The Science of Morgan’s Road

Repub­lished from DECEMBER 14, 2017
* SPOILER ALERT *
It’s a lit­tle hard to talk about the sci­ence involved in a sto­ry with­out actu­al­ly dis­cussing some of the aspects of the sto­ry. So as a fore­warn­ing, I rec­om­mend that you read the sto­ry first and come back to this arti­cle. I’ll con­tin­ue with the arti­cle in the next para­graph. The sto­ry “Mor­gan’s Road” is avail­able here.

* * * * *

Mor­gan’s road began as a sto­ry about the lunar regolith. Regolith is essen­tial­ly lunar dust. Due to repeat­ed bom­bard­ment by objects rang­ing in size of moun­tains to micro­scop­ic grains, the moon’s soil has been beat­en down into tiny dusty grains. This dust is every­where, and as expe­ri­ence by the crews of the Apol­lo land­ings, it gets onto every­thing. Most of the sam­ple con­tain­ers returned to the moon did not seal prop­er­ly. Con­se­quent­ly, there was sig­nif­i­cant con­t­a­m­i­na­tion of the soil by the atmos­phere of the space­craft and lat­er the Earth­’s atmos­phere [1].

The moon’s lack of atmos­phere has ensured that any dis­tur­bance of the regolith will last for years. In fact, the dis­tur­bance in the regolith asso­ci­at­ed with the Apol­lo mis­sions remain to this day. The lunar recon­nais­sance orbiter LRO, imaged each of the Apol­lo land­ing sites, show­ing the tracks left by the astro­nauts and lunar rovers[2].   Morgan’s road is an exten­sion of this idea of long last­ing or per­ma­nent tracks. Nel­son will be able to track Mor­gan back to his secret – the ice that allows him to sur­vive on the moon. The tracks asso­ci­at­ed with Morgan’s crawler would be a per­ma­nent record of every place that Mor­gan vis­it­ed, includ­ing the source of the ice.

The moon held a secret until long after the Apol­lo mis­sions had con­clud­ed. In fact the sci­en­tif­ic par­a­digm of the era held for a dry moon. Use of radar from the Earth, and the flight of the Clemen­tine mis­sion past the moon revealed hints of water ice exist­ing in the per­ma­nent­ly shad­owed cre­ators of the lunar poles. Lat­er mis­sions, notably the LCROSS mis­sion con­firmed the dis­cov­ery [3].

Part of Morgan’s Road deals with the eco­nom­ics of space­flight in gen­er­al and lunar explo­ration specif­i­cal­ly by look­ing at the issue of Lunar sup­plies. Sup­pos­ing that water was nev­er dis­cov­ered on the moon, any water used by the peo­ple on the moon would have to be shipped there. Includ­ing water and oxy­gen, twen­ty five thou­sand pounds of sup­plies are need­ed to sup­port one per­son for one year on the moon. To put that in per­spec­tive, that is about the mass deliv­ered to the sur­face by the Apol­lo Lunar mod­ule. So, that would mean that the equiv­a­lent of a Sat­urn V launch every year to sup­port one per­son on the sur­face. To make this viable the sup­port costs need to be reduced by in situ resource uti­liza­tion ISRU [4] capa­bil­i­ty and the abil­i­ty to recy­cle the water [5].

In Morgan’s Road, Nel­son pays approx­i­mate­ly a hun­dred dol­lars a gal­lon for water. The price seems extreme, since enough water for a per­son to sur­vive a month would be fif­teen hun­dred dol­lars a month. This would seem almost unsus­tain­able for all but the rich­est indi­vid­u­als going to the moon on their own dime. But its even more finan­cial­ly dif­fi­cult than that. The price per gal­lon in Morgan’s road has to be heav­i­ly sub­si­dized. For exam­ple, to put a pound of pay­load on the moon for Apol­lo was over sev­en­ty thou­sand dol­lars. So at ten pounds per gal­lon, it would cost Apol­lo sev­en hun­dred thou­sand dol­lars to ship a gal­lon of water to the moon. Even the most aggres­sive schemes in the mod­ern era sug­gest that the price per pound to the sur­face of the moon would be about a thou­sand dol­lars.  Morgan’s Road shows that unless there is a sig­nif­i­cant shift of the bur­den of resource man­age­ment, an unsup­port­ed pop­u­la­tion on the lunar sur­face is dif­fi­cult to achieve.

Though it makes for a good sto­ry, Morgan’s secret is hard­ly a secret to us. The moon has water and some inter­est­ing mech­a­nisms for gath­er­ing it. It also has been a sur­prise to find water in the lunar soil at equa­to­r­i­al lat­i­tudes. This dis­cov­ery, using the moon min­er­al­o­gy map­per and the Cassi­ni space probe, changed all per­cep­tions of the moon. The exis­tence of this water is a major game chang­er for the eco­nom­ics of space flight [6]. The water can be used to make pro­pel­lant, which in turn changes the cost func­tion for activ­i­ties in cis­lu­nar space, since that pro­pel­lant does not come from Earth.

References:

1.  https://www.hq.nasa.gov/alsj/TM-2005–213610.pdf

2.  https://www.nasa.gov/mission_pages/LRO/news/apollo-11.html

3.  http://“https://www.nasa.gov/mission_pages/LCROSS/main/prelim_water_results.html

4.  https://www.nasa.gov/exploration/analogs/isru/

5.  https://www.nasa.gov/content/water-recycling

6.  https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930004795.pdf