NASA/TM-2011-216988 

 

Entry, Descent and Landing Systems Analysis 

Study: Phase 2 Report on Mars Science Laboratory 

Improvement 

Mark C. Ivanov - Study Lead, Eric M. Blood, Brant T. Cook, Louis R. Giersch, Myron R. Grover, Julie K. 

Jakobowski, Tommaso P. Rivellini and Robbie P. Su 

NASA Jet Propulsion Laboratory, Pasadena, California 

Jamshid A. Samareh, and Thomas A. Zang 

NASA Langley Research Center, Hampton, Virginia 

Richard G. Winski 

Binera, Inc., Yorktown, Virginia 

Aaron D. Olds 

Analytical Mechanics Associates, Inc., Hampton, Virginia 

David J. Kinney 

NASA Ames Research Center, Moffett Field, California 

January 2011 
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NASA/TM-2011-216988 

 

Entry, Descent and Landing Systems Analysis 

Study: Phase 2 Report on Mars Science Laboratory 

Improvement 

Mark C. Ivanov - Study Lead, Eric M. Blood, Brant T. Cook, Louis R. Giersch, Myron R. Grover, Julie K. 

Jakobowski, Tommaso P. Rivellini and Robbie P. Su 

NASA Jet Propulsion Laboratory, Pasadena, California 

Jamshid A. Samareh, and Thomas A. Zang 

NASA Langley Research Center, Hampton, Virginia 

Richard G. Winski 

Binera, Inc., Yorktown, Virginia 

Aaron D. Olds 

Analytical Mechanics Associates, Inc., Hampton, Virginia 

David J. Kinney 

NASA Ames Research Center, Moffett Field, California 

National Aeronautics and 

Space Administration 

Jet Propulsion Laboratory 

Pasadena, CA 91109-8099 January 2011 
This research was carried out at the Jet Propulsion Laboratory, 

California Institute of Technology, under a contract with the 

National Aeronautics and Space Administration. 

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service by trade name, trademark, manufacturer, or otherwise, does 

not constitute or imply its endorsement by the United States 

Government or the Jet Propulsion Laboratory, California Institute 

of Technology. 

© 2011. All rights reserved. 

Available from: 

NASA Center for AeroSpace Information 

7115 Standard Drive 

Hanover, MD 21076-1320 

443-757-5802 
3

Table of Contents 

List of Figures ......................................................................................................................................... 5

List of Tables........................................................................................................................................... 5

Acknowledgements .............................................................................................................................. 6

MSL‐I Team.............................................................................................................................................. 6

1 Executive Summary....................................................................................................................... 7

2 Overview of the MSL‐I Study....................................................................................................... 8

2.1 Design Reference Mission ............................................................................................................. 9

2.2 Study Process ................................................................................................................................. 9

3 EDL Enabling Technologies ......................................................................................................10

3.1 Criteria of Selection .................................................................................................................... 10

3.2 Initial Technology List ................................................................................................................ 11

3.3 Reduced Technology List ............................................................................................................ 11

3.4 Technology Sets ........................................................................................................................... 11

4 Simulation Models & Integration............................................................................................12

4.1 Mass Model .................................................................................................................................. 12

4.2 Aerothermal Modeling ................................................................................................................ 13

4.3 Parachute Model ......................................................................................................................... 13

4.4 POST2 Simulation Integration .................................................................................................. 14

5 Performance Results...................................................................................................................14

5.1 TS-1 - Iso-tensoid ......................................................................................................................... 15

5.2 TS-2 - Iso-tensoid ......................................................................................................................... 16

5.3 TS-3 - Tension Cone .................................................................................................................... 16

5.4 TS-4 - Tension Cone .................................................................................................................... 16

5.5 TS-5 - Trim Tab........................................................................................................................... 17

5.6 TS-6 - Supersonic Ringsail Parachute ....................................................................................... 17

5.7 TS-7 – “SABr ” Supersonic Air Brake ...................................................................................... 18

5.8 TS-8 – “SABr with Trim Tab” ................................................................................................... 18

5.9 Unconstrained IAD mass for TS-2 and TS-4 ............................................................................ 18

5.10 MSL-I Performance Summary ................................................................................................ 18

6 Mechanical Integration Concepts ...........................................................................................20

6.1 Parachute and Parachute Accommodation .............................................................................. 20

6.1.1 30	meter	Ringsail	Parachute	...................................................................................................................	21

6.2 Iso-Tensoids and Tension Cones ................................................................................................ 23

6.3 Trim Tab ...................................................................................................................................... 24

6.3.1 Trim	Tab	Actuator	.......................................................................................................................................	25

6.3.2 Trim	Tab	Panel	.............................................................................................................................................	25

6.4 SABr - Supersonic Air Brake ..................................................................................................... 25

6.5 SABr with Trim Tab ................................................................................................................... 27

7 Cost, Risk and Cross‐Cutting Applicability ..........................................................................28
4 

7.1 Development Cost ........................................................................................................................ 28

7.2 Risk ............................................................................................................................................... 29

7.2.1 Development	Risk	........................................................................................................................................	29

7.2.2 Performance	Risk	........................................................................................................................................	29

7.2.3 Overall	Risk	....................................................................................................................................................	30

7.3 Cross-Cutting Applicability ....................................................................................................... 30

8 Technology Set Evaluations......................................................................................................31

8.1 Technology Set Development Cost ............................................................................................. 31

8.2 Technology Set Performance Summary .................................................................................... 31

9 Conclusion ......................................................................................................................................32

Bibliography .........................................................................................................................................34

Appendix A:		Ground Rules & Assumptions ...............................................................................35

Appendix B:		Initial Technology List.............................................................................................37

Appendix C:		Abbreviations, Acronyms and Symbols List.....................................................40
5 

List of Figures 

Figure 1. MSL EDL Sequence of Events ....................................................................................... 9

Figure 2. MSL-I Primary Technologies Studied .......................................................................... 10

Figure 3. Eight MSL-I Study Technology Sets ........................................................................... 12

Figure 4. Sensitivity to Entry Velocity ........................................................................................ 15

Figure 5. Performance as Chute Deploy Mach Number Varies .................................................. 17

Figure 6. TS-6 Parachute Size Sensitivity ................................................................................... 17

Figure 7. TS-2 Altitude Gain ....................................................................................................... 19

Figure 8. TS-4 Altitude Gain ....................................................................................................... 19

Figure 9. Ringsail Results ............................................................................................................ 20

Figure 10. MSL DGB Result ....................................................................................................... 20

Figure 11. Summary of Technology Set Touchdown Performance ............................................ 20

Figure 12. Aeroshell Evolution and Parachute Accommodation ................................................. 21

Figure 13. SPTT Parachute Configuration ................................................................................... 21

Figure 14. MSL-I Parachute Packing Density ............................................................................. 22

Figure 15. Iso-Tensoid and Tension Cone SIADs ....................................................................... 24

Figure 16. SIAD Cover Options .................................................................................................. 24

Figure 17. Trim Tab Configuration ............................................................................................. 25

Figure 18. SABr Stowed and Deployed, Unwebbed and Webbed Configurations ..................... 26

Figure 19. SABr System Components ......................................................................................... 26

Figure 20. SABr + Trim Tab Configurations .............................................................................. 27

Figure 21. Technology Development Cost Space ........................................................................ 29

Figure 22. Technology Set Development Cost Space ................................................................. 31

Figure 23. Technology Set Evaluation Summary ........................................................................ 32

List of Tables 

Table 1. Technology Set Final Design Points .............................................................................. 15

Table 2. Technology Set Parachute Sizing Metrics ..................................................................... 22

Table 3. Evaluation Criteria ......................................................................................................... 28

Table 4. MSL-I Technologies Initial Overall Risk Estimates ...................................................... 30

Table 5. Criterion of Selection Definitions .................................................................................. 37

Table 6. Initial Technology List ................................................................................................... 37
6 

Acknowledgements 

The MSL-I team would like to acknowledge the valuable contribution of the MSL-I Robotic 

Screening Committee (RSC) who provided important technical and programmatic guidance and 

input during the MSL-I study: Stephen J. Hughes, Michelle M. Munk, Richard W. Powell, 

Tommaso P. Rivellini, Miguel San Martin, Adam D. Steltzner, Henry S. Wright and Michael J. 

Wright. 

The team is also appreciative of the efforts of Farhad Tahmasabi of the Office of the Chief 

Engineer for his guidance and support, and especially for the efforts of our sponsor, Mike 

Ryschkewitsch, the NASA Chief Engineer. 

Finally, the MSL-I team is also appreciative of the persistent and effective advocacy and 

guidance provided of Walter C. Engelund. 

MSL-I Team 

The following people comprise the MSL-I team and made significant contributions to the content 

of this report: 

Flight Performance 

 Rick Winski LaRC 

 Aaron Olds LaRC 

 Jeremy Shidner LaRC 

 Alicia Dwyer Cianciolo LaRC 

 Dick Powell LaRC 

 Juan Cruz LaRC 

Mass Modeling 

 Jamshid Samareh LaRC 

 Sasan Armand LaRC 

Aerothermal/Aerodynamics 

 Dave Kinney Ames 

 Dinesh Prabhu Ames 

 Kathy McGuire Ames 

 Joseph Garcia Ames 

 Matt McMullen Ames 

 Paul Stremel Ames 

 Eric Lau Ames 

Technology Evaluation 

 Rob Grover JPL 

 Eric Blood JPL 

Mechanical Integration 

 Tom Rivellini JPL 

 Robbie Su JPL 

 Brant Cook JPL 

 Louis Giersch JPL 

 Julie Jakoboski JPL 

 Tom Moreno JPL 

 Bill Allen JPL 

Management 

 George Chen JPL 

 David Hash Ames 

 Aga Goodsell Ames 

 Tom Zang LaRC 

 Walt Engelund LaRC 

 Ron Sostaric JSC 

 Mark Ivanov JPL 
7 

1 Executive Summary 

The Mars Science Laboratory Improvement (MSL-I) study is an effort to identify and assess 

promising, next-step technologies that provide incremental performance improvement to the 

Mars Science Laboratory (MSL) entry, descent and landing (EDL) architecture. Initiated with an 

exhaustive effort to identify all EDL technologies with potential to enable more capable robotic 

Mars missions, selection criteria that included being flight ready by 2024 at a development cost 

of less than $200M are applied establishing seven technologies for further focus of the study. 

