BUZ
Building Utilities for Zenith
“To Infinity and Beyond!”
Fairview High School
Team 3
Division 3
19 April 2013
Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
1.0 Introduction
The name of our design team is BUZ, which is an acronym for “Building Utilities for Zenith.” Our
assigned task is to design a payload to accompany NASA’s mission to Enceladus, one of Saturn’s moons.
This payload will fly on a UAH-designed spacecraft. The payload must meet the following requirements:
1) mass no more than 5kg, 2) volume of no more than .43 m x .225 m x .29 m, 3) do not interfere with the
spacecraft, and 4) survive the environment. Our team decided that we would name our payload
Commander.
Enceladus, one of Saturn’s moons, has a temperature of -200° Celsius, is covered in ice and water
and also has crater volcanoes. Rhea and Dione are also moons of Saturn. These two moons are known as
twin moons because they reflect similar properties in many categories. Rhea and Dione are different from
Enceladus in that they have a very hot surface temperature. It takes approximately 19 ½ years for the
spacecraft to reach Enceladus; therefore, we will have to ensure our payload has a very long battery life as
well as a powerful energy source.
Our team has designed a payload that will measure the atmospheric pressures and temperatures of
Enceladus, Rhea, and Dione. As the spacecraft flies by Rhea and Dione, a probe will be deployed toward
each moon. When the spacecraft enters Enceladus’ orbit, our third and final probe will be deployed into
the atmosphere. Our data collection will begin when the probe is deployed by high pressure helium. The
probe will continue to measure the atmospheric pressures and temperatures until it reaches the surface of
the moon. Data will be sent back to NASA through an antenna and a processor as our probe descends to
the surface of the moon.
2.0 Science Objective and Instrumentation
Our objective is to deploy three payloads into the atmospheres of Enceladus, Rhea, and Dione to
explore the atmospheric pressures and temperatures of these three moons. This data will serve as a
helping hand to NASA by determining if the pressures and temperatures of the atmosphere are suitable
for future missions to these moons. We will also be able to compare the three moons’ atmospheres with
one another.
Table 1. Science Traceability Matrix
Science Objective
To measure the
atmospheric temperature
and pressures of
Enceladus, Rhea, and
Dione
Measurement Objective
To determine the
atmospheric pressures and
temperatures
Measurement Requirement
To successfully send our data
back to NASA without
interfering with their primary
mission objective
Instrument Selected
Thermocouple
Accelerometer
Pressure Transducer
Antenna
Processor
To determine the atmospheric pressures and temperatures of Enceladus, Rhea, and Dione, it is
with great importance that we choose the highest quality of instruments to complete our mission.
Instrumentation requirements are shown in the table below.
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Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
Table 2. Instrument Requirements
Instrument
Mass (kg)
Power (W)
Raw Data
(Mb)
Lifetime
Frequency
Duration
Thermocouple
.28 kg
0W
Temperature
Infinity
Accelerometer
.0015 kg
7W
Acceleration
Infinity
Pressure
Transducer
Antenna
.425 kg
1W
Pressure
Infinity
.2 kg
8W
Infinity
Processor
.5 kg
5W
Sends
signals
Process
Information
2 seconds24 hours
2 seconds24 hours
2 seconds24 hours
2 seconds24 hours
2 seconds24 hours
1.33 E3
seconds
1.33 E3
seconds
1.33 E3
seconds
1.33 E3
seconds
25 years
Infinity
3.0 Payload Design Requirements
The design of the analyzer portion required study of much background information to decide what
direction our probe will shoot out from the orbiter. The velocity of our probe will be 1.31 E8 m/s when
our payload will reach the surface of the moon. The trajectory of the payload will increase distance
around the moons by shooting backwards from the orbiter. With our concept having a missile shaped
design, the probe will be able to collect data while limiting the possibility of tossing and turning during
descent. Our payload, Commander, will have to endure temperatures of less than 200° Celsius.
Commander will also have to reach its destination, send data back to NASA, and die out without an
explosion. The probe must not exceed 5 kilograms, and fit into a box with a volume of .43 m x .225 m x
.29 m. Commander must also not interfere with the UAH mission.
