Tab 04 SOW.pdf

Puncture Disk Microvalve Development Statement of Work

1. Objective/Requirements

1.1 Scope

This statement of work (SOW) defines the effort to be contracted in support of the Goddard Space Flight Center (GSFC) Venus Mass Spectrometer (VMS) Instrument Project for the delivery of a prototype Puncture Disk Microvalve (PV), three foil cartridges, and associated hardware. These valves and cartridges were developed as part of an earlier design effort; this contract is for their delivery to GSFC.

1.2 Puncture Disk Microvalve Description and Operation

The PV will be used to hermetically seal the VMS Gas Processing System from the time of ground integration closeout until entry into the Venusian atmosphere. The VMS PV assembly shall have two commanded states “Open” and “Closed”. The initial “lance” (or pintle) configuration is “open” with the foil seal (or rupture disk) used to create a hermetic seal intact. VMS currently plans to use four PV assemblies (TBC) and each PV is integrated into the instrument system in the “retracted” foil seal intact state. All of the PV foil seals will remain intact throughout ground testing to keep the VMS and Venus Tunable Laser Spectrometer (VTLS) Gas Processing System hermetically sealed under internal vacuum. The PV assemblies remain in this sealed configuration throughout instrument system level testing, through launch, and cruise phases of DAVINICI mission.

Figure 1 Notional Puncture Valve Assembly

After approximately 2 years the DAVINCI spacecraft will reach the planet Venus, and the Descent Sphere containing the VMS instrument will be deployed. During the descent to the surface, each of the PVs will be individually commanded (TBC) to the “extended” state so that the PV lance punctures the hermetic foil seal. Once the seal is punctured, the lance will be individually commanded (TBC) to return to the “retracted” position to allow the Venus atmosphere into the instrument through the Gland Nut Port (see Figure 1 - item #5).

Foil seal

Platinum seal

“l an ce

1.3 Management, Reporting, Documentation and Reviews

1.3.1 Management

The Seller shall designate a single individual who will be given full responsibility and authority to manage and administer all phases of the work specified by the contract and ensure that all objectives are accomplished within schedule constraints.

The Seller shall designate and identify by name a single individual who shall serve as a point of contact with the GSFC Contracting Officer Representative (COR) for all technical aspects of the PV contract.

The Seller shall provide for managing all resources, controlling schedules, managing all engineering, manufacturing and procurement activities, configuration management, Quality Assurance, documentation control, and distribution.

2 Requirements

2.1 Puncture Disk Microvalve Operational and Performance Requirements

Each puncture disk microvalve (PV) shall meet the following operational and performance requirements:

a) With the foil seal intact, the (external) puncture valve seat leak rate shall be less than 1 x 10-10 atm-cc/sec for Helium after continuous exposure to helium for 5 minutes across the foil seal.

b) The outer case and internal puncture valve parts having vacuum interfaces, such as braze joints, welds, and the bellows assembly, and foil seal, shall have a leak rate less than 1 x 10-10 atm-cc/sec for Helium after continuous exposure to helium for 5 minutes.

c) The coil to case resistance shall be > 2GΩ at 250Volts. (This is a high impedance, high potential requirement.)

d) The hot operational temperature of the PV assembly over the mission will be approximately at least 140C over 65 minutes TBC (GSFC thermal analyst to determine thermal gradient due to heat soak)

e) The operational lifetime of the actuating the PV to puncture the foil seal will be approximately 1 cycle at ~140C TBC (setpoint)

a. qualify that the valve shall operate NN number of times (robustness)

b. qualify at approximately TBD cycles at TBD temp. (qual temp)

c. life test TBD

f) The foil seal with a vacuum on its internal surface shall be remain intact for the following external pressure delta conditions: Venus atmospheric pressure (pressure equivalent to ~39km above surface of Venus TBR + dynamic pressure due to freefall TBD), vacuum of space, and Earth sea level pressure (GSFC to supply values)

g) The PV including the foil seal shall be made of Venus atmospheric compatible material (Ti TBC) note: approved material list shall be provided by VMS

h) The open and closed actuation time shall be < 5 msec.

i) The survival temperature shall be from -55C to + 210C TBC (VMS will also need a qual range; and bake out spec, note: DraMS indicates 250C)

j) The PV shall be able to be commanded so the lance/pintle punctures the foil seal

(“Close” position) and then shall be able to be separately commanded to retract the lance to valve (“Open” position).

k) The puncture valve lance shall be held “open” above the foil seal TBD distance above and not “move” during all mechanical disturbances (note: microvalve open distance is 0.030”)

l) The puncture valve shall puncture/lance “Close” position at TBD force with margin to break the foil seal

m) The foil seal shall be broken so as not to reduce the gas conductance more than TBD flow rate (GPS lead’s analysis; will combine each inlet needs into one req)

n) The lance/puncture retraction force (“Open” position) shall be TBD force with margin (to ensure there is no FOD and has opened)

a. TDB “Open” clearance requirement?

o) The puncture valve assembly may have a position sensor (TBR)

p) The lance open/close position shall be measured (mechanical movement indicator) OR can we read the position within TBD range to know the valve is open or closed

q) The puncture valve shall be able to withstand DAVINCI launch loads in the Open position.

r) The puncture valve shall be able to withstand DAVINCI and Descent Sphere shock loads in the “Open” position

s) The quasi-static limit load for the microvalves shall be TBS g.

t) The random vibration input load for the microvalves shall be the amplified TBS g

RMS value resulting from the DAVINCI input of TBS g RMS.

u) The mass of each puncture valve shall be less than or equal to TBS grams. (note:

microvalve is 25g)

v) The solenoid actuator assembly shall be removable from the valve body so the valve body can be baked at a higher temperature TBD (if we need this requirement?).

w) The overall length of each puncture valve shall be less than TBD (note:

microvalve is 1.75 in – note: no hard constraint on overall length) inches

x) The diameter of each puncture valve body shall be less than TBD inches (note:

microvalve is 0.6).

y) The puncture valve must be able to survive at least 12 bakeout cycles at an upper temperature of + 275C TBC (for three hours) with the solenoid removed while still maintaining the above performance requirements.

z) After puncturing the foil, the puncture valve must be able to survive ~90 atm of internal pressure (Venus surface pressure) with vacuum on the exterior of the valve body

3. Place of Performance Contractor facility

4. Period of Performance Delivery shall be within 2 weeks ARO.