DIEHARD Data Analysis Final Draft.doc...DIEHARD Colorado Space Grant Consortium University of...
Transcript of DIEHARD Data Analysis Final Draft.doc...DIEHARD Colorado Space Grant Consortium University of...
DIEHARD Data Analysis
Demonstrating Intensity of Electromagnetic High Altitude Radiation Determination
Team HASP
Taylor Boe
Kevin Dinkel
Amanda Covington
Melanie Dubin
Space Grant Student Research Coordinator
Brian Sanders
December 9, 2008
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 2 of 26 December 5, 2008
DIEHARD Data Analysis
The organization of the topics below covers the three main components of the DIEHARD
project. This consists of the main science mission implemented by the photometers, the
secondary mission of imaging stars, and the third mission, the overall engineering of the payload.
Each of these areas will be described in detail and include an analysis of functionality and the
conclusions that have surfaced as a result of the data trends.
Table of Contents
1.0 Mission Overview ............................................................................................................................................3
1.1 Flight Overview ...........................................................................................................................................3
1.2 Design Solution Overview ...........................................................................................................................3
1.3 Conclusion ...................................................................................................................................................3
2.0 Photometers ......................................................................................................................................................4
2.1 Standard Tube Photometer ...........................................................................................................................4
2.2 Filter Wheel..................................................................................................................................................5
2.3 Calibration....................................................................................................................................................5
2.4 Analysis........................................................................................................................................................6
2.4.1 Change in Voltage ...............................................................................................................................6
2.4.2 Time to Integrate .................................................................................................................................7
2.4.3 Light Intensity .....................................................................................................................................9
2.4.4 Photometer Spectrum ........................................................................................................................12
3.0 Imaging...........................................................................................................................................................14
3.1 Telescope CCD ..........................................................................................................................................14
3.2 Wide Angle CCD .......................................................................................................................................16
4.0 Payload Engineering.......................................................................................................................................17
4.1 Temperature and Thermal Design............................................................................................................118
4.1.1 Computer .........................................................................................................................................118
4.1.2 Outside ............................................................................................................................................119
4.1.3 Electronics Board ............................................................................................................................119
4.1.4 Science Instruments...........................................................................................................................20
4.1.5 Stepper Motors ..................................................................................................................................20
4.1.6 Disconnected Sensors........................................................................................................................21
4.2 Platform Stability and Accelerometer ........................................................................................................22
4.3 Pressure ......................................................................................................................................................23
4.4 Compass .....................................................................................................................................................24
5.0 Conclusion......................................................................................................................................................25
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 3 of 26 December 5, 2008
DIEHARD Data Analysis
1.0 Mission Overview
The University of Colorado at Boulder student team will determine the viability of high
altitude observatories by diurnal imaging of celestial bodies, measuring and recording light
intensity in the stratosphere as a function of altitude, and by nocturnal imaging of celestial
bodies to determine atmospheric turbulence and light intensity due to residuals in the
atmosphere. The DIEHARD payload data will establish whether high altitude platforms are
capable of capturing high quality images of celestial bodies at a lower cost compared to
launching a space telescope like Hubble or constructing a ground based observatory.
1.1 Flight Overview
The DIEHARD payload was launched from Fort Sumner, New Mexico, on September
15, 2008. The approximate launch time was 7:20 AM and the first data package retrieved
from the payload was timed at 7:46 AM. During the daytime, the payload experienced
thermal problems as the computer repeatedly overheated and needed to be manually powered
off. This limited the amount of data points received during the daytime. Once the sun set, the
computer experienced no further thermal problems. The HASP platform ascended to
approximately 36 kilometers and hovered for 32 hours. The CCD camera returned excellent
results throughout the night, capturing stars with both the telescope and wide angle views.
The photometer returned interesting data during the night; however, with the computer
failure throughout the day, a limited amount of data was retained. All platform sensors
returned quality data with the exception of the digital compass, which experienced
interference from all of the electronics onboard.
