Lunar Surface Systems Crew Time Analysis Overview

Transcription

1 Lunar Surface Systems Crew Time Analysis Overview Chel Stromgren Strategic Analysis Team January 14, 2009 Page 1

2 Key Points Primary goal of this effort was to begin an integrated analysis of potential crew time restrictions on lunar scenarios Objective is not to solve for a crew time availability result but rather to explore crew time drivers, to evaluate sensitivities, and to identify potential crew time issues Historical ISS experience has taught us that it is difficult to carve out a significant amount of time for utilization, especially during build-up - smaller crew, assembly/outfitting tasks, infant mortality General LSS team feeling is that we must break that paradigm for LSS and ensure that there is a sufficient amount of time available for utilization right from the start Lunar specific challenges: Increased EVA rates Large fraction of time planned for SPR excursions Large number of dynamic elements - chassis, ATHLETE, SPR, ISRU, etc. Potential for large amount of unloading, movement, and site work No planned visiting crews to augment time Page 2

3 Current Observations Given current outpost crew time assumptions and priorities: It is likely that the projected number of SPR Excursions in a typical 180- day stay will be: 4 Long Duration (14-days each) 4 Short Duration (3-days each) 68 total days in SPR Current manifesting analysis assumes for a 180-day stay: 4 Long Duration (14-days each) 8 Short Duration (3-days each) 80 total days in SPR 15% decrease in projected number of SPR Excursions from current scenarios Total fraction of surface time devoted to utilization (science) could be less than 20% Maximizing time on SPR excursion limits any utilization at the outpost Page 3

4 Crew Time Model Crew time model is an integrated scenario-level analysis, incorporating scenario and architecture data for: Maintenance and repair estimates Offloading / Set-up task estimates EVA schedule Mobility schedule Model is derived from the VIPER ISS crew time model, modified to account for differences in ISS and LSS operations Maintenance/Repair and Offloading/Set-up estimates derived specifically for LSS architecture Utilization time is treated as the dependent variable NO time estimates included for additional potential outpost activities such as: Berming Moving of regolith for radiation protection Landing pad preparation Crew ISRU support Road construction Page 4

5 Crew Time Liens Estimates for crew time Liens were derived from historical ISS crew time distributions Liens are crew time usage not devoted to maintenance/repair or utilization Examined actual daily schedules for every ISS day from 2005 to 2007 Developed statistical data and adjusted for differences between ISS and LSS Task Type Average Weekly ISS Time (Hours/ Day/Crew) LSS Time Weekly Estimate (Hours/Day/Crew) Routine Ops Inspection % Change Notes Conference / Tag-Ups % Reduced tag-ups regarding in-lab science experiments Training Work Prep % Less in-lab science prep Traffic % No docking / undocking of vehicles Medical Public Relations % Increased public interest Stowage / Inventory % Application of RFID technology Exercise % Reduced exercise requirement due to EVA rate Food Prep % Simpler MRE style meals Meals hour/crew/day Pre / Post Sleep hour/crew/day Sleep hour/crew/day Personal Comm R&R Margin Page 5

6 Historical Comparison of Time Distribution Compared working LSS crew time distribution to other analogs Dean Eppler provided time logs for his Antarctic ANSMET experience in Averaged times for all regular working days Excluded relocation days where camp was struck-down and moved ISS Strategic Planning and Integration (SPI) team provided strategic planning values for future 6-crew ISS missions Aggregated historical ISS data from D. Eppler Antarctic Data - Average Non- Relocation Day (Hours/Day/Crew) ISS Strategic Planning Values (Hours/Day/Crew) Observed ISS Values (Hours/Day/Crew) Working LSS Values (Hours/Day/ Crew) Sleep/Pre/Post Meal Prep/Meals Personal/Down Time/Exercise Logistics Team Activities/Conference/Training Work Total Page 6

