New Mars Forums

I apologize if, in skimming the previous postings, I might have missed something. It seems to me that a Mars calendar needs to keep two facts in mind:

1. Most work will be done inside, not outside. Agricultural societies need calendars tied closely to seasons, but Mars will not be an agricultural society in that sense.

2. Most "Martians" will be interacting intensively with work colleagues, families, and friends on Earth. Hence most people will be asking themselves "what's today on Earth? What day of the week is it? What time is it in my wife's house right now?"

Computers will help take care of a lot of that, and a Mars colony obviously will not ignore when the sun is up and adopt a terrestrial 24-hour day. But it is not clear Martians really will need to know the seasons intimately. They'll need to know when the dust storm season starts or when it will end. But their computer can tell them that.

So I suspect the easiest calendar to start with will simply be a modified terrestrial calendar. It just so happens that 36 sols is equal to 36.99 days; in other words, roughly every Gregorian month, the Martian calendar gets off by one day. So why not stick to a modified terrestrial calendar like this:

Month        Earth days    total        Mars sols    total
January    31        31        30        30
February    28        59        28        58
March        31        90        30        88
April        30        120        29        117
May        31        151        30        147
June        30        181        29        176
July        31        212        30        206
August        31        243        30        236
September    30        273        30        266
October    31        304        30        296
November    30        334        29        325
December    31        365        30        355
I don't know how well the table will come across, but basically you eliminate the 31st day in all months when there is one, and two other days as well. Then when it is November 1 on Mars, it is November 1 (more or less) on Earth as well. This makes it much easier to keep track of children's and spouse's birthdays, colleagues' vacations, etc. It also means Christians know when it is Christmas, Jews know when it is Yom Kippur, Americans know when it is July 4th, etc. And everyone can still celebrate their terrestrial birthdays on Mars, unless it falls on one of the days eliminated (in which case, celebrate it the day before or after).

For those who want Mars to have a distinctive calendar, it will have one, even if it still beats to a terrestrial rhythm. And there will still be Monsol, Tuesol, etc; I don't think that will be avoided. People are used to a seven day rhythm of the work week and there's no reason to change it. Indeed, it will make it easier for Christians, Jews, and Muslims to worship on Sunsol, Satursol, and Frisol respectively (which is likely to happen).

It seems to me that, idealism aside, a modified 12-month Gregorian calendar is by far the most practical solution, and will be what most people will do anyway even if another calendar is official.

           -- RobS

The danger from anything larger than a grain of sand is miniscule anyway because they are so rare. The Earth is hit by objects a meter or more across just once a year or so. When they had functioning Apollo seismometers on the moon, they deteched only one impact in the kilogram-range (and that was over a few years).

The surface of the moon is safer than low earth orbit because of all the orbiting space junk in the latter domain. A Space Shuttle window was pitted once by an impact; they concluded the object was about the size of a fleck of paint. It would have come from a spacecraft. A French satellite was once crippled by a space collision and they later determined it had hit an old French third-stage booster from a launch several years earlier. There are now protocols about not losing small objects; a wrench (spanner) dropped by an astronaut constructing ISS could come around and punch a hole in it a year later (because orbits change over time, it could hit hard, too). Third stage boosters used to explode a few days after launch because left-over cryogenic fuel would vaporize in the tanks and burst them. Now there are pressure vents, so the stage stays intact and doesn't get disintegrated into lots of small pieces. The Space Shuttle orbits the earth with its main engines pointing forward, so if the vehicle gets whacked, they take the punch and not the crew quarters. The ISS modules are all armored (which is one reason it costs more than Mir and Skylab, launched in less debris-filled times).

But on the moon, all you have to do is bury your habs under a few meters of regolith or sandbags (regolithbags?). You'll have micrometeoroid protection and radiation protection to boot.

            -- RobS

My information on this is twenty years old and may need updating, but I believe the Martian surface has no craters smaller than about 100 meters across, which means meteorites that can make smaller craters are destroyed by the atmosphere. At any rate, close examination of the surface will tell us what sizes of meteorites are stopped.

One of the main differences between the surfaces of the moon and Mars is particle size. Mars seems to be one giant rock field. The moon, on the other hand, seems mantled in beach sand and gravel. The reason is because micrometeorites pulverize the lunar surface, but not the Martian surface.

I'm pretty sure habs are as safe from falling space debris on Mars as they are on Earth.

