Status of LRC program on space shuttle environmental control and life support system

Clark, L. G.

Osborne, R. S.

English

NASA Technical Reports Server

PR_ GSOr_PAG_BLA_ NOTPZL_'O
" PREL_IINAEY RESULTS OF SPACE SINJTTLE EC/LSS STUDIES
Lenwood G. Clark and r_obert S. Osborne
NASA Langley Research Center
Hempton_ Virginia
35" 71
_TRODUCTION
',_', if|
_e purpose of this paper is to indicate overall status of the
I_,m_gley Research Center l_rogr_n on space shuttle envirorumental control/
life support systems (EC/LSS), present preliminary results of studies
_ being conducted, and provide a current assessment of technology
,,_,_.,,, _ advancements required.
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LR(: prp_ram._status
Primary elements of the program currently consist of two contracted
: EC/LS systems studies and design of a flight trace contaminant sensor
system. Other Langley research activities not supported directly by
shuttle funding also have application to shuttle life support problems
and will be identified later.
The llamilton Standard effort includes conducting subsystem trade-
off studies, assembling a conceptual system, and identifying pacing
technology for shuttle orbiter EC/LS. It is about 50 percent complete
and, as noted by the recent milestone, a midterm progress report has
been pubiiM_ed.
Lockheed is concentrating on four orbiter EC/LSS problems: cargo
module system concepts, shuttle/space station interfaces, integrated
cabin thermal control for all mission phases, and subsystem reusability.
This contract has been underway for only about three months and results
are limited.
The design phase of the contractual effort to develop a multi-gas
:_ trace contaminant sensor system will be initiated shortly.
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CO_, !lumidlty_ mtd The_n_l Control
b_aeh of iIs_niltonStandard's effort to date has involved subsystem
trade-off studies. The most extensive of these studies is in the area
of C02, humidity, and thermal control. In th_s case esmdidate concepts
which include all of these EC/LS functions are being evaluated since
most CO2 removal methods also control or affect humidity and have an
_pact on the cabin temperature control system. One aspect of this
evaluation is shown in the figure where the total equivalent weight
(includes hardware weight, power and heat rejection pens/[ties_ expend-
ables_ etc. ) of a number of concepts varies w_th mission duration.
'l_ese es/Icu.lationsinclude consideration cf a typlc_ hea5 rejection
system for a nominal heat load (includes metabolic, avionic, wall, a_d
_el cell loads). _%e increase in weight with time reflects t_ll_e
losses, bs_keout requir_nents, snd expendables _Ithough somo additional
penalty is incurred for operation beyond the 7-do_ design point for
some of the concepts.
Systems considere_ include lithium hyd_'oxide, molecD/ar sieve_ and
H2 depolarized concepts, each with either condensing heat exchangers or
desiccants, and a solid mnine concept which collects both C02 and water
vapor and is regenerated by vacuum desorption. The figure indicates
that the solid amine concept is the lightest syst_1 for missions longer
than about 4 days. Other factors, however, ranging from safety to cost
to maintainability must be considered in the selection process. For
i example, during the reentry and ferry mission phases, only the LiOH/
condenser and the }12depolarized/condenser concepts active34f control
CO2 m_d humidity, while the other concepts must rely on either cabin
tr_msients or auxiliary equipment. Additionally, the LiOH/condenser I'
concept is developed and proven with the added advantage of fewer par_s W
and lower initial cost. On a cost-through-first-flight basis, the
expend_ble Li0H/condenser concept would be chosen_ however_ on a total-
program (10 years) cost basis, the regenerable solid amine system, would
be chosen.
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I) co_HuMIoITY,A.oTHER_LCONTROL
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four men
nominalheatload• 50,:_0 BTUIhr
2400 optlmlz_for"/days m.s.Icond.
v_ ppCO2 - 5 mmHg m.s.Ides.
" _ 2200 H2 dq).Icond.' Q
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, ._ >: H2 d_. Ides.
