Byrne, Lawrence

Calvert, Derek

Dankanich, John W.

Hickman, Tyler

Kamhawi, Hani

Szabo, James

NASA Technical Reports Server

The Iodine Satellite (iSat) Project Development towards 
Critical Design Review
IEPC-2015-303  
Presented at Joint Conference of 30th International Symposium on Space Technology and Science
34th International Electric Propulsion Conference and 6th Nano-satellite Symposium,
Hyogo-Kobe, Japan
July 4 – 10, 2015
John Dankanich, Derek Calvert, Hani Kamhawi, Tyler Hickman, James Szabo and Lawrence Byrne
https://ntrs.nasa.gov/search.jsp?R=20150016535 2019-08-31T06:21:52+00:00Z
iSAT Mission Concept Overview
2
High value mission for SmallSats and for future higher-class mission 
leveraging iodine propulsion advantages.
The iSAT Project is the maturation of iodine Hall technology to enable high ∆V primary propulsion for 
NanoSats (1-10kg), MicroSats (10-100kg) and MiniSats (100-500kg) with the culmination of a 
technology flight demonstration.
- NASA Glenn is leading the technology development and is the flight propulsion system lead
- Busek delivering the qualification and flight system hardware
- NASA MSFC is leading the flight system development and operations
The iSAT Project launches a small spacecraft into low-Earth orbit to:
- Validate system performance in space
- Demonstrate high ∆V primary propulsion
- Reduce risk for future higher class iodine missions
- Demonstrate new power system technology for SmallSats
- Demonstrate new class of thermal control for SmallSats
- Perform secondary science phase with contributed payload
- Increase expectation of follow-on SMD and AF missions
- Demonstrate SmallSat Deorbit
- Validate iodine spacecraft interactions / efficacy
The SmallSat Market
3
The final system will be a highly capable 12U CubeSat Bus
Why Iodine?
4
Today’s SmallSats have limited propulsion capability and most spacecraft have none
• The State of the Art is cold gas propulsion providing 10s of m/s ∆V
• No solutions exist for significant altitude or plane change, or de-orbit from high altitude
• SmallSat secondary payloads have significant constraints
• No hazardous propellants allowed
• Limited stored energy allowed
• Limited volume available
• Indefinite quiescent waiting for launch integration
Iodine is uniquely suited for SmallSat applications
• Iodine electric propulsion provides the high ISP * Density (i.e. ∆V per unit volume)
• 1U of iodine on a 12U vehicle can provide more than 5 km/s ∆V
• Enables transfer to high value operations orbits
• Enables constellation deployment from a single launch
• Enables de-orbit from high altitude deployment (ODAR Compliance)
• Iodine enables > 10km/s for ESPA Class Spacecraft
• GTO deployment to GEO, Lunar Orbits, Near Earth Asteroids, Mars and Venus
• Reduces launch access by 90%
• Reduces mission life cycle cost by 30 – 80%
• Iodine is a solid at ambient conditions, can launch unpressurized and sit quiescent indefinitely 
The technology leverages high heritage xenon Hall systems
• All systems currently at TRL 5 with maturation funded to achieve TRL 6 in FY16
• The iSAT System is planned for launch readiness in early 2017
5Iodine vs. Alternatives
Iodine has unique characteristics well suited for mission application
Propellant Storage Density Boiling Point, oC Melting Point, oC Vapor Pressure @ 20oC
Xe (SOA) 1.6 g/cm3 -108.1 oC -111.8 oC Supercritical (>15MPa)
Iodine 4.9 g/cm3 184.3 oC 113.7 oC 40 Pa (0.0004 atm)
Bismuth 9.8 g/cm3 1,564 oC 271.4 oC Solid
Magnesium 1.74 g/cm3 1,091 oC 650 oC Solid
6Microsatellite Advantages
Primary mission advantages are due to 1) Increased ISP * Density
2) Low storage pressure
Iodine allows very small tanks with manufacturing advantages.
SmallSat Applications: 
USASMDC / ARSTRAT
7
Low Cost
• Per-Unit Cost Very Low
• Enables Affordable Satellite Constellations
• Minimal Personnel and Logistics Tail
• Frequent Technology Refresh
Survivability
• Fly Above Threats and Crowded Airspace
• Rapid Augmentation and Reconstitution
• Very Small Target
Responsiveness
• Short-Notice Deployment
• Tasked from Theater
• Persistent and Globally Available
• Can Adapt to the Threat
DISTRIBUTION A. Approved for public release; 24 July  2013  Release Number 3105
8Geocentric MicroSat Application
Large increase in demand for MicroSat constellations and 
in-space responsive capabilities.
- The 12U with 5kg of iodine can perform 4km/s ∆V
- 20,000km altitude change
- 30o inclination change from LEO
- 80o inclination change from GEO
- Larger spacecraft can perform even greater ∆V
Iodine is enabling for propulsive missions.
iSAT Mission Requirements
9
iSAT will be the first CubeSat to demonstrate significant post 
launch maneuverability.
 Demonstrate no less than 100m/s of ∆V
 Determine thrust within 5% uncertainty
 Determine specific impulse within 10% uncertainty