The seven technologies are subsonic ringsail parachute, supersonic ringsail parachute, an isotensoid supersonic inflatable aerodynamic decelerator (SIAD), a tension cone SIAD, an aeroshell 

trim tab, a rigid deployable aeroshell drag augmentation technology called Supersonic Air Brake 

(SABr), and SABr combined with trim tab. These seven technologies are assessed on the basis 

of performance, mechanical implementation, cost, risk and cross cutting applicability, with the 

goal of providing an investment recommendation on next-step Mars EDL technologies. 

In assessing performance, the seven EDL technologies are paired into eight technology sets. 

Each technology set contains a parachute, either subsonic or supersonic, and one of the four 

other technologies. Performance was assessed using a dynamic simulation, each technology set 

sized and optimized to maximize landing site elevation and/or landed mass. The results show 

that technologies that augment the drag of the aeroshell during the supersonic flight phase, such 

as the SIAD technologies or the SABr, are able to achieve the best landing site elevation 

performance. Because of its structural mass efficiency, the trim tab technology provided the 

greatest landed mass performance. The addition of a supersonic ringsail parachute alone 

provides the second best landed mass performance. Two of the technology sets contain the 

subsonic ringsail parachute paired with one each of the SIAD technologies, and resulted in the 

least benefit to performance. 

A mechanical implementation concept is developed for each of the seven technologies included 

in the assessment. The implementation concepts serve as proof of implementation feasibility, 

inform mass estimates used in the performance simulations, and help establish a basis for cost 

and risk assessments. 

Using past and current analog technology development efforts, a very preliminary development 

cost estimate is provided for each technology, and each technology set. A major distinguisher of 

development cost is the need or no need for a supersonic high altitude flight test program. 

Technologies requiring a supersonic flight test program, which include the supersonic ringsail 

parachute and SIAD technologies, fall into a ~$150M development classification. The SABr 

technology falls into the $100M classification, and the subsonic ringsail and trim tab are the 

lowest costed technologies falling in the $50M classification. Considered as a technology set, 

because all technology sets contain either a supersonic ringsail parachute or a SIAD and thus 

require a supersonic high altitude flight test, all technology sets fall into development cost 

estimation range of $100M to $250M. The cost estimates are an initial assessment and further 

refinement is needed. The assessment of development risk leads to the general conclusion that 

flexible technologies, particularly the SIAD technologies, have higher development risk than 

rigid technologies. Performance risk and overall risk also divide in a similar way into higher risk 

and lower risk based on flexible versus rigid technologies. 
8 

The work of the MSL-I study results in the following technology conclusions and 

recommendations for missions on or before 2024: 

Conclusions 

1. The best altitude performers provide higher drag earlier in the supersonic phase 

 Iso-Tensoid with Supersonic Parachute (TS-1) 6.0 km 

 Tension Cone with Supersonic Parachute (TS-3) 6.0 km 

 SABr with Supersonic Parachute (TS-7) 4.9 km 

2. The best landed payload performers provide higher lift (Trim Tab) or higher drag 

(Supersonic Parachute) 

 Trim Tab with Supersonic Parachute (TS-5) 1462 kg 

 Supersonic Parachute alone (TS-6) 1309 kg 

 Trim Tab + SABr with Supersonic Parachute (TS-8) 1256 kg 

3. A subsonic parachute with an IAD in lieu of a supersonic parachute provides the least 

performance improvement 

 Iso-Tensoid with Subsonic Parachute (TS-2) 2.5 km / 1086 kg 

 Tension Cone with Subsonic Parachute (TS-4) -1.28 km / 1123 kg 

4. The maximum payload that can be landed in 2024 using an Atlas V with an improved 

MSL architecture is 

 0 km MOLA: ~1450 kg 

 +3 km MOLA: ~1250 kg 

5. Based on the technologies assessed, a larger supersonic parachute combined with one 

other technology is necessary to make any significant increase in landed payload mass 

and/or altitude 

6. The following technologies have some feed-forward potential 

 Trim Tab (aero control surfaces in general) 

 SIADs (as a step towards HIADs) 

 Bi-propellant engines (not included directly in the technology sets but was reviewed as a potential 

enhancer) 

Recommendations 

1. Although all the technologies require more study, it can be concluded from the results to 

date that the following key enabling technologies strongly warrant investment: 

 Supersonic ringsail parachute (critical for all technologies identified) 

 Bi-prop engines (critical for all the heavier payload options) 

2. Conduct Pre-Phase A studies for all the MSL-I technologies to fill in the remaining 

performance, design, risk, and cost gaps to better inform investment decisions 

 Add bi-prop engines to the technologies 

o TS-9: capsule + parachute + bi-prop engines 

o TS-10: trim tab + parachute + bi-prop engines 

 Evaluate landed accuracy for all Technology Sets 

 Conduct thorough Development Risk assessment of all technologies 

 Mature all technologies to Pre-Phase A level

Further information on the MSL-I work is available in the report NASA/TM-2011-2169891

. 

2 Overview of the MSL-I Study 

The MSL-I study is a continuation of the analysis performed for the Entry, Descent and Landing 

Systems Analysis study year one effort2

. The purpose of the MSL-I study is to examine enabling 
9 

technologies that incrementally improve performance of the MSL EDL system while minimizing 

change to the MSL EDL architecture, as a way of shedding light on a path forward to landing 

heavier payloads and/or payloads at higher landing site elevations. Technologies considered are 

required to be feasibly mission-ready on or before 2024. Constraining the technologies 

considered is a cumulative development cost limit of $200M to develop new technologies in a 

given architecture option. As well, launch mass/volume is constrained to the capability of an 

Atlas V-551 launch vehicle. 

2.1 Design Reference Mission 

As a point of departure, a modified MSL EDL architecture serves as the design reference mission 

(DRM) for the study, and includes the following high level features: 

 A rigid, blunt-body hypersonic entry vehicle 

 Guided, lifting entry 

 The use of a parachute to achieve terminal descent initiation conditions 

 A sky crane architecture for providing terminal descent and landing of the payload 

Shown in Figure 1 is the MSL EDL sequence of events illustrating the salient features of the 

MSL-I DRM. MSL-I DRM variations from MSL include a slightly larger diameter 4.7 m entry 

aeroshell, a 5.75 km/s entry velocity, and a 0 km with respect to MOLA reference landing site 

elevation. The performance of the DRM architecture serves as a reference starting point for 

assessments of enhancing technologies. 

 

2.2 Study Process 

A study process with multiple stages is used in the MSL-I study to first exhaustively identify 

possible enabling technologies, then down select to the most promising technologies based on 

Figure 1. MSL EDL Sequence of Events 
10 

predicted cost, performance potential, development scope and technical feasibility. This pool of 

down-selected technologies become a set of seven technologies assessed in more detail during a 

second phase of the MSL-I study. The criteria used to assess the seven technologies are 

performance, mechanical implementation feasibility, and cost/risk estimation. In order to 

provide a selection of technology sets for possible Mars applications, eight technology set 

pairings (discussed further in Section 3) of the seven selected technologies are generated forming 

eight variations on the MSL-I DRM, called Technology Sets 1-8. Landed payload mass 

performance as well as mechanical implementation feasibility are assessed for each set. Figure 2 

illustrates by flight regime the variations in technologies contained in the eight technology sets. 

Mach > 5 Mach <= 5 Mach <= 1 

Lifting Capsule 

(reference) 

Iso-Tensoid IAD 

Lifting 

 Capsule 

w/ Trim Tab 

MSL SkyCrane 

Tension 

Cone 

IAD Subsonic 

Parachute 

(reefed ringsail) 

Supersonic 

Parachute 

(reefed ringsail) 

Rigid Supersonic 

Air Break 

(SABr) 

Figure 2. MSL-I Primary Technologies Studied 

3 EDL Enabling Technologies 

In February of 2010, the MSL-I team identified EDL technologies that enable an increase of 

landed payload mass capability, increase of landing elevation capability, increase of landing 

accuracy capability, reduction of risk or a combination of the aforementioned to the existing 

MSL architecture. This identification served as the EDL-SA Team Initial Evaluation of the 

MSL-I technologies, a crucial step in the MSL-I study plan. Section 3.1 identifies the criteria of 

selection that all technologies that passed the first down-select met. Section 3.2 lists all of the 

initial technology families that were brainstormed (the full list is in Appendix B: Initial 

Technology List). Section 3.3 presents the reduced technology list and the final technologies 

that were chosen for the MSL-I FY10 Study. 

3.1 Criteria of Selection 

The MSL-I team chose specific criteria in which to evaluate every technology against. These 

include development time, DRM/GR&A, flight system technology, EDL-SA scope, technology 
11 

relevance, and FY10 scope. For definition of each criterion, please see Table 6 in Appendix B. 

As well, technologies were also eliminated from further evaluation based on whether the 

technology did or did not fall within the technical expertise domain of the MSL-I team. 

3.2 Initial Technology List 

The initial technology list was split up into the following technology families: Angle of Attack 

(AoA) and Drag Control, Alternate Entry Geometries, Improved Inertial and Atmospheric 

Relative Knowledge (onboard vs. external), Improved Terrain Relative Knowledge, TPS 

Improvements, Inflatable Aerodynamic Decelerators (IADs), Improved Parachutes, Propulsive 

Augmentation, Improved Staging (Mechanisms and Triggers), General Systems Improvements, 

Policy Changes, Improved Guidance Algorithms, Entry from Orbit, Skip Entry, and Propulsive 

Targeting. The entire list of technologies considered is in Appendix B: Initial Technology List. 

