JOURNAL OF PROPULSION AND POWER
Vol. 17, No. 4, July–August 2001
Low Mass Components for Mars Ascent Propulsion
Keith Dyer
VACCO Industries, South El Monte, California 91733
†
George Yankura
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
and
Jesus Acosta
VACCO Industries, South El Monte, California 91733
The Jet Propulsion Laboratory is planning a sample return mission for early in the next century. To accom-
plish this, the Mars ascent stage must be landed on the Martian surface and then, after actuation, ascend to
Mars orbit. Given this mission pro le it is necessary to develop propulsion components of substantially lower
mass than were previously available for spacecraft applications. Low mass is especially critical to the Mars as-
cent stage because mass reduction of this stage affords the greatest leverage for the reduction of the total mis-
sion system mass at Earth liftoff. In addition to very low mass, these components must be rugged, reliable, and
compatible with fuel, oxidizer, pressurant gas, and environmental extremes. Three separate components were
developed for a liquid bipropellant baseline stage propulsion system: A high- ow etched-disk lter with a mass
under 90 g, an all-metal miniature ll and drain/vent valve with a mass under 9 g, and a miniature high- ow
check valve with a mass under 20 g. The design and development of these components as well as test data are
summarized.
Introduction
The Mars ascent miniature ll and drain valve (FDV) is a simple
and lightweight design capable of leakage rates below 1 10
6
N uncrewed sample return mission to Mars is being planned
by NASA/Jet Propulsion Laboratory (JPL) for the near future.
To accomplish this, the mass of the propulsion systems of various
mission vehicle stages must be minimized.
scch GHe. Because of its nonrotating stem, the valve’s seat life is
prolonged and particle generation is minimized. The primary valve
mechanismismade upoftwo movingparts(stemanddrive)retained
in a valve housing. A dowel pin prevents rotation of the stem and
limits the stems axial movement. External threads on the stem mate
with internal threads on the drive. The drive is trapped between a
shoulderinthe housingandthe retainer.Whenthedriveisturned,the
rotation is converted into axial motion by the thread interface with
the stem.The openingand closingof theprimarysealrequiresuse of
specialized ground support equipment (GSE). When the actuation
mechanismis locatedin the GSE tool, the mass of the ight portion
is minimized.
A
To use liquid propulsion for the Mars ascent stage, the compo-
nents must have substantiallylower mass, increased reliability and
durability,and compatibilitywith fuel, oxidizer,pressurantgas, and
the environmental extremes found between Earth and Mars. Low
mass of the Mars ascent stage is especiallycritical because any ex-
tra mass here has the greatest compounding effect of all stages on
the total vehicle mass at Earth liftoff.
Three separate components were developed for the mission
propulsion system: 1) a high- ow etched-disk lter with a mass
under 90 g, 2) an all-metal miniature ll and drain and vent valve
with a mass under 9 g, and 3) a miniature high- ow check valve
with a mass under 20 g.
The high- ow etched-disk lter incorporatesa diffusion-bonded
element stack that uses a high-efciency etched disk. Diffusion
bonding the element stack substantially reduces the mass of the
lter for a given ow and pressure drop. Traditionally, lters with
similar ow/pressuredrop requirementswere approximately990 g;
The Mars ascent check valve is the latest in a product line that
has been improved continuouslyover the last 15 years. This simple,
compact design reduces the mass from 227 g for a typical check
valve to just under 20 g. This was accomplished even though the
ow requirement increased from 13 SCFM to 87 SCFM, thereby
demonstrating a much higher ow to weight ratio than other tra-
ditional check valves. The check valve consists of a piston/poppet
assembly that is spring loaded against a seat machined into a tita-
nium inlet cap. The inlet cap and housing are joined with a single
the high-efciency lter is only 86 g.
®
electronbeamweld to formthe pressureboundary.A Te on poppet
In addition to mass reduction,the high-efciency lter has fewer
internal piece parts than traditional lters and has a greater dirt
capacityper ltersurfacearea.Testingveri edtheexpectedincrease
in dirt holding capacity. The proven ltration methodology is the
same as used in thousands of other successful etched-disk lters.
Brie y, the ow paths’ etched depth determines the micron rating
of the lter. The main differencebetween the traditionaletcheddisk
and the high-efciency design is the improved manufacturability
and assembly. The new design allows for an increase in open area
of the element stack.
is pressed and pinned onto a titanium piston.
All threecomponentdesignsdrewfrompastdesignsalreadyqual-
i ed and own on numerous successfulmissions. Each component
was tested to the Mars ascent program requirements with excel-
lent results in each case. The technology developed here has broad
applicationsto other programs where low mass is important.
Design and Development
The Mars ascent propulsion system components were designed
and developed with the goal of reduced weight while meeting the
operating requirements of the JPL specication.
Presented as Paper 99-2149 at the AIAA/ASME/SAE/ASEE 35th Joint
Propulsion Conference, Los Angeles, CA, 20–24 June 1999; received 26
Etched-Disk Filter
July 1999; revision received 8 January 2001; accepted for publication 29
Typically,a traditionaletched-disk lter assemblyconsistsof two
main components: a lter body with an inlet port and an element
assembly with an outlet port (see Fig. 1). The entire lter assembly
may be constructedfrom either titanium or stainlesssteel. The lter
January 2001. Copyright c 2001 by the American Institute of Aeronautics
and Astronautics, Inc. All rights reserved.
Senior Project Engineer, Engineering Department.
Fluids Components Engineer, Propulsion Flight Systems Group.
†
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