1.2 Design Solution Overview
Of the problems that the DIEHARD payload faced, all of them can be fixed to enhance
the findings in future experiments. The compass is a vital part of determining the orientation
of the platform. Having a fully functional compass that can record directional orientation of
the payload will be a valuable addition. This shall allow for more accurate identification of
the stars captured on video. Another area for improvement includes the resolution of the
CCD cameras. Having higher quality video shall enhance the amount of stars visible in the
viewing field.
The computer posed a large problem throughout the daytime as it continually overheated.
This shall be fixed by providing a much larger heat sink for the computer electronics to pour
heat into. Because of the reoccurring manual shut down of the computer, there was not
enough photometer data points recorded throughout the first half of the flight. By correcting
the thermal problems with the computer, this inherited photometer malfunction shall also be
corrected.
1.3 Conclusion
The graphs displaying the data are plotted against the hours of flight. Each plot starts at
approximately 7 hours. Each hour of flight after launch is the next consecutive value up to
hour 31. The sun set at approximately hour 20 and rose again at 30 hours. From the data that
the DIEHARD payload retrieved, much progress has been made toward proving the
feasibility of high altitude observatories. The stability of the platform and the physical
capability of capturing images of celestial bodies through relatively low quality CCD
cameras help to provide valuable evidence. The photometers provided interesting data
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 4 of 26 December 5, 2008
DIEHARD Data Analysis
regarding the sky brightness in the upper atmosphere throughout the flight. This document
shall bring the possibility of high altitude observatories one step closer to becoming a
realistic future mission.
2.0 Photometers
Photometers were used to record light intensity readings throughout the flight. Quality
data trends of ambient light intensity shall determine the feasibility of seeing stars at different
altitudes and positions. Each of the three photometers, oriented at different positions as
shown in figure 2.0a and 2.0b, return quality data trends that will help determine the altitude
at which quality imaging can be maximized. It is evident from analysis that each photometer
had its own unique behaviors. This must be taken into account when reviewing the
photometer data.
2.1 Standard Tube Photometer
The standard photometers, figure 2.1, successfully recorded light intensity throughout the
flight. Sky brightness readings are calculated by measuring the time necessary to fill up each
capacitor and its corresponding final voltage from a photodiode. The equation used to
determine sky brightness in watts per square meter is L=(4/π)(n2/a
2)(C/K)(∆V/∆t) as cited
from Yorke J. Brown, PhD. This
equation gives the value of light
intensity in watts/m2-sr of the
“glowing” patch of sky observed
by each photometer. Each
photometer was built with a 10½
inch baffling tube so that the
light striking each photodiode is
essentially parallel.
Figure 2.0b: This figure represents the relative angles of the
scientific instruments mounted onboard.
Figure 2.1: This photograph shows the orientation of the photometers mounted in the payload
Figure 2.0a: The science instruments in the payload take data
from two sides of the box.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 5 of 26 December 5, 2008
DIEHARD Data Analysis
Figure 2.3: This photograph shows the three photometer
circuits mounted inside the payload.
For the first half of the flight when the sun was high in the sky, the photometers took only
seconds to completely integrate, and the change in voltage reaches the maximum of 10V.
Once the sun has set, the integration time exceeds 200 seconds due to a dramatic decrease in
light intensity.
2.2 Filter Wheel
Photometer #1 incorporated a filter wheel, figure 2.2, which allowed the photometer to
focus on a single spectrum of light at a time. A motor made it possible to switch the filter
after each consecutive light reading. The data from this particular sensor shall provide
answers to determine the spectrum of light that is most prevalent from distant celestial
bodies.
The filters included:
0-No Filter: all wavelengths
1-Green (visible): 495–570 nm
2-Red (visible): 620-750 nm
3-Infrared: 750-1000 nm
During the flight, an error was received about the functioning of the filter wheel. It is
highly possible that the wheel may not have been changing filters during flight. From the
data found in the sections below it is evident that there is no real difference between the light
captured by the different filters. This suggests that the wheel may have indeed not been
turning during flight. Thus, only one filter may have been read. However, in the section
below, the readings are split up by filter.
2.3 Calibration
One challenge that the DIEHARD team faced was the calibration of the three
photometers onboard the payload. Hundreds of hours went into reconfiguring the circuits to
transfer the light readings from each photometer to the computer in the form of numerical
data. In future missions, this particular challenge shall be improved.
