Yet another Mars architecture

SpaceNut · 2020-02-19 20:07:39

https://en.wikipedia.org/wiki/List_of_c … sion_plans
https://en.wikipedia.org/wiki/Human_mission_to_Mars

when are the best times

louis · 2020-02-19 20:35:12

So the talk of 2024 was BS?

SpaceNut wrote:

https://en.wikipedia.org/wiki/List_of_c … sion_plans
https://en.wikipedia.org/wiki/Human_mission_to_Mars
when are the best times
https://upload.wikimedia.org/wikipedia/ … e_appr.png

SpaceNut · 2020-02-19 20:59:28

Not to mars and maybe not to the moon as they are going at it. They have nothing yet to land in, No lunar rover pressurized prototype only. They are still exploring radiation protection devices. They are not going to stay as they are not building anything just science...

RobertDyck · 2020-02-20 03:22:11

louis wrote:

So the talk of 2024 was BS?

Donald Trump was serious. He wanted a human to orbit the Moon in 2019, because his re-election is in 2020. And he wanted human boots on Mars in 2024, because that's the last year of his second term. All could be done, but NASA refused.

GW Johnson · 2020-02-20 09:15:02

Well, if you look at actions instead of words, then NASA has no intention of going to Mars unless Congress specifically orders it. Not the President (regardless of who that is), Congress. Congress has the $, which is what talks.

And, if you look at actions not words, Spacex is many years away from going to Mars (talking about "Starships" on Mars in 2022 or 2025 is just arrant nonsense). They will have to reach LEO first, then the moon, before they can go to Mars. And they will have a Challenger-type disaster or two along the way, which will delay things. I think they'll have their first one just trying to demo re-fuelling on-orbit.

What is being done by NASA (not what is talked about) is a budget-busting return to moon that might not land there. It's a boondoggle. Corporate welfare. Another $100B ISS in some kind of elliptical orbit around the moon. Not needed for a return to the moon, much less going to Mars. Just another way to kill a crew with solar flare radiation, actually, if not by microgravity diseases.

What is being done by Spacex is an attempt to build a transport craft large enough to take a small crew and lots of supplies to Mars. That's good for a small, temporarily-occupied science base resupplied from Earth. And it only works if they can make thousands of tons of propellant on Mars in a 2-to-4 year time frame. Otherwise, it's a one-way suicide mission, even with "Starship". "Starship" is not, and will never be, a practical colonization ship. Talking about it as if it were, is also arrant nonsense.

GW

elderflower · 2020-02-21 03:59:22

Re Starship , GW. What constitutes a colony? There weren't many people in the ships that set up the early European colonies in Eastern North America. They depended initially on resupply from the home countries and on the native populations until they were able to support themselves by agriculture. I don't see early Mars settlement being much different, apart from the scarcity of natives. Starship would be sufficient to perform the initial settlement, support and evacuation (if needed) roles provided, as you say, that huge quantities of fuel can be manufactured on Mars.

GW Johnson · 2020-02-21 08:46:26

Hi Elderflower:

Well, looking at the history, one small shipload of people does not have a very good track record getting North America settled from Europe. Doesn't matter what the definition of "colony" is; what matters is how the settlement thrives or not.

The Roanoke landing failed, with those folks disappearing without a trace, leaving only the cryptic word "Croatoan" carved on a tree. The Jamestown landing came within an ace of suffering the same fate as Roanoke (settlement very nearly depopulated by disease and starvation). Even the Plymouth landing would have suffered the same fate, were it not for humanitarian aid getting food from the Indians.

There will be no Indians or easily-accessed resources or food on Mars. So, how many tons of food, water, and oxygen do you carry per person to survive for 2-4 years until the next ship carrying supplies can get there? You can trade this off as 1 ton of cargo roughly equal to one passenger on a 6-8 month voyage.

You're really looking at 5-10 people at most, and a couple to three hundred tons of supplies and equipment. And many tons of that is your return propellant production plant. Which you won't know "for sure" works until you try it. Odds are, they will perish. Either for lack of supplies, or the inability to return home at all. Or both.

The math doesn't lie. If you stay away from the politics, neither do the history books. 2 for 3 in North America could just as easily have been 0 for 3.