--1' sOlidamine
_:_ 12 1600 IlohIcond.
IlohIdes,
1400
0 5 10 ]5 20 25 30
, MISSIONDURATION,DAYS
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M  ement
lhuothe_,example of the subsystem trade-off studies b_ing conducted
by Hamilton Sts_ud_rdinvolves the selection of a shutti_ waste manage-
ment eye,tam. In this ease the use of a conventions/ sitdown eonmlodeis
considered as the only prattles& feces collection systsmo Such a syS-
tem would irErolveno residualhandling of fec_l m_terial s_d thereby
should be highly acceptable to crew and passengers both practieslly and
aesthetically.
_e fixate shows th_ weight pen_ty of six es_didate concepts _
_kmction of crew/passenger size fo_ a 7-d_Y mission. An integrated
v_eutuudrying concept in which waste m_t_rial is co!lected_ processed_
m_d stored in a single traith_s th_ lowest wolght followed by the ]_dro-
John _d liquid go_om_ieideconcepts. All of the other concepts involve
hlgh-t_mpe_'_turoprocessiug _ud use _ high rate of expend_blo_ and/or
p_o_:e_.%_ey also require two collectors for processing in order that
the w_stc d_co:l@ositionprocess e_ take plac_ _nd _ooI down before
_he v_cu_ d_ring concept using tissue wipes is the selected system
not only because of its low weight and volume, but also because it is
relatively s_,_plesystem with good reliability and mission flexibility".
l_e number of waste management units required will depend upon not only
the n_nber of crew or passengers, but on their location in the shuttle
vehicle.
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Tecnnol%._ Recommendations,
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Air Flow Urine_ Conee_
• _he waste management subsystem for the shuttle requires a number
of technological advances to improve crew/passenger acceptability. The V
Hamilton Standard artist's concept shown illustrates a new 3 more
•' conventional, height adjustable, wall-mounted urinal which eliminates
body contact with the urine collection device. An air stream within
,., the collector facilitates urine collection and delivery to the separa-
tion system. Appropriate filters are used for odor and bacteria con-
trol of the air and a water flush is incorporated within the urinal.
The requirement for urine collection tanks will depend upon overboard
dtunping limitations.
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_lit-Flow Colmmode_Conqept
'[_ewaste mmls_;_nent subsystem for the slLutt].eshol_l.dac;co_nodato
both m_les s_Idfemales and be as conventional and earthlike as possible !
:" for crew/passenger acceptm_ce _id convenience. The Hamilton Standar_
i artist's concept shown illustrates a zero "g" commode concept for
meeting shuttle requirements. Baslca&ly_ the unit consists of an air
• .,, flow urine collector (similar to that previously illustrated) inte-
grated with a feces collector. The two collectors are separated by a
deflector which is positioned down for male use and up for female use.
Separate collection of urine is desirable since it cm_ be readily
stored m_d/or disposed of to vacuum. Fecal collection is aided by alr
, flow into the unit wheze the feces are shredded by a motor-driven
_linger aud then vacuum dried. As with the urinal3 appropriate filters
are used for odor and bacteria control.
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Cargo Module EC/LSS
A
_itiallyl Lockheed has Used system cost as a basis for selecting I_'
the best type of EC/LSS for tb_ _tle r_rload or cargo module. The
study was based on an assumed 13-Year traffic model recently generated
by the NASA Space Station Task Force. As shownI the model includes 93
flights wherein passengers are located within the module. Another
assumption was that a four-mau_ 7-daMEC/LS wot,_dbe used for the forward
crew compartment of the orbiter_ and that development costs for that unit
are covered in the basic shuttle development cost.
Customized 2-, 6-, and 12-man systems were considered and compared
in various combinations with single or multiple four-man units to fulfill
requirements for individual flights. Results of this cost-effectiveness
study show that the basic four-man EC/LSS modularized for p_yload appli-
cation is the optimum approach. Other parameters such as flight fre-
quency and scheduling, mission length, and system weight and volume will
be considered later during the course of the contract in order to pro-
vide a complete analysis.
