2025 or so (just like Mir did before it),  unless it is rebuilt or replaced in some way.  If it were me,  I'd build replacement modules as the issue arises,  launch each one to the station,  use it to replace the corresponding worn-out module,  and then de-orbit the junk ,module.  Another one starts failing,  do it again.  And again,  etc.  Same thing applies to the solar panels,  too.  Same age problem,  plus degradation of polymers and crystals by intense UV. 

Doing it piecemeal like that gets you two really important advantages:  (1) low political visibility (more probable funding),  and (2) you could add a centrifuge module and finally study what level of partial gee is actually therapeutic.  That last is crucial for long term deep space travel and off-world bases with men. 

Launching a series of 15-20 ton modules one at a time over several years can be done with the current launcher fleet,  for >10-factor launch cost reduction under what we paid using shuttle to build it originally.  Later this year should be Falcon-Heavy's first flight.  That one could launch 50-ton items for factor-30 savings over costs with shuttle. 

Those costs and payload capabilities being what they are,  I fail to see the purpose in wanting to restore the shuttle,  other than nostalgia.  And I also fail to see the purpose in the new giant NASA rocket,  because it represents an increase in launch costs over what we now how,  not the decrease it should have been.  What we have right now (US,  European,  and Russian launchers) is simply way better.  Different from previous and pre-conceived notions,  but better.

GW

SpaceX successfully landed a rocket in the ocean
Business Insider
By Jessica Orwig and Kelly Dickerson
17 hours ago
http://l1.yimg.com/bt/api/res/1.2/M8ZYc … d452dd441e
Jon Ross at @zlsadesign and zlsa.github.io Artist's impression of a SpaceX rocket landing.

After three attempts followed by three scrubbed launches, SpaceX successfully launched  a Falcon 9 rocket on Wednesday at 6:03 pm ET.

For some, the launch was less exciting than the company's attempt to land a rocket on a barge in the Atlantic. If successful, the landing would have been the first in history, pioneering the way toward a new era or reusable rocket technology.

But SpaceX announced on the day of the scheduled, potentially historic landing, that the ocean waves are rocking the barge too much for a safe attempted landing. Instead, they would attempt a soft landing in the ocean, in which they try to control the rocket enough to land it vertically, though not on the drone ship.

Shortly after launch, SpaceX CEO and founder, Elon Musk, tweeted that the rocket had made it safely into the rocky ocean:

"The drone ship was designed to operate in all but the most extreme weather," SpaceX stated in a recent report . "We are experiencing just such weather in the Atlantic with waves reaching up to three stories in height crashing over the decks."

Musk, retweeted this chart from TWC Space Weather showing just how high the waves have grown in the last few hours:

After Wednesday's launch, SpaceX will have 16 more chances in 2015 to attempt a rocket landing on the barge.

Musk didn't have high hopes for the success of this water-soft landing to retrieve the first stage for re-use, though:

SpaceX has never recovered a rocket for reuse. And they're taking extra precautions by not attempting the landing this time around because the first time around ended in a fiery explosion.

The rocket had trouble on its most recent attempt, because it ran out of hydraulic fluid, sending it careening out of control on its way onto the drone ship:

Rail? On Mars? Are you serious? Mars has as much surface area as all dry land on Earth. You want to build a rail infrastructure from nothing on a planet that large? Are you nuts? Any reasonable system will not include any such infrastructure: no rails, no roads, no nothin'. Just rovers driving across undeveloped land, aircraft, and rockets. So no infrastructure for any thoroughfare.

louis wrote:

The weakness in your argument is that we have very good data on lots of sites already through orbital observation and rover exploration.

You cannot bet the lives of astronauts without a ground truth: you can suppose that in Elysium Planitia there is a huge buried glacier and send a minimalist mission, where astronauts/colonists are suppose to support themselves and synthesize return propellant with locally extracted water, but if they discover that water is now evaporated or is buried too deep for their drilling machines.

louis wrote:

No one would put humans on Mars without proper prospecting of a favoured site.  If - for some reason - you discover a site you thought was good proved bad, then obviously you have to re-think the mission.  But the idea it will take more than 2-4 years to determine that is ridiculous. 

Basically a first mission needs a bit of solid flat ground. Not a lot more.

But to have a good prospection you have to send astronauts, so the firs mission has to relay on what you bring from Earth (even ISRU has to be based on imported LH2) and the firsts goals has to by science & exploration to select the best site for a permanent base.
I like very much GW's plans with an all-in-one exploration, prospection and colonization experiment.

Colonization will not begin until we have enough exploration data to make a good guess about a colony location. Any colony that is attempted before then is doomed to certain failure. That said Mars "covered wagon" colonies to explore secondary site sound like a very good idea to me. Though initial exploration will provide enough data to choose a site with a very high chance of a successful colony it will not find prime locations for a colony to thrive. A mobile colony seems like a good idea of a way of prospecting for a prime location.

Habs can be moved. Indeed, one mission design (from MarsDrive) had the habs be actual vehicles, with the intent to travel around the planet looking for the best location. Much easier to do if you have your return ship in orbit, and a light SSTO to reach it...

If you were to attempt such a mission design using solar, you'll want to be moving during the night. Stop during the day, lay out the solar panels to recharge your fuel cells, and explore the area. Once you've refuelled, move on to the next location. You don't need to move that fast; 10 km/hr would allow you to cover a lot of ground during the mission. But I don't know how much energy that would take, and whether the advantages are worth it.