The technologies listed in red were not selected for this study in the first reduction phase due the 

inability to meet one or more of the aforementioned criteria. The technologies listed in orange 

meet all of the criteria, but were not selected for this study in the second reduction phase due to a 

perceived lower priority. 

3.3 Reduced Technology List 

After the initial down-select in which technologies that did not meet all of the criteria were 

eliminated, eleven technologies were chosen for their perceived higher potential for improving 

the MSL architecture. They are: Trim Tab, Lifting SIAD, Drag SIAD (AoA and Drag Control); 

Apollo, Alternate TBD (Alternate Entry Geometries); Terrain Relative Navigation, Hazard 

Detection (ALHAT Type Sensors); Larger and/or faster parachute (improved parachute); Simple 

Supersonic Retro-propulsion (Propulsive Augmentation); Upgrade Apollo, NPC (Improved 

guidance algorithms, entry and prop). 

A rigid deployable aerodynamic decelerator was added after the initial technology list was 

created. This technology effectively falls under the “SIAD or L/D Augmentation” family. This 

technology was named the Supersonic Aerodynamic Brake (SABr). Two variants of SABr were 

considered: webbed and non-webbed. Because of the added complexity of the webbed version, 

only the performance of the non-webbed version of SABr was evaluated in this study. The 

MSL-I study evaluated the following reduced set of seven technologies: trim tab, SABr, SABr 

combined with trim tab, drag only iso-tensoid, lifting tension cone, supersonic ringsail parachute 

and subsonic ringsail parachute. 

3.4 Technology Sets 

Performance of the technologies is evaluated by combining each technology with either the 

supersonic ringsail parachute or the subsonic ringsail parachute, yielding the eight technology 

sets (TS) shown in Figure 3, all technology sets a variation on the reference DRM. Technology 

set two (TS-2) and TS-4 utilize the subsonic ringsail parachute while all other technology sets 

utilize the supersonic ringsail parachute. TS-6, contains only the supersonic ringsail parachute 

without pairing with an additional technology. In evaluating TS performance, each technology 

set is optimized to exploit its performance strengths. 
12 

I 

Iso-Tensoid 

Drag Only IAD 

Supersonic 

Parachute 

Lifting 

Capsule 

II 

Subsonic 

Parachute 

Iso-Tensoid 

Drag Only IAD 

IV 

Subsonic 

Parachute 

Tension Cone 

Lifting 

Supersonic 

Parachute 

VI 

Supersonic 

Parachute 

VII 

Rigid 

Deployable 

III 

Supersonic 

Parachute 

Tension Cone 

Lifting 

Supersonic 

Parachute 

VIII 

Trim Tab+Rigid 

Deployable 

Lifting 

Capsule 

Lifting 

Capsule 

Lifting 

Capsule 

Lifting 

Capsule 

Lifting 

Capsule 

Lifting 

Capsule 

MSL 

SkyCrane 

MSL 

SkyCrane 

MSL 

SkyCrane 

MSL 

SkyCrane 

MSL 

SkyCrane 

MSL 

SkyCrane 

MSL 

SkyCrane 

V 

Supersonic 

Parachute 

Trim Tab 

MSL 

SkyCrane 

Lifting 

Capsule 

Figure 3. Eight MSL-I Study Technology Sets 

4 Simulation Models & Integration 

4.1 Mass Model 

Mass models used for the MSL-I project are parametric models represented by mathematical 

equations that relate mass components to vehicle dimensions and mission key environmental 

parameters such as maximum dynamic pressure and total heat load. The major mass components 

shared across the MSL-I architecture sets are: backshell (structure and TPS), balance masses 

(cruise and entry), descent stage, heatshield (structure and TPS), parachutes (ring sail & DGB), 

payload, propellant, SABr drag device, SIADs (iso-tensoid and tension cone), and trim tab. 

There were additional miscellaneous mass components allocated for avionics, cabling, cover 

panels, parachute can, and scar masses (e.g., scar masses for trim tab and SIAD). A 30% margin, 

a factor of 1.43, was applied to all mass components except SABr and DGB parachute. A 25% 

mass margin was applied to SABr. 

The backshell and the heatshield TPS masses were based on total heat load and their projected 

areas. The trim tab mass was based on the Shuttle body flap with correction for higher aspect 

ratio. A subsequent finite-element analysis showed that the trim tab mass estimate was very 

conservative. The SIAD mass models are based on models proposed and tested in the 1960’s 

and on some recent model updates. The iso-tensoid parametric mass model accounted for the 

radial cords, canopy fabric, 50% inflation gas based on airbag gas generators, burble fence, inlet 

assembly, reinforced webbing, and joints. The tension cone parametric mass model consisted of 

radial straps, gores, gas barrier, and gas generators. The SIAD mass models are based on using a 
13 

load factor of safety of 4, per NASA requirement3. There were no knock-down factors on the 

material strength due to possible elevated temperatures, and the SIAD models did not include a 

TPS component. The SIAD aerothermal and TPS requirements need to be further investigated. 

4.2 Aerothermal Modeling 

Seven different vehicle configurations were analyzed for the MSL-I effort. These configurations 

included: 

1. Baseline capsule configuration, based on a circular heat shield and an MSL backshell 

2. Three parametric variations of a tension cone Inflatable Aerodynamic Decelerator (IAD) 

3. Three parametric variations of an iso-tensoid IAD 

4. Two variations of the SABr concept, one with, and one without webbing 

5. A baseline entry trim tab configurations 

6. A Tab concept which uses a single SABr panel on entry 

The aerodynamic models for all the configurations were a combination of engineering, Euler, 

and Navier Stokes solutions. The engineering level analysis was performed with the CBAERO 

software tool set. CART3D was used to provide Euler level analysis, and both DPLR and 

LAURA were used to provide high-fidelity aerodynamic and aerothermal analysis. The baseline 

capsule aerodynamics and aerothermal models were generated by leveraging the CEV 

aerodynamic and aerothermal databases, allowing CBAERO to correct for both vehicle size and 

atmosphere. The aerodynamics for the IAD and SABr concepts in the subsonic to supersonic 

range were developed using CART3D, with viscous corrections provided by CBAERO. The 

aerodynamics for the trim tab, and SABr + trim tab configurations were generated using 

CART3D, using a priori calculated post shock ratio of specific heats appropriate for the flight 

Mach numbers evaluated. 

The final aerodynamic databases were provided as FORTRAN front ends to an underlying C++ 

software tool that performed simple table look up for axial, normal force, and pitching moments. 

Aerothermal indicators were provided for the heatshield of the baseline capsule configuration. 

4.3 Parachute Model 

The ringsail parachute model consists of two parts: the inflation model and the aerodynamics 

model. The ringsail parachute inflation model was adapted from a Launch Abort System (Orion) 

POST2 simulation. The actual inflation times were assumed to be instantaneous for 

conservatism on parachute loads. The over-inflation factor was scaled from the Knacke data 

using the same margin as was used for the MSL DGB design. The ringsail aerodynamics was 

based on Knacke data and assumed a drag coefficient of 0.75 as the nominal used for 

performance analysis. Due to the lack of supersonically deployed ringsail test data a Mach 

efficiency curve, from the MSL DGB parachute model, was used to scale the drag coefficient 

across the Mach range. A high drag curve was also generated for use in the parachute loads 

calculation, which was constrained to an upper limit of 65,000 lbs. This model does not model 

mortar fire or time to line stretch. In the optimizations the disreef time and reefing ratio were 

varied. Note that this study made assumptions about the ringsail aerodynamics since there exists 

little test data at the current time. Results in this study and future system level studies depend on 
14 

having believable and realistic models. 

4.4 POST2 Simulation Integration 

The simulation used to evaluate the MSL-I technology sets is the Program to Optimize Simulated 

Trajectories (POSTII), which has extensive heritage for simulating ascent, descent, and orbiting 

trajectories. The code employs standard atmosphere (MarsGRAM), planet and gravity models as 

well as MSL-I specific models including aerodynamics, mass properties, guidance and terminal 

descent. MSL-I specific models were delivered and integrated into the POST2 source code as 

needed.

The hypersonic guidance scheme used was designed to mimic the Apollo guidance, which has a 

range control phase and a heading alignment phase and is called the theoretical guidance. 

During the range control phase the bank angle magnitude is used to control range to the target 

and bank angle direction is used to control cross range. After, during the heading alignment 

phase, the bank angle is used to remove residual cross range error. For this study landing 

accuracy is not assessed. 

Powered descent in the MSL-I simulation is modeled in a simplified fashion with correction 

factors applied to the results to mimic MSL performance in terms of propellant and altitude 

required. The MSL powered descent profile includes a number of phases that account for 

uncertainties and sensor limitations that would be difficult or impractical to reproduce effectively 

for the range of architectures in the MSL-I study. Similar to MSL, powered descent in the 

MSL-I simulation is a constant thrust gravity turn performed by 8 descent engines at 80% 

throttle. The total propellant mass result is designed to represent the minimum propellant 

required to complete powered descent with an MSL-like strategy with 3σ dispersions. 

5 Performance Results 

The system performance results presented here are the end product of optimization of trajectories 

that have included some margined criteria based on MSL experience. No Monte Carlo analysis 

was performed for this study. Generally, the technology sets were optimized for multiple 

reasons. One case was designed to deliver the maximum amount of payload to 0 km MOLA. 

Another case was designed to deliver to the maximum altitude. Where the maximum altitude 

was felt to be high considering near term mission requirements, a 6 km MOLA landed altitude 

case was run. This level of landed altitude would allow the vehicle to land at nearly any point on 

the surface of Mars. For other technology sets, if the vehicle could not deliver the payload to 

0 km MOLA then the altitude was maximized without lowering the maximum entry mass. For 

comparison, the MSL Eberswalde landing site under consideration is approximately -1.4 km 

MOLA and the MSL rover payload is approximately 919 kg. 