             -- RobS

Thank you, Robert, for the information about an ion engine with a specific impulse of 8300 seconds. Incredible! Just what we need, to go to Jupiter and Saturn and beyond. But what do you know about electrical requirements? I gather if you fire your ions out the back at twice as much speed, it takes much more than twice as much electricity to do it. Right now with a specific impulse of 3,000 seconds, it only takes about 2-3 tonnes to push 16-19 tonnes of cargo to near escape. I am not sure it helps much, if we reduce the propellant to 1 tonne and increase the mass solar panels by 5 or 10 tonnes! Hence my question about the efficiency of these sorts of engines.

The visualization of a small chemical synthesis plant being about the size of a refrigerator helps a lot. The mass can't be much in a volume like that, either; maybe 1 tonne. But how much can something that size make? Ten kilograms of something a day? That might be plenty if you can accumulate the material; that's 3.6 tonnes per year.

       -- RobS

Well, this does inspire me to write a novel, and I may do that! Seriously, though, I may try to write this up better, but to do that, I need help. My plan has problems:

    1. Can you armor the bottom of a vehicle with a heat shield, still use engines mounted on the bottom without destroying the heat shield (maybe doors can open in it?), and then reuse the heat shield. Reuse of the heat shield is essential for multiple use; if nothing else, the craft has to aerobrake at Mars and the Earth.

     2. Exactly what do we need, in terms of equipment and the mass thereof, to make plastics, synthesize chemicals, refine metal, and work metal? Does a Mars base need 100 tonnes of stuff and 20 people to do those things, or can 3 people do those things with 16 tonnes of stuff?

     3. How safe is it, really, for four people to set out across the Red Planet in two pressurized rovers, with a supply cart tagging along behind, bulldozing routes as they go?

     4. Are the masses really adequate? The exchange Robert Dyck and I had illustrate the difficulties of determining the masses of things, even basic things like solar panels.

Anyway, help! Ideas are needed.

           -- RobS

This is a fascinating idea. I'd like to know the delta-vee penalty as well. I suppose the big problem is that one has to stay more than 350 days in order to return to Earth, which means your solar panels get plunged into total darkness at some point before the launch window opens. Also, you can't set up anything permanent at the poles, because of the cold, windy, dark half-year nights.

         -- RobS

OVERVIEW OF PHASE 3 (YEARS 11 AND 13, MISSIONS 5 AND 6; OR LATER)

The base now has 5 habs and 5 greenhouses, able to accommodate up to 15 people and feed about 10. Electrical capacity on Mars is now about 300 kilowatts. Transportation capacity between the planets is now 8 people in either direction. Phobos now provides almost enough fuel to supply all the needs of Mars missions, including pushing the automated cargo vehicles to Mars on a Hohmann trajectory.

There are now three Mars Shuttles and two Cargo Shuttles, with three at Mars most of the time. No more are needed for several years. Two pairs of Ihabs now ply space between the worlds. The surface base now has considerable life support self sufficiency, extensive exploration capacity, and modest construction capacity.

Phase 3’s goals are to expand the life support and construction capacity so that the base can carry a greater share of the effort to expand Martian facilities. This requires launching a third Ihab each time, expanding the transport capacity to 12 and the surface population to 16 or more.

EQUIPMENT, PHASE 3

Expanded Cargo Transport Vehicle (ECTV) Now that Martian fuel is available, the 19 tonnes of payload launched with SEV propellant from Earth does not have to include the fuel needed to send it on a Hohmann trajectory to Mars; this can be provided at L1.
    Cargo:                        14.5 tonnes
    Structure, avionics                0.5 tonnes
    TMI Stage (an Interorbital Propulsion Stage)    1.5 tonnes
    Aeroshield                    2.5 tonnes (15% of total)
    TMI fuel (from Phobos via L1)        5.0 tonnes

The TMI fuel has a large margin, allowing the stage to adjust the orbit after arrival at Mars.

Note that by building a transportation system and using SEVs, we are now able to land 60% of each 24-tonne payload on Mars, whereas the initial Mars Direct system using chemical propellant could land only 16-20%.

