Payload Concept Proposal
Venus Explorer Mission
Spring 2014
Cold Springs High School
Team 3
E.P.I.C.
Explosive Plasma Interactions with Venusian Composition
“Got H2O?”
Payload Concept Proposal
Venus Explorer Mission
Spring 2014
1.0 Introduction
Venus is continually bombarded by solar winds. On Earth, the magnetosphere interacts with the solar
winds to protect Earth from the effects of the solar winds. Since Venus has no magnetosphere, scientists
long believed that all of the solar winds bombarded the planet; however, MESSENGER detected what
scientists believe was a hot flow anomaly (HFA). Hot flow anomalies are explosive outbursts of plasma
above a planet’s atmosphere characterized by a large fluctuation in the direction of magnetic fields. Hot
flow anomalies occur outside Earth’s atmosphere and Earth’s atmosphere experiences little effect from
the phenomenon; however, hot flow anomalies on Venus occur at the upper boundary of the ionosphere
because Venus does not have a magnetosphere. Scientists believe that as solar winds collide with Venus,
the planet’s bow shock deflects them away from the planet creating hot flow anomalies which act as a
vacuum to remove elements from the ionosphere.
E.P.I.C. (Explosive Plasma Interactions with Venusian Composition) has developed a scientific
payload, to be accommodated aboard the orbiter element of the Venus Explorer Mission, to investigate
interactions between the solar winds and Venus’s atmosphere. Many believe Venus was once much like
Earth; however, no water has been discovered on Venus. Some scientists believe the HFAs are
responsible for the absence of water on Venus because they are removing oxygen and hydrogen ions from
the ionosphere. The payload consists of two components: an orbiter based component and a probe
component. The orbiter based component, Olympus, will remain on the orbiter. Like the gods on Olympus
watching from afar, Olympus will monitor Venus for spikes in oxygen ions rather than hydrogen ions
because hydrogen ions are already present in the solar winds. Finding oxygen would present the
possibility of water on Venus. The probe component, Poseidon, will deploy into regions in which the
oxygen ions are detected to verify changes in the magnetic field caused by HFAs. In the Odyssey, a wellknown epic, a hero goes on a journey in which he encounters Poseidon, the Greek god of the sea. In much
the same manner, Poseidon will journey into hot flow anomalies on an epic quest.
2.0 Science Objective and Instrumentation
The science objectives are to determine the presence of oxygen ions outside Venus’s atmosphere and
determine changes in magnetic fields in the regions in which oxygen ions are detected. The primary
purpose for the science objectives is to determine if the absence of water on Venus is caused by hot flow
anomalies. Since water is required as a transport medium for biological functions, determining that water
is being removed from Venus can shed light on whether Venus could have supported life at one time.
To achieve the science objectives, E.P.I.C. selected a Q Stick USB spectrometer to measure the
composition of the region immediately above the atmosphere to determine if there is a spike in oxygen
ions. A fluxgate magnetometer will be housed in a probe that will deploy to measure changes in Venus’s
magnetic field. To maintain the location of the probe and verify that it is collecting data in the intended
region, each probe will be equipped with an accelerometer.
Table 1. Science Traceability Matrix
Science
Objective
Determine presence of oxygen ions
Determine changes in magnetism
Measurement
Objective
Composition
Magnetism
Measurement
Requirement
Continuously
Continuously
Instrument
Selected
Q Stick USB Spectrometer
Fluxgate Magnetometer
Table 2. Instrument Requirements
Instrument
Q Stick USB Spectrometer
Fluxgate Magnetometer
Mass
(kg)
0.025
0.1
Power
(W)
0.15
0.4
Data
Rate
200 ms
Triaxial Accelerometer
0.0136
0.03
-------
30bps
Page ‐ 1 Lifetime
4 years
168
seconds
168
seconds
Frequency
(samples/minute)
1
120
Duration
(seconds)
1
0.5
60
1
Payload Concept Proposal
Venus Explorer Mission
Spring 2014
3.0 Payload Design Requirements
While designing Poseidon and Olympus, E.P.I.C. considered the project requirements set forth in the
Interface Control Document (ICD), functional requirements, and environmental requirements. In addition
to the constraints, the ICD responsibilities provide the payload with 10 Watts of continuous power while
it is onboard the space craft and access to the spacecraft’s data delivery system. In addition to the project
requirements, E.P.I.C. developed functional requirements for the payload. Functional requirements are
tasks the payload must meet to satisfy the objectives. Moreover, E.P.I.C. considered the environment in
which the payload must function and developed environmental requirements which the payload must
meet to satisfy the science objectives.
Table 3. Requirements Table
Project
Requirements
Mass: no more than 5 kg
Volume: 44 cm x 24 cm x 28 cm
Power: up to 10 W continuous
Function autonomously
Cause no harm to UAH craft
Functional
Requirements
Deploy
Provide power
Take measurements
Collect data
Transmit data
House Instruments
Environmental
Requirements
Survive cosmic radiation
Survive electromagnetic radiation
Survive space temperatures of
-43°C to -173°C
Survive HFA temperatures up to
727°C
4.0 Alternative Concepts
To develop alternative concepts, E.P.I.C. divided into two groups. Each group independently
developed an alternative concept for the payload. Following the payload status review, the team
recognized positive attributes of the two alternative concepts. The engineering team then developed a
third concept that incorporated the positive attributes of both alternatives.
4.1 Concept 1
Concept 1 is composed of two components: an orbiter-based component and a probe component. The
orbiter-based component, Olympus, will remain aboard the orbiter for the entire mission and house the
spectrometer and deployment system. The housing for the spectrometer and deployment tubes is
constructed of aluminum as a single piece that contains 10 launching tubes and a spectrometer housing in
the center. The spectrometer housing will house a Q Stick USB Spectrometer and CubeSat Mission
Interface Computer that will be hardwired to communicate with the orbiter’s data delivery system and
powered by the orbiter. When an increase in oxygen ions is detected, a teardrop shaped aluminum probe,
Poseidon, will deploy on a trajectory into Venus’s upper atmosphere. The probe will house a
magnetometer, a CubeSat Mission Interface Computer, a triaxial accelerometer, and a UHF transmitter
and antenna. The probes will collect data once every 0.5 seconds and continuously transmit data to the
orbiter. The probes will be powered by primary batteries and will deploy using pressurized helium.
Figure 1. Concept 1 Probe
Figure 2. Concept 1 Orbiter based Component
4.2 Concept 2
Concept 2 also involves two components. The orbiter-based component will remain aboard the orbiter
for the entire mission and consists of 10 rifled aluminum launchers and a separate aluminum spectrometer
housing. The spectrometer housing will contain a Q Stick USB Spectrometer and a CubeSat Mission
Interface Computer that will be hardwired to communicate with the orbiter’s data delivery system and
powered by the orbiter. When an increase in oxygen ions is detected, a rocket shaped aluminum probe,
Poseidon, will deploy using pressurized helium on a trajectory into Venus’s upper atmosphere. The probe
will house a magnetometer, a CubeSat Mission Interface Computer, a triaxial accelerometer, and a UHF
Page ‐ 2 Payload Concept Proposal
Venus Explorer Mission
Spring 2014
transmitter and antenna. Poseidon will collect data once every 0.5 seconds and continuously transmit data
to the orbiter. The probe will be powered by primary batteries.
Figure 3. Concept 2 Probe
Figure 4. Concept 2 Launcher
Figure 5. Concept 2 Orbiter-based Component
4.3 Concept 3
Following the payload status review, E.P.I.C. realized there were positive attributes of both previous
concepts that could be combined to create a third concept. Concept 3 is a combination of Concept 1 and
Concept 2. The team realized the advantages of a launcher and the spectrometer housing being
constructed as one piece rather than individual pieces. For this reason, Concept 3 features four rifled
aluminum launchers and aluminum spectrometer housing attached to an aluminum base. The
spectrometer housing will contain a spectrometer and a CubeSat Mission Interface Computer which will
be hardwired to communicate with the orbiter’s data delivery system. Both instruments will be powered
by the orbiter. The probe design for Concept 3 is the same rocket shaped probe design for Concept 2 that
will house a magnetometer, an accelerometer, a CPU, a UHF transmitter and antenna, and primary
batteries. The probe will deploy from the launcher using pressurized helium, collect data once every 0.5
seconds, and continuously transmit data to the orbiter.
Figure 6. Concept 3 Probe
Figure 7. Concept 3 Launcher
5.0 Decision Analysis
To determine which alternative concept would be the final concept, E.P.I.C. evaluated figures of merit
for the proposed concepts. The team was provided with the first seven figures of merit and tasked with
developing three additional figures of merit. The figures of merit were assigned a value of 1, 3, or 9
depending on the level of importance with 9 being the highest. The team decided that the most important
aspect of the concepts were science objective, project requirements, likelihood of mission success,
launcher stability, and data accumulation, so these figures of merit were assigned a value of 9.
