New Mars Forums

It would seem that SLS ("Senate Launch System" as some have called it) is encountering the big problem that it is too expensive to use, and it will become available both after the Falcon Heavy and about the time the "Mars Transport" megarocket is launched:

http://www.nasaspaceflight.com/2016/01/ … fest-plan/

monsoons, huricanes, cyclones, tornado ect.....and if you are not in those the weather is dry forever......

So we will do a Mars version of a julian day calendar (1,2,3,4...668 then starting back at 1) with no day names or months with the martian people creating there own holidays for what they feel are the important things in life.....

Terraformer wrote:

Why would you start your year at winter? I know we do - though we haven't always done so - but it means starting at the "death" stage of the birth-death-rebirth cycle, rather than the "rebirth" stage (spring).

Because it minimizes the changes colonists would have to adapt to after relocating to Mars.
Mars, like the Earth has four seasons, and each of those four seasons has 3 months associated with it. For winter it is the tail end of December, January, February, and the beginning of March. For Spring we have the tail end of March, April, May, and the beginning of June. For Summer, its the end of June, July, August, and the beginning of September, and for Autumn we have the end of September, October, November, and the beginning of December. We can adjust this for Mars by making those months longer. People would look at a Martian calendar and know what time of the year is, without having to learn new names for months. People like to keep what they are used to, if it is not broken. To give you a counter example, during the French Revolution, a new metric time standard was proposed and a new calendar with new names of the months, 10 day weeks and 30 day months, with the remaining 5 or 6 days as loose days at the end of the year. This calendar was so different, that nobody liked it and it was dropped. The old Gregorian Calendar worked fine for most people, and they saw no reason to adopt the French Revolutionary Calendar just because they overthrew their king.

louis wrote:

Energy intensity is not an issue for a small colony on Mars - per capita energy generation on Mars will be absolutely huge and the element required to produce plastic relatively small.

Your link says ordinary plastics biodegrade - so not sure what your point is.

I think the key issues are "usefulness" and "labour input".

Ok, I'll accept that. "Labour input" is a good measure. My point is you want durable goods, not something disposable. The link also emphasized the distinction between biodegradable and compostable. In the 1990s, "biodegradable plastic" was normal petroleum plastic with some starch mixed in. The starch would decompose, but plastic didn't. Not useful. Bioplastic is compostable. But my point is it isn't durable, so you have to replace it. Bioplastic makes great flatware for a picnic or quick meal from a cart vendor on the street, but a Mars colony will want durable goods.

Why would you start your year at winter? I know we do - though we haven't always done so - but it means starting at the "death" stage of the birth-death-rebirth cycle, rather than the "rebirth" stage (spring).

Rob,

That's what an individual capsule looks like when you include more consumables than are required for immediate survival and active propulsion.  It was also intended for lunar landings.  Our target has an atmosphere.

The Mars reentry capsule has two primary functions:

1. Survive entry into Mars atmosphere from LMO.

2. Soft land the person inside.

Anything more sophisticated than a capsule that performs those two tasks is expensive and complicated extravagance.

The micro capsule I have in mind is a two piece unpressurized aeroshell so small and light that the astronaut inside can open it by hand after he or she has landed.  The top shell contains a parachute and perhaps a backup parachute.  The bottom shell contains HIAD.  While still in orbit, a small service module provides propellant and thrusters for attitude control and deceleration used for reentry.

The astronaut inside wears a MCP suit, he or she sits on a fabric seat suspended by bungees inside the shell.  The avionics are incorporated into the astronaut's suit and instrumentation readouts are projected onto the astronaut's visor.  The only flight controls are a pull handle to release the parachute and a hand controller to orient the capsule for reentry.

It's a real capsule versus a suit designed for a Red Bull style stunt, but it's a minimalist design that performs two functions and only two functions.  It doesn't do anything else because it doesn't need to do anything else.