GW

Last edited by GW Johnson (2020-02-21 08:50:59)

RobertDyck · 2020-02-21 11:24:46

Saint John's was established as a fishing camp in 1496. The first house was built in 1497 to allow a single caretaker to overwinter 1497-1498. Commercial fishermen came every summer to fish the Grand Banks, returned to England every winter. The camp grew to become a town, then became a city. It's still there; now the capital city of the Canadian province of Newfoundland. It was established before any government colony. I use this as an example how to set up a settlement. Not government, rather private business.

Of course I could argue trying to send a giant ship with 100 settlers as the first ship to Mars is a bad idea. First you send something small, something with supplies so they don't have to live off the land. A science/exploration mission to prove technology. Sure, build a greenhouse with that first mission, but send enough supplies that they can be healthy even if the greenhouse fails. Prove the technology first, then build up. I'm thinking something the size of Mars Direct.

St. John's was discovered by John Cabot, an explorer funded by the British government. They heard of the riches Christopher Columbus found for the Spanish. John Cabot first set out along the northern route with a pair of Icelandic guides in 1495. He had a labour dispute, and had to return home. Resolved that, set out again in 1496. He discovered Newfoundland, mapped it's Atlantic coast, discovered a bay that formed a natural harbour, and discovered the Grand Banks. When he returned to England later the same year and told them of the fish in the Grand Banks, fishermen set out immediately! There was an official government document that claimed all these dates were one year later, but a letter by John Cabot's son said he was on that expedition, and confirmed the dates I gave.

But again, government explorer with a single ship went first. Then returned. Only after a commercially viable resource was documented and a safe place for workers to live and work, only then did commercial business set out. Fishermen didn't have to worry too much about food, because they could catch fish for their own meals. They brought supplies and intended to return home. Built up a fishing camp, then grew to become a village, which grew to become a town, which grew to a city. They didn't try to found a government colony with the first expedition. How well did that work out for Roanoke?

SpaceNut · 2020-02-21 16:58:25

Its that commercial investment for goods not available was the reason more kept coming to america for the dream of getting rich and leaving behind the strife of the country that they had left.
I have made not of thee posts in the my Hacienda topic as a means to discribe how we transision from a toehold, foothold to being able to stay right after one of RobertDyck's post on the first page..
Where I am hoping that a mission could go to blaze the way for others even with 2 crewmen with the current level of hardwarre with many preplanned drops of equipment and goods to dig in with.
Critical even for that first mission is getting water, processing mars air for oxygen all to create fuel and of course the first greenhouse growing fast going foods. Power limitations for solar are in the preload plan as 40 kw plus battery landers and if Nasa will a minimum of 4 x 10 kw reactors.

elderflower · 2020-02-22 07:41:49

Clearly the fuel issue is key. Starships are capable of shipping a few people, habitats, exploration equipment and 4 years of survival supplies to Mars. They are not capable of getting back without ISRU.
When is the ISRU test unit going to be installed on Mars, with its acre of solar panels or other power source? Without a tried and tested fuel source any visit to Mars is going to be a one way trip.

RobertDyck · 2020-02-22 11:59:37

elderflower wrote:

When is the ISRU test unit going to be installed on Mars, with its acre of solar panels or other power source?

Mars 2020 rover will include oxygen generation. This was going to be demonstrated on the Mars 2001 lander, but that lander was cancelled. The lander was recycled to become Mars Phoenix; the oxygen generation experiment is one of those removed to turn it into Phoenix. Now it will be done by Mars 2020. That rover includes a nuclear power source. The rover chassis and its power source are identical to Curiosity.

NASA: Mars 2020 mission overview

GW Johnson · 2020-02-23 00:19:23

What RobertDyck wrote in post 733 is exactly right. So is what I wrote in post 732.

The difference between St. Johns's and the three attempts I described (Roanoke, Jamestown, and Plymouth) is the overall process used to carry this out, exactly as RobertDyck described.

For St. John's, there was a government explorer sent (twice before success actually happened), who found recognizable resources that could be exploited, followed by a small commercial settlement to exploit those resources, which subsequently grew over time into a colony.

For the other three that I described, there was a government funded and sanctioned colonization mission sent. The people in all 3 of those missions were sent without knowledge of how to fend for themselves, and without any planning for how the future colony was to sustain itself economically. 2 of the 3 worked, but ONLY by the merest chance. Could just as easily have been 0 for 3, as I already indicated.

That abysmal track record argues against anything NASA has ever had in mind for Mars (or the moon actually!!!), beyond sending very small and very temporary exploration missions to "find out what is really there". NO government has EVER really understood colonization, not even our own.

The real way to do this is that "somebody else" sends the actual colony, and NOT as a big effort (!!!), based on what the government-sponsored small explorations really find.

"Somebody else" might be Spacex, and then again, might not be (sorry Louis, but them's the facts). As I have said before on these forums, Spacex has its hands more-than-full enough, just trying to come up with a space transport vehicle big enough to do a reasonable job sending stuff to the moon and Mars.

Sending 1 or 3 or 6 people in a space capsule to Mars, while hoping to send the stuff they need to survive in other ships, is just not a very reliable way to do the exploration / colonization job on Mars. There is at this time NO reason to think any such separate supply ships will ever land within feasible range for the crew to reach! Another ugly fact of life.

That objection is true for Spacex as well (again, sorry, Louis!). Until and unless "somebody" comes up with a landing navigation aid analogous to both GPS and to a terminal area landing beacon of some kind.

So far, NO ONE has. And THAT is the most egregious "ugly little fact of life" about this Mars thing.

Sorry, but those ugly little facts of life have to be dealt with. Effectively. Or anybody you send there is dead, and not very long after arrival.

GW

elderflower · 2020-02-23 08:09:45

Well only a pioneering mission is going to find a good spot with the right resources and install a beacon in that area. That mission must be able to get itself home, so it is going to be a little one, possibly of short duration.

GW Johnson · 2020-02-23 11:05:46

With direct entry from interplanetary trajectories, it takes a lot more than just a beacon at the site to get ships landed where you want them.

It will require a small constellation of satellites in orbit about Mars specifically engineered to interact with incoming spacecraft, so that they can triangulate an exact final course correction to hit an exact entry corridor "window" (small keyhole, actually), that will put them within perhaps a km of the needed touchdown point. No surface beacon can do that.

There is no radio/radar/EM communication of any kind during the hypersonic portion of entry, due to the hot plasma sheath surrounding the spacecraft. It's as true on Mars as it is here, although the "blackout" is a little bit shorter because the entry speed (~7-7.5 km/s) is a little bit slower than from LEO here at Earth (8 km/s). You will be flying that "dead reckoning" using inertial guidance equipment. Period.

Once the hypersonics are slow enough to end the EM blackout, then a site beacon can guide the vehicle to a very high precision touchdown, if it has lift and side force capability with attitude control and aerodynamic asymmetry. Unlike here, there are mere seconds in which to act for that precision touchdown, because for large ballistic coefficients (inherent with large vehicles), the end-of-hypersonics Mach 3 point is at very low altitude on Mars (~3-5 km). You MUST fly a strongly lifting trajectory to shallow-out the trajectory down angle. Either way, you are seconds, not minutes, from impact.

What I am saying about this process applies to ANY vehicle design intended for direct entry at Mars! Them's just the ugly little entry facts of life for that planet. The only way to get more time for guiding the precision terminal touchdown is to enter slower. Such as from low Mars orbit, for which the entry interface speed is only about 3.6 km/s. You come out of hypersonics a bit higher up, and a bit earlier along the trajectory, so you have a few more seconds before impact to use flying while guiding on the beacon.

For the one-way trip, decelerating into low Mars orbit requires a substantially-higher delta-vee capability of the spacecraft. The de-orbit burn is fairly trivial, being only 50 m/s, or thereabouts. Higher delta-vee capability requires a higher propellant fraction, reducing payload fraction. You ain't gonna land successfully if you have a low inert fraction. You have to have landing legs and a heat shield, and you have to take the entry airloads in a somewhat-broadside attitude. You CANNOT do that at 5% inert fraction.

So there's a lot of trade-offs to make in any transport vehicle design, just setting the basic mission architecture. That makes or breaks your design in the very first feasibility-exploration steps. And that's just for the one-way trip there.

GW

elderflower · 2020-02-23 14:57:26

So a prior mission is needed to put an MPS constellation in orbit. Maybe Falcon Heavy could do that. This constellation could also provide full comms coverage.
The pioneering mission has to locate specific resources and determine that they can be accessed and used, so it may have to hop around to find a good site. The best way of finding stuff is to employ a couple of field geologists and a couple of chemists with good equipment on the surface. A possible method might be to use remote operated equipment with a team in orbit to narrow the candidate site list, then excursions to the surface to finalise/confirm the choice of location. This team still has to come home using only what they took with them.

