Aerospace & Defense Technology - June 2024 - 22

SpaceVPX
SATCOM System
Key
SE
Utility Plane
Utility Plane Expansion
Utility Plane
S
E
S
E
User Defined
S
E
S
E
S
E
P0/J0
S
E
Diff
P1/J1
Diff
P2/J2
Diff
P3/J3
User Defined
Diff
P4/J4
User Defined
Control Plane - Thin Pipes
Diff
P5/J5
User Defined
Diff
P6/J6
Key
S
E
Diff
P6/J6
Key
To SpaceUM
Key
S
E
Diff
P6/J6
16 Pairs
8 Pairs
S
E
Diff
P5/J5
S
E
Diff
P4/J4
User Defined
Data Plane - 16 Fat Pipes
S
E
Diff
P5/J5
User Defined
S
E
Diff
P4/J4
Switched
Managemant
Plane (IPMB)
Switched
Utility Plane
Includes power
Controller
Selection
A and B (HLD)
Power A and B
Utility Plane
Data Plane - 4 Fat Pipes
Utility Plane Expansion
Utility Plane
S
Key
S
E
Diff
P3/J3
Diff
Expansion Plane - 32 Pairs P2/J2
KeyKey
S
E
Diff
P3/J3
Control Plane
16 TP
Control Plane
(TP)
Contrl
Plane
Contrl
Plane
Contrl
Plane
Contrl
Switch
Contrl
Switch
Contrl
Plane
Contrl
Plane
Contrl
Plane
Data
Plane
Data
Plane
Data
Plane
Data
Plane
Data
Plane
Data
Plane
Data
Plane
Data
Plane
TP
TP
S
E
Key
SE
P0/J0
Diff
P1/J1
Utility Plane
S
E
User Defined - 8 Fat Pipes
User Defined
Utility Plane Expansion
Utility Plane
S
E
Key
SE
P0/J0
Diff
P1/J1
Diff
P2/J2
User Defined
Data Plane
4 FP
Slot
numbers
are logical,
physical
slot
numbers
may be
different
Data Plane
(DFP)
Payload slots
VPX
1
Expan
Plane
VPX
2
Expan
Plane
VPX
3
Expan
Plane
VPX
4
VPX
5
VPX
6
Payload slots
VPX
7
Expan
Plane
VPX
8
Expan
Plane
VPX
9
Expan
Plane
IPMC IPMC IPMC ChMC
ChMC IPMC IPMC IPMC
3W
This is an image from the NASA Engineering & Safety Center (NESC) Interoperability Assessment that describes the basic building blocks of a SpaceVPX-aligned
embedded computing module. (Image: NESC)
In the article, the two engineers
describe SpaceVPX as a " standard for
creating plug-in cards (PICs) from its
slot profile and module (protocol)
profiles. In turn, these building blocks
create interconnected subsystems and
systems. " They go on to state that the
primary goal of SpaceVPX is to
" cost-effectively remove bandwidth as
a constraint for future space systems. "
SpaceVPX and Interoperability
SpaceVPX seeks to give next generation
spacecraft the ability to perform
flight control and other bandwidth
intensive applications using smaller and
lighter avionics boxes that are more
interoperable, less expensive to develop
and leverage modern processors and data
networks and protocols. In September
2022, NASA Engineering & Safety Center
(NESC) published an in-depth understanding
of the goals of the use of the
22
SpaceVPX standard, and what aspects of
the standard still need to be revised.
NESC's " SpaceVPX Interoperability
Assessment, " is a 92-page assessment of
SpaceVPX's goals of incorporating fault
tolerance features that are required by
spaceflight systems as well as how it creates
interoperability between spacecraft
avionics. Leveraging use cases, embedded
computing product surveys and SMEs
and briefings to gauge industry and government
interest internationally in the
use of SpaceVPX-aligned systems, the
assessment found that " VITA-78 allows so
much flexibility that interoperability
between modules cannot be assured. "
The assessment also includes an overview
of what a SpaceVPX embedded processing
or computing module looks like,
which at its most basic description is a
radiation hardened processing module
that can operate in the extreme temperatures
and environment of space and
mobilityengineeringtech.com
includes payload inputs, processing
cards, memory and power in a package
that can be linked to other embedded
spacecraft systems via SpaceWire, Ethernet
or other data control networks.
The NESC report states that in evaluating
the use of OpenVPX for potential space
usage, several shortcomings were observed.
" The biggest deficiency was the lack of features
that could support a full single fault
tolerant and highly reliable configuration.
Utility signals were bussed and, in most
cases, only supported one set of signals, via
signal pins to a module. Therefore, a pure
OpenVPX system has opportunities for
multiple failures, " the report states. " As the
typical OpenVPX control planes are PCI
Express or Ethernet, this was a concern
since their usage in space applications was
minimal, at the time, and SpaceWire was
the dominant medium speed data and
control plane interface for most spacecraft.
This has evolved since the inception of
Aerospace & Defense Technology, June 2024
Payload input
Payload input
Payload input
Processing card
Processing card
Switch card
Memory card
Output card
Power card
Control Slots
SpaceUM
Slots
Control Slots
http://mobilityengineeringtech.com
Aerospace & Defense Technology - June 2024

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