 Perform propulsion altitude change of no less than 250km
 Perform propulsive node change
 Demonstrate no less than 80 hrs of thruster operation
*Nearly 2x TacSat-2
 Include instruments to assess thruster plume environment
*Radiometer from TacSat-2
 Include instruments to assess future payloads environment
*Photometer from TacSat-2
 De-orbit the spacecraft in less than 90 days following end of mission
10
iSAT Propulsion System
BHT-200-I Thruster: 
- Heritage to TacSat-2
- Most studied thruster since SPT-100
- Material changes for iodine compatibility
Cathode:
Electric Cathode
- Minimize power requirements
Compact PPU:
- 3rd PPU iteration ongoing
- Based on BPU-600
- 80% Mass reduction
- 90% Volume reduction
- Initiated under AF ORS SBIR
11
Feed System and DCIU
(Applicable to future iodine systems)
Propellant sublimes at low temperature (<100C) 
to become low pressure (~50 torr) gas source
GFSSP 
Modeling
Iodine PFCV
Cathode 
Ignition
Component Characterization
System Schematic
12
Attitude Determination and Control
13
iSAT CONOPS
14
Ground 
Contact
Charging
ThrustThrust
Remain in 
LVLH
Turn to 
LVLH
Turn to 
Solar 
Inertial
Initial orbit @ 600 km
Final orbit @ 300 km
• Burns in opposite direction from velocity vector
• Will thrust 2 of every 4 orbits
Launch in a PSC 12U Deployer on NRO (TBD) 
Launch Vehicle (Atlas V)
• Eject from PSC 12U Deployer
• Unfold Solar Arrays
• Checkout/Activation Process
Perform Propulsive Altitude Change
Perform Propulsive Inclination 
Change
Place iSAT in disposal orbit 
(<90 day decay)
15
Project Schedule / Milestones
iSAT project has ~25% schedule reserves remaining for April PSR.
 CDR: Summer, 2015
 SIR: Spring, 2016
 TRR: Summer, 2016
 PSR: Spring, 2017
 Launch: Fall, 2017 (TBD)
Design Evolution
16iSAT Design has Evolved Significantly as the Design Matured
PDR
DAC-2
Pre-Phase A:
Phase A: Phase B:
Phase C:
DAC-3
PDR
Technical Performance Metrics Progress
17
Significant progress since PDR to meet all mission requirements.
Bus Future Use
18
In addition to the propulsion, the bus has future mission applicability.
 The iSAT spacecraft leverages a high performance integrated bus solution in a 12U Package
 100W Solar Array
 Thermal solution for high power density small spacecraft
 Large suite of avionics I/O capability
 Full ACS System with Star Trackers, Reaction Wheels, Mag Torquers, IMU, etc.
 Power system for >200W >10min power bursts at 28V
Summary
19
 Propulsion remains a key limiting capability for SmallSats that iodine can address
 High ISP * Density  (∆V per volume)
 Indefinite quiescence, unpressurized and non-hazardous as a secondary payload
 The iSAT project is a fast pace high value iodine Hall technology demonstration mission
- Partnership with NASA GRC and NASA MSFC with industry partner – Busek
- Air Force SMC Sponsored Contract to Busek
- Aerospace Corporation contributed cameras
- AFRL contributed instrumentation
- Delivery for launch spring of 2017
 Preliminary system-level testing complete with SPRITE and additional testing throughout 
life-cycle development
 Long duration thruster testing at NASA GRC in May 2015
 The project has successfully passed mission PDR and is heading towards CDR summer 2015
 Both the propulsion system and the spacecraft bus have significant future mission potential
Questions?
20
Backup
21
22
There is an emerging and rapidly growing market for SmallSats
- SmallSats are significantly limited by primary propulsion
- Desire to transfer to higher value science / operations orbit and responsive space
- Desire to extend mission life / perform drag make-up
- Requirement to deorbit within 25 years of end-of-mission
Limitations on SmallSats limit primary propulsion options
- Requirements imposed by nature of secondary payloads
- Limitations for volume, mass and power
- Limitations on hazardous and stored energy from propellants
- Limitations for high pressure systems
- Systems must sit quiescent for unknown periods before integration with primary
Why perform flight validation?
- Reduce risk of implementation of iodine for future higher class missions
- Gain experience with condensable propellant spacecraft interactions
- Reduce risk of custom support systems
- Power generation, storage and distribution
- Thermal control
- Cost effective risk reduction before maturing higher power systems
iSAT Project Overview
Mission Justification
23
Material Testing - Literature
Limited relevant data in the literature.
24
Material Testing – MSFC Matrix
Significant material testing ongoing at NASA MSFC.
25
Communications
(PDR Design – Currently S-Band Only)
Baseline to use Near-Earth-Network; only 3/15 stations for the baseline


The Iodine Satellite (iSat) Project Development Towards Critical Design Review

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