New Mars Forums

Louis,

The use of plain water has nothing whatsoever to do with "looking cool".  You may be obsessed with "looking cool", but engineers probably aren't.  AFFF (Aqueous Film-Forming Foam) is used on liquid petroleum fires, such as kerosene fires.  As someone who's actually sprayed AFFF on an actual DFM (Diesel Fuel Marine) fire, I have a pretty good appreciation for what it can and can't do.  It wouldn't do anything at all to prevent a gas like Methane from escaping from beneath the AFFF, which is intended to act as a vapor seal between vaporized and liquid kerosene or fuel oil distillates.

Edit:

AFFF is also pretty useless for fighting gasoline-fueled fires, which is why it doesn't get used on those, either.  If the rocket in question was loaded with RP-1, then SpaceX should have some kind of AFFF system installed in the landing area.  Since they're actually using Methane, having AFFF is pointless.  The water can cool hot metal components and interrupt combustion from direct contact, but the surface film that AFFF creates over fuel oils can't prevent volatile gases like Methane from vaporizing and continuing to combust.  The rule of thumb is AFFF for kerosene, diesel, or bunker fuel.  AFFF would also work on a coal / wood / plastic fueled fire, but water is every bit as effective there, so again, there's no point to doing that.

Unfortunately, the ability to post-flight examine the Raptor engines went up in a ball of flames. I guess there was still significant amount of Methane left in the fuel tanks?

The issue with the rinkydink landing legs needs to be addressed pretty soon. I'm in favor of Falcon-style folding legs with a much wider "footprint," as well as more ground clearance.

I agree with GW about having some fiberglass insulation and foil to protect the vulnerable engine plumbing. Maybe they don't care if they lose a prototype, but this last incident shows there's still a way to go with the Raptor engines reliability.

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Voyager Station(s), a little more.
Others may have already gathered the information I will put here.
One thing is they will not recycle water back to humans.  Instead they plan to make propellants out of it.  That sort of makes some sense, as they can sell the propellants, and their high end customers will not have to think about drinking other peoples recycled fluids.
Even though it is highly probable that every time we drink water it is water that passed through other creatures bodies in the past.  Still a pretty smart move, I think.  So for raw materials, for propellants they would have available cast off water fluids, and CO2 exhaled by humans.   So how much Hydrolox, how much Metholox do they create?
I presume that at first they lift up the food that is to be fed to the clients.  Later, then maybe farm "Worlds" near by?  I wonder what the Carbon cycle will be like?  No need for Carbon phobic weirdos on this please.  Don't know if Carbon from Mars would be competitive or not.  Maybe if it were a farm product, the farms in orbit, the CO2 from that atmosphere.
And eventually, the water from the Moon?  Not at first though. 
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Also, for radiation protection they plan to make some kind of an ice shield.  And they may be considering magnetic protections as well, not sure on that.
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These "Pilot Programs" are to be precursors to such devices being deployed all over the solar system, according to them.   I guess I believe that solar would be possible at Jupiter with concentrating mirrors, and maybe even Saturn/Titan/ect.
But eventually I guess some kind of nuclear would need to figure in.
As I see it, a companion farm type device, could be built from inner system rocky materials, and then pushed out twards large ice deposits, and filled with water.\
In the case of smaller moons for Saturn, Uranus, and Neptune, eventually some of those moons would be strip mined all the way down to rocky materials by this method. 
From there, I guess a method for Pluto/ect.
Or the robots kill us all
I will probably be dead anyway at that point.  Almost certainly.
But until dead, dreams can be nice.
Done.

For Louis re #16 --- thanks for confirming you've been following the field ...

I noted your use of the word "meaningful" .... that is a reasonable choice, as I think about it, because (of course) humans have been sending "meaningful" RF for over 100 years.

December 12, 1901
On December 12, 1901, Marconi attempted to send the first radio signals across the Atlantic Ocean, in spite of predictions that the radio waves would be lost as the earth curved over that long distance.

