S.K.Y.P.E
Students Keeping You Posted on Enceladus
Fairview High School
Team 1
Division 2
“Skype us today; we’re only 19 years
away!”
“Skype us today; we’re only 19 years away!”
Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
1.0 Introduction
We are SKYPE (Students Keeping You Posted on Enceladus) and we have designed a payload that
will accompany UAH’s spacecraft to Enceladus. Enceladus is one of Saturn’s innermost moons with a
very unique landscape. One of the most unique features of Enceladus is the tiger stripes. The tiger stripes
are a network of cryovolcanoes that expels icy material that forms the outmost ring of Saturn. Enceladus
surface temperature is -166 degrees Celsius because it reflects 100 percent of sunlight, yet heat emits
from the tiger stripes. We believe this is due to a phenomenon called tidal flexing which are tidal forces
between an orbiting natural satellite and the intense gravity by the planet that it orbits. The satellite is
pushed in and out generating heat due to friction. We will be using accelerometers to measure this
movement on Enceladus.
2.0 Science Objective and Instrumentation
Team SKYPE’s mission is to create a payload that will successfully complete our science
objective. The science objective of the team is to deploy all our probes (which house the accelerometers)
from our payload, Scattergun, onto Enceladus. The probes will measure movements caused by tidal
flexing to determine the heat source of the tiger stripes.
Science Objective
Measure tidal flexing
Table 1. Science Traceability Matrix
Measurement Objective
Measurement
Requirement
Accelerations on the
Every second for one
surface
hour
Instrument
Mass (kg)
Processor
Accelerometer
Battery
Antenna
0.03 kg
.001 kg
0.01 kg
.002 kg
Table 2. Instrument Requirements
Power (W)
Raw Data
Lifetime
(Mb)
.00045 W
.001 W
3.00 V
0.06 W
0.31 Mb
4.00 Mb
N/A
0.25 Mb
1 hr
1hr
1 hr
1hr
Instrument Selected
Accelerometer
Frequency
Duration
60 s
60 s
60 s
60 s
1 hr
1 hr
1 hr
1 hr
3.0 Payload Design Requirements
UAH has given us a maximum weight of 5 kilograms and a maximum volume of 44 cm x 24 cm
x 28 cm that cannot be exceeded. The payload and any other extensions must survive Enceladus
environment which is -166 Celsius and has an irregular icy surface. All of our instruments must be
capable of completing our science objective.
4.0 Alternative Concepts
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“Skype us today; we’re only 19 years away!”
Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
Concept 1: Our first concept will have four probes containing two accelerometers in carbon fiber
casings in the shape of a cone. They will be deployed with high-pressured helium 250 km above
Enceladus north pole. The cones will have weights on the top to ensure that they will plunge into the ice.
Each cone will have two batteries, an antenna, two accelerometers, and a CPU. The other two probes will
be spherical and contain the same instruments. When the spacecraft lands on the south pole, these spheres
will be pushed out with high-pressures helium through a trap door.
Figure 1: Concept 1
Concept 2: Our second alternative concept will use the force of gravity, as well as pressurized helium, to
deploy our payloads. The payloads consist of four spherical carbon fiber shelled, each containing two
batteries, an antenna, two accelerometers, and a CPU. Two probes will be projected through two pipes at
a 45 degree angle using pressurized helium; similar to a potato gun. The other two probes will stay with
the spacecraft until it lands. Once it lands, the G-force of the landing will cause the probes to fall out of
the payload onto the south pole’s surface.
Figure 2: Concept 2
5.0 Decision Analysis
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“Skype us today; we’re only 19 years away!”
Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
FOM
Mass ( Must be 5 kg) ↓
Volume ↓
Lifetime of Battery ↑
Appearance ↑
Impact Survivability ↑
Accurate Science ↑
Precision ↑
Science ↑
Table 3: Payload Decision Analysis Concept 1 and 2
Weight
Concept 1 Sum (Weight
Concept 2
x Concept 1)
3
9
27
9
3
27
3
3
9
1
1
1
9
3
27
9
9
81
3
3
9
9
9
Total
81
27
27
9
1
81
27
9
Sum(Weight x
Concept 2)
27
27
9
1
81
27
9
81
81
262
262
According to the design analysis, both concepts 1 and 2 had the same results, neither was better
or worse. We decided to combine the two concepts into one concept, Scattergun.
Figure of Merit
Mass
Volume
Lifetime
Appearance
Impact Survivability
Accurate Science
Total
Table 4: Scattergun Design Analysis
Weight
Concept 3
3
3
9
9
3
9
1
3
9
9
9
9
Sum
9
81
27
3
81
81
282
.
Concept Scattergun scored twenty points higher than concept one and two proving that it is the
best payload to achieve our science objective.
6.0 Final Design
This concept has six probes. Similar to concept 1, two probes will be deployed at 250 km above
Enceladus north pole. Like concept 2, two probes will be deployed in the potato launched at a 45 degree
angle. Like both concepts, the last two payloads will be dropped off the lander when the spacecraft lands
on the south pole.
Figure 3: Scattergun
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“Skype us today; we’re only 19 years away!”
Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
Table 4: Final Design Mass Table
Function
Mass (kg)
0
.003 kg
.003 kg
.22 kg
.031 kg
1.64 kg
Deploy
Measure
Collect Data
Provide Power
Send Data
House/Contain Payload
Total
Table 5: Payload Design Compliance
Requirement
Payload Design
No more than 5 kg of mass
1.64 kg
Fit within 44cm x 24 cm x 28 cm when stowed
Yes
Survive environment
Testing (TBD)
No harm to the spacecraft
Launching at 45˚angle
Calculations
Table 6: Calculations
Formula
Results
Final Velocity
Vf2 = Vi2 + 2ad
212.6 m/s
Orbital Velocity
Fg = G(Mm/r2)
127.0 m/s
Impact of G-load on probes
Vf2 = Vi2 + 2ad
10.83 g
Page - 5
“Skype us today; we’re only 19 years away!”
Payload Concept Proposal
Enceladus Orbiter and Lander Mission
Spring 2013
Final Velocity of V-shot
Vf2 = Vi2 + 2ad
M= Mass of Enceladus: 1.080 E 20 kg
Radius of Enceladus= 252 Km
Gravity of Enceladus= .133 m/s
Escape velocity= .239 Km/s
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126.0 m/s