YEAR 11 (MISSION 5) Seven launches necessary

Launch 1: Ihab5, 3 tonnes extra consumables, 5-tonne SEV tank with propellant

Launch 2: Consumables (19 tonnes) and a 5-tonne SEV tank with propellant

Launch 3: ECTV with Hab (8 tonnes), greenhouse (6 tonnes), spares (0.5 tonnes), and IPS4 (1.5 tonnes)

Launch 4: ECTV with 6 tonnes solar panels and 8.5 tonnes of regolith moving and processing equipment, with 5-tonne SEV tank and propellant and IPS5 (1.5 tonnes)

Launch 5: ECTV with 8 tonnes of chemical and plastic synthesis equipment and 6.5 tonnes of equipment for Phobos (solar panels, more drilling equipment, another docking pad), with 5-tonne SEV tank and propellant and IPS6 (1.5 tonnes)

Launch 6: 7 tonnes of refurbishment supplies for Ihab1 and Ihab3, 12 tonnes LOX/methane fuel, and a 5-tonne SEV tank with propellant

Launch 7: 12 astronauts. They fly to L1 in a preexisting taxi vehicle using 30 tonnes of Phobosian propellant and carrying 4 tonnes of ecological supplies (fish in fishtanks, rabbits, chickens, seeds, seedlings, etc.).

Total mass going to Mars with astronauts: 19 (launch 1) + 19 (launch 2) + 4 (launch 6) + 16 (Ihab 1) + 16 (Ihab 3) + 17 (Mars Shuttle1) + 17 (Cargo Shuttle 1) = 108 tonnes, requiring 36 tonnes of Phobosian LOX/methane (note that the refurbishment supplies in launch 6 replace some of the mass in the Ihabs and thus does not increase their mass). The three landers require 15 tonnes more, and the 12 astronauts and taxi 30 tonnes more; total 81 tonnes (the previous mission flew 70)

Launches 1-3 propel themselves to L1. The astronauts fly up as well.

The central docking “cube” is arranged as follows: Ihab1 and Ihab3 opposite each other; Ihab5 and Mars Shuttle2 opposite each other; Cargo Shuttle1 with nothing opposite it (it will occupy the spin axis). The three habs and two shuttles aerobrake separately and rendezvous in a high Mars elliptical orbit. Four fly to Phobos in CS1 and remain in the hab there for two weeks doing routine maintenance and exploring the moon. MS2 and eight crew fly to the surface. A week later, the other Mars Shuttle on the surface goes to Phobos to retrive the crew there (if it has mechanical problems, MS or CS1 can fly them down).

Once the ECTVs arrive, the shuttles fly up and bring the cargo down to the surface. The cargo of launch 5 includes items for Phobos; a crew flies up, flies it to Phobos, sets it up, refuels, and returns to the surface.

With 15 astronauts on Mars, exploration continues apace but considerable more human resources are devoted to chemical and plastic synthesis and metal refining. Methane and carbon monoxide are starting materials for many plastics and metal carbides (which are liquid at reasonable temperatures and easy to pour and cast). After four years the base can make metal buildings, plastic greenhouses, furniture, and many other items.

YEAR 13 (MISSION 6) Six launches necessary. A repeat of Mission 5, except Launch 4’s regolith moving equipment is replaced by more automated supply carts, and Launch 5 carries an 8-tonne hab and a Moonlet Fueling Plant to Deimos. The Mars Shuttle visits Deimos for a month when the cargo from launch 5 arrives, deploys the fueling plant, sets up the hab, and explores the moonlet.

Dirt tracks now circle Mars near the equator and extend to the north and south polar regions. A track now runs the length of Valles Marineris and to the top of at least one of the Tharsis volcanoes.

This proposal for an L1 Gateway is important for several reasons, both political and scientific.

1. As you can see from some of my postings, it is possible to do quite a lot without building a new heavy-lifting booster if you can assemble small payloads and if you use solar electric or solar thermal rockets. But you need assembly points, one deep in the Earth's gravity well, one at the edge. L1 is perfect for this. Thus this proposal can be supported by the Space Shuttle lobby; it does not "dejustify" their program.

2. The moon lobby and the Mars lobby can agree on L1, rather than fighting with each other. L1 allows the creation of a common transportation architecture (especially if you remember that many lunar vehicles need heat shields if they are to aerobrake into low earth orbit).

3. The International Space Station lobby can support L1 Gateway because it complements their facility.

4. As the article notes, we have relatively little "deep space" experience. Developing that experience and the automated operations it requires is a key to going to Mars.

Complementing existing facilities and supporting their inevitable lobbies is a good thing, since you'll never beat them.

             -- RobS

Yes, you may need to use cleated tires, rather like snow tires in winter on Earth.

Driving on Phobos; now that would be a challenge! The gravity is something like 6/10,000 of Earth.

           -- RobS

Here is an expanded proposal for reorganizing Mars Direct. I am still revising it, but the moving target is not moving as fast, now, so here it is. As it was originally composed in Word, importing it onto this Bulletin Board messed up some formatting. I welcome your comments.