A Science Odyssey: People and Discoveries: Marconi ... - PBS
www.pbs.org › wgbh › aso › databank › entries

I understand you meant something other than "meaningful" so I'll give you the benefit of the doubt.

The energy required to send a signal to Voyager had to have been on the order of what is required for a power delivery application.

Military radar systems that can observe objects in LEO and beyond are also operating at power levels comparable to those required for this application.

These systems have been operating for many decades ...

June 17, 1935
It is historically correct that, on June 17, 1935, radio-based detection and ranging was first demonstrated in Britain. Watson Watt, Wilkins, and Bowen are generally credited with initiating what would later be called radar in this nation.

History of radar - Wikipedia

(th)

Choice of food will ultimately be driven by consumer preference. But there are a number of reasons why I would expect microalgae to dominate the food supply in early Martian settlement phase. Firstly, there is simple economics. Land based vegetable plants must be grown in pressurised greenhouses. The total area needed per person is quite large and they (may) need to be heated at night. This makes vegetable plants relatively expensive on Mars and cereal crops very expensive. Microalgae in contrast, can be grown in 3d printed plastic panels on the surface. You would need about a third of the total area compared to a greenhouse growing vegetables and you can drain the panels into an insulated tank overnight. So no absolute need for heating, though it may boost productivity. There are thousands of different edible microalgae. Not all of them are unpleasant to taste. As most human food is now processed, it will make little difference to the consumer whether the pasta on their plate comes from an algae panel or a field of wheat. But the price they pay will be very different. In a competitive market, the cheapest solution usually wins. Finally, microalgae are more nutritious than most land crops, because nutrition is not diluted by superfluous structure. So I think that by the 23rd century, this will be a normal food source and land plants and meat will be seen as niche.

I don't know when the optimum time will be for Mars to declare independence. But I doubt it will be taken kindly by the Earth government elites. These people tend to be hostile towards regimes that they cannot directly control. The US reaction towards Russia expelling Jewish oligarchs being a good example. Even with all of the natural resources and land that Russia has, the US restrictions imposed on it has an impact on the prosperity of its people. If you are stuck on an airless planet, where all botanical products and many technology products must be imported, a trade embargo could be devastating. Of course, that might not be an issue if the Mars government policies just happened to be approved of by Earth political elites. If it was a woke establishment, controlled by Earth approved oligarchs, for example. But I accept the fact that that is unlikely to be appealing to most people. The question is, how far along does a Mars colony have to get, before it can do without the approval of these people?  If Mars is providing something essential, that cannot easily be substituted from other sources, it could be soon.  If it is instead one nation amongst many, it may take a while.

I don't think Mars will need to control population numbers for a long time to come.  If population pressures increase, then space based manufacturing will provide abundant new living space by the 23rd century.  In fact Mars may struggle to maintain a large resident population, when the asteroid belt offers so many more opportunities.  The Belta Lowda may turn out to be the most prosperous people in the solar system.

Following up on #8 ...

There is no reason why a particular location on Earth could not be supplied with abundant SPS power from LEO.

In post #7, the existence of a class of polar orbits that are always in sunlight was considered for delivery of power to a location on Earth for 30 minutes every 24 hours. 

There is no reason that I can see for why there could not be multiple satellites in this particular polar orbit.

Each satellite would be busy sending power to fixed locations along its track, so the satellite would never be without a destination for collected energy.

The cost of delivery of power to the ground stations would thus be divided among the ground stations.

If a given satellite has an orbital period of 90 minutes ( and I do ** not ** know what the orbital period of a sun synchronous satellite might be) then there would be three stations along the track to receive power.  With 48 satellites in operation, there would be 3 x 48 or 150 - 6 or 144 ground stations in the network.  As a reminder (for myself, in particular) the Sun Synchronous orbit plane passes through the center of the Earth.  Satellites in that orbit can serve locations on Earth that are experiencing sunset (on one side of the Earth) and sunrise (on the other). 

Many of these receiving stations would be on islands, where power could be collected and used to make useful products like hydrogen and oxygen, or whatever the market might find valuable.

A few locations might be on floating platforms where that would make economic sense.