4.0
Alternative Concepts
Initially, we developed two alternative concepts that would be able to accomplish our scientific
objective. See the illustrations below for details of these alternative concepts.
Figure 1: Concept 1
Figure 2: Concept 2
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Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
Concept 1 (above) consists of a payload that will deploy with high pressure helium. It will collect
data with a thumb drive, which will have a processor, and transmit data back through a UHF antenna. The
payload will provide power with batteries, which will be a simple design to build. The batteries can be
turned on easily from the NASA orbiter, which will make our mission go smoothly and as planned.
Concept 2 (above) consists of a payload design which will deploy with high pressure helium. It will
collect data through a thumb drive with a processor, and transmit data with a UHF transmitter. It will
provide power with an energy based system which will allow our payload to build up and create its own
energy through gears. The payload will be housed within a metal and insulator combination.
The team decided that Concept 1 would exhibit a simple deployment from the orbiter. Concept 1 is
also a simpler design to build. Our team agreed that Concept 1 was going to work better and would have a
greater chance of successfully completing our mission.
5.0
Decision Analysis
Our team decided on seven Figures of Merit to use in our decision analysis. The FOM’s are important
to our mission because our probe must reach exact mass and volume requirements on the Enceladus
orbiter. Also, our probe must be able to live for 19 ½ years before we reach Enceladus, Rhea, and
Dione. We ranked the concepts on a scale of 1, 3, or 9. 1 is weighted the least important and 9 is
weighted the most important. In the table below, the arrows indicate whether the FOM is to have a
higher or lower value. Concept 1 won our decision analysis with 333 points.
Table 3. Decision Analysis
FOM↑↓
Mass↓
Lifetime↑
Simplicity↑
Volume↓
Science↑
Structure↓
Deploy↑
Total
Weight (1,3,9)
9
9
3
9
9
3
3
Concept 1 (Batteries)
9
3
9
9
9
3
9
333
Concept 2 (Gears)
3
9
1
3
9
1
1
225
6.0 Design Analysis
We have incorporated numerous Physics and math concepts and equations while finding the descent
of our payload. The main requirement is for our payload to determine the atmospheric pressures and
temperatures of the three moons. Our probes must also be able to send back data to NASA as it descends
to the surface the moons.
Table 4. Calculations Summary
CALCULATION
Orbital Velocity
Time of Impact
Angle of launch relative to
orbiter
Velocity from Helium
FORMULA
V2 = (GM)/r
T= d/v
Arcsin (y/x)
ENCELADUS
4.59 E6 m/s
1.33 E3 seconds
210°
RHEA
1.19 E9 m/s
1.33 E3 seconds
210°
DIONE
1.76 E7 m/s
1.33 E3 seconds
210°
Vf2= vi2+2ad
150 m/s
150 m/s
150 m/s
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Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
7.0 Final Design
The final design consists of a spiraled barrel which will deploy the payload. The payload will be shot
backwards away from the direction of the spacecraft so that the payload will have more time in each
atmospheric layer to collect data. The payload will be powered by batteries in order for the scientific
instruments to collect data. A payload will be launched to Rhea, Dione, and Enceladus. Figure 3
represents how the Enceladus orbiter will circle around Rhea and Dione, and eventually land on
Enceladus. Our payload, Commander, will deploy a single probe at each moon.
Figure 3 – Concept of Operations
Figure 4. Payload Final Design
Figure 6. Top Cone
Figure 5. Inside Body View
Figure 7. Bottom Inside
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Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
Figure 8. Overall Payload Design
Table 5. Final Design Mass Table
Function
Mass (kg)
Deploy
0 kg
Measure
.912 kg
Collect Data
.6 kg
Provide Power
.072
Send Data
.2 kg
House/Contain Payload
1 kg
Table 6. Payload Design Compliance
Requirement
Payload Design
No more than 5 kg of mass
2.7 kg
Fit within 44cm x 24 cm x 28 cm when stowed
Yes
Survive environment
Yes
No harm to the spacecraft
Yes
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