It is evident that errors were made in replacing capacitors, as photometers #2 and #1
integrated 10 times faster than photometer #3. Photometer #2 and #1 were found with 100 pF
capacitors, instead of the preferred 1000 pF capacitor. We compensated for this error in our
photometer analysis.
Also, each photometer board, figure
2.3, though built with the exact same
materials and in the exact same manner,
each returned completely unique data,
both in tests and during the flight. Each
photometer must be analyzed relative to
itself and not to other photometers, as they
behave so differently. This makes data
Figure 2.2: This photograph shows the filter wheel photometer. The
wheel cycled through the filters powered by a stepper motor.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 6 of 26 December 5, 2008
DIEHARD Data Analysis
analysis immensely difficult, and the validity of the data is brought into question. This is an
error that must be improved upon for future flights.
2.4 Analysis
Judging by the trends shown in the figures below, the photometers appear to have returned
relatively accurate data with respect to the time in flight and the known position of the sun
and moon.
2.4.1 Change in Voltage
Figure 2.4.1a shows the voltage change in all three photometers. As can be seen, they all
behaved quite differently. Photometer #3 seemed to charge up to its full capacity (almost
10V) throughout the entire flight. This seems also true for photometer #2 until night time.
This is very interesting because both photometers should have been looking at the same night
sky. The broadband filter on photometer #1 seemed to charge halfway during the night,
setting an average between the other two photometers.
It is is evident that photometer #2 may
have been looking at the balloon for the
entire flight, especially at higher altitudes
where the balloon grows to an enormous
size. Using trigonometry, figure 2.4.1b, this
hypothesis seems probable. Estimating that
the radius of the balloon is 600ft and the
flight string is 600ft below the bottom of
the balloon leaves an angle of sight that
must be less than 63.74 degrees.
Photometer #2 was mounted at
Figure 2.4.1a: This graph shows the voltage change in all three photometers throughout the duration of the flight.
Figure 2.4.1b: This diagram represents the possibility of the balloon obstructing
the view of photometer #2.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 7 of 26 December 5, 2008
DIEHARD Data Analysis
approximately 64.79 degrees above the horizon. Perhaps the fully inflated balloon prohibited
it from seeing the small amounts of light from stars.
2.4.2 Time to Integrate
Figure 2.4.2a shows the time it took for the photometers to integrate. Once again it is
visible that photometer #2 was not taking in much light during the night, as it maxed out at
300 seconds before reset every time. This is also true for the broadband filter on photometer
#1. In this graph there is an interesting artifact found around 24 hours and 27.5 hours for
photometer #1, 26 hours for photometer #2, and 25 hours for photometer #3. These
downward spikes look very similar; however, they occur at different time intervals.
It seems to be a valid
hypothesis that the
photometers may be
picking up reflected light
from the moon. Again,
the reason for this may
have much to do with the
different angles at which
the photometers were
mounted, figure 2.4.2b.
In the videos, the moon is
seen mostly on the right
edge of the screen at
approximately the hour
29 of the flight. As the
moon rose in the night
sky, its light was first
picked up by photometer
#1, and later by
photometer #3, both of
which are at lower angles, as shown in the figure above. Later, the moon’s intense light was
discovered by the steep angle of photometer #2. As the moon began to set, photometer #1
was fortunate enough to catch its light again. Finally, around the 29th
hour the wide angle
CCD camera, set at 25.84
degrees, captured the moon
as it set.
Figure 2.4.2c shows a
zoomed in view of the
integration time during the
day. It is evident that each
of DIEHARD’s three
photometers had very
different integration rates.
The capacitors used on
photometer #1 and #2
integrated ten times faster
Figure 2.4.2b: This diagram shows the orientation of the moon throughout the flight at the approximate
times to which the data correlates.
