Brief Summary: There was one EVA conducted today.

EVA-5:

Context: MDRS Crew 61 Rover Failure/Walkback Procedure
Duration: 03:05 - 6:00
Weather: Clear and Sunny
Maximum distance traveled from Hab: 5.50 km.

Participants: EVA Team-5 (Marcus Medley, Elizabeth Wolfe, Pieter Jan Van Asbroeck, and Alex Diaz - out of sim support); HABComm (Irene Schneider Puente); Suit Techs (Irene Schneider Puente and Alex Diaz).

Equipment: GPS, map, radios, notepad/pen, camera, and simulated unpressurized rover (pick-up truck)

Route: EVA Team-5 drove 5.5 km north on Lowell Highway on a simulated unpressurized rover (pick-up truck).

Objectives - Work Done: Last week, MDRS Crew 61 performed several walking average speed tests. The average speed obtained was around 5.2 km/hr. Based on these results, we made a conservative assumption that, in the event of a rover breakdown, MDRS astronauts would be able to maintain an average walking speed of 2.6 km/hour (about 50% reduction). This is about half the walking speeds achieved by several members of MDRS Crew 61 over distances of several kilometers. The 2.6 km/hr assumption makes allowances for negotiating broken terrain (i.e. slope, rocky, uneven surfaces, etc), rest, and other unexpected emergencies.

Emergency Scenario Assumptions: 1) PLSS batteries can provide 4 hours of air circulation, 2) Unpressurized Rover is immobilized at the end of Site 3 EVA (2.50 km from Hab), 3) There is no communication with Hab, and 4) There is no back-up rover available for rescue at Hab.

EVA Team-5 visited three EVA sites:

• For Site 1, crew traversed 5.50 km from Hab to UTM location 12S 0517833E 4254328N (traverse time from Hab to Site 1 was 16:53 min at moving average of 20.3 km/hr). Crew performed a 30 minute EVA and located a cave. Note, walkback constraints dictate that the farthest site be the first stop (Site 1). In the event of rover failure at Site 1, crew would have the largest possible supply of PLSS consumables.
• For Site 2, crew returned 2.02 km on the same route to UTM location 12S 0518659E 4252922N (traverse time between Site 1 and Site 2 was 7:20 min at moving average of 16.5 km/hr). Crew performed a 29 minute EVA and located a lake.
• For Site 3, crew continued driving 1.05 km back towards the Hab to UTM location 12S 0519077E 4252178N (traverse time between Site 2 and Site 3 was 2:55 min at moving average of 21.6 km/hr). Crew performed a 27 minute EVA and located an area of petrified rocks. At the end of EVA 3, crew performed a simulated rover failure. Crew went through a pre-established contingency set of actions and spent 20 minutes attempting rover repair. Given pre-established procedures, the crew decided to walkback the remaining 2.50 km to the Hab. Crew walked-back at an average walking speed of 5.2 km/hr and arrived at the Hab with about an 1 hour left in PLSS battery supply.

Lessons Learned:

• Pre-established protocols were very conservative. Crew was able to walkback at the same walking speeds that had been obtained last week, 5.2 km/hr, not the allocated 2.6 km/hr for the simulated rover failure walkback procedure. The 50% safety factor reduction in walking speed is perhaps too conservative, but from a safety perspective is acceptable.
• This walkback procedure development was performed for an MDRS scenario. However, it is expected that future Mars surface exploration will use a similar approach in determining Martian walkback procedures. Martian walkback procedures will of course take into account Martian environmental factors (i.e. reduced gravity and pressure, thermal extremes, etc), EMU Design Factors (i.e. suit assembly design, PLSS capacity, etc), and Human Factors (i.e. physiological condition, psychological condition, load capacity, etc).