Concept 2 received a 9 for project requirements and manufacturability because the individual launch
tubes had lower mass and a simpler design. The separate spectrometer housing of Concept 2 makes it
possible to adjust the angle at which the spectrometer is mounted resulting in more accurate data
collection; hence, it was rated as a 9 for science objective, mission success, and instrument orientation.
The team totaled the weighted scores of all concepts and Concept 2 had the highest total score, so the
team decided to move forward with Concept 2.
Table 4. Payload Decision Analysis
Figure of Merit
Weight
Science Objective
Project Requirements
Science Mass Ratio
9
9
3
Concept
1
1
1
3
Concept
2
9
9
3
Concept
3
3
3
3
Page ‐ 3 Rationale
Must complete science objectives
Must remain within constraints
More mass devoted to science
instrumentation
Design Complexity
ConOps Complexity
Likelihood of
Mission Success
Manufacturability
Launcher Stability
Instrument
Orientation
Ease of Launch
Total
1
3
9
1
1
1
3
1
9
9
1
3
1
9
9
1
9
1
9
1
9
3
3
3
3
9
158
1
360
3
168
Payload Concept Proposal
Venus Explorer Mission
Spring 2014
Low complexity design is desired.
Low complexity ConOps is desired.
Must acquire needed data
at correct destination
Must be simple to construct
Must deploy with minimal jarring
Must allow for probe to deploy on
correct trajectory
Must deploy without errors
6.0 Payload Concept of Operations
Prior to the mission launching from Earth, the payload will be stowed aboard the orbiter and
positioned on the portion of the orbiter that will face Venus during orbit. Once orbit has been established,
baseline values for the spectrum analysis and magnetic field will be established. To establish the baseline
for the spectrum analysis, Olympus will conduct spectrum analysis for two complete orbits (2.88 Earth
hours). To establish baseline values for the magnetic field, one Poseidon probe will be deployed into the
uppermost atmosphere. Once the baseline values are established, the payload will begin the experimental
portion of its mission. The concept of operations consists of two components: the orbiter based
component and the probe component. Each component has its own concept of operations and the concept
of operations for the orbiter-based component interacts with the probe component.
Orbiter Based Component
Probe Component
Phase 1:Data Collection
Phase 1: Deployment
 Spectrum analysis (once each minute).
 Launcher pressurizes to 1508 psi.
 Activates probe deployment with
 Pressure releases.
detection of oxygen ions.
 Probe ejects at a 90°angle from orbiter.
Phase 2:Data transmission
Phase 2: Data collection and transmission
 Transmits data to orbiter every 2 hours
 Data collection (every 0.5 s)
 Continuous data transmission
Figure 8. Concept of Operations Flowchart
Figure 9. CONOPS graphic
7.0 Engineering Analysis
Team E.P.I.C. found it necessary to evaluate several parameters of the payload’s design. The
evaluation included structural and battery mass analysis, launch barrel analysis, launch pressure analysis,
spectrometer housing angle, orbital period, and free fall time analysis.
7.1 Structural Mass Analysis
Since there are mass constraints and the mass of the probes is needed to calculate the launch velocity,
the team decided it was necessary to determine the structural mass of the probes, launchers, and
spectrometer housing. Since the density of a material is its mass divided by its volume, the team used the
density and volume of aluminum, polyethylene, and PICA to determine the mass. Since the team desired
Page ‐ 4 Payload Concept Proposal
Venus Explorer Mission
Spring 2014
to collect as much science data as possible, all original concepts contained ten probes; however, the
number of probes had to be reduced to eight probes to remain within the mass constraint. The structural
mass of the entire payload is 3.1 kg.
7.2 Orbital Velocity
Poseidon will require an initial velocity of 1% of the orbital velocity and the orbital velocity will be
needed to calculate the transmission time; therefore, the team decided calculating orbital velocity was
essential for the engineering analysis. In calculating the orbital velocity, the team assumed a circular orbit
and calculated the orbital velocity to be 7,191 m/s.
7.3 Transmission Time
Team E.P.I.C. decided it was important to determine how long the orbiter would be within range to
receive data transmissions from the probes. To calculate transmission time, the team assumed a circular
orbit, spherical planet, and the orbiter would be within range for 30% to 40% of its orbital path. The team
used the formula for the circumference of a circle to determine the linear distance of the orbit and then to
determine 30% of that distance and 40% of that distance. Once the team determined the linear distance,
they used the formula for velocity (v = d/t) and solved for time. The transmission time was determined to
be 1,586.36 s – 2,115.15 s which exceeds the amount of time the probes will function and ensures data
will be transmitted to the orbiter.
