This viewgraph presentation gives a general overview of the Phoenix spacecraft evolution, entry, descent, landing and system architecture

Desai, Prasun N.

Grover, Myron R.

NASA Technical Reports Server

IPPW-5
26 June 2007 Grover/Desai -1
National Aeronautics and Space
Administration
Jet Propulsion Laboratory
California Institute of Technology
Evolution of the Phoenix EDL 
System Architecture
 
  
R. Grover,  Jet Propulsion Laboratory
P. Desai,  NASA Langley Research Center
International Planetary Probe Workshop 5
26 June 2007
Bordeaux, France
National Aeronautics and Space Administration
Jet Propulsion Laboratory California Institute of Technology
https://ntrs.nasa.gov/search.jsp?R=20080013505 2019-08-30T04:07:26+00:00Z
IPPW-5
26 June 2007 Grover/Desai -2
National Aeronautics and Space
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Jet Propulsion Laboratory
California Institute of Technology
Presentation Overview
• The Phoenix Story
• Spacecraft Overview
• Phoenix EDL Overview
• Mission Design Comparison
• Hypersonic Subphase Evolution
• Terminal Descent Subphase Evolution
• Summary
IPPW-5
26 June 2007 Grover/Desai -3
National Aeronautics and Space
Administration
Jet Propulsion Laboratory
California Institute of Technology
The Phoenix Story
• Started as Mars Surveyor 2001 Lander
– Faster, better, cheaper spacecraft
– Sister spacecraft of Mars Polar Lander
– Cancelled after Mars Polar Lander failure in 1999
• Not enough time to address findings of MPL failure review prior to
2001 launch window
• Reborn as Phoenix in 2003
– Same spacecraft, modified science payloads
– Enhanced radar
– Addition of EDL communication subsystem
– Enhanced test program
IPPW-5
26 June 2007 Grover/Desai -4
National Aeronautics and Space
Administration
Jet Propulsion Laboratory
California Institute of Technology
Spacecraft Overview
Pre-Entry Configuration Entry Configuration
Terminal Descent Configuration
Parachute Configuration
Post HS & Leg Deploy Configuration
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26 June 2007 Grover/Desai -5
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Jet Propulsion Laboratory
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Lander Prep
Parachute
• Radar Activated: E+259s, L- 160s
• Heat Shield Jettison: E+239s, L-180s, 9.8 km,  109 m/s
• Parachute Deployment: E+224s, L-195s, 11.5 km, Mach 1.46  
• Peak Heating: 45 W/cm2         Peak Deceleration: 9.3G
• Cruise Stage Separation: E-7min
• Lander Separation: E+382s, L-37s, 0.94 km, 53 m/s  
• Throttle Up: E+385s, L-34s, 0.72 km
• Constant Velocity Achieved: E+404s, L-15s, 0.047 km
• Touchdown: E+419s, L-0s, 0 km, Vv=2.4 ±1 m/s, Vh<1.4 m/s   
• Entry Turn Starts: E-6.5 min.  Turn completed by E-5min.
• Leg Deployments: E+249s, L-170s
• Dust Settling: L+0 to L+15min
Landing at
-3.5 to -5.0 km
Elevation (MOLA
relative)
Entry Prep
• Fire Pyros for Deployments: L+5s
• Begin Gyro-Compassing: L+75min
• Solar Array Deploy:  L+15min
* Entry altitude referenced to equatorial radius.
  All other altitudes referenced to ground level
• Final EDL Parameter Update: E-3hr;  Entry State Initialization: E-10min
Terminal Descent
Hypersonic
• Entry: E-0s, L-419s, 125 km*, r=3522.2 km, 5.6 km/s, γ = -13.0 deg  
Communications: UHF-band to Orbiters
Apr 2007Note:  Information in this graphic represents a nominal entry (67.5N Open, -3.7 km site elevation).  Dispersions exist around all values.
Phoenix EDL Overview
IPPW-5
26 June 2007 Grover/Desai -6
National Aeronautics and Space
Administration
Jet Propulsion Laboratory
California Institute of Technology
Mission Design Comparison
• Mars 2001 Lander
– Equatorial landing region
– 7.2 km/s entry velocity   ⇐
– +2.5 km (w.r.t MOLA) landing site elevation   ⇐
• Phoenix Lander
– Northern landing region:  65º N to 72º N
– 5.8 km/s entry velocity   ⇐
– -3.5 km (w.r.t MOLA) landing site elevation   ⇐
IPPW-5
26 June 2007 Grover/Desai -7
National Aeronautics and Space
Administration
Jet Propulsion Laboratory
California Institute of Technology
Driving Constraints at Chute Deploy
• Parachute Deploy Opening Loads
– Lander structure load limit is 12,700 lbs (51,893 N)
– Constrains parachute opening dynamic pressure to 520 Pa
– Results in EDL systems most rigid constraint
• Parachute Deploy Mach Number
– Transonic instability forces need to keep Mach at chute deploy
comfortably away from Mach 1.0
– Angle of attach at chute deploy is critical for three reasons:
• Parachute inflation qualification limits
• Off-axial load limits on Lander structure
• Vehicle oscillatory dynamics (wrist mode) while hanging from
parachute
• Parachute opening load drives down chute deploy point while Mach
constraint drives up chute deploy point
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26 June 2007 Grover/Desai -8
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Hypersonic Evolution (1/3)
Guided Trajectory
(Ballistic Reference)
Lifting Trajectory Ballistic Trajectory
-12.5 EFPA -12.5 EFPA -13.0 EFPA
2005 20062004
10 km 250 km 140 km
Redesign Drivers
• Reduced complexity
• Higher chute deploy Mach
& altitude
Redesign Drivers
• Reduced footprint
IPPW-5
26 June 2007 Grover/Desai -9
National Aeronautics and Space
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Jet Propulsion Laboratory
California Institute of Technology
Hypersonic Evolution (2/3)
• More guidance authority (smaller footprint)
• Larger chute deploy alt. dispersions99% High
99% Low
99% High
99% Low
C
hu
te
 D
ep
lo
y 
A
lt.
 D
is
pe
rs
io
n
99
%
 L
ow
 T
im
el
in
es
• Less guidance authority (larger footprint)
• Smaller chute deploy alt. dispersions
Guidance & Chute Deploy Dispersions
IPPW-5
26 June 2007 Grover/Desai -10
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Hypersonic Evolution (3/3)
• CFD of Aero/RCS flow field shows
potential for strong interaction from
hypersonic regime to parachute
deployment
– RCS Pitch authority is degraded
– RCS Yaw authority is low to non-
existent (potential for control
reversal exists)
– Baseline is to increase control system
deadbands to minimize/eliminate
RCS thruster firings to avoid this
flow interaction
Aero/RCS Flow Interaction Phenomenon
CFD of Yaw
Thruster Firing
IPPW-5
26 June 2007 Grover/Desai -11
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Jet Propulsion Laboratory
California Institute of Technology
Terminal Descent Evolution (1/2)
New Requirement
The distance between the center of mass of the lander and center of mass of the
backshell shall be greater than 35m from 5s after lander separation to touchdown of
both bodies
35m
In cases of low wind and no wind terminal descent scenarios, there is an increased
probability the backshell/parachute will recontact the lander
– Issue existed for MPL and Mars ’01 EDL designs
– Phoenix BAM used to mitigate
Parachute zone30m
Backshell Avoidance Maneuver  (BAM)
IPPW-5
26 June 2007 Grover/Desai -12
National Aeronautics and Space
Administration
Jet Propulsion Laboratory
California Institute of Technology
Terminal Descent Evolution (2/2)
Wind direction
0 5 10 15 20
0
5
10
15
20
25
sec
B
A
M
 