Some sensitivity cases were also generated by changing the parachute size, using the MSL DGB 

parachute, or varying the parachute deployment velocity. Note that the MSL DGB has a 

different drag performance than the ringsail parachute as well as a smaller diameter, 21.5 m. The 

first round of analysis was performed using a 35 m maximum diameter ringsail parachute. After
15

Table 1. Technology Set Final Design Points 

Touchdown Altitude (km) 6 2.53 6 -1.28 1.83 2.86 4.89 4.77

Payload (kg) 1134.9 1086 1156.7 1123.16 1462.36 1309.3 1131.72 1255.84

Entry Mass (kg) 4295 4295 4295 4295 4490 4295 4295 4490

IAD Diameter (m) 7.95 15.44 5.76 9.19 ---- ---- 6.9 (rigid) 6.9 (rigid) 

Max IAD dyn pressure (kPa) 1.51 2.64 1.31 4.09 ---- ---- 1.44 1.58

IAD mass (kg) 54.52 200.0 (limit) 14.5 200.0 (limit) ---- ---- 256.2 342.99

Parachute Diam. (m) 30 30 30 30 30 30 30 30

Mach at Deployment 2.3 0.8 2.3 0.8 2.3 2.3 2.3 2.3 TS-6 Max Altitude Max Entry Mass TS-7 Max Altitude Max Entry Mass TS-8 Max Altitude Max Entry Mass

Objective/Constraint

IAD

Parachute

TS-1

Max Payload

6 km MOLA

TS-2

Max Altitude

Max Entry Mass

TS-3

Max Payload

6 km MOLA

TS-4

Max Altitude

Max Entry Mass

TS-5

Max Altitude 

Max Entry Mass

iteration with mechanical design, the maximum diameter was lowered to 30 m due to packaging 

concerns of the parachute within a mortar. Another important point that applies to all the 

technology sets is the launch mass limitation. The study assumed launch on an Atlas V 551 

which limits the launch mass to 5130 kg. This constraint becomes active for multiple technology 

sets, which limits the achievable payload mass. No cases were run to analyze what payload 

could have been achieved without this constraint. Table 1 details the performance and design 

parameters of the final design points for the technology sets. 

5.1 TS-1 - Iso-tensoid 

Technology set one (TS-1) is a hypersonically 

guided entry with a supersonically deployed 

iso-tensoid, modeled as a drag only IAD, coupled 

with a supersonically deployed ringsail parachute. 

The design point achieves a payload mass 

slightly more than the MSL rover mass. To 

take advantage of the iso-tensoid and 

achieve this altitude, the trajectory does loft 

some amount. This could possibly cause 

some guidance challenges although no 

analysis was done in this study to 

determine the impact. 

An additional sensitivity was examined for 

higher entry velocities. A set of simulation 

runs were performed to parametrically vary 

the entry velocity for TS-1 (iso-tensoid) 

from 6-7.5 km/s. The cases generated are 6 

Design Point TS-1 

Payload (kg) 1134.9 

Landed Altitude (km MOLA) 6.0 

Figure 4. Sensitivity to Entry Velocity 
16 

km MOLA landed altitude cases. Figure 4 shows a low sensitivity to higher entry velocities. 

For this study the assumption of a variable entry point was made to account for downrange 

differences corresponding to variable entry velocities. 

5.2 TS-2 - Iso-tensoid 

Technology set two (TS-2) is identical to TS-1 with 

the exception that the ringsail parachute is deployed 

subsonically, at Mach 0.8. The design point 

achieves a payload mass slightly more than the MSL 

rover mass. As expected, using the IAD to decelerate the vehicle to subsonic velocities 

necessitates a larger IAD. Two main drivers appeared in the TS-2 results. One was the IAD 

performance through the transonic and subsonic regimes. The aerodynamic model used for the 

IADs in this study shows a spike in the drag coefficient in the transonic regime followed by a 

precipitous decrease in the subsonic regime. Therefore, for a subsonic parachute deployment, 

the IAD design diameter must grow to increase the drag area to compensate for the low subsonic 

drag. 

The second driver, the terminal velocity margin, became a problem for the parachute deploy 

event. Like the vehicle approaching terminal velocity on the parachute, the vehicle can also 

approach it on the IAD, which occurred in TS-2. The effect was to drive a steeper entry flight 

path angle which increased the maximum dynamic pressure on the IAD resulting in an increased 

IAD mass. 

5.3 TS-3 - Tension Cone 

Technology set three (TS-3) is a hypersonically 

guided entry with a supersonically deployed tension 

cone, modeled as a lifting IAD, coupled with a 

supersonically deployed ringsail parachute. The 

design point achieves a payload mass higher than the MSL rover mass. To achieve this altitude 

and take advantage of the tension cone, like the iso-tensoid, the trajectory does loft some amount. 

Again, this could possibly cause some guidance challenges although no analysis was done in this 

study to determine the impact. 

5.4 TS-4 - Tension Cone 

Technology set four (TS-4) is a hypersonically 

guided entry with a supersonically deployed tension 

cone, modeled as a lifting IAD, coupled with a 

subsonically deployed ringsail parachute, nominally 

at Mach 0.8. This design point is the maximum altitude case which has the maximum allowed 

entry mass. This altitude is below the desired altitude of 0 km MOLA and bumps against the 

200 kg limit of IAD fabric mass. The same reasons that TS-2 has poor altitude performance and 

high IAD masses, the terminal velocity margin at parachute deploy, apply to TS-4. Two 

methods for achieving a 0 km MOLA altitude were investigated; one was to decrease the entry 

mass and the other was to relieve the IAD mass constraint. Both solutions worked but allowing a 

Design Point TS-2 

Payload (kg) 1086.0 

Landed Altitude (km MOLA) 2.53 

Design Point TS-3 

Payload (kg) 1156.7 

Landed Altitude (km MOLA) 6.0 

Design Point TS-4 

Payload (kg) 1123.2 

Landed Altitude (km MOLA) -1.28 
17 

larger IAD mass enabled a larger payload mass. Note that using the latter solution might impose 

more pressure on packaging the IAD. Figure 5 illustrates the sensitivity in altering the parachute 

deployment from supersonic to subsonic; this very sensitive result illustrates the dependency of 

the results on the IAD aerodynamic model. This result applies to TS-2 also and highlights the 

dependence of the systems analysis results on the fidelity of the models. 

Figure 5. Performance as Chute Deploy Mach Number Varies 

5.5 TS-5 - Trim Tab 

Technology set five (TS-5) is a hypersonically 

guided entry using a trim tab to generate lift instead 

of entry balance masses (EBM) coupled with a 

supersonically deployed ringsail parachute. One 

advantage is the mass savings as the EBM consist of hundreds of kilograms and the trim tab is on 

the order of tens of kilograms. This mass savings can be directly transformed into payload mass. 

The TS-5 design point is the maximum altitude mission which achieves a large payload mass 

beyond the MSL rover mass. 

5.6 TS-6 - Supersonic Ringsail Parachute 

Technology set six (TS-6) is a hypersonically 

guided entry coupled with a supersonically 

deployed ringsail parachute, which allows 

quantification of the independent effect of the 

ringsail. The TS-6 design point is the 

maximum altitude mission which achieves 

lands payload mass larger than the MSL rover 

mass. Figure 6 shows some sensitivity to 

Design Point TS-5 

Payload (kg) 1462.4 

Landed Altitude (km MOLA) 1.83 

Design Point TS-6 

Payload (kg) 1309.3 

Landed Altitude (km MOLA) 2.86 

Figure 6. TS-6 Parachute Size Sensitivity 
18 

ringsail maximum diameter. 

A benefit of the ringsail parachute is the ability to deliver large payloads to significant altitudes; 

generally the MSL (21.5 m) DGB performance falls off quickly at these payload masses. To 

determine the dependency on the maximum diameter of the ringsail, the diameter was 

parametrically varied, from 21.5 m to 35 m, for a set of optimized cases. The cliff on the curve 

occurs with maximum diameters lower than 25 m. 

5.7 TS-7 – “SABr ” Supersonic Air Brake 

Technology set seven (TS-7) is a hypersonically 

guided entry utilizing a supersonically deployed 

rigid decelerator (SABr) coupled with a 

supersonically deployed ringsail parachute. This 

design point is the maximum altitude mission which achieves a payload mass larger than the 

MSL rover mass. Note that the rigid deployable used a different mass margin policy than the 

inflatable decelerators. Also, the rigid deployable design was fixed, not allowing any growth in 

the diameter, unlike the inflatable decelerators. An additional option is to have a webbing 

between the deployable panels or not which alters the aerodynamic performance. 

5.8 TS-8 – “SABr with Trim Tab” 

Technology set eight (TS-8) is a hypersonically 

guided entry utilizing a deployable panel as a trim 

tab, a supersonically deployed rigid decelerator 

coupled with a supersonically deployed ringsail 

parachute. Like TS-5, TS-8 uses a deployable trim device instead of EBM thereby saving mass; 

the difference here is that the trim device is one of the SABr panels, not a specifically designed 

trim tab. The TS-8 design point is the maximum altitude mission, non-webbed supersonic rigid 

deployable, which achieves a payload mass of greater than the MSL rover mass. Note that the 

rigid deployable used a different mass margin policy than the inflatable decelerators. Also, the 

rigid deployable design was fixed, not allowing any growth in the diameter, unlike the inflatable 

decelerators. 

