New Mars Forums

Hmm...

I know that all of this applies to the current ISS and Transhab designs, but it does raise questions.

Could a station or other orbital assembly craft be designed for assembly from small packages in LEO?

Is the three-storey Transhab really the smallest inflatable structure that can be used for human habitation?  If not, can a smaller version fit on Zenit booster?

What gear (science and otherwise) can be designed to fit in suitcase-sized chunks?  What can't?

What absolutely must arrive already assembled?  What can be built on site if you can just get it in the docking port?

In short: How unfurnished is unfurnished?

Why does the seawater have to arrive distilled and ready to go?  Why not create a set of large inland saltwater reservoirs to serve as evaporating ponds?  The only difficulty would lie in dealing with the excess salt, but if continuous flow could be arranged over a wide enough area, there’s no need to evaporate the brine down to the point where it couldn’t be pumped back out.

What about an unmanned stationary probe to drill for water in likely spots?

Drilling to the depths necessary to reach even the highest expected water table on Mars is likely to be a very complicated endeavor.  The sandy surface layers expected will require pressurizing a wet bore hole to keep the bore hole from collapsing and trapping the shaft during drilling, which will in turn require bringing something to wet the borehole with.  All known drilling methods (including the use of sonic bits) require moving parts and lots of power.  The depths expected will require a long shaft, which must be stowed and deployed by an automated probe.  Everything coming out of the >100m bore hole (at least a ton of sand, rock fines, and wetting agent for every 100m) must be processed and exhausted by the drilling rig without getting it covered in the stuff.  Everything coming out of the bore hole must be analyzed, in at least a cursory fashion, to monitor the drilling progress. 

That's probably at least a half-ton of wetting agent, drilling rig and other systems sent to Mars for a single borehole.  Taken altogether, none of that is particularly worthwhile for geological prospecting when all one has to do is find a spot where the rocks you want happen to be exposed right at the surface.  Mars is an entire planet, and you should be able to find exposed native rock somewhere on it.  I also do not regard the search for extraterrestrial life to be sufficient justification for such an undertaking, since the probability of successful detection would be low without striking water, and the sampling methods needed to look for biological activity amid a ton of dessicated rock fines would hinder the drilling.  A deep drilling rig would only be worthwhile if, in addition to all the requirements mentioned above, another arbitrary requirement were imposed:

If it finds water, the probe must leave the well in suitable condition for later use, and remain usable for any necessary redrilling or reconditioning.

I believe that the only rational justification for sending a probe capable of drilling deeper than 100m is to scout out water for use in manned exploration.  I also believe that it will be an eventual necessity, and should probably even precede the first manned excursion along with the ERV.  That way, the first crews on Mars can re-use the drilling rig upon their arrival.

I also think it would look better not to have the first thing we send to our Mars base be the escape pod.

Sample data from the Viking landers back in the 1970's shows that the regolith is chemically reactive.  However, just being reactive doesn't mean it's reactive enough to use as a compact fuel source.

Hmm... Perhaps the martian dust could be used in a fuel cell. 

Do you have a reference for this?  I'd like to read it.

And no, I don't know that the smaller grains are silica sand.  I just used something with a known density for comparison to show how the blueberry density could be estimated.

I’ve done a little preliminary analysis of some of the soil sample micrographs, looking for a size distribution pattern in the hematite blueberries at Eagle crater.  The following mosaic is a good example of some soil micro-photos by the Opportunity rover:

[http://marsrovers.jpl.nasa.gov/gallery/ … 2R1_br.jpg]http://marsrovers.jpl.nasa.gov/gallery...._br.jpg

and this non-micrograph picture of the “Berry Bowl” site was interesting as well:

[http://marsrovers.jpl.nasa.gov/gallery/ … 0R1_br.jpg]http://marsrovers.jpl.nasa.gov/gallery...._br.jpg

It’s been noted that the size distribution of these hematite concretions is not uniform or balanced.  There appears at first glance to be a distinct upper and lower limit to their size throughout the Eagle Crater site, with the average size of the globules being closer to the upper limit than the middle of the range. 