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i.!Uar_o__od.u:leEC/LSS Cost Comparison
The cost comparison for tha customized and modul_ _ approaches to
_argo module EC/LSS for the total of 93 flights is presented graphically '_
for two different values of cost per pound for transportation to orbit.
These value_ of $281/pound and $160/pound represent a range currently
_uder consideration by shuttle system planners.
i_:both comparisons, estimated launch weight and unit costs are
lower for the customized systems. However I the large added cost of
desigu_ deve!opmemt, hest_ aud evaJ_uation results in the total estl-
,':ated_,ost of these syst_lIS being substautis_&y g_e ter than for the
modular tulits. It should be noted that signlfic_ce should be attached
ot_y to the differences in cost. Absolute costs could be altered about
equa&ly in al] cases _M_en one considers costs of system integration and
mainten_Ice3 for ex_]_ple. It is also significant that the cost of DDT
m_d E estimated for the customized Systems could be reduced as much as
,: 50 percent without altering the conclusions reached.
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Work by Lockheed in this area has been very limited to date. The
ehs_t makes on_'tytwo points. First_ early in the space station missions !Q
if the station EC/LSS is designed for 12 men and only 6 a_e onboard_ the
station system can accommodate the shuttle orbiter relief crew of six
men. However, after the station crew has grown to 12 men, presence of
the slx-man shuttle transfer crew will result in an 18-mau load on the
station EC/LSS for as long as 5 days. The problem will be even more
seveze for a 12-man trausfer.0 The station EC/LSS will then require
either support from the shuttle systam or ml overdesign capability from
the station syste_nitself. The other point is that, for reasons of crew
safety_ the shuttle must be maintained read_ to leave the station under
emergency conditions at any time while docked.
_IutesratedThermal Control
On_y a limited effort has been conducted to date to define a cabin
or internal thermal control system for shuttle orbiter laUnch_ on orbit,
reentry, crulse_ landing, and ferry mission phases. Early results
indicate onboaa.dfuels can be used as heat sinks and provide advantages
for the reentry, cruise, and ferry phaseS.
It would also be desirable for several reasons (reentry heating
and cargo door operations, for example) to offer an alternative to the
customary practice of rejecting heat to space from a radiator located
on the inside of the shuttle cargo doors. An attractive concept for
this purpose is the cryhoeycle system. The cryhocycle has been proposed _ ,
by both Lockheed studGrumman and consists of collecting waste cabin heat
and utilizing it in a turbine generator to produce electrical power.
Hydrogen is used as the working fluid. Theoreticallyl such a sFstem
. would eliminate the need for fuel cell power systems as well as radiators
for heat rejection. A disadvantage would be losing the availability of
fuel cell water to meet crew and passenger needs.
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J,C/L_q_qReusability
L:,ek2_eed ham conducted a survey of maintenance practices of _A s
_k:ited, and Eastern Airline_ to determine applications to shuttle EC/LSS
quick turn-around and reusability. Onbosmd a_reraft system monitoring
methods used include AZDS (Aircraft Integrated Data System), ADAS
(Automatic Data Acquisition System), and M_d]AR (Malfunetionj Analysi_j
Deteetion_ and Repair), This kind of data acquisition is recommended
on the shuttle by including EC/LSZ fault isolation data. Also, critical
pars/neters sud_ as those for aircraft engines are monitored eontlnuously
b__ the airlines and trend data are snal_.zed for corrective action by
grom_d facilities. Fol_ the shuttle, EC/LSS parameter trend data should
be included in the syst_,
'__e _i,_'!_nossahodu_Le ma.:ln1_on_%eeon _ nonflisht Interference basis
ru_,_will not dol04r flights to repair m_or items. They a!0o perform
_ _ _d ovo_ha_CLs on the basis of f_llu'_'es_the_ th_% time i_ so_-
vlee. _oy h_vo foD/_d that___epla.eomont or,a time schedule_ does not p_e-
elude fail_es, es_eei_ily since mo_t _;L_flm_Ltlo_ occur no_ the
besimdug of the o_er_tional llfe of _ component. Anotho_ _ctlee is
to _emove and zeplace _ failed _mit _ther than try to rep_Iz it on the
_ircr_ft. If _ problem cannot be Isolated, all suspected components _e
removed and _eplaced. All this m_inten_nce philosophy is recommended
for applic_tlon to the shuttle. ,
In _ddltlon# airline experience has shown that actual operating
hours of equipment such as that used for EC/LSS are high. In some cases,
component life is of t1_e ssm_emagnitude or greater than the operating
life of the shuttle itself. %_Is enhances the confidence level of _'_!',_'
reliability to be expected for the shuttle.