 

5.9 Unconstrained IAD mass for TS-2 and TS-4 

Both TS-2 (iso-tensoid) and TS-4 (tension cone) ran up against the IAD fabric mass limit of 200 

kg, which was instituted due to packaging concerns. In an effort to quantify possible benefit 

from additional IAD mass, parametric results were generated. Figure 7 shows the potential 

altitude gain with increased IAD mass for TS-2 and Figure 8 shows the TS-4 results. As 

expected, the payload mass is traded with the IAD mass to generate the altitude gain. 

5.10 MSL-I Performance Summary 

Figures 9 and 10 indicate that there is not one technology set that will achieve all foreseen 

competing mission goals, in terms of altitude and payload performance. Some of the decelerator 

technologies investigated perform well in a region of high landed altitude where others can

Design Point TS-7 

Payload (kg) 1131.7 

Landed Altitude (km MOLA) 4.89 

Design Point TS-8 

Payload (kg) 1255.8 

Landed Altitude (km MOLA) 4.77 
19

deliver more payload to lower altitudes. And other solutions may be preferable when a vehicle 

component reaches its current technological limit, e.g. parachute deployment Mach. 

Figure 9 depicts payload as a function of altitude for the eight technology sets that use a reefed 

ringsail parachute with a maximum diameter of 35 meters. Figure 10 shows results for a 

selection of these architectures with a 21.5 m DGB parachute. All of the technologies 

investigated achieve a higher altitude payload delivery by the larger parachute. The technology 

sets most affected by the addition of a larger supersonic parachute are those with deployable drag 

devices: TS-1, 3, 7, and 8, i.e., the SIAD and SABr architectures. The lower ballistic coefficient 

of these technology sets allow the parachute deployment condition (Mach 2.3) to be met at 

higher altitude, where the vehicle can only be decelerated effectively by the larger parachute. 

Figure 11 shows the design points selected for each of the eight technology sets. The design 

points were chosen to represent the highest touchdown elevation attainable utilizing the full 

launch mass. This figure presents a set of non-dominated solutions, in terms of payload as a 

function of altitude, namely technology sets 1, 3, 5, 6, and 8. Technology sets 1 and 3, the 

SIADs coupled with supersonically deployed parachutes provide more altitude capability than 

any of the other options. Technology set 5, utilizing the hypersonic trim tab, provides the most 

payload mass at the relatively lower site elevations, due to the mass savings over replacement of 

the entry balance masses. The architectures that are not the best at delivering payload to a 

particular altitude, TS 2, 7, and 4, each have strengths not quantified in this study. TS 2, and 4 

have large SIADs that allow for subsonic deployment of the large ringsail parachute, which can 

relieve the parachute environment and would reduce the cost of a parachute development 

program. Additionally there are a range of solutions for parachute deployments between Mach 

0.8 and Mach 2.3 for the SIAD options that allow trades in performance and level of supersonic 

ringsail technology development. TS-7 is the SABr rigid, deployable drag device, which could 

provide lower uncertainty in deployment dynamics than an inflatable device. 

TS-6 Point 

Design 

Decreasing 

parachute 

diameter 

TS-2 Point 

Design 

Increasing IAD 

mass 

Figure 7. TS-2 Altitude Gain Figure 8. TS-4 Altitude Gain 
20

Figure 9. Ringsail Results Figure 10. MSL DGB Result

For architectures limited to a 21.5 m DGB parachute, Figure 10 shows that the MSL-like 

reference case more effectively delivers payload with the exception of SIAD's landing above 

Figure 11. Summary of Technology Set Touchdown Performance 

1 km MOLA. Results for TS-8 were not obtained with the 21.5 m DGB parachute. The SIADs 

are able to land more payload at higher altitudes than the reference design due to their capacity to 

decelerate the vehicle to parachute deployment conditions at higher altitude. However, the 

limited drag performance of the 21.5 m parachute doesn't allow the level of improvement seen 

on TS-1 and 3 with the addition of the larger parachute. 

6 Mechanical Integration Concepts 

6.1 Parachute and Parachute Accommodation 

Mechanical accommodation of the parachute for each of the technology sets was patterned after 

the mortar system used on MSL, with modifications made to increase stowage capacity for the 

larger parachutes with minimal impact to the backshell outer mold line (OML). Figure 12 

TS-4

TS-2 TS-6

TS-5

TS-7 TS-8

TS-1 TS-3
21 

compares the MSL-I aeroshell with the MSL aeroshell. 

Figure 12. Aeroshell Evolution and Parachute Accommodation 

6.1.1 30 meter Ringsail Parachute 

A ringsail style parachute was selected for this study due to the previous parachute work done in 

the Mars Program as late as 2005. The two prime motivators for selecting a ringsail type 

parachute are that it has excellent subsonic drag performance and is much easier to reef than a 

disk gap band parachute. Reefing is required to minimize the peak accelerations of the 

spacecraft at parachute inflation. MSL’s 9 G’s (achieved with a 21.5 m parachute) was used as a 

working upper limit. 

The Subsonic Parachute Technology Task (SPTT) developed by Mitcheltree, Slimko, Cruz in 

2005 was used as the configuration for this effort. The SPTT parachute, shown in Figure 13, was 

designed for a 20,000 lbf peak inflation load, so the mass of the SPTT parachute was scaled up to 

account for a maximum flight limit load of 65,000 lbf. The parachute subcontractor, Pioneer 

Aerospace, confirmed the mass estimate of 130-145 kg. 

Figure 13. SPTT Parachute Configuration 

Using a guideline that trailing distance should be 8 times the forebody diameter for subsonic 

chutes, and 10 times for supersonic chutes, the differences in forebody diameter for TS-1 through 
22 

TS-8 resulted in a large variance of riser length, and therefore total chute mass and stowed 

volume among the technology sets. The masses were broadly binned into 160, 185, and 230 kg 

variants, for which mortar can configurations were modeled in CAD. This is summarized in 

Table 2. 

Table 2. Technology Set Parachute Sizing Metrics 

The MSL-I design interfaces with the MSL Backshell Interface Plate (BIP), and uses a similar 

support structure sized for the same peak loads. 

Assumed parachute packing density was kept at a very conservative 42 lb/in3

, in line with MSL’s 

design density and below the densities used on Mars Pathfinder, MER, and Apollo. The addition 

of reefing components (cable cutters and reefing rings) limits the max pack density that can be 

safely achieved without incurring damage to these components. 

Figure 14. MSL-I Parachute Packing Density 
23 

6.2 Iso-Tensoids and Tension Cones 

A Supersonic Inflatable Aerodynamic Decelerator is a deployable softgoods device that 

increases the drag of a vehicle after SIAD deployment. Because the SIAD is a softgoods device, 

it can be stowed in a compact volume and deployed to a large size. In order to minimize the 

changes to an MSL-like vehicle while still allowing the integration of a SIAD, the SIAD 

configuration was chosen such that the SIAD-vehicle interface was near the heat shield-backshell 

interface plane at the perimeter of the vehicle; a SIAD could also be configured such that the 

SIAD trails the vehicle in a way similar to a parachute, however this configuration was not 

examined here due to the lower drag coefficient of a SIAD in the trailing configuration. 

Four types of SIAD were considered here: a 7.95m diameter iso-tensoid, a 15.44m diameter isotensoid, a 5.76m attached torus (small diameter tension cone), and a 9.19m diameter tension 

cone. Shown in Figure 15, these configurations correspond to TS-1, TS-2, TS-3, and TS-4, and 

the masses for these SIAD softgoods was estimated to be 55 kg, 200 kg, 15 kg, and 200 kg, 

respectively. The mechanical interfaces to the vehicle were similar for all 4 SIAD 

configurations. 

The air volume inside an iso-tensoid is generally larger than the air volume inside a comparable 

tension cone or attached torus. The air enclosed within an iso-tensoid is partially or completely 

provided by ram air inlets located on the forward face of the SIAD. It was assumed here that 

half of the air mass required by fully deployed iso-tensoids would need to be provided by a gas 

generator system in order to initiate SIAD deployment. The air enclosed within a tension cone 

and attached torus is provided entirely by a gas generator system. The gas generators used for 

the Mars Exploration Rover airbag system were used to estimate the quantity and mass of the gas 

generator system required for each SIAD configuration: the gas generator masses were estimated 

to be 3.4 kg, 41 kg, 17 kg, and 65 kg for TS-1, TS-2, TS-3, and TS-4, respectively. 

A cover panel system is required to protect the stowed SIAD softgoods from the hypersonic 

thermal environment associated with planetary entry. A spectrum of cover panel systems was 

considered here. At one end of the spectrum was a “hard cover” system that used a rigid thermal 

protection system (TPS) over rigid panels similar to the vehicle backshell. At the opposite end 

of the cover panel system spectrum is the “soft cover,” which consists of only a flexible TPS 

material such as AFRSI. In the middle of the cover panel spectrum are a number of “hybrid” 

cover panel options that would use some amount of flexible TPS and some amount of rigid 

structure. A low mass, high speed panel ejection system is considered a significant issue for the 

implementation of a hard cover system. 

Assuming a packing density of 400 kg/m3

 (25 lbs/ft3) allows for the estimation of the volume 

required for the stowed SIAD configurations. For SIAD configurations with a softgoods mass 

below 62 kg, the stowed SIAD can fit within both a straight or curved cover panel envelope with 

at least a 25mm gap between the SIAD and the cover panel. At a softgoods mass of 112 kg, the 

stowed SIAD completely fills the volume inside a straight cover panel system but still has a 

34mm gap to the curved cover panel system. At 200 kg, the stowed SIAD completely fills the 

volume inside the cover panel system (Figure 16).
24 

Figure 15. Iso-Tensoid and Tension Cone SIADs 

Figure 16. SIAD Cover Options 

6.3 Trim Tab 

Trim tab mechanical development starts with the assumption that the panel area shall produce a 

lift/drag value of approximately 0.35. Using CBAERO and CART3D and based on balancing 

the aerodynamic performance and packaging requirements, a 0.75 m2 panel area was derived. 