Everyone here and at NASA keeps trying to "what-if" all the possible contingency scenarios ad nauseam rather than accept that certain landing scenarios are not survivable, short of simply landing the crew in a fully functional surface habitat module.

As you stated, if the cargo that makes this mission possible doesn't land successfully, then all we've lost is some expensive hardware.  The reentry system should be stupidly simple, lightweight, and inexpensive.  Complication cravings should be satisfied elsewhere.

What's more complicated and expensive to design and test?

A: Multi-person pressurized capsule propulsively landed and refueled for return to the MTV (or Earth, as some here would like to do) on another planet

B: Single-person unpressurized capsule parachute landed and thrown away

Edit:

The entire point of landing the habitat modules and other equipment first is to have everything required for surface survival in place before the astronauts arrive.  I think it's a really good idea, but that solution also requires a separate crew landing.  There's no reason to replicate a miniature version of the surface habitat vis-a-vis a multi-person capsule system.  It only ensures that funding for such an endeavor is years or even decades away.

A micro capsule is something that NASA can develop in the interim that doesn't cost so much that absolutely no development of human landing technology occurs in the interim, which is exactly what we have now.

Land the humans in the surface habitat or land the humans in a capsule that only lands them, rather than attempts to replicate what the habitat provides.  Pick one, not both.

We seem to be rehashing the same topics of old all over again rather than connecting them together.....

Mars is an oddity:  too little air to do much with,  yet too much to ignore. 

A conical shape for a two-way lander makes good sense,  pointy-end forward for a lower-drag ascent,   blunt end forward with a heat shield for aero deceleration on descent.  The air is thin enough you can use a short,  squat cone,  as you leave any sensible air at rather low velocities on ascent.  Short and squat is far more stable when landing on rough ground.  That's a good thing. 

For a one-way lander,  cylindrical is OK,  as you just need a blunt end with heat shield for entry aero-deceleration.  Keep it short and squat for landing stability. 

The heat shield need not be as capable as those we use returning to Earth,  because entry speeds and peak heating are lower,  plus you need shallow entry angles at Mars to keep from smacking the surface during the hypersonics.  Shallow angles reduce entry gees and peak heating.  The problem gets to be very easy if you enter from LMO:  speed at entry is only about 3.6 km/s vs the 8 km/s here.  Peak heating varies crudely as speed cubed,  all else being equal. 

I like the idea of a propulsion core surrounded by an annular cargo or habitat space,  for easy entry with fold-down hull panels that become entry ramps.  On a two-way design,  that propulsion core can be tipped with an ascent stage,  and/or an abort bail-out capsule.

The Red Dragon design is a one-way delivery to the surface of 1 to no more than 2 tons.  I don't know whether that is from LMO or a direct entry from an interplanetary trajectory,  but the tonnage is too low for it to act as a crew landing vehicle,  I suspect.  It makes a dandy abort capsule on a larger lander,  though.

GW

SpaceNut wrote:

Tom the image in post #53 brings to mind the venus effect inside the dome.....unless we place cooling loops within the water that is inside the dome to keep it from becoming vapor...This is a few pumps,computer to control, temperature sensors and a loop to the outside cooler temperatures of the mars surface.

Why do we want a high circular arch for the dome?

Also what is the hieght of the air under the water barrier where the crew would live?