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!F_:]_i_l_tTrace Contm.inmlt Sensor _stem
_iq,isdevelopment program is intended to furnish a flight-qualifiable
_E
sensor which will be o.apable oF identifying and quantifying contaminants
present in a closed atmosphere. 'l_is essentially self-contained _
_lytical system is applicable to the monitoring of a broad spectrum of
gaseous organic and inorganic compounds having molecular weights of up
to mass 14'3. _e hybrid sensor consists of two main units: an aecumu-
!_ttez'cell inlet syst_n a_ida .mass spectromeLer arLalyzer system.
_.e accumuJator cell inlet s,vstemLconsists of from one to three
gas/vapor som_tion units. Eac1_ eel]_ contains a glvon amount of a
partiettlar sorbent _,,hiehis capable of quantitatively adsorbing the low
level atmospheria contaminant(s) f_o_i_ _ a__air stream passing through the
cell. It _,ff_a._ tively_°concentrates the adsorbed compound(s) to a level
that permits quautitative evaluation, When the adsorption cycle is
,omplete, the residual cabin atmosphere is removed from the cell and
the co_t_inaats are desorbed by the application of heat to the cells.
'lhegases leave the cell and enter the mass spectrometer by means of
the i_Oet leak between the cell and the mass spectrometer. The exact
numbe_- of cells employed for a given operation will depend upon the
degree of enalytics.l monitoring desired.
•i%e mass spectrometer mrtlc.pated for use is the Nier-Johnson
double focusing mass spectrometer. This instrument uses a 90° electric
solda 90° magnetic sector and is presently near optimum in te_s of
flight design.
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ishuttle mission is
a relatively short one s normaj[ly 7 day_;
_zd generally an open-cycle or expendable envirornnen_aE control/life
_upport system can be used. The technology for such a system is avail-
able from a combination of Apollo spacecraft and aircraft h_rdw_e.
However, _,<hilesuch a system might be satisfactory for very early
shuttle flights_ certainly a more sophisticated system should be pursued
for the large bulk of the routine operational flights. It is here that
improvements in technology can result in reduced cost_s reduced welght s
simpler systems_ and inci'eased passenger aceQptabi_ity. I
A solid m_:Ine system for removal of carbon dioxide and humidity
control, for e×_ple, e_ save weight m_d ultimately reduce costs as
compared to the ]itlli_i hydi'oxide/condensing heat exch_ulger combination.
!die c_V]_ocycle the_nT_alcontrol concept, if developed and utl]ized_ cou.ld
replace tl_etroublesome heat i'ejection radiator ms well as the fuel
ce]]__,.equired for electric power m_d result in a simpler, more reliable_
mid possibly .lig]_terweight _wstem. _d certainly the development of
more earthlike male mid female urine mid feces collection devices would
restult in t!_e increased passenger acceptability which will be necessary
if the shuttle is to become part of a routine and widely utilized
space trm_sportation system.
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Preliminary results of space shuttle EC/LSS studies

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