High and low aspect ratio tabs were included in the analysis, resulting in a 1m long by 0.75 m 
25 

wide trim tab deployed perpendicular to the vehicle z-axis 

Figure 17. Trim Tab Configuration 

The major mechanical subsystems of the trim tab include the trim tab panel and 

deployment/retraction actuators. 

6.3.1 Trim Tab Actuator 

The trim tab is deployed exo-atmospherically and remains deployed during entry. The 

deployment mechanism must be able to deploy the trim tab in less than five minutes and then 

withstand entry loads. These loads were calculated based on the aerodynamic performance 

analysis. After entry, the trim tab must retract in 5-10 seconds at Mach 2.5, just before parachute 

ejection. 

Multiple actuation methods were considered including ball screws, hinge actuators, and 

pneumatic pistons. A dual pneumatic piston system provides feasible mechanical advantage due 

to attachment point flexibility, reasonable mass estimates, and fast retraction times. Two 63 mm 

outer diameter pistons will meet the load requirements. For the deployment subsystem designed 

in this study, a pressurant system must provide 1800 psi prior to deployment. This pressure 

needs to be maintained for less than 60 minutes. 

During launch and after retraction, the trim tab panel will be locked into its stowed 

configuration. This can be accomplished with a launch lock/retention mechanism incorporated 

into the pneumatic actuators. During retraction, the actuators will also act as dampers, limiting 

the retraction speed while still meeting the 5-10 second retraction requirement. 

6.3.2 Trim Tab Panel 

The panel was designed to withstand structural entry loads. A structural analysis was 

performance to determine that a M55J carbon fiber face sheet/aluminum honeycomb core panel 

will withstand the loads determined in the aerodynamic performance analysis, with an estimated 

mass of 10.5 kg. Due to high thermal loads on the panel, PICA TPS is needed on the exposed 

panel surface. 

The estimated total trim tab system mass is 31.0 kg. 

6.4 SABr - Supersonic Air Brake 

Technology set seven (TS-7) contains a supersonically deployed aerodynamic braking device 
26 

coupled with a supersonically deployed ringsail parachute. TS-7 uses EBMs mounted in the heat 

shield to obtain a prescribed angle of attack during hypersonic and supersonic flight. At Mach 

4.5 a Supersonic Aerodynamic Brake, or SABR, is deployed. Immediately prior to parachute 

deployment at Mach 2.3, the “straighten up and fly right” (SUFR) maneuver is performed to 

prepare for parachute deployment. SABr panels are retracted simultaneously with parachute 

inflation so as to maximize overall system aerodynamic stability. 

Figure 18. SABr Stowed and Deployed, Unwebbed and Webbed Configurations 

The rigid decelerator is comprised of 9 composite articulating panels, 9 inflatable pneumatic 

actuators, 9 launch locks, and a single manifolded gas generation system. The panels can either 

be uncoupled, or coupled via fabric webbing, as seen in Figure 18. The Panel Components are 

shown in Figure 19. 

Figure 19. SABr System Components 

The unwebbed version provides a projected surface area increase of 1.7x the projected area of 

the heatshield alone. The webbed version provides a 2.0x increase. 

Panel deployment is initiated with the firing of a cable cutter that releases the preloaded launch 

lock interface. Immediately following is the lighting off of the gas generation system. The gas 

generation system is a solid fuel combustion gas generator commonly used in the aerospace 

industry. The combustion gases are manifolded to all 9 panels simultaneously. As the gases 
27 

flow into the pneumatic actuator, which is a fabric tube, the inflation pressure creates a motive 

force on the panel. The panel quickly accelerates into the free stream, at which time, the 

prevailing dynamic pressure applies a counter force on the panel. The gas generation system and 

all other components in the system have been sized in order to overcome the free stream dynamic 

pressure and to deploy the panel to its fully deployed position within 1 sec. One second was 

chosen as the deployment time in order to minimize aerodynamic disturbances to the vehicle. 

Immediately prior to, or simultaneous with the parachute mortar firing, an actuated relief valve 

on the pneumatic actuator is opened. The valve is sized to allow the force of the dynamic 

pressure on the panels to force the panels closed, while still providing enough resistance to create 

a viscous damper to eliminate a high speed impact between the panel and the backshell. Once 

the panel is out of the free stream the retraction cables provide a constant force to guarantee the 

panels are pulled completely closed and remain closed under the dynamic oscillations of the 

vehicle experienced during parachute deployment. 

By allowing for a panel retraction prior to full parachute deployment, the SABR design allows 

the parachute 10x trailing distance to be minimized. 

TS-7 is a drag system that can be built using existing technology. It can also be tested in existing 

wind tunnels. TS-7 has an estimated mass of 200 kg. 

6.5 SABr with Trim Tab 

Technology set eight (TS-8) is hypersonically guided utilizing a SABr panel as a trim tab, a 

supersonically deployed rigid decelerator (SABr) coupled with a supersonically deployed 

ringsail parachute. TS-8 deploys a single panel of the SABr system exo-atmospherically in order 

to trim the vehicle to a specified angle of attack. This eliminates the need for EBMs and the 

dead mass associated with them. The basic configurations can be seen in Figure 20. 

Figure 20. SABr + Trim Tab Configurations 

TS-8 utilizes the same pneumatic actuators as seen in TS-5, however the panel is a stronger and 

stiffer SABr panel. The panel is also equipped with a thicker layer of PICA TPS. This protects 

the panel against the higher aero-thermal heat rates expected at hypersonic speeds. The details of 

the pneumatic actuators required can be found in the TS-5 and TS-7 sections. 

TS-8 is a combined trim tab and drag system that can be built using existing technology. It can 
28 

also be tested in existing wind tunnels without the need for a supersonic high altitude flight test. 

TS-8 has an estimated mass of 211 kg. 

7 Cost, Risk and Cross-Cutting Applicability 

In addition to the performance and mechanical implementation assessments covered in Sections 

5 and 6, cost, risk and cross-cutting applicability were evaluated for each technology and 

technology set. The results presented in this section and the following section represent an initial 

cost and risk assessment, and because cost and risk were not evaluated in this study to the degree 

and depth that were performance and mechanical implementation, these results should be 

regarded as having a significant level of uncertainty until future work provides clearer definition. 

The evaluation process leveraged the collective experience and expertise of the MSL-I Robotic 

Steering Committee in establishing cost and risk levels. This was accomplished in part via 

written evaluation inputs from RSC members, as well as by verbal inputs and feedback during 

reviews and consultations. The RSC written evaluation inputs were compiled and where scored 

they were averaged, and were used in establishing risk levels as well as influencing the 

development cost estimation process. Table 3 contains the evaluation criteria definitions and 

score metrics used in the evaluation process. Detailed scoring results are not presented in this 

document, however the resulting risk levels are presented. 

Table 3. Evaluation Criteria 

Evaluation Criteria Definition

Significant Development Cost Drivers Significant drivers to the cost of developing the technology from its current TRL to TRL 6.

Development Risk

Areas of significant risk to successfully developing the technology from its current TRL to 

TRL 6.

Scoring: 1=Low Risk, 2=Medium, 3=High Risk.

Performance Risk Significant areas of potential risk associated with the performance of the technology.

Scoring: 1=Low Risk, 2=Medium, 3=High Risk

Overall Risk A qualitative assessment of the overall level of risk associated with the technology.

Scoring: 1=Low Risk, 2=Medium, 3=High Risk

Cross-Cutting Applicability The applicability of the technology to other Mars exploration applications and other solar 

system destinations.

7.1 Development Cost 

Given the relative immaturity of understanding of the details of required effort for the 

development of the MSL-I technologies, two simple approaches were taken to provide an initial 

estimated development cost. For all technologies except the trim tab, an analogy cost estimation 

technique was employed4

. For the trim tab, expert opinion was used to establish a development 

cost estimate. Because of significant uncertainty in these initial cost estimates, the cost 

estimations were then used to place the technologies into a development cost space comprised of 

overlapping domains of $50M, $100M, $150M, $200M and $250M development costs. In this 

space, a particular technology may be a member of more than one cost domain signifying to first 
29 

order the level of uncertainty in the present understanding of development cost. Figure 21 shows 

the placement of the technologies in the development cost domains. 

More details about the initial cost estimation process utilizing analogy cost estimation can be 

found in NASA/TM-2011-216989. 

Figure 21. Technology Development Cost Space 

7.2 Risk 

The MSL-I RSC was asked to evaluate three categories of risk for each MSL-I technology: 

development, performance and overall risk. These categories are described in Table 3. Because 

of the uncertainty remaining in understanding of the risk associated with each technology, a 

detailed assessment of risk is not presented. Instead, broader risk observations resulting from the 

MSL-I work and derived from the RSC evaluations is presented as a guide to future work. 

7.2.1 Development Risk 

For the MSL-I study, development risk is defined as the risk inherent in developing a technology 

from its current TRL to TRL 6. To first order, development risk for the MSL-I technologies is 

delineated by rigid technologies vs non-rigid technologies, with rigid technologies having lower 

development risk. In general, the development of rigid structures is a more tractable 

development problem that leads to the division of development risk groups for the technologies. 

For inflated SIADs (iso-tensoid & tension cone), which fall into the higher risk category, the risk 

can be delineated again into smaller more rigid SIADs and larger more flexible SIADs. Because 

of their quasi-rigid characteristic, small diameter SIADs are assessed to have lower development 

risk than larger, more flexible SIADs. 

