Lidar Wind Profiler Comparison to Weather Balloon for Support of Orion Crew Exploration Vehicle Landings

61 MB·English

by  Houtas, Franzeska

Lidar to Weather Balloon Profile Comparison for Support of Orion Crew Exploration
Vehicle Landings

ABSTRACT

A comparison study by the National Aeronautics and Space Administration Dryden Flight
Research Center, Edwards, CA and the Naval Post Graduate School Center for Interdisciplinary
Remotely-Piloted Aircraft Studies, Marina, CA was conducted to show the advantages of an
airborne wind profiling lidar system in reducing drift uncertainty along a reentry vehicle descent
trajectory. This effort was in support of the once planned Orion Crew Exploration Vehicle
ground landing. A Twin Otter Doppler Wind Lidar was flown on multiple flights along the
approximate ground track of an ascending weather balloons launched from the Marina Municipal
Airport. The airborne lidar used was a 5-milli-Joules, 2-micron infrared laser with a 10-
centimeter telescope and a two-axis scanner. Each lidar wind profile contains data for an altitude
range between the surface and flight altitude of 2,700 meters, processed on board every 20
seconds. In comparison, a typical weather balloon would traverse that same altitude range with a
similar data set available in approximately 15-20 minutes. These tests were conducted on
November 15 & 16, 2007. Results comparing the balloon and a 10 minute multiple lidar profile
averages show a best case absolute difference of 0.18 m/s (0.35 knots) in speed and 1 degree in
direction during light and variable (<5 knots, without constant direction) wind conditions. These
limited test results indicated a standard deviation wind velocity and direction differences of 0.71
m/s (1.3 knots) and 7.17 degrees for 1800Z, and 0.70 m/s (1.3 knots) and 6.79 degrees, outside of
cloud layer.
National Aeronautics and Space Administration
CIRPAS Twin Otter
is non-pressurized
turbo-prop, twin-
Lidar to Weather Balloon Profile engine aircraft.
Comparison for Support of Orion Crew
Exploration Vehicle Landings
Twin Otter Doppler
Goal of testing was to determine the
Wind Lidar
integrated wind profile at the landing
mounted on star-
site in order to predict the amount of
board side of
Dryden Flight Research Center
vehicle drift under chute from the
the aircraft.
desired landing location creating a
Authors: Franzeska Houtas Edward H. Teets Jr.
&
reduced area of uncertainty.
Significant difference between balloon and lidar profiles due to
calibration for the lidar and effective wind for the balloon profile.
(for further description, see Data Analysis in paper)
Abstract: Height adjustments Speed, m/s of absolute differences for overlapping average
and combined average at specific height intervals
A comparison study by NASA
2500 Cloud tops 2500 Cloud tops Time (Z)
1800 Z balloon 1800 Z balloon
1801.25 Z – 1811.00 Z 1801.25 Z – 1811.00 Z Altitude 1801.25- 1802.25- 1804.50- 1806.08- 1808.48- Combined
Dryden Flight Research Center,
1803.27 1805.47 1807.06 1809.47 1811.00 average
2000 2000
Edwards, CA and the Naval
500 m 0.49 1.95 2.39 1.07 0.47 1.09
m m
Post Graduate School Center ht, 1500 ht, 1500 1000 m 0.76 1.34 1.71 1.57 1.11 0.91
g g
ei ei
c h c h 1500 m 0.92 0.49 0.35 0.03 0.06 0.44
for Interdisciplinary Remotely- etri etri
m 1000 m 1000 2000 m 0.67 0.19 0.24 0.76 0.78 0.18
o o
e e
G G
Piloted Aircraft Studies, 2500 m 1.13 1.09 1.11 0.91 0.98 1.30
500 500
Marina, CA was conducted to
Average difference and standard
deviation for combined profile
show the advantages of an
0 0
0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10
Wind speed, m/s Wind speed, m/s
090292 090294
airborne wind profiling lidar Standard Standard
Average Average deviation deviation
direction (deg) speed (m/s) direction (deg) speed (m/s)
system in reducing drift uncer-
Overlapping interval averages of the lidar Combined average of all lidar data into one profile Entire profile 7.89 0.02 54.00 1.00
tainty along a reentry vehicle
Excluding 5.22 0.08 7.17 0.71
descent trajectory. cloud layer
2500 2500
Cloud tops Cloud tops
1800 Z balloon Balloon
1801.25 Z – 1803.27 Z Lidar
1802.25 Z – 1805.47 Z Conclusion:
This effort was in support of 2000 1804.50 Z – 1807.60 Z 2000
1806.80 Z – 1809.47 Z
1808.48 Z – 1811.00 Z
the once planned Orion Crew m m
• Averaging all lidar data into one

, ,
ht 1500 ht 1500
g g
ei ei
Exploration Vehicle ground h h
single profile gives best results
c c
ri ri
t t
e e
m m
1000 1000
landing. A Twin Otter Doppler o o
e e
G G
• Lidar benefits
Wind Lidar was flown on
500 500
multiple flights along the – Rapid profiles (5 min. versus
0 0
0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10
approximate ground track of 15 min. with balloon to test
Wind speed, m/s Wind speed, m/s
090298 090306
an ascending weather balloon altitude)
launched from the Marina
Difference between balloon and overlapping
– Reduction in time to obtain
interval average profiles Difference between balloon and combined average
Municipal Airport. The airborne
profiles
lidar used was a 5-milliJoule,
2500 2500
Cloud tops Cloud tops
1801.25 Z – 1803.27 Z
Difference lidar
– Data always taken over site
2-micron infrared laser with a 1802.25 Z – 1805.47 Z to balloon
1804.50 Z – 1807.60 Z
1806.80 Z – 1809.47 Z
2000 2000
(no balloon drift)
1808.48 Z – 1811.00 Z
10-centimeter telescope and a
m m

, ,
two-axis scanner. These tests ht 1500 ht 1500
g g • Best case results
i i
e e
h h

c c
were conducted on Nov. 15 ri ri
t t
e e
m m
1000 1000
o o
e e – Mean difference of 0.08 m/s
G G
and 16, 2007. The following
and 5.22 deg
500 500
figures are only for 1800 Z on
Nov. 16, 2007.
– Standard deviation of 0.71 m/s
0 0
–4 –3 –2 –1 0 1 2 3 4 –3 –2 –1 0 1 2 3
Wind speed difference, m/s Wind speed difference, m/s
090302 090310
and 7.17 deg