7.4 Orbital Period Analysis
As part of the concept of operations, Olympus will establish baseline values for the spectrum analysis
for two complete orbits. E.P.I.C. decided it was necessary to determine the orbital period to provide a
timeframe over which the baseline will be established. To accomplish this, the team assumed a circular
orbit and a spherical planet. The orbital period is 5,190 seconds (1.44 hours).
7.5 Launch Barrel Length Analysis
E.P.I.C. understood there was a relationship between launch pressure, tube length, and exit velocity.
The team performed launch tube analysis to help determine the length of the barrel for the launcher. The
team calculated the velocities attained using 0 psi to 4,500 psi and three different barrel lengths. As a
result, the team determined that a longer launch tube would allow the probe to reach the required velocity
with less pressure resulting in less stress on the probe. As a result of this analysis, the team decided to use
a 15 cm launch barrel.
Figure 10. Launch Tube Length Analysis
7.6 Launch Pressure Analysis
For the purpose of the Concept of Operations the exact launch pressure needed to be calculated.
Poseidon must exit the launch tube at 71.9 m/s. When performing the calculations, E.P.I.C. assumed
constant pressure and velocity in the barrel, no back pressure, and a frictionless barrel. The launch
pressure is 1,508 psi.
7.7 Spectrometer Housing Angle Analysis
Since the probe will have both horizontal and vertical velocities when it is deployed, the trajectory
will be a parabolic path rather than at a 90° angle to the orbital path. Because the activation of probe
deployment depends on the detection of oxygen ions, the team needed to ensure the probe will be
deployed into the area in which the oxygen ions are detected. To accomplish this, E.P.I.C. assumed linear
motion of the orbiter at the moment of deployment and a launch angle of 90° from the orbiter. The team
used vector resolution to determine the horizontal and vertical components of the probe’s velocity and
Page ‐ 5 Payload Concept Proposal
Venus Explorer Mission
Spring 2014
then calculated the angle of the velocity vector of the probe upon deployment and decided to mount the
spectrometer housing at a 0.6° angle to the orbiter so that it faces the direction of the orbiter’s motion.
7.8 Gravity Analysis
Since Poseidon will be launched from 230 km above Venus, E.P.I.C. realized that acceleration due to
gravity would not be the same at 230 km as it would be on the surface. For this reason, E.P.I.C. calculated
acceleration due to gravity from 230 km to 0 km in altitude steps of 1 km. The calculation provides more
accurate acceleration due to gravity and makes calculations for operational time more accurate.
7.9 Operational Time
E.P.I.C. found it necessary to determine the time for Poseidon to collect data to ensure adequate
battery mass was provided. Since the hot flow anomalies extend above the atmosphere, Poseidon will
collect data prior to reaching the atmosphere. The team calculated the time it will be in freefall. To
accomplish this, the team used two formulas, df = di + vit + gt2 and vf = vi + gt, to calculate the values
for df and vf at 1 second intervals. For each time step, the value for vf became the value of vi and the value
for df became the value of di for the following step. The team adjusted gravitational acceleration at 5 km
intervals. Poseidon will fall through the HFA region for 168 seconds before reaching the atmosphere.
7.10 Battery Mass Analysis
To ensure adequate battery mass was allotted to allow the probes to function for the required amount
of time, E.P.I.C found it essential to calculate the battery mass of the 400 W*hr/kg batteries required to
power the probes. The team used the operational time of 6 minutes and a power consumption of 1.70 W
to determine the mass of primary batteries is 0.000424 kg for one probe.
8.0 Final Design
The final design for the payload consists of eight aluminum, cylindrical launch tubes that will be
rifled to provide spin stabilization as eight probes are ejected from the orbiter using pressurized helium.
Each probe will be constructed of aluminum, lined with polyethylene to shield from radiation, and
covered in PICA heat shielding. Each probe will be equipped with a magnetometer, computer, transmitter,
and accelerometer. The spectrometer housing aboard the orbiter will be mounted at a 0.6° angle to the
orbiter and contain the spectrometer and a computer which will be hardwired into the orbiter’s data
delivery system. Both the spectrometer and the computer in the spectrometer housing will be powered by
the orbiter. After all probes have been deployed, the spectrometer will continue to measure composition
for the remainder of the mission.