7 Assumptions/Methodology No repair or maintenance performed while on SPR excursion - emergency fix only to get back to outpost Model inputs prioritize allocation of time - priorities can be reset or balanced For the baseline analysis the following priorities are used: 1. SPR EVA Time (up to 24 hour/week/crew limit) 2. SPR Driving Time (up to 6.67 hours/day) 3. SPR Excursion Days (up to manifesting assumptions) 4. Outpost Utilization EVA Time (up to 24 hour/week/crew limit) 5. Outpost Utilization IVA Time Certain tasks do not have to be performed while on excursion but must be made-up at a pro-rated rate once crew has returned to outpost: training, medical, personal comm., stowage/inventory, and R&R Model attempts to achieve 24 hours/week of EVA and 6 hours of driving time per day while on excursion Remaining SPR time is used complete as much of liens as possible while on excursion No assignment of IVA science time in SPR No Utilization requirement at Outpost: For initial runs only minimal amount of EVAs, required to complete maintenance and logistics are completed at outpost - no EVA time required for science No IVA science requirement at the outpost is assigned Aside from SPR excursions, there is NO consideration in the model that certain tasks may require continuous time blocks - all time may be efficiently used Page 7

8 SPR Assumptions Current manifesting of SPR Excursions is based on six-week centers (SAT team is running variations) 1 Long (14-day excursions) 2 Short (3-day excursions) 14-day r&m 14-day r&m 14-day r&m 14-day r&m 3-day 3-day 3-day 3-day Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Repeat Long Excursion (14-Day) Rest & Maintenance (r&m) Short Excursion (3-Day) Short Excursion (3-Day) Yields 80 days on excursion in a 180-day outpost stay (4 Long & 8 Short) Assume 2 SPRs and 4 crew per excursion 24-hours per week max EVA rate On 3-day excursions it is possible to complete 24 hours/crew during 3-day excursion with no additional EVAs for remainder of week Page 8

9 Maintenance & Repair Time Estimates Page 9

10 Offloading/Set-Up/Outfitting Time Estimates Page 10

11 Lunar Exploration Architecture Manifest Scenario Human Lunar Return Initial Core Capability Start of Continuous Human Presence Test Flight Rover HLR MCT CDK OSE MPU SPR SPR CMC RA RPLM-1& PSU Tri- ATHLETE x2 LCT OPS Plant & Tools Core Hab & PSU Tri- ATHLETE x2 OSE OPS Plant & Tools RPLM-2 & PSU Notes: 500 kg of payload (e.g., scientific research, commercial, Education and Public Outreach (EPO), International Partners, etc.) is delivered for each mission The 7 day missions have a rover and 250 kg of payload Payload, unpressurized goods, liquids, and gases are not shown Through FY30, there are day and day SPR excursions Adv ECLSS DPLM & PSU DPLM & PSU DPLM & SSU DPLM & SSU DPLM & SSU Begin series of 3 Missions per year for one year followed by one year with 4 Missions. Series repeats as necessary to support sustained continuous human presence FY19 FY20 FY21 FY22 FY23 FY24 FY25 FY # - Crew Size # - Surface Duration # - Mission Number Page 11

12 Results for a Typical 180-Day Increment 17,280 hours Outpost: 10,752 hours (112 Days) SPR: 6,528 hours (68 Days) Outpost IVA Work Time Liens (1472 hrs) Outpost IVA Maint. (767 hrs) Sleep/PS (4480 hrs) R&R/ Personal (1424 hrs) Food/ Meals (912 hrs) Exercise Pro-Rated (640 hrs) SPR Non- Work Liens (831 hrs) Required Outpost EVA (123 hrs) IVA Util SPR Work (104 hrs) Time Liens (854 hrs) Sleep/PS (2720 hrs) Personal (87 hrs) Food/ Meals (553 hrs) Exercise (374 hrs) SPR IVA/ Driving EVA Util (1804 hrs) (1056 hrs) Outpost IVA requirements drive total required outpost days (not required EVAs) 112 required outpost days do not allow currently manifested excursion schedule 68 excursion days 4 long and 4 short - are projected 80 excursion days 4 long and 8 short are currently manifested Maximizing SPR time virtually eliminates any outpost utilization (IVA or EVA) Additional time for outpost utilization (local EVA or lab in hab) will reduce total excursion days Average time per crew devoted to work items = 7.0 hours/day (7 days a week) 5.7 hours/day on ISS Total fraction of surface time committed to utilization (including driving) = 12% All of which is in the SPR Page 12