Figure 2.4.2a: This graph shows the time to integrate for all three photometers
throughout the flight. Notice the interesting spikes during the night.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 8 of 26 December 5, 2008
DIEHARD Data Analysis
than the capacitor on
photometer #3. Photometer
#3 used a 1000 pF capacitor,
while the other two used 100
pF capacitors. The use of
different capacitors was a
fundamental engineering
flaw in the science
component of the DIEHARD
platform. However, this
difference was accounted for
in analyzing the light intensity
readings of the photometers.
Figure 2.4.2c: This graph shows the integration time for all three photometers during the day.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 9 of 26 December 5, 2008
DIEHARD Data Analysis
2.4.3 Sky Brightness
Photometer #1:
This photometer utilized
a filter wheel during flight.
The graphs on the left show
only the readings from the
broadband spectrum. The
brightness readings
throughout the flight seem
very plausible. During the
day, sky brightness varied
mostly between .007 and .01
watts/m2-sr. There seems to
be more fluctuations from
hour 15 to hour 20. During
this time the sun is at a lower
angle in the sky, nearing the
angle at which photometer #1
is mounted, 55.23 degrees.
Direct sunlight most likely
entered the baffling tube
during this time, causing the
relevant spikes in the data.
During the night, the sky
brightness is much lower,
barely surpassing a zero
value. However, there is
unmistakably some light that
enters the photometer tube.
The spikes occurring at night
could be a function of the
light from the moon, as
discussed above.
Entire Flight
Day Time
Night Time
Figure 2.4.3a: These graphs show the relative sky brightness of photometer #1 throughout the flight.
They have been separated into night time and day time to better display the minor fluctuations
throughout the night.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 10 of 26 December 5, 2008
DIEHARD Data Analysis
Photometer #2:
Photometer #2 had the
steepest angle of all the
photometers. This may
explain why during the
middle of the day, when the
sun is overhead, the sky
brightness is consistantly
higher than the other
photometers. Its average
range is between .05 and .12
watts/m2-sr from hour 10 to
15 and drops steadily after
hour 15.
During the night,
Photometer #2 barely took in
any light, as the readings are
essentially zero. There was
one very small spike around
26 hours, however, even that
spike is only about 7.0E-4
watts/m2- sr.
Entire Flight
Day Time
Night Time
Figure 2.4.3b: These graphs show the relative sky brightness of photometer #2 throughout the flight.
They have been separated into night time and day time to better display the minor fluctuations
throughout the night.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 11 of 26 December 5, 2008
DIEHARD Data Analysis
Photometer #3:
Photometer #3
fluctuated from .0025 to
.012 watts/m2-sr during the
day, which was relatively
darker than photometer #2,
possibly due to its lower
angle. There is a
considerable amount of
fluctuation from hour 16 to
19. This could be caused by
the sun which, like with
photometer #1, may send
light directly into the tube
as it approaches the low
angle of 54.05 degrees in
the sky. Direct sunlight
would have caused the
drastic spikes in this time
range.
During the night, not
much light entered into the
photometer. However, the
light that does charge the
diode is considerably more
intense than the light which
entered photometer #2.
Entire Flight
Day Time
Night Time
Figure 2.4.3c: These graphs show the relative sky brightness of photometer #3 throughout the flight.
They have been separated into night time and day time to better display the minor fluctuations
throughout the night.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 12 of 26 December 5, 2008
DIEHARD Data Analysis
2.4.4 Photometer
Spectrum
Integration Time:
The integration time for
the filter wheel followed the
same basic trend as the other
photometers. By zooming in
on the data from just the
daytime it is evident that
different filters had no real
affect on the time it took for
the photometers to integrate.
During the night there is also
no real difference. All of the
different filters took the
maximum time of 300
seconds to fill up for the
entire night, with the
exception of the downward
spikes.
Change in Voltage:
During the day, all of the
frequencies completely charged to 10V,
figure 1.1.4.4. During the night there
seems to be minimal fluctuation. The
green filter seems to produce the most
voltage, followed by infrared,
broadband, and red. However, this data
trend is not extremely reliable due to
the minimal amount of data points for
each filter.
Entire Flight
Day Time
Figure 2.4.4a: These graphs show the integration time for the filter wheel photometer
for the entire flight and zoomed in to see the fluctuation during the day.
