Mk II Model O
"Established B.F. Goodrich as the lead US full-pressure suit contractor before Mercury existed"
| Pressure | 4.3 psi / 29.6 kPa |
| Suit mass (1g) | 309 lb (system) |
| Life support (primary) | PLSS 8 hr; regenerative CO2 removal |
| Life support (backup) | SOP 30 min |
| EVA duration | 8 hours |
| Program | ISS |
| Agency | NASA |
| Manufacturer | Hamilton Sundstrand + ILC |
| First use | 1998 |
| Status | Active legacy / aging |
| Donning / entry | Modular rear-entry HUT with SAFER, REBA, heated glove, METOX |
Heated glove, REBA power, METOX CO2, ISS interface upgrades
ISS assembly and maintenance — primary orbital EVA workhorse
EVA-23 water intrusion 2013; glove injuries; aging hardware; OIG 2025 critical sustainment flag
"Long-life EVA programs shift from design problems to sustainment, anomaly and industrial-base problems"
Primary direct predecessor to any replacement orbital EVA system
First US EVA physically exhausting and low-productivity despite suit functioning; glove productivity inadequate for task completion
→ Suit capability and worksite design must be developed together, not sequentially
Unexpected arm growth when shoulder restraint cable failed; seized pulley caused overheating in crotch-thigh region
→ Critical restraint paths need redundancy or condition monitoring. Small mechanical hardware in pressure-load paths creates outsized crew risk
Suit inflation during Leonov's EVA made movement and airlock re-entry critically difficult — Leonov had to partially deflate to re-enter
→ Make ingress/egress and self-rescue a separate verification gate from EVA capability itself
Numbness, bladder bunching, and palm-bar wear-through into hand across multiple crew members
→ Glove verification must include extended-use comfort and injury surveillance, not just pressure integrity and cold-object performance
Water entered Luca Parmitano's helmet during EVA — vision impaired, comms degraded, breathing compromised
→ Cooling-water management is a primary safety-critical function, not a nuisance issue. Contamination tolerance must be designed in from day one
Aging suits, obsolescence, contractor quality issues, supply-chain weaknesses — OIG 2025 flagged as mission risk
→ Industrial-base fragility becomes a technical failure mode in long-lived fleets. Supplier resilience must be a first-class design and program requirement
Repeated orbital use shifted primary risk toward maintenance, drying, recharge, and replaceable component management
→ Not all critical failures are dramatic punctures. Slow fleet degradation from poor maintenance design matters as much as acute failures
"Established B.F. Goodrich as the lead US full-pressure suit contractor before Mercury existed"
"Parallel development track alongside Model O testing different mobility solutions"
"Naval and NASA pressure suit research tracks cross-pollinated significantly in this era"