13 Outpost Utilization Time Results attempt to maximize SPR excursion days, once outpost time requirements have been satisfied (non-utilization) No remaining time for utilization at the outpost - Local EVA, rock sorting, lab in hab, etc. EVA rate at outpost is far less than allowable hours out of 1536 hours allowable (8%) Increased outpost utilization time will directly decrease excursion time Similarly, any added outpost tasks (berming, site prep., regolith moving) will decrease SPR time Page 13

14 Scenario Results Initial utilization is low Large build-up Limited surface days ISS-Like Average utilization across across scenario = 3.9 hours/ day/crew (including driving) SPR days more limited on initial missions Only achieve 60% of excursion days in current manifest on first five crewed mission 85% over scenario SPR IVA Utilization time averages approx. 7.1 hours/day/crew (incl. driving time) Page 14

15 Scenario Results (cont.) Total SPR Time 34.9% SPR IVA Utilization/ Driving 10.0% Outpost IVA Work Time Liens 8.0% Outpost IVA Maintenance/Set-Up 3.4% SPR Food/Meals 3.0% SPR Utilization EVA 6.0% SPR Sleep/PS 14.5% Outpost Sleep/PS 27.1% SPR Work Time Liens 1.4% Outpost IVA Utilization 0.4% Pro-Rated SPR Liens 7.4% Outpost R&R/Personal 8.3% Outpost EVA 1.0% Outpost Exercise/Med 3.9% Outpost Food/Meals 5.5% Total Outpost Time 65.1% Page 15

16 SPR EVA Options Projected Current Manifesting (no crew time restrictions) SPR EVA (7%) SPR EVA (4%) SPR EVA (9%) Inside SPR (31%) Inside Hab (61%) Inside SPR (41%) Inside Hab (54%) Inside SPR (36%) Inside Hab (50%) Hab EVA (1%) Hab EVA (1%) Hab EVA (5%) Page 16

17 Path Forward Need to work with functional area leads to identify opportunities to improve time requirements for various areas of operation Model can be used to establish goals: ~10% reduction required across the board for all crew time liens in order to enable full current manifested excursion days (80 days per 180 day increment) - 14 hour/week/crew reduction ~30% reduction required across the board for all crew time liens in order to enable full current manifested excursion days PLUS full EVA schedule at the outpost hour/week/crew reduction ~40% reduction across the board for all crew time liens in order to enable full current manifested excursion days PLUS full EVA schedule at the outpost PLUS ~60 hours per week of IVA utilization hour/week/crew reduction Since certain liens likely cannot be significantly reduced, larger gains will be required in other areas Task Type LSS Time Weekly Estimate (Hours/Crew) Routine Ops 3.0 Inspection 1.5 Conference / Tag-Ups 7.0 Training 2.0 Work Prep 3.0 Traffic 0.0 Medical 4.0 Public Relations 1.5 Stowage / Inventory 1.0 Exercise 10.0 Food Prep 2.0 Meals Pre / Post Sleep 10.5 Sleep 59.5 Personal Comm. 1.5 R&R 20.0 Margin 0.75 Page 17

18 Future Issues Initial LSS Maintenance & Repair estimates are substantially lower than ISS historical data Pushing to lower-level repair will increase time More sophisticated ECLSS and mobility will increase time On-site manufacturing & scavenging will increase time No inclusion of infant mortality Additional outpost tasking will further reduce excursion capability Site prep Landing pads / moving of landers Moving of regolith for radiation protection ISRU support There is potential for use of robotics and tele-operations to reduce certain time requirements Page 18