7.2.2 Performance Risk 

Performance risk is the risk that once developed, a technology will not perform as expected or 

predicted. As with development cost, non-rigid technologies were also assessed as having higher 

risk associated with performance, with parachutes assessed as having the most performance risk, 

iso-tensoids and tension cones being next, followed by the inherently rigid technologies. 
30 

7.2.3 Overall Risk 

Overall risk is the integration of all the risk associated with a technology. It is not a roll-up of 

the other risk category assessments, rather the RSC was asked to provide an assessment of the 

overall risk associated with the MSL-I technologies. As shown in Table 4, the overall risk 

assessment led to a delineation between technologies assessed as having high overall risk, which 

included the SABr + trim tab, the iso-tensoid and the tension cone; and those assessed as 

medium/low overall risk, which included both parachute options, the trim tab and SABr. Table 4 

also contains the optimized landed payload performance for each technology and development 

cost estimation, as presented previously. Additionally, Table 4 contains an assessment fidelity

rating indicating the level and depth of analysis supporting the result. Optimized performance 

received the most effort and had the highest fidelity analysis and thus the results receive a 

medium-high assessment fidelity level. The assessment of both overall risk and development 

cost were initial efforts in this study and thus are rated as low and medium-low in fidelity, with a 

corresponding high level of uncertainty in the results. 

Table 4. MSL-I Technologies Initial Overall Risk Estimates 

An initial assessment - further evaluation is needed 

 Trim Tab SABr SABr + 

 Trim Tab

 Iso-

 Tensoid

 Tension

 Cone

Supersonic

Ringsail

 Subsonic

 Ringsail

Optimized Performance

(Paired with Supersonic Ringsail)

MediumHigh1.8 km,

1462 kg

4.9 km,

1132 kg

4.8 km,

1256 kg

6.0 km,

1135 kg

6.0 km,

1157 kg

2.9 km,

1309 kg

2.5 km,

1086 kg

Optimized Performance

 to 0 km

(Paired with exisitng MSL DGB)

MediumHigh 1132 kg 1088 kg Unavailable 1108 kg 1101 kg N/A N/A

Overall Risk Low LowMedium Medium High High High Medium Low

Development Cost

Estimation

LowMedium <$50M $50M-

$100M

$50M-

$150M

$100M-

$200M

$100M-

$200M

$100M-

$200M <$50M

Technology

Assessment

Fidelity Assessment

7.3 Cross-Cutting Applicability 

Cross-cutting applicability is defined as a technology’s potential for use beyond the MSL-I DRM 

including other Mars missions, at other solar system destinations and toward NASA overall 

exploration objectives. The trim tab is assessed as having potential for use for other Mars 

missions, including scalability to larger class missions, as well as use at other solar system 

destinations. SABr is assessed as having limited application beyond the MSL-I DRM due to a 

high mass penalty when scaling the technology. Application to destinations with thicker 

atmospheres may also be limited. SABr + trim tab applicability is the combined potential and 

limits of the individual technologies. Both SIAD technologies are assessed as having minimal 

cross-cutting applicability. The supersonic ringsail parachute is evaluated as having only robotic 

mission applications at Mars, with some potential for deployment extraction application on 

larger Mars vehicles. The subsonic ringsail parachute is assessed as having no application 
31 

beyond the MSL-I application. Because of the limits of the cross-cutting applicability 

assessment in this study, it is recommended future studies consider this topic again in more 

depth. 

8 Technology Set Evaluations 

Having provided an evaluation of individual technologies in the previous section, this section 

provides a summary of the overall evaluation by showing how the individual technology 

evaluations map into the MSL-I Technology Sets. 

8.1 Technology Set Development Cost 

Because each technology set contains two assessed technologies, the development cost for a 

technology set is the combined development cost of the two technologies. Two methods were 

employed to combine the development costs. First, if the development efforts for the two 

technologies appear to first order to be independent and decoupled, the development costs for the 

two technologies were simply added, yielding a likely conservative overall development cost. 

Second, if the technologies both require a supersonic high altitude flight test, it is assumed there 

would be significant savings by combining the flight test programs, so that 30% of the lowest 

development cost technology was added to the cost of the other technology development cost. 

The resulting technology set development cost estimates were used to place the technology into 

the development cost space described in the previous section. Figure 22 shows were the 

technology sets fall in the development cost space. 

Figure 22. Technology Set Development Cost Space 

Because each technology set contains either a SIAD or a supersonic parachute, all technology 

sets require a supersonic high altitude flight test, which is a primary cost driver, and thus all 

technology sets are a member of at least the $100M domain and higher. All technology sets 

except Technology Set 6 occupy the $150M, $200M and $250M domains. 

8.2 Technology Set Performance Summary 

Figure 23 is a summary of the performance capability of each technology set. Performance is 

shown in terms of technology set elevation capability vs landed payload mass. The rectangular 
32 

boxes shown on the elevation capability/landed payload mass plane encompass the performance 

capability of each technology set. TS-1, TS-3 and TS-7 perform well in delivering to higher 

elevations. This is because SIADs and SABr provide increased drag area earlier in the 

supersonic phase. TS-5, the trim tab, delivers the most landed payload mass, followed by TS-6 

and TS-7. TS-6 in particular has good landed payload mass performance with just the addition 

of a supersonic ringsail parachute. TS-2 and TS-4 are the subsonic parachute technology sets 

and perform least well of all the technology sets. This is because delaying parachute deployment 

to subsonic conditions forces the growth of companion SIADs that increases structural mass and 

reduces landed payload mass capability. Shown in the black box is the capability box of the 

baseline architecture with supersonic DGB parachute. Each technology set label lists the 

technologies that comprise the technology set. 

Figure 23. Technology Set Evaluation Summary 

9 Conclusion 

The purpose of the MSL-I study is to examine enabling technologies that incrementally improve 

performance of the MSL EDL system while minimizing change to the MSL EDL architecture for 

missions on or before 2024. Assessed purely on performance, those technologies that increase 

aeroshell drag earlier in the supersonic phase, such as the SIADs and the SABr, enable landing 
33 

MSL class payloads at elevations as high as 6 km. The trim tab technology was shown to deliver 

the most mass, while the replacement of a supersonic DGB parachute with a supersonic ringsail 

parachute also provided better mass capability over MSL performance. The study also shows 

that a subsonic ringsail parachute, when combined with SIAD technology, provides the least 

incremental improvement. In general, the development cost of the technologies is driven 

significantly by the cost of a supersonic high altitude flight test program. The SIAD 

technologies and the supersonic ringsail parachute require this test program and thus were 

estimated as $100M to $200M developments. Because all technology sets examined by the 

MSL-I study included either a SIAD or a supersonic parachute, the cost domains occupied by the 

technology sets range from $100M and higher, with all but TS-6 occupying the $150M, $200M 

and $250M domains. To first order, overall risk associated with the technologies was established 

to be a function of technology rigidity with rigid technologies being assessed as having less 

inherent risk than flexible technologies. 

The MSL-I study provides an initial assessment of the seven technologies. Because it is an 

initial assessment, it is a challenge to derive specific technology investment recommendations 

given that there remains performance, cost and risk uncertainty. However two initial conclusions 

are possible. First, the marginal performance of the subsonic ringsail technology sets eliminates 

the subsonic ringsail as a technology worth pursuing for robotic Mars missions. Second, the 

performance enhancement provided by the supersonic ringsail parachute across all other 

technology sets warrants continued development of this technology. Although not included as an 

assessed technology, development of a higher performing bi-propellant descent engine was 

identified during the study as a possible high leverage technology that should be considered 

along side, and possibly instead of, the supersonic ringsail parachute. To further the process of 

understanding the benefits of each technology, it is recommended that future work include the 

establishment of Pre-Phase A study teams to fill the in the performance, mechanical integration, 

cost and risk knowledge gaps for the SIAD, SABr, trim tab and supersonic ringsail technologies. 
34 

 

Bibliography 

1. Grover, M.R., et al., "Entry Descent and Landing Systems Analysis Study: Mars Science Laboratory 

Improvement Final Design Review Slide Package", NASA Technical Memorandum TM-2011-

216989, 2011 

2. Dwyer Cianciolo, A.M., et al., “Entry, Descent and Landing Systems Analysis Study: Phase 1 Report”, 

NASA Technical Memorandum TM-2010-216720, pgs 71-79, 2010 

3. "Structural Design and Test Factors of Safety for Spaceflight Hardware", NASA-STD-5001A, 

August 5, 2008 

4. Shishko, R., “Developing Analogy Cost Estimates for Space Missions”, American Institute of 

Aeronautics and Astronautics, AIAA 2004-6012, 2004 
35 

Appendix A: Ground Rules & Assumptions 

EDL-SA Ground Rules and Assumptions 

This section lists the Ground Rules and Assumptions (GR&A) as employed in the EDL-SA 

Study. 

General Ground Rules and Assumptions 

The ground rules and assumptions applicable to both robotic studies are 

 Mass growth allowances and margins will be applied to all technologies and systems as 

described below: 

In developing mass estimates, three separate estimates should be provided. These are: 

Current Best Estimate (CBE) Mass: This mass constitutes an assessment of the most recent baseline 

design including factors of safety or various knockdown factors. The estimate does not include any 

mass growth allowance. 

Maximum Expected Value (MEV) Mass: This constitutes the CBE mass with the addition of mass 

growth allowance (MGA), where mass growth allowance consists of the predicted changes to the CBE 

based on an assessment of the design maturity. 

MEV Mass = Current Best Estimate + Mass Growth Allowance 

Allocated Mass: The allocated mass is the MEV mass with the addition of system margin. 

Allocated Mass = MEV Mass + System Margin 

The total mass growth allowance does not include any TRL-based augmentation. 

In the case of the MSL-I study, the JPL mass margin policy will be applied. The JPL policy addresses 

both a mass growth allowance for each component (to achieve individual MEV’s estimates) as well as 

a total system/vehicle margin (to achieve the total allocated mass estimate). Other than a slightly 

different calculation for computing the total allocated mass, the JPL policy is essentially the same as 

the standard NASA policy. At the component level, the margin practice will be per the AIAA standard 

document S-120-2006. The total system allocated mass will be defined per the JPL mass margin 

policy as follows: 

Allocated Mass = CBE / (1 – System Margin %) 

The system margin % to be used will be 30% per the recommended value in JPL-D-17868. 

