Author: Torn

The Science of “Golf and Outgassing”

Repub­lished from APRIL 14, 2018

* SPOILER ALERT *

It’s dif­fi­cult 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 Golf and Out­gassing is avail­able here.

* * * * * *

Golf and Out­gassing is a sto­ry regard­ing the return to the moon some­time in the next decade of an alter­nate his­to­ry.   It revolves around the land­ing site Fra Mau­ro, the loca­tion of the 1971 land­ing of Apol­lo 14 i ii. The title itself is sug­ges­tive of the event end­ing the two-day stay of Apol­lo 14 — Alan Shep­ard’s famous lunar golf shots iii. The out­gassing piece is from part of the pre­lim­i­nary sci­ence results for the mission.

Fra Mau­ro high­lands is a region on the east­ern edge of the Ocean of Storms, near the cen­ter of the disk of the full moon. It was select­ed because of the rel­a­tive­ly recent (and deep) impact crater called Cone Crater. Cone Crater seemed to be deep enough that it might have punched through the under­ly­ing sur­face geol­o­gy and blast­ed pieces of the bedrock dur­ing the impact. One of the sci­ence goals of Apol­lo 14 was to trav­el to the rim of Cone Crater and sam­ple the rocks from with­in. The bulk of the sec­ond EVA involved Alan Shep­ard and Edgar Mitchell work­ing their way up the Cone Crater slope iv v

The rest of the sci­ence back­ground for the Golf and Out­gassing sto­ry is the Apol­lo Lunar Sur­face Exper­i­men­tal Pack­age ALSEP vi. One of the ALSEP exper­i­ments detect­ed water vapor. This occurred weeks lat­er after Shep­pard and Mitchel had depart­ed the moon and returned to the earth. An exper­i­ment called the Suprather­mal Ion Detec­tor Exper­i­ment vii (SIDE) detect­ed the water sig­na­ture viii. It’s like­ly that the result was con­sid­ered void because of no equiv­a­lent event at anoth­er Apol­lo land­ing site. Also, the dry moon par­a­digm became stan­dard. It remained in effect until the Clemen­tine mis­sion sug­gest­ed oth­er­wise ix.

The crawler, or pres­sur­ized rover, is based on a vehi­cle that has been con­sid­ered by NASA as part of the can­celed Con­stel­la­tion pro­gram. It had been devel­oped as part of the desert rats exer­cis­es. The crawler’s capa­bil­i­ties enables lunar explo­ration in a shirt sleeve envi­ron­ment, leav­ing EVA’s to han­dle spe­cial cir­cum­stances that could not be han­dled by robot­ics x

The exis­tence of a sky­light cave struc­ture under Cone Crater is made up for pur­pos­es of the sto­ry. There are sky­light caves on the moon, dis­cov­ered by the Selene (a Japan­ese Lunar Mis­sion) xi They are expo­sures of sub-sur­face lava tubes. Like polar craters, a lava tube could act as a cold trap, allow­ing the volatile sub­stances such as water to accu­mu­late inside of the caves. The expla­na­tion that is inferred in “Golf and Out­gassing” is that the water detect­ed by the SIDE was from a cave con­cealed under Cone Crater that released vapor after the Apol­lo 14 mis­sion. If such a cave exist­ed, dis­cus­sion about return to the moon would like­ly include Fra Mauro.

Ref i: NASA Apol­lo 14 page. 

Ref ii: Wikipedia Apol­lo 14 page 

Ref iii: PGA News Lunar Golf Shots 

Ref iv: Fra Mau­ro land­ing site

Ref v: Report on Geol­o­gy of Fra Mauro 

Ref vi: Apol­lo 14 Sci­ence Experiments 

Ref vii: Suprather­mal Ion Detec­tor Experiment 

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