Chariot 

to the Moons of Mars

A NASA Planetary Sciences Deep Space SmallSat Studies Mission Concept
The Chariot Team

PI: David A. Minton 

Science Co-I: Briony H. N. Horgan

Systems Engineer Co-I David A. Spencer 

Students:

Mayank Aggarwal 

Rohan Deshmukh

Jacob R. Elliott 

Andrew J. Hesselbrock

Connor R. Tinker 

CAV Design Co-I: Zachary R. Putnam 

Students: 

Giusy Falcone 

Destiny M. Fawley 

Elizabeth M. Fleming 

Thomas R. Smith 

James W. Williams 

Instrument Co-I: Philip R. Christensen 

Collaborator: Erik Asphaug 

Spacecraft Co-I: Austin Williams 

Spacecraft Co-I: Jordi Puig-Suari 

Collaborators:

Matija Ćuk

Francesca DeMeo

Masatoshi Hirabayashi

Jean-François Smekens

Andrew Rivkin
The origin of Phobos and Deimos 

remain highly uncertain
VIS/IR spectra of Phobos and Deimos are similar to 

carbonaceous meteorites and their asteroid analogues 

Rivkin et al. 2002
The spectral similarity between Phobos and Deimos and carbonaceous 

asteroids is the basis of the Intact Capture Hypothesis for their origin

Under the intact capture hypothesis, the two satellites likely have analogues in the asteroid belt, and 

possibly also analogues in the meteorite collection 
Triton

Regular satellites (likely formed in disks)

Irregular satellites (likely captured)

s 

s

The orbits of Phobos and Deimos do 

not resemble captured satellites 

Phobo

and

Deimo
The “regular” orbits of Phobos and Deimos suggest they 

formed from a protosatellite disk in orbit of Mars 
There are many different protosatellite

disk origin models in the literature

Giant impact formation with a cyclic breakup 

and re-formation of Phobos

(Hesselbrock and Minton, 2017). 

In-situ formation alongside Mars

(Ronnet et al., 2016)

Formation from giant impact ejecta 

(Canup and Salmon, 2016, 2018; Citron et al., 2015; 

Craddock, 2011; Rosenblatt et al., 2016; Ronnet et al., 2016)
Each origin model implies something different about 

the bulk composition of Phobos and Deimos

Testing these hypothesized origins 

will require a dedicated 

multispectral survey of both 

Phobos and Deimos.

Is a remote sensing 

SmallSat/CubeSat mission in 

Mars orbit feasible?

Yes!

See also Pignatale et al. (2018). ApJ, 853(2), 118.
Chariot to the Moons of Mars

3-axis stabilized 12U CubeSat

3 remote sensing instruments 

Cold gas propulsion for maneuvering.

Direct-to-Earth communication downlink

Cruise-Aerocapture Vehicle (CAV)

Free-flyer cruise from Earth to Mars

Autonomous 12U CubeSat delivery to Mars orbit via aerocapture
Chariot is a big remote sensing 

mission in a tiny package 
Chariot will produce visible and thermal 

imagery as well as VNIR and TIR spectra 

using a COTS payload

Color Camera

(Malin ECAM C-50)

• Global color mosaic - 9 

m/pix

• Targeted imagery - <1 m/pix

• Morphology and geology

• Heritage: OSIRIS-Rex/ 

TAGCAMS

TIR Multispectral Imager

(Modified FLIR Tau 2)

• Global 8-band day & 1-band 

night mosaics - 20 m/pixel

• Targeted imagery - 2 m/pixel

• Regolith thermophysics, 

variability in bulk composition

• Heritage: ODY/THEMIS

VNIR Point Spectrometer

(Ocean Optics QEPro)

• Global moasic - 5 km/pixel

• Targeted spectra - 200 

m/pixel

• Mafic and hydrated minerals, 

space weathering

• Heritage: MSL/ChemCam, 

LCROSS/Alice

*All resolutions for Phobos
Chariot will expand on existing VNIR/TIR spectral data that 

indicates significant spectral variability on both moons

Giuranna et al (2011)

Fraeman et al (2013)

PFS/TES

CRISM

The specific mineralogy leading to this diversity and the origin of the differences in 

mineralogy is poorly understood.
Chariot will address major science questions that 

require observations of both Phobos and Deimos

Chariot to Phobos Chariot to Deimos

The Chariot Mission has three high-level science goals

1. Constrain the origin of Phobos and Deimos 

2. Evaluate the feasibility of ISRU on Phobos and Deimos 

3. Evaluate processes contributing to the ongoing evolution of the PhobosDeimos system 
Specific observations of both Phobos and Deimos from Chariot are 

designed to address our major objectives 

Red unit

Blue unit

Tectonics

Boulders Regolith properties

Craters

Spectral variability Space weathering

Thermal environment

Mass wasting
Chariot to the Moons of Mars

The baseline Chariot mission architecture involves two identical 

spacecraft, one each to Phobos and Deimos
Chariot would represent the first demonstration of aerocapture, a 

critical technology in NASA’s human exploration roadmap.

Deployed 

Configuration

Fuel

Cubesat &

Launcher

Drag Skirt

Unlike aerobraking, which occurs over a prolonged period, aerocapture 

uses a single atmospheric pass to circularize the orbit
The Cruise-Aerocapture Vehicle would enable future 

exploration of Mars with Cubesats
Despite the challenges of a CubeSat platform (power, thermal, 

telecomm) we can meet all our high level objectives!

~2 kbps

If we could use Mars orbiting data relays it would be better, but they were designed to 

communicate “down” to rovers/landers, not “up” to spacecraft at Phobos and Deimos.
Chariot to the Moons of Mars would be a 

groundbreaking mission for both Mars science and 

cubesat technology

• Chariot would provide critical new constraints on the origin and evolution 

of Phobos and Deimos through a dedicated remote sensing mission to 

both moons utilizing a novel aerocapture approach

• Our PSDS3 study has shown that:

1)An imaging-based CubeSat mission with high science return is 

possible at Mars with existing technology and telecom support

2)A CubeSat mission to the moons of Mars could address many high- priority NASA/MEPAG/SBAG goals for science and human exploration

3)CubeSats are not adequately supported by the existing Mars and DSN 

telecom architecture
Chariot would be managed and operated out of Purdue!

Interplanetary SmallSats are a new platform to bring greater University engagement in 

planetary science and engineering