http://orig05.deviantart.net/48fd/f/201 … 9mhdbw.png
Well first of all this diagram is not to scale, so the dome might not be as high as you think. As for how high the intermediate layer of water is, it has to be higher than the tallest building in Manhattan. For the purpose of this exercise, we'll assume it is 2016 AD Manhattan, where the tallest building is One World Trade Center also known as the Freedom Tower, on Mars we'll call it "One Mars Trade Center" One World Trade Center is 546.20 meters tall, we have to be careful that no place else in New York City or across the false Hudson River in New Jersey is higher. I think its fairly safe to say that from all points in the circle, you look up to the top of the Freedom Tower, not down. Okay, so lets make the elevation of the intermediate water layer at 600 meters above the surface of the Hudson River, which we'll use as our "sea level" for this crater. So the crater has to be at least 600 meters deep and 25.6 km wide to serve as the base for our replica of New York City on Mars. The dome need not be so high, it need not even be one continuous dome, it could be a "Crystal Palace" type structure. Or a cluster of domes joined on the side, with a number of cables perhaps connecting the tent fabric to the floor. Or it could have a flat top and be curved at the edges in the shape of a disk. All that is really necessary is that the roof be transparent to let in sunshine. No one lives in the upper portion, the air pressure is sufficient to allow liquid water to exist at room temperature and only that, the weight of the water provides the compression for the atmosphere underneath. The water also provides a source of water for the sprinkler systems in the ceiling of the inhabited area underneath the water area, by pumping surplus water to the upper water layer the regulator system would cause holes to open up at the bottom of this layer, causing it to "rain" on the city below. Perhaps holographic displays underneath can provide appropriate imagery of cloud cover to indicate to the people below, that it is about to rain, so they can get their umbrellas out in time, precede this with a few artificially generated gusts of wind and increased humidity in the atmosphere to tell people it is about to rain!, a few displays of false lightning might get the message across too.

Controlling the temperature inside the dome should be fairly easy on Mars, instead of dumping the excess heat into the atmosphere, we dump it into the ground instead, and the average temperature of the ground, even at the equator is quite cold, so it won't get too hot. The greenhouse effect is quite helpful on Mars, we want a comfortable temperature after all, we also might want to retain heat for the Martian night so it doesn't get too cold under the dome.

668 sols divided by 2 equals
334 sols for half a year then divided by 2 equals
167 sols for each season

But this is the Mars seasons time frame posted next:
Spring…7 months, Summer…6 months, Fall…5.3 months, and Winter…just over 4 months.

The way that scientists mark the time of Mars year is to use solar longitude, abbreviated Ls (read "ell sub ess"). Ls is 0° at the vernal equinox (beginning of northern spring), 90° at summer solstice, 180° at autumnal equinox, and 270° at winter solstice.
Mars is at aphelion (its greatest distance from the Sun, 249 million kilometers, where it moves most slowly) at Ls = 70°, near the northern summer solstice, and at perihelion (least distance from the Sun, 207 million kilometers, where it moves fastest) at Ls = 250°, near the southern summer solstice. The Mars dust storm season begins just after perihelion at around Ls = 260°.

That said by looking at the numbers the only mark is a half year the lines up for the months totals on winter/spring or for summer/fall but its the length of the seasons that do not line up for the next interval of division of 2.
The orbit of mars is very egg shaped.

What I am trying to figure out is why the window to launch from earth is 2 yrs 7 weeks (779 days) when the mars sols are 668 (684 Earth days) in a Martian year.

louis wrote:

A silly argument. There were plenty of atheists who died in support of the Soviet State in the Civil War and WW2 or in the Spanish Civil War. They could have hung back, but they were keen to be in the forefront of the action.

Tom Kalbfus wrote:

Why would an atheist want to go to Mars? He might die, conquering the frontier is dangerous, there is an increased risk of death if you go to Mars. You won't get the most advanced medical care if you go their, it is on the frontier and you are far from help. Atheists don't believe in the afterlife, so they will want to stay as safe as possible!

Why would they do that if they thought this life they have is all there is. Seems to me that people who go to war, do not value life so highly if they are willing to sacrifice it. A person who believes in life after death would be more willing to forfeit their own for some greater purpose knowing that their rewards would be in heaven. That would be the logical expectation. An Atheist has every reason not to sacrifice their own lives or not to take unnecessary chances and risks with their only life they know about. Were these people who sacrificed their lives for the Soviet Union really Atheists? Maybe they believed in something other than their own existence and therefore were not Atheists. I think the Soviet Union was a stupid reason to sacrifice one's life for, as it does not work. Lenin or Stalin could promise you nothing if you sacrificed your life for "Mother Russia". You are just a carcass if you get in harms way and lose.