I think that there is indeed a consistent upper limit to the size of the hematite blueberries, which is on the order of about 3mm but actually varies significantly from sample to sample.  The largest blueberries exceed 5mm but those are quite rare.  The average is between 2mm and 3mm, despite the fact that the median value is usually closer to 1.5mm.

There is an observable lower limit in several of the samples, but not all.  Further, this lower limit is not consistent from sample to sample.  I think we can attribute this to two effects: 1) resolution limits and other artifacts in the images which make my sampling technique of sliding a ruler around my screen unable to discern the smallest particles, and 2) size separation of particles due to saltation in the soil samples.

This link is an article discussing size separation of particles in a collection of vibrated (or windblown) granules:

[http://jfi.uchicago.edu/~jaeger/group/p … Nature.pdf]http://jfi.uchicago.edu/~jaeger....ure.pdf

The graph at the beginning of the article is very interesting, as it indicates what would be necessary for large particles (like the hematite blueberries) to separate and rise within the surrounding sand grains as the soil is blown along the surface.  This data suggests that the largest blueberries would rise to the top of the windblown sand over time as they were carried along, with the smaller blueberries remaining buried, thus segregating them according to size and concentrating the larger blueberries on top.  It also suggests that the blueberries are either significantly heavier than the smaller particles that comprise the rest of the windblown sand or (an intriguing possibility) a dozen times lighter than the surrounding sand. 

How large this difference in density is may provide an additional clue to the composition of the little spheres.  For example, if they are porous, their distribution will vary slightly from that of solid hematite granules.

Hmm...

A Zenit booster only lofts 5 tons to LEO, as opposed to 20 tons for a Delta.  How am I supposed to get my spaceship from my backyard to the moon if SeaLaunch puts the Beoing's Delta Division out of Business?   

In the Mars Direct mission profile, crew transit between the Hab and ERV is a necessary portion of the mission.  This makes the rovers used by the crew a vital mission component.  So, why not combine it with another vital mission component, the crew hab?

A pressurized passenger vehicle similar in size to a modern recreational vehicle (with bigger tires and a broader wheelbase, please! ) could be incorporated into the hab during the outbound trip, then disconnected and driven off the lander as a mobile base.  Constructing the hab in in this fashion could allow large portions of the crew cabin to be discarded before the descent to the surface, saving propellant.  Using the rover as the primary living space for the entire crew would enable a mission profile with longer surface forays over greater distance.  The ERV crew cabin -- not that of the Hab vehicle -- could be used for additional living space, allowing the crew to remain close to the vehicle that they must spend their time setting up to take them home rather than spend time with a vehicle that will ultimately be abandoned. 

Power and fuel may be a prohibitive requirement, as the rover vehicle would be hauling around a substantial portion of the mission architecture with it.  However, the extra fuel may well prove worthwhile if the mission range could be greatly extended with a matching reduction in the propellant required for landing.

I think we should try another tack.

Errorist, I believe your analysis of the mass-energy equation is insufficient to prove your point.  Use of units is an adopted convention, and needn’t necessarily reflect reality, but it is the convention in which the mass-energy equation was derived.  You can’t get rid of it without voiding a key assumption.

To really argue your point, it might be best to forget E = m c^2 and appeal directly to Mother Nature.

Nuclear fission and fusion, as well as antimatter annihilation, produce energy by the conversion of mass.  Electron spin releases energy spontaneously (and without exhaustion – electron spin doesn’t run down) via quantum transitions.  However, I think you’ll be more interested in processes that produce mass – or mass effects – from energy.

One example is Inertial Frame Dragging.  This is one of the confirming observations of General Relativity, and is the effect used to explain a boost to the orbital precession of Mercury, Mars, and other planets.   As it turns out, the sun’s rest mass alone cannot account for its gravitational field.  A small portion is due to the energy of its internal reactions (energy creating gravity), and another small portion is due to its angular momentum (angular momentum creating gravity).  It’s referred to as frame dragging because the contribution isn’t all in one direction.  The energy of reactions contributes a new outward component (swamped by the mass contribution) and the angular momentum contributes a net sideways component.  This sideways component of the sun’s gravity nudges the planets’ precession to such an extent that relativistic corrections are necessary for the orbital mechanics computations for a journey to Mars. 

The implication is that energy creates gravity, just like mass.