SpaceNut · 2020-02-23 15:39:47

The current population of rovers is just not cutting it which means a minimal manned flight is really needed in sub crew member numbers long before any larger can be had.

There will be a ton of preload landers with cargo, equipment and other resources that we do not need with use at the site. If these ships all enter the atmospher in a cluster then they should all arrive to the same location within reason. They will be setting up the target base for all followers for x marks the spot. As for the constellation of satelite for mars it would seem that a constellation of a modified version of the starlink would work just fine.

RobertDyck · 2020-02-23 16:32:21

Navstar GPS currently has 31 active operational satellites in Earth orbit. For GPS to work, a device such as a smartphone must "see" at least 3 satellites at once. How many satellites would be needed to build a GPS system about Mars? Can we use CubeSats? Mars Cube One was an auxiliary experiment on InSight; a pair of cubes, flyby only in 2018. It Yes, I know, GPS has significant technology. Navstar includes at least one quartz ball held in a vacuum chamber with laser range finders from ball to wall in each direction: left/right, top/bottom, front/back. The satellite maintains orbit around the quartz ball, ensuring perfect gravitational orbit, no distortion due to any wisp of atmosphere that may still be in orbit. An atomic clock on each satellite ensures absolutely perfect timing. GPS signals are so precise, they must be adjusted for relativity due to time passing a different speed in orbit vs surface of the planet. GPS works by measuring time it takes for a radio signal to travel from satellite to your handheld device (eg smartphone). Position is calculated by intersecting spheres, using distance measurements from 3 satellites with known positions in orbit. Similar to triangulation, but with distance instead of angles. GPS is so precise, it measures the phase of the radio signal. This allows measurement of distance to a fraction of a wavelength of the radio signal. Yea, that's a lot, but could all that be miniaturized using today's technology to fit in a CubeSat? Could we just give Mars a GPS system?

SpaceNut · 2020-02-23 16:41:55

I did suggest both in another topic and the response was that they are not robust enough, not large enough ect... in this case we need cheap as there are none there currently to perform that function.

Here is that topic GPS system for Mars?

RobertDyck · 2020-02-25 23:07:05

I think SpaceX reads our forum. Have they argued against our position of starting small? Elon Musk tweet today...
(Yes, that's Alita Battle Angel)

Terraformer · 2020-02-26 04:20:30

What relevance does a Martian Cyborg have to Elon Musk?

RobertDyck · 2020-02-26 09:31:24

Terraformer wrote:

What relevance does a Martian Cyborg have to Elon Musk?

In the movie, Alita was supposed to be a warrior who came from Mars. Elon tweeted this image. The slogan "All or Nothing" indicates his intention to send the big ship. He refuses to start with a reasonable explorer like Mars Direct.

Terraformer · 2020-02-26 11:01:31

Oh, I know that, I saw it twice.

One of Elon's other ventures is neuralink. He likes Martian Cyborgs.

SpaceNut · 2020-03-20 12:54:27

All cyborgs need not apply as we need to be able to land on mars to be able to explore not just assimulate...

News for any mission to mars is like driving in reverse at this time with a huge detour sign sitting in the way saying we are going to the moon.

High Mass Mars Entry, Descent, and Landing Architecture Assessment

RobertDyck · 2020-03-20 14:43:47

Thank you for keeping the thread alive. The paper you linked studies inflatable heat shield technology, HIAD, and doesn't even consider extensible heat shield that opens like an umbrella, ADEPT. Mars Direct was designed to use ADEPT. ADEPT was under develop by NASA in the 1980s before Mars Direct, Robert Zubrin and his partner David Baker simply used the latest technology of the time. Not considering ADEPT at all is startling; I consider Mars Direct to be baseline. The abstract for the linked paper says the maximum landed payload is 37.3 t (metric tonnes). The paper I posted elsewhere on this forum states the study baseline for ADEPT is landed payload mass of 40 t. Note Mars Direct has a landed payload mass of 28.6 t ERV and 25.2 t habitat, according to Robert Zubrin's book "The Case for Mars" first edition 1997.

SpaceNut · 2020-03-20 17:24:06

https://www.sworld.com.au/steven/pub/IAF98pap.pdf

A FLEXIBLE REUSABLE SPACE TRANSPORTATION SYSTEM

Space x woulds say yes that it is a way to reduce costs but does some pieces not work when they get to large to lift off from earth and can not do anything once ther except land back on earth....

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