Figure 11. Final Concept Probe
Figure 12.Final Concept Launcher
Figure 13. Final Concept Spectrometer Housing
Table 5. Final Design Mass Table
Function
Component
Deploy
Measure
Aluminum Launch Tube
Fluxgate Magnetometer
Q Stick USB Spectrometer
Model 3000A Triaxial Accelerometer
CubeSat Mission Interface Computer
Collect Data
Quantity
Page ‐ 6 8
8
1
8
9
Mass (kg)
0.180
0.1
0.025
0.014
0.062
Total
(kg)
1.438
0.8
0.025
0.109
0.558
Mass
Provide Power
Send Data
House Payload
Batteries
TI 430 CCRF Microcontroller
Aluminum Probe Structure
Polyethylene (Probe)
PICA
Aluminum Spectrometer Housing
Payload Concept Proposal
Venus Explorer Mission
Spring 2014
8
0.00042
0.00034
8
0.05
0.4
8
0.104
0.834
8
0.014
0.111
8
0.01
0.08
1
0.618
0.618
TOTAL MASS
5.0
Table 6. Payload Design Compliance
Requirement
Mass: No more than 5 kg
Volume: 44 cm x 24 cm x 28 cm
Power: 10W continuous (aboard orbiter)
Function autonomously
Cause no harm to UAH spacecraft
Survive electromagnetic radiation
Survive cosmic radiation
Survive space temperatures of
-43°C to -173°C
Survive HFA temperatures up to 727°C
Deploy
Take Measurements
Collect Data
Transmit Data
House Instruments
Provide Power
Solution
5.0 kg mass
Payload dimensions: 15.2 cm x 12.5 cm x 15.0 cm
1.4 W continuously for mass spec and computer
Probes deploy from orbiter
No incendiary process used to exit the spacecraft
Constructed of aluminum and lined with polyethylene
Constructed of aluminum and lined with polyethylene
Instruments function within temperature range
PICA heat shield protects instrumentation in probes
Deploy from an aluminum launcher using pressurized
helium
Instruments that will be used:
- Fluxgate Magnetometer
- Q Stick USB Spectrometer
- Model 3000A Triaxial Accelerometer
CubeSat Mission Interface Computer
TI 430 CCRF Microcontroller
Aluminum Probes
400 Watt * hr/kg primary batteries will provide power
9.0 Community Engagement Activity Summary
E.P.I.C. conducted three different types of community engagement activities in which they engaged
455 visitors. The team educated students and teachers in elementary and high school classes at Cold
Springs schools about the nature of the InSPIRESS project. The team also conducted a science
experiment with a sixth grade class and held an exhibit at which they shared with the community about
their final design and their project.
9.1 Educational Presentations
Members of team E.P.I.C. visited ten different classrooms in which they made a presentation aimed at
educating the audience about NASA, InSPIRESS, Venus, and team E.P.I.C.’s science objectives. Team
E.P.I.C. used a power point presentation to aid them in completing the 30 minute presentation. Following
the presentation, team members answered questions from the audience. There were 226 students and
teachers who participated in the presentations.
Figure 14. Presentation to students
Figure 15. Presentation to students
Page ‐ 7 Figure 16. Presentation to students
Payload Concept Proposal
Venus Explorer Mission
Spring 2014
9.2 Science Experiment
Members of team E.P.I.C. conducted a science experiment with a class of 26 sixth grade students.
Team members began the experiment by sharing their science objectives with students and explaining that
the spectrometer in their design would identify elements. E.P.I.C. explained to students how light is
broken down into its component colors depending on the wavelength of the light. Each group of students
was stationed at a spectrum tube containing a different element or compound, students looked at the light
through the spectroscope, and drew the spectrum they saw with colored pencils. After all groups finished
drawing the spectrum of their spectrum tubes, students with different elements and compounds were
asked to line up in the front of the room so everyone could compare their results. Team E.P.I.C. asked
students questions about the differences between the spectrums of different elements and compounds.
Students concluded that no two elements or compounds had the same spectrum. Students related the
unique spectrum of each element or compound to fingerprints in humans. E.P.I.C. explained that the
spectrometer in their payload would also identify elements based on each element’s unique spectrum.
Figure 17. Students collecting data
Figure 18. Students collecting data
Figure 19. Student comparing data
Figure 20. Student data samples
9.3 Design Exhibit
Team E.P.I.C. held an exhibit during which they set up a display table containing a display board
outlining their project, a prototype, and a presentation of the team’s design features. The exhibit was held
at two times: during the school day for students to attend and in the evening for family and friends to
attend. 203 visitors attended the design exhibit. During the exhibit, the team talked with visitors about
Venus, the science objectives, and aspects of the final design. The team also answered questions from
visitors.
Figure 21. Talking with visitors
Figure 22. Talking with visitors
Page ‐ 8 Figure 23. Talking with visitors