// VAR-015 · United States

Enhanced EMU

Hamilton Sundstrand + ILC · 1990–present
EVA Active legacy / aging

Technical Specifications

Pressure4.3 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 duration8 hours
ProgramISS
AgencyNASA
ManufacturerHamilton Sundstrand + ILC
First use1998
StatusActive legacy / aging
Donning / entryModular rear-entry HUT with SAFER, REBA, heated glove, METOX

Engineering Analysis

Key Subsystem Architecture

Heated glove, REBA power, METOX CO2, ISS interface upgrades

Mission Role

ISS assembly and maintenance — primary orbital EVA workhorse

Limitations & Failures

EVA-23 water intrusion 2013; glove injuries; aging hardware; OIG 2025 critical sustainment flag

Program Lesson
"Long-life EVA programs shift from design problems to sustainment, anomaly and industrial-base problems"
Future Relevance

Primary direct predecessor to any replacement orbital EVA system

Documented Failure Cases
High 1965

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

High 1960s

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

High 1965

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

High 1980s–1990s

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

Critical 2013

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

Critical 2010s–2025

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

Medium 1977–

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

// Related Suits

Same Program Family

PROTO-001 Prototype EXPERIMENTAL
Mk II Model O spacesuit photograph

Mk II Model O

USAF · B.F. Goodrich
1956
Pressure
TBD
System mass
TBD
Life support
Not publicly documented
EVA duration
N/A

"Established B.F. Goodrich as the lead US full-pressure suit contractor before Mercury existed"

View Full Archive →
PROTO-002 Prototype EXPERIMENTAL
Mk II Model R spacesuit photograph

Mk II Model R

USAF · B.F. Goodrich
1956
Pressure
TBD
System mass
TBD
Life support
Not publicly documented
EVA duration
N/A

"Parallel development track alongside Model O testing different mobility solutions"

View Full Archive →
PROTO-003 Prototype EXPERIMENTAL
Mk IV Arrowhead spacesuit photograph

Mk IV Arrowhead

US Navy · B.F. Goodrich
late 1950s
Pressure
TBD
System mass
TBD
Life support
Not publicly documented
EVA duration
N/A

"Naval and NASA pressure suit research tracks cross-pollinated significantly in this era"

View Full Archive →