The same principle could apply to Mars, with the distinct difference there are no oceans to worry about.

Edit #1 - SPS in LEO could be spaced every degree of latitude, or perhaps even more closely.  Each could serve three clients for 30 minutes on a given orbit.

Service could be modified by demand through control from ground stations managing the network.

If there are 360 satellites (which seems reasonable (at least to me)) then they would serve 360 * 3 or 900 + 180 or 1080 ground stations in each orbit.

But the Earth is rotating underneath, so the total number of ground stations to be served would be greater.

I'm not sure how many ground stations could be served, but I'm assuming that at a minimum, 24*60 minutes divided by 90 minutes (16) tracks are possible.

That would yield 1080 * 16 service opportunities in 24 hours for 360 satellites. pr 17,280 in all.

Edit#2: Google came up with this citation from Wikipedia for Sun Synchronous Polar Orbits ...

Typical Sun-synchronous orbits around Earth are about 600–800 km in altitude, with periods in the 96–100-minute range, and inclinations of around 98°. This is slightly retrograde compared to the direction of Earth's rotation: 0° represents an equatorial orbit, and 90° represents a polar orbit.

Sun-synchronous orbit - Wikipedia
en.wikipedia.org › wiki › Sun-synchronous_orbit

Edit#3: Google came up with this estimate of the diameter of the Earth pole-to-pole

Image result for diameter of earth pole to pole
Equatorial vs Polar Diameter:
Because of this, the diameter of the Earth at the equator is about 43 kilometers (27 mi) larger than the pole-to-pole diameter. As a result, the latest measurements indicate that the Earth has an equatorial diameter of 12,756 km (7926 mi), and a polar diameter of 12713.6 km (7899.86 mi).Jun 14, 2008

What is the Diameter of Earth? - Universe Todaywww.universetoday.com › diameter-of-earth

Circumference would be 24906 miles, so locating satellites every 100 miles would allow only 249.

Separating the satellites every 10 miles would allow for more interesting total of 2490.

That number times 16 yields 39840 power delivery opportunities. 

Thus, the cost of 2490 satellites would be distributed over 39840 ground stations, each of which would receive 30 minutes of delivered solar power each day.

The cost of the ground stations would include storage capability, to allow the 30 minutes of input to be metered out over 24 hours.

Flow batteries might be a good fit for this application.

(th)

According to your video, there is a fairly consistent answer, which is 100 -150 years after first settlement.  So that would put independence towards the end of the 22nd century, or beginning of 23rd.

They envisage the transition of power being gradual and peaceful.  So there would be no need for an MCRN or UNN, as seen in the Expanse series.  I'm not so sure.  If the former colony begins to compete with the home world for access to resources from the asteroid belt, there is certainly scope for tensions.

The Expanse novels foresee a population of 4-9billion by about the middle of the 23rd century.  That also is surprisingly realistic.  If we reach a population of 1million by 2050 (ambitious, but possible) then 200 years of population growth at 4.5% per year, results in a population of 6.7billion by 2250.

At first sight, it might appear improbable that we could feed that many people on Mars, given its apparently desolate appearance.  But farming based on microalgae, blue-green algae, fungi, aquaculture and C4 land plants, etc, with integrated recycling of micronutrients, could be very productive.  Many people find the idea of algae as food unappetising.  But as a processed food ingredient, with flavourings added, it could mimic many foods that we are familiar with and be more healthy overall.  It roughly 3 times more efficient at converting sunlight photons into food starch, carbohydrates and proteins.  So all the food for one person could be grown in a space of a few tens of square metres.  A population of 10billion could be fed on a few hundred thousand square kilometers of equatorial Martian land, which is less than half of one percent of Martiansurface area.  With abundant fusion energy, indoor (stacked underground) farms are possible as well.  So a population rivalling that of Earth is certainly possible.

It seems odd to think of a thriving human civilisation of billions, on a planet where you would be dead in two minutes without an environment suit.  That is the greatest gift that technology has bestowed on human beings.  It allows us to live almost anywhere.  Provided of course,be have a suitable and sufficient energy source.