Figure 2.4.4b: This graph shows the change in voltage for the filter wheel
photometer for the entire flight.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 13 of 26 December 5, 2008
DIEHARD Data Analysis
Sky Brightness:
During the day the sky
brightness readings for each
filter produced very similar
values, averaging around .01
watts/m2-sr with the
exception of the spikes,
which could possibly be due
to the setting sun.
During the night, all the
filters were relatively dark,
falling between a range of
1.2E-5 to 2.2E-5 watts/m2-
sr. The differences in the
values are so minimal that it
is hard to distinguish if the
filter makes that much of a
difference.
From the gathered data, it
is evident that for the most
part, all visual frequencies
seem to be equally prominent
during both day and night in
the upper atmosphere. During
testing, we discovered that
infrared seemed to integrate
at a small fraction of a
second slower than the rest of
the tested spectrum, but
during flight, the infrared did
not differ very drastically at
all from the other filters. It
seems that with our
instrumentation we could not
decipher any real difference
in the sky brightness of
different frequencies in the
upper atmosphere.
Entire Flight
Night Time
Figure 2.4.4c: These graphs show the relative sky brightness of the filter wheel photometer
throughout the entire flight and zoomed in during the night to display the small
fluctuations in brightness.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 14 of 26 December 5, 2008
DIEHARD Data Analysis
3.0 Imaging
Imaging of stars from a high altitude platform can be successful, as shown in the
telescope video and wide angle CCD recordings. The hard evidence displayed by the cameras
provides undisputable support for additional research concerning imaging stars from lighter-
than-air platforms. Nevertheless, there is vast room for improvement from the standpoint of
image quality. As well as capturing physical images of stars, the CCD camera on the payload
also helps to determine the stability and orientation of the platform while in flight.
3.1 Telescope CCD
The telescope video portrays an interesting
point of view. Being much more “zoomed in”
than the wide angle CCD (field of view near one
degree, figure 3.1a), the smallest movements in
the platform are evident in the movement of the
stars. After closely observing the videos, it
became clear that the platform does occasionally
oscillate, noted by stars that move across the
screen with slight up and down movements.
Through analyzing the pitch of the platform in a
one percent field of view, there is distinct
movement; however, it is less than 5 percent of
the one degree viewable field, indicating that
the pitch of the platform oscillates in a very
minimal range. This analysis reveals that the
platform maintains relative stability in the vertical axis. A change in rate at which the
platform rotates is also very clear, indicating that there may be slight winds in the
environment that speed up and slow down
the movement of the platform
(HASPFLIGHTcam2.16-09-08.05_17_47).
The types of movements detected are
hypothetically caused by the movements of
the balloon above. With its enormous
surface area, movement will be influenced
by a small magnitude of air current.
Physically, the video captured with the
telescope shows stars, but being only a one
degree field of view, they pass through the
shot quickly and begin to lose focus
moving through the left quarter of the
screen. The unknown focusing error was
not an issue for analyzing the data, which
will be explained later. The rate of the stars’
apparent movement changes throughout the
flight, but on average a star does not stay in view for more than five seconds and sometimes
less than a second. Taking still screen shots does not do justice to what was actually captured
on video. The telescope recorded visible stars as the sun went down
Figure 3.1a: This diagram represents the difference between the
field of view of the telescope CCD video versus the wide angle
CCD video
HASPFLIGHTcam2.15-09-08.19_02_28
Figure 3.1b: This screenshot from the telescope CCD video
shows the first visible star during the flight which was captured
around 7:02 PM.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 15 of 26 December 5, 2008
DIEHARD Data Analysis
(HASPFLIGHTcam2.15-09-08.19_02_28) and also may have captured recognizable
constellations like Orion (HASPFLIGHTcam2.16-09-08.00_33_50). Overall, the telescope
more effectively portrayed the behavior of the platform on video rather than recording
quality images of celestial bodies. However, valuable information from DIEHARD shall help
achieve further success on future missions.