a
n
g
e
l
 
(
d
e
g
) Grav Turn Offpt
BAM Timer (sec)
Extra delta-v in upwind direction
BAM angle
BA
M
 A
ng
le
 (d
eg
)
• Aim the maneuver upwind  (Assumption: all residual horizontal velocity is
due to wind)
• Upwind direction is estimated from the navigated horizontal velocity
• Start the BAM at tip up
• Compute the angle from horizontal velocity
• Two conditional tests constrain conditions of use
BAM Design
IPPW-5
26 June 2007 Grover/Desai -13
National Aeronautics and Space
Administration
Jet Propulsion Laboratory
California Institute of Technology
Summary
• Phoenix is a return to flight of the cancelled Mars ’01 Lander,
emphasizing thorough and extensive testing
• Mission design leads to more benign entry velocities and a much
lower landing site elevation relieving pressure on EDL timeline
• Due to complexity, hypersonic guidance was de-scoped in favor of
simple ballistic entry
• Immature understanding of thruster effectiveness in
hypersonic/supersonic low led to relaxed attitude control
• A backshell avoidance maneuver was added to mitigate risk of
backshell/parachute recontact of the Lander during terminal descent
and at touhdown
• Changes to Phoenix EDL system architecture provides a more robust
design for Mars EDL


Evolution of the Phoenix EDL System Architecture

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