Another example is the momentum of light.  The impact of light on an object creates a slight thrust, as well as imparting other energy.  Solar sails are supposed to take advantage of this for propulsion.

This implies that energy has momentum, just like mass.

Another example is the Sysiphus effect, seen in the sub-Doppler laser cooling used to cool atoms to absolute zero temperature.  The laser light’s photons exchange momentum with the atoms, slowing their motion, but the recoil of photon impacts on the atoms should set a lower limit for how low their temperature can get.  The lowest thermal energy attainable for each atom should be related to the energy of the photons slamming into it, but it isn’t.  Instead, it looks like the atoms are able to undergo quantum transitions at lower energies than the photon energy, particularly when the reaction rate (the slamming about by photons) exceeds the rate at which the atom can emit photons of its own.  This can create a net energy deficit on the scale of a single atom (i.e, lower temperature), even though the atom mainly only emits at its driving frequency (the frequency of the incoming light).  The outgoing energy slightly exceeds the incoming energy for each atom, but only when it’s driven faster than it would normally emit.  The difference in energy is related to the frequency of interactions between atoms and photons, and not to the total energy involved.

This strongly suggests than energy has quantum uncertainty, just like mass.

And then there’s pair production from gamma rays.  Gamma rays of sufficient energy can transform spontaneously into free electrons and positrons.  In this case, a massless photon forms two or more massive particles, just by virtue of having sufficient energy to do so.  Furthermore, the resulting positrons and electrons are attracted to each other.  If they contact another free particle, they can transform right back to a photon, but the transition can also happen spontaneously for a high enough energy electron, just like it can for a high enough energy photon.  For an example, check this out: 

[http://www.hep.princeton.edu/~mcdonald/ … e1202.html]http://www.hep.princeton.edu/~mcdonald/ … e1202.html

This implies that matter and energy are not just convertible but equivalent and interchangeable – that mass, fundamentally and of its nature, is a form of energy.

I feel obligated to point out that the actual equation is:

E = SQRT( ( a * m * c^2 )^2 + ( p * c )^2 ),

where E is energy, m is mass, c is the speed of light, p is momentum, and a is the relativistic correction factor:

a = 1 / SQRT( 1 - (v / c)^2 ),

where v is the velocity.  (SQRT() is the square root operator that I can't make HTML give me...)  (The whole universe can be thought of as being "off" by the relativistic correction factor.  For example, m(v) = a * m is the formula for relativistic mass increase, L(v) = a * L is the formula for relativistic length contraction, E(v) = a * E is a good approximation for the energy formula above, etc.)

E = m * c^2 holds true for the special case of v=0.  It's also about right when v is very small.

For a photon, E is not equal to m * c^2.  E = p * c for a photon, because m = 0 for a photon in this convention.

That said, the argument still can't be put to rest just by saying "Aha! Photons have no mass! See!", because photons still have momentum.  Without mass.

And you guys thought energy without mass was odd... 

Iron-rich minerals deposit all the time on Earth.  However, most of that recently deposited iron is not hematite.  Most of the hematite ore found on Earth is found in formations dating from well before the cambrian period, so much so that geologists speculate that some event during this time caused a massive deposition of hematite in the world's oceans. 

One such speculation is that the first introduction of oxygen by living organisms oxidized the iron in the oceans, depositing it all as rust and iron sulfides in a few million years.  Another speculation is that iron-metabolizing microbes (similar to those known today) deposited the iron.  However, all that is really known is that most of Earth's hematite formed relatively quickly, deposited in only a few geologic layers.

The satellite survey of the Meridiani area indicates that the hematite layer is very thin. 

This means that Mars may have experienced banded iron formation just like Earth. 

My guess is that it happened for the same reason.

RE: Inflatable furniture, I'd have thought throw pillows for sure... 

RE: SUV's, they're hardly the most reliable things on the planet (Earth!), but more importantly as a class they're hard to work on.  Lots of modern cars are made to be repairable only with specialized equipment.  While it's reasonable that the first crews would bring any equipment with them that was necessary to repair their vehicle, it's also reasonable that they would look for vehicles that didn't require much to repair them in the field.

Unfortunately, many other types of vehicle have the same difficulty: You need a garage to fix them.  They are designed to exclude repair in the field.