 Subsystem performance parameters (e.g., engine Isp, engine T/W, vehicle inert mass 

fraction) are to be based upon historical data and trends. 

 The atmosphere model used for this study will be MarsGRAM 2005. 

 Turbulent flow onset will be estimated using the Reθ = 200 criterion. For Reθ >200, the 

entire forebody will be considered to be turbulent. 

 POST2 will be used for simulations. 

 Representative guidance algorithms will be developed. Theoretical guidance algorithms 

will also be used. 

 Vertical velocity at touchdown will be <= 1 m/s. 

 On-orbit assembly will not be considered. 

 Landed altitude capability will be a minimum of 0 km above MOLA. 

 Landing site altitude sensitivities will be evaluated for -1 km MOLA to 2.5 km MOLA. 
36 

 Entry date: October 15, 2025. 

MSL-I Ground Rules and Assumptions 

The following ground rules and assumptions are applicable to the MSL-I Study 

 The launch vehicle is the Atlas V-551. 

 Interplanetary mission design will be direct to entry (e.g. no aero/propulsion capture into 

a Mars parking orbit). 

 Entry vehicle will have a 4.7 m maximum diameter (to fit Atlas V fairing), with an 

Apollo forebody shape, and scaled elements as necessary for g-load, heat load, chute 

inflation loads, payload mass, etc. 

 The descent stage thrust to weight will be greater than 2.7 for all cases studied 

 Descent & landing phase mission design will be a scaled version MSL descent stage with 

skycrane. 

 All selected technologies considered capable of achieving sufficient TRL in time to 

support a 2024 launch. 

 The following timeline margin will be enforced for all EDL simulations: >= 15 s from 

heatshield jettison to radar lock and >= 15 s from radar lock to backshell jettison; both 

margins are 3 sigma low values. 

 The simulation is allowed to optimize several parameters. The parameters include but are 

not limited to: 

o the size of the drag device, 

o entry state 

o bank angle and/or cg control location, 

o heading alignment velocity 

o deploy Mach numbers 

o bank reversals 

o lift-to-drag ratio 

o powered descent initiation 

 In the landed payload/site elevation trade, the landed payload (at 0 km MOLA) is the 

objective, and the sensitivity is that of landed payload to site elevation. 

 The constructed EDL architecture should seek to minimize deviation from the current 

MSL EDL architecture. 

 EDL architectures should be comprised of technologies that individually cost ~$200M or 

less to mature to sufficient TRL. 

 The launch opportunity will be 2024 to support the MSR lander. 
37 

Appendix B: Initial Technology List 

Table 5. Criterion of Selection Definitions 

Criterion Definition 

Development Time The technology must be capable of being matured to TRL 6 in time for a 2024 

launch opportunity 

DRM/GR&A The technology must be in line with MSL-I DRM and GR&A 

Cost The technology must be capable of being matured to TRL 6 at a cost less than 

$200M 

Flight System Technology The technology must be a vehicle based technology (e.g. no database upgrades or 

precursor probes) 

EDL-SA Scope The Technology must be within the general EDL-SA Scope 

Technology Relevance The technology should address an area of need (i.e. not seek to improve upon a 

system or instrument that is already capable of meeting mission needs out to 2024) 

FY10 Scope Insufficient time for adequate analysis, e.g. required model fidelity prohibitive for 

FY10 

Table 6. Initial Technology List 

Red = Eliminated during first reduction Orange = Eliminated during final reduction

AoA and Drag Control Elimination Rationale 

CG Control Priority 

Propulsion Aids Technology Relevance & Cost 

Extend equilibrium glide 

Aerodynamic body flaps 

Structurally supported fabric system Cost and Development Time 

 

Alternate Entry Geometries Elimination Rationale

Elipsled 

DRM/GR&A & Technology 

Relevance 

Rigid Deployable (in space) Cost and Development Time 

Morphing entry body (time varying geometry) Cost and Development Time 

Apollo shape 

Optimization for drag/lift/packaging/heating/stability 

Aeroshell shape/CG management coupling 

Wings 

DRM/GR&A & Technology 

Relevance 

Asymmetry Options Priority 

Alternate heatshield geometries 

 

Improved Inertial and Atmospheric Relative Knowledge (onboard vs. 

external) Elimination Rationale

Mach Sensor Priority 

Extend MEDLI MEADS system/feedback loop 

Higher precision/accuracy/reliability IMU EDL-SA Scope 

Improved wind estimation (pre entry estimation) Flight System Technology 

Landing Beacons Flight System Technology 
38 

ALHAT 

Precursor atmospheric scouts Flight System Technology 

Real-time atmospheric sensing (on-board), FADS Cost 

Reduce delivery state dispersion (nav knowledge) Priority 

Improved feed forward engineering datasets Flight System Technology 

Improved transition triggers Priority 

 

Improved Terrain Relative Knowledge Elimination Rationale

High precision IMU Technology Relevance 

ALHAT 

Terrain relative sensing at higher altitudes Priority 

 

TPS Improvments Elimination Rationale

Phase Change materials for heatload offset DRM/GR&A 

 

IADs 

2018 SIAD 

Asymmetric burble (inflatable body flap) Cost 

Towable/trailing ballute Cost 

Heat pulse IAD Cost & DRM/GR&A 

SHADI/HHIAD/LHIAD/SIAD Cost 

Tension cone/stacked toroid/iso-tensoid Redundant 

Staged IADs (both for drag and AoA modulation Drag 

Inflatable body flaps for AoA management Cost 

Deformable IADs for steering Cost 

Inflation concepts - Ram air vs. GG vs. etc 

 

Improved Parachutes Elimination Rationale

Steerable parachutes Cost 

Larger and/or faster parachutes 

Alternate trailing drag device Covered by other technologies 

 

Propulsive Augmentation Elimination Rationale

Supersonic Retropropulsion 

Anything but simple eliminated due 

to cost 

Enter parking orbit first (propulsive and aero capture approach) DRM/GR&A 

Ram jet engine cost 

Propulsive targeting correction DRM/GR&A 

Phase Change materials for RCS DRM/GR&A 

All propulsive option DRM/GR&A 

Rocket copter/gyrocopter DRM/GR&A 

 

Improved Staging (Mechanisms and Triggers) Elimination Rationale
39 

Improved staging (obliteration of separated bodies, higher HS sep, tractor 

rockets, etc.) Priority 

 

General System Improvements Elimination Rationale

Higher landed velocity allowable Flight System Technology 

Higher precision IMU Technology Relevance 

Terrforming to increase atmospheric density Cost & Flight System Technology 

Propellant depot in Mars orbit Cost & DRM/GR&A 

Reduced Entry mass (light-weighting) EDL-SA Scope 

Reduce Delivery State Dispersions (nav knowledge) Flight System Technology 

Improved Data Fusion / Computation Power EDL-SA Scope 

Smart Descent Stage EDL-SA Scope 

Land at Night Flight System Technology 

 

Policy Changes Flight System Technology 

Improved guidance algorithms Elimination Rationale

Upgrade Apollo 

NPC 

 

Entry from Orbit DRM/GR&A 

Skip Entry Technology Relevance 

Propulsive Targeting 
40 

Appendix C: Abbreviations, Acronyms and Symbols List 

AFRSI Advanced Flexible Reusable Surface Insulation 

ALHAT Autonomous Landing and Hazard Avoidance Technology 

AoA Angle of Attack 

BIP Backshell Interface Plate 

CAD Computer Aided Design 

CdA Coefficient of Drag Time Area 

DGB Disk Gap Band 

DRM Design Reference Mission 

EBM Entry Balance Mass 

EDL Entry Descent and Landing 

EDL-SA Entry, Descent and Landing Systems Analysis 

FY10 Fiscal Year 2010 

GR&A Ground Rules and Assumptions 

IAD Inflatable Aerodynamic Decelerators 

L/D Lift Over Drag 

MER Mars Exploration Rovers 

MOLA Mars Orbiter Laser Altimeter 

MSL Mars Science Laboratory 

MSL-I Mars Science Laboratory Improvement 

NASA National Aeronautics and Space Administration 

OML Outer Mold Line 

PICA Phenolic Impregnated Carbon Ablator 

RSC Robotic Steering Committee 

SIAD Supersonic Inflatable Aerodynamic Decelerator 

SABr Supersonic Aerobrake 

SPTT Subsonic Parachute Technology Task 

SUFR Straighten Up and Fly Right 

TPS Thermal Protection System 

TRL Technology Readiness Level 

TS Technology Set 
41 

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1. REPORT DATE (DD-MM-YYYY) 

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4. TITLE AND SUBTITLE 

Entry, Descent and Landing Systems Analysis Study: Phase 2 Report 

on Mars Science Laboratory Improvement

5a. CONTRACT NUMBER 

NAS7 03001

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6. AUTHOR(S) 

Ivanov, Marc C., Blood, Eric M.,Cook, Brant T., Giersch, Louis R., 

Grover, Myron R., Jakobowski, Julie K., Kinney, David J., Olds, Aaron 

D., Rivellini, Tommaso P., Samareh, Jamshid A., Su, Robbie P., Winski, 

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14. ABSTRACT 

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 

2008 to identify and roadmap Entry, Descent and Landing (EDL) technology investments needed to develop 

technologies to successfully land large payloads at Mars for both robotic and human-scale missions. This report 

summarizes the work the Mars Science Laboratory Improvement (MSL-I) team carried out as part of Phase 2 of 

the study in 2010. The MSL-I study assessed seven Mars EDL technologies selected for their near-term 

potential to incrementally improve the performance of the Mars Science Laboratory EDL system. The 

assessment was made based on landed mass performance, mechanical implementation, cost, risk and crosscutting applicatbility. 

15. SUBJECT TERMS 

Systems Analysis; Mars Missions; Atmospheric Entry; Descent; Landing; Robotics; Parachutes; Inflatable Spacecraft 

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