       -- RobS

The Mars-24 Plan, version 2.0

The plan derives its name from the idea that Mars can be explored by human beings using the Space Shuttle or large commercial rockets capable of launching about 24 tonnes to low earth orbit. It derives its ideas from various authors. One feature is the reusability of the principal transportation elements.

EQUIPMENT

1. SOLAR-ELECTRIC VEHICLE (SEV)
High-efficiency solar panels (900 square meters, 300 kw), ion engine (Isp, 3,000 seconds), avionics, etc.

I'm glad to see so much discussion of some of these very intersting technical details and problems. I've been preparing another very long posting, but it isn't ready yet; lots of things to check.

The question about photolytic cracking of water is interesting and I have enjoyed your postings about them, Bill White. I didn't not figure it in because it is still very experimental. What works in the laboratory on Earth will take a lot of research to make it work on Mars, where the temperature is about 50 below zero Centigrade. I suspect it can be made to work, but who knows how many hundreds of millions of dollars must be invested. I was trying to stick to known technology. So I didn't rule it out, and please keep up apprised of future developments.

Thank you, Robert, for more details about the solar panels. There are so many different "facts" available it is mind-numbing. Mars Direct says somewhere that a 100- kilowatt solar array would weigh 27 tonnes. Zubrin says he was assuming 15% efficiency. The new gallium-arsenide solar cells have achieved 32% efficiency in the lab. I assumed 30% efficiency because that seems achievable in 10-15 years, and because we know there will be a lot of commercial investment in the technology.

I think I gave some of these details already, but I refined my design a bit since: if you assume a six-meter in diameter lander and the cargo floor (once the cargo is removed) is covered with solar panels, the floor has a 28 square meter area. The circumference is 18 meters (yes, I know, it's a little bit more). Four petals would be 18/4 = 4.5 meters wide at the base. I assumed that the cargo lander was covered by petals up five meters (beyond that would be a nosecone) and at the top the petals are 3.1 meters wide. Thus each petal has an area of 19 square meters. I then assumed that each petal was hinged at the end and that a second panel rested on top of the first one that could be folded out, making the panels a  total of ten meters long. The extension petal would probably be cut in half down the middle so that each half could fold out separately; that descreases the mass and makes it easier for a rover, controled telerobotically from Earth, to lift and swing the extension petal. Airbags could probably do a lot of the work of unfolding the petals, but maybe rovers would have to finish the job.

Each petal and each extension petal has an area of 19 square meters. Thus 19 x 8 = 152 square meters. Add the 28 square meters of the floor of the cargo hold and you have 180 square meters. I calculated the power output based on 500 watts per square meter (Mars insolation) x 0.3 efficiency x 0.3 (because the sun is up half the time and not overhead; basically, the inverse of pi) which gives a power output of 45 watts per square meter. You need 21 square meters to make a kilowatt of power (on a continuous basis; when the sun is overhead, the same area makes 3 kilowatts). Thus 180 square meters makes 8 kilowatts.

Since I have seen masses for solar panels range as high as 10 kg per square meter and much lower, I figures on about 5 kg per square meter to be on the safe side, and threw in another 500 kg for electric cables (to connect to the next nearest lander), voltage conversion, and maybe a fuel cell system. So I came up with 1.5 tonnes and 180 square meters to produce 8 kilowatts.

Yes, there are a lot of other ways to figure the problem. Right now, I'm trying to figure out a way to make a bigger array easily, because if you need about 1 kilowatt of power output to make 1 tonne of fuel a year, and you need to run a base as well, you really need 80-100 kilowatts of power output. I can see landing 5 or 6 of these small landers and connecting them together, but the more landers, the more complicated this scheme gets. Once people land, they can pick up panels, walk around with them, deploy them, and wire them together, but with robots that's tricky (especially with a 5-45 minute time delay!). It seems to me the best one can do before people arrive, realistically, is wire together a 40-50 kilowatt array, and even that may be unrealistic. That doesn't produce all the fuel the crew needs to take off before they land, which is one of the Mars Direct criteria.

Anyway, more later.

             -- RobS

P.S.: One more tricky problem to this design; the rovers have to drive down a petal (which would serve as a ramp) to get off the lander. So at least two of them would have to be reinforced. With the "extension petal" design, the extension petal is folded up on top of the inner petal, so the solar arrays themselves would be enclosed and not driven on directly. Presumably one petal has to be deployed in order to let the rover out; it then can bulldoze rocks out of the way so that the others can be deployed safely. The entire procedure would take months.

Regarding revision of the Mars Direct mission, I would like to propose the following approach and scenario: