Anthony Colaprete 

Amanda Cook 

David Mauro 

Sam Montez 

NASA Ames Research Center 

Planetary Science Deep Space SmallSat Mission Concepts 

March 18, 2018 
 

 

 

 

 

 

 

 

Why Aeolus? 

Previous and ongoing missions to Mars have provided a partial 

definition of the present climate system, but have not - and 

cannot - illuminate the nature of the processes involved. 

They lack two fundamental observations: 

1. Direct measurements of winds 

2. Full characterization of the diurnal cycle 

 Winds are responsible for the movement of dust, water vapor, CO2, and 

trace gases around the planet 

 Winds determine the distribution of their sources and sinks at the surface 

 Winds have a large unmeasured diurnal variation that strongly controls 

transport 

2 
Current Derivation of Winds 

The gradient approximation can result in significant errors 

• Winds calculated using the gradient method and temperatures from the 

NASA Ames Mars GCM 

• These approximate winds differenced from the “truth” (the model winds) 

• Areas in white indicate errors beyond contour levels 

• Errors frequently exceed 100% 

Modeled Wind Speeds Derived Wind Speeds Modeled - Derived 

(a) (b) (c) 

3 
 

 

 

Diurnal Significance 

Strong diurnal variability in Mars temperatures and winds 

• Missions to date have been generally sun-synchronous, thus only observing two times 

a day (e.g., 2am/pm) 

• The observed energy budget (TOA solar and IR) will be a strong function of local time 

of observation 

All Times of Day 

with Aeolus Orbit 

4 
 

 

 

 

 

Mars Atmosphere Dynamics 

Energy and angular momentum budgets drive the dynamics of 

the Mars climate system 

• Energy in/out at surface 

• Energy distributed through the atmosphere (dust and clouds) 

• The balancing of energy (temperature) and momentum results in the 

winds/transport 

• A “full set” of observations would be the product (winds) plus the forcing 

agents (energy at surface and in atmosphere and aerosols) 

5 

Winds 

Aerosols Energy 

Radiative 

Transfer 
 

 

 

 

 

 

 

 

 

Science Baseline 

Planetary Science Aeolus Science Science Decadal Survey Objectives Themes Questions 

What is the four-dimensional 

wind structure of the Martian 

atmosphere from the surface 

boundary layer to the upper 

atmosphere? 

What are the processes 

controlling the variability of 

the present-day climate? 

What are the processes 

coupling the carbon dioxide, 

dust, and water cycles? 

Characterize Mars global circulation 

processes, including seasonal and diurnal 

changes. 

Determine the global energy balance at 

Mars by measuring incoming solar 

radiation, reflected radiation, and thermal 

emission from the Martian surface and 

atmosphere. 

Measure Martian atmospheric aerosol 

( H2O clouds and dust) content. 

Winds 

Energy Balance 

Radiative Drivers 

6 
The Aeolus Payload 
 

Payload Fields of View 

SHS Orthogonal FOVs provide wind vector 

 TLS and SHS total FOV (at limb) is 100km 

with <5km vertical resolution 

 SuRSep nadir footprint is 100km 
Mission Design 

NeMO 

Aeolus Comm links 

Commanding 

• Launch with NeMO 

• Quiescent for 25 

month NeMO cruise 

and orbit insertion 

• After Aeolus 

deployment transfers 

to 383km, 73deg 

inclined orbit 

• 24 months of science 

observations 

9 
Science Orbit 

• 383-km average orbit altitude 

• 73-deg inclination 

• Orbit precession moves local time 2-hours in 10 day 

• Measurements every 3 minutes 

SHS 10-days of observations with yaw in day 5 

10 
 

Spacecraft Design and Analysis 

Key Spacecraft Elements Key Spacecraft Specs 

Resource CBE 

Volume 45 x 35 x 52 cm 

Total Launch Mass 37.6 kg 

Total Power 53 W 

SC Delta V 237.5m/s 

SS Data Storage (Vol) 8Gb 

Data Throughput (UHF DL) 1Mbps 

Power System Modeling 

Thermal Modeling of Extreme Cases 

11 
 

 

 

 

 

Budget Estimate 

Full grass-roots estimate 

• Based on resource loaded WBS and 

IMS 

• 30% reserves on Phase B-D, and 

10% on Phase E-F (25.6% overall) 

Notes: 

• Currently traditional cost 

estimation tools are incomplete or 

not applicable for SmallSats 

• Cost models do not adequately 

address existing SmallSat 

technologies and may 

underestimate maturation costs 

FY18($k) 

WBS Element Total (Phase A-E) 

01 PM $6,952 

02 SE $4,942 

03 MA $1,119 

04 Science $3,094 

05 Payload $7,117 

06 SC $19,318 

07 Mission Ops $6,840 

08 Launch Services $96 

09 Ground Systems $4,436 

10 Systems I&T $3,589 

Reserves $14,715 

Grand Total $72,219 
 

 

 

 

 

 

 

 

 

General Recommendations / Findings 

1. Establish clear ground rules / expectations for interface mechanisms (ICDs) and level 

of in-Project development of key systems 

2. Telecomm systems represent a major hurdle for deep-space SmallSats 

3. SmallSat operations can be as (or more) demanding as their larger counterparts 

4. Assuming cost-capped SmallSat programs with limited vehicle resources, missions 

may be expected to have very few science descope options 

5. SmallSat missions are well suited for Class D classification, however, well defined and 

stable program requirements are required to keep risks and costs down 

6. Due to the immaturity in a number of systems higher than normal margins were 

maintained (for example, >40% wet mass, >50% power, >35% SC ∆V); this margin 

provides “commodity” (e.g., mass) used to mitigate risks 
 

Summary 

Aeolus is a low-cost, small spacecraft, but delivers big science! 

• Development via the Planetary Deep Space 

SmallSat Studies Program (Thank you!) 

 Included trade analysis, costing and 

scheduling to bring the concept to CML 

4/5 

• Completely novel observations of winds, day 

and night 

• Observations across all times of day 

• First dedicated energy balance observations 

• Simultaneous observations of the key 

circulation drivers, including temperature and 

aerosols 

14 
Thank you! 
 

 

 

 

 

 

 

 

Orbit: Driving Requirements 

1. To prevent seasonal aliasing in 

Aeolus, the orbit needs to 

precess over all local times at 

least once every two months. 

2. The inclination of the orbit 

must be 70-75° to sufficiently 

measure polar regions. 

3. Science requires 10 orbits per 

day to achieve sufficient 

mapping resolution. 

4. Planetary Protection: the orbit 

must be stable for at least 50 

years. 

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