08.00_33_50
HASPFLIGHTcam2.16-09-08.00_33_50
Figure 3.1c: This screenshot from the telescope CCD video
shows a group of stars that may be the constellation Orion.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 16 of 26 December 5, 2008
DIEHARD Data Analysis
3.2 Wide Angle CCD
The video from the CCD camera
portrays the relative stability as the
platform slowly spins. Stars do not
become visible until
HASPFLIGHTcam1.15-09-
08.19_36_41, which is approximately
11 hours into the flight. This particular
video shows great potential for the
ability to image celestial bodies from a
high altitude platform. Due to the fact
that the sun is still above the horizon,
the video is gray, indicating remnant
light in the environment, and stars are
still visible using a low quality CCD
camera. Under these conditions and
using a high quality imaging device,
spectacular images could plausibly be
captured, essentially proving the
overarching mission of DIEHARD
With the wide angle CCD camera
viewing a twenty degree field
(reference figure 3.1a), several videos
were incrementally viewed throughout
the duration of the flight to analyze the
rotational rate in particular. The
platform’s rate of rotation, figure 3.2b,
ramained relatively constant but
seemed to rotate slightly quicker right
after sunset and two hours after. This
occurrence could be due to the flow of
air masses while the sun is still present
as warm and cool air mingle to cause
more movement of the balloon and
consequently the platform. Being that
there were little or no stars to use as
reference during the day, the rotation
could not clearly be determined until
stars were visible. The rotation ranged
from .5 degrees per second down to
.12 degrees per second, a relatively
mild rotation rate.
Figure 3.2a: These screenshots from the wide angle CCD camera show a
group of stars right after sun set as they move across the screen left to right.
Interestingly, there is a stationary bright point which may be a pixel.
HASPFLIGHTcam1.15-09-08.19_36_41
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 17 of 26 December 5, 2008
DIEHARD Data Analysis
As the mission progressed, star images became
more vibrant, capturing several constellations,
including a clear view of Orion
(HASPFLIGHTcam1.16-09-08.02_03_24). To
further enhance the images taken from DIEHARD,
we will attempt to stack still images from the CCD
video to try and enhance faint stars hiding in the
background. With more vibrant star patterns,
constellations shall be more readily identified to
indicate the orientation of the platform at a given
time. This part of our investigation is still in
progress could lead to determining more visible
constellations. This has not been the focus of our
analysis because we are primarily concerned with
proving that stars can be imaged from a high
altitude observatory, and this has been
accomplished with relatively simple instruments.
4.0 Payload Engineering
Engineering the DIEHARD payload involved creating a design which provided thermal
protection for all components and a solid structure to ensure data recovery post landing. The
payload was fitted with several temperature sensors as well as accelerometers, a compass and
pressure sensor.
Figure 3.2b: This graph shows an average rate of rotation of the platform throughout the flight derived from the wide angle videos.
Figure 3.2c: This screenshot shows an excellent view of the Orion constellation
from the wide angle CCD camera
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 18 of 26 December 5, 2008
DIEHARD Data Analysis
4.1 Temperature and Thermal Design
The following sections show the thermal status of our payload for the duration of the flight.
The DIEHARD payload had 12 temperature sensors; however, only 10 were functioning
during flight. Two of them were disconnected or removed prior to launch. Figure 4.1 shows
the location of the temperature sensors inside the payload.
4.1.1 Computer
The temperature readings internally
and externally gave insight into the
thermal attitude the DIEHARD payload.
As the computer continually approached
the point of overheating itself, it was
manually shutdown. The computer was
turned back on once it cooled to 38
degrees Celsius. This is demonstrated by
the abrupt diagonal lines in figure 1.3.1a.
As the flight progressed, the computer
cooled down at a faster rate, which is
indicated by the steeper diagonal slope.
This is most likely caused by the colder
outside temperatures. In future missions,
this problem can be solved by providing a
larger conduction surface for the
computer to expel its heat.
Figure 4.1.1: This graph shows the temperature recorded by the sensor attached to the
computer. Notice the negative sloping linear sections. These represent the times when
the computer was shut down.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 19 of 26 December 5, 2008
DIEHARD Data Analysis
4.1.2 Outside
The outside temperature profile,
represented in figure 1.3.1b, demonstrates
the greatest fluctuation of any of the
payload’s temperature sensors. It has a
minimum of -50 degrees Celsius, which is
a result of the extremely cold nights in
near space, and a maximum of 70 degrees
Celsius, which may be due to the extreme
heat from the sun during the day or the
conduction of the heat from inside the
payload. The coldest time of the flight
occurred after the sun set, which was at
about 20 hours. The graph’s rapid spikes
during the daytime could be caused by the
rotation of the platform. When the outside
temperature board is pointed directly at the sun in the upper atmosphere, the temperature
spikes upwards very fast. Likewise, the platform also cools very fast when it is pointed away
from the sun.
4.1.3 Electronics Board
The electronics board temperature profiles
are shown in figure 1.3.1c. The power board
temperature seemed to fluctuate more than
any of the other electronic boards. This is
interesting, as it oscillated at 10 degrees
amplitude regularly over the course of just a
few minutes.
Figure 4.1.2: This graph shows the temperature recorded by the sensor
attached to an exterior outside wall of the payload. The linear sections
represent the times when the computer was shut down.
Figure 4.1.3: This graph shows the temperature recorded by the sensor s
attached to the large interior circuit boards. These recorded relatively
warm temperatures throughout the flight due to the heat created by the
electronics.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 20 of 26 December 5, 2008
DIEHARD Data Analysis
4.1.4 Science Instruments
The science instrument temperature
sensors, figure 1.3.1d, were mounted on the
CCD wide angle camera and photometers
#2 and #3. The three science instruments
were spread evenly throughout the payload,
covering three of the four corners. This
graph demonstrates that the internal
temperature seemed to be fairly evenly
distributed throughout the payload for the
duration of the flight.
4.1.5 Stepper Motors
The stepper sensor’s temperature profile is shown in
figure 1.3.1e. The sun shade, though outside, is seen at
relatively high temperatures for the duration of the
flight. This is most likely a result of the sensor being
attached to a hot running motor. The filter wheel,
located inside the payload, got colder at a slower rate
than the sun shade, which was exposed to the outside
elements.
Figure 4.1.4: This graph shows the temperature recorded by the sensor s
attached to the science instruments. This data shows the most accurate
internal temperatures throughout the flight.
Figure 4.1.5a: This photograph shows the location of the external
temperature sensor which was mounted on the stepper motor controlling
the sun shade. There was a second temperature sensor located internally
on the stepper motor controlling the filter wheel.
Figure 4.1.5b: This graph shows the temperature recorded by the sensor s
attached to the internal and external stepper motors (reference figure
4.1.6b).
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 21 of 26 December 5, 2008
DIEHARD Data Analysis
4.1.6 Disconnected Sensors
Although these temperature sensors,
figure 1.3.1f, were disconnected or removed
for the flight, they still produced data
readings. This is due to the fact that the wires,
although disconnected from the temperature
sensor, were still connected to the
corresponding port on the serial data read-in
to the computer. So, all of the noise created by
the electronics onboard were picked up by the
disconnected wires. This errant data does not
represent any bias toward the data from the
other functioning sensors.
Figure 4.1.6: This graph shows the temperature recorded by the
disconnected sensors. Interestingly, they follow the same general trend as
the rest of the temperature sensors due to the ability of the open serial
wires to conduct the excitement of electrons as temperature changes.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 22 of 26 December 5, 2008
DIEHARD Data Analysis
4.2 Platform Stability and Accelerometer
The accelerometer onboard the
payload, figure 4.2a, was used to
determine the turbulence during
flight. The accelerometer data
corresponds with the video images
which results in an accurate
account of the flight’s stability.
After plotting data from the
accelerometers, an interesting
occurrence arises. Clearly visible in
the accelerometer data, the X axis
shows some intriguing behavior,
figure 4.2b. While the Z axis and Y
axis fluctuate within a ½ G value,
the X data fluctuates up to 3½ G’s.
By plotting the basic temperature
trend of the HASP platform next to
the accelerometer data, figure 4.2c,
an interesting conclusion arises. It
seems plausible that the X axis of
the accelerometer was getting an
error reading due to the drastic
decrease in temperature of the
flight. The errors in the
accelerometer data correspond
directly to the two coldest parts of
flight, launch and during the night.
The accelerometer data was not
of much use in analyzing the
behavior of the platform. It seemed
to stay relatively calm throughout
the duration of the flight. This is
very promising for the prospect of
a high altitude observatory.
Accelerometer
behind heat sink
Figure 4.2a: The accelerometer in the figure above gave data for X, Y,
and Z axis for the duration of the flight.
Figure 4.2b: The accelerometer error is visible in the black x axis.
Figure 4.2c: The error visibly relates to the relative temperature during the
flight.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 23 of 26 December 5, 2008
DIEHARD Data Analysis
4.3 Pressure
The pressure sensor was located
inside the payload on the avionics board,
figure 4.3a. The pressure data, figure
4.3b, shows how the pressure decreases
as the altitude increases. A half hour into
the flight, the pressure decreased to
nearly half of what it is on Earth’s
surface, from 14 pounds per inch2 (PSI),
to 7 PSI. After reaching maximum
altitude, the pressure decreased to 1.5
PSI, which is what we would expect in a
near space environment.
Pressure Sensor
Figure 4.3a: The pressure sensor was hidden behind the heat sink.
Figure 4.3b: The pressure data matches the trend that was expected prior to flight.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 24 of 26 December 5, 2008
DIEHARD Data Analysis
4.4 Compass
The compass was located inside the payload directly above the CCD wide angle camera,
figure 4.4a. It encountered an error during flight due to electromagnetic interference from the
computer and other components onboard the payload, as can be seen by the flat line, figure
4.4b. This is an unfortunate result, as the compass could have helped determine the
orientation of the platform at any given time during the flight. It could have also given
accurate rotational speeds and the precise attitude behavior of the platform. For future
missions, the compass error will have to be corrected in order to provide accurate directional
orientation.
Compass
Figure 4.4a: The compass failed because of its location
relative to the overhanging computer.
Figure 4.4b: The compass failure is denoted by the strait
line obtained from the data.
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 25 of 26 December 5, 2008
DIEHARD Data Analysis
5.0 Conclusion
The DIEHARD mission, stationed on the HASP balloon, has made gigantic strides in
proving the feasibility of stationing an optical observatory at the edge of space. The first
question asked of such an observatory would be its ability to capture images of the stars with
precision and quality. The HASP payload was able to capture hundreds stars during the night
and even during sunset with a simple CCD wide angle camera. The telescope CCD also
captured light from more distant stars. The videos also demonstrated accurately the
conditions of the upper atmosphere. From a free hang below a balloon the maximum
rotational velocity was a very mild ½ degree per second. With a simple stabilization system,
a lighter-than-air observatory could easily counteract this disturbance. The photometer data
showed that there is definitely enough light during the night time to be seen visually. Even
the very small patches of night sky detected were enough to provide charge from the
photodiodes. This is very impressive and is promising for the prospect of optical viewing of
the cosmos at high altitudes.
However, some questions still remain. Can stars be observed even during the day time?
With our simple video capturing devices, the sky was an unfortunate gray during the day.
However, with more advanced instruments and image editing capabilities, it is very feasible
that stars could be viewed during the day time. Hopefully the evidence from the DIEHARD
payload is enough to accurately set the course for the mission of HASP Flight 2009, one
which may further prove the practicality and benefits of a balloon-stationed observatory.
These are constructed airship prototypes that may be used to carry a small telescope to high altitudes
in order to take high quality images of celestial bodies.
http://thinker.colorado.edu/space/fall_2007/downloads/airship_spie.pdf
DIEHARD
Colorado Space Grant Consortium
University of Colorado at Boulder
Page 26 of 26 December 5, 2008
DIEHARD Data Analysis
Acknowledgements:
On behalf of the 2008-2009 HASP team, we would like to give thanks and recognition to
the following individuals:
Dr. Robert Fessen, Dr. Yorke Brown, Dr. Elliot Young, Kyle Kemble, Grant Fritz, Viliam Klein,
Ahna Isaak, Brian Sanders, Chris Koehler and all of those at the Colorado Space Grant
Consortium who have offered guidance.