Fluxgate Magnetometer Core Technology Demonstrator
A NASA Cubesat Launch Initiative Proposal from the Columbus Space Program
Contact Information:
Columbus High School
PI: Luther Richardson
1700 Cherokee Avenue
Columbus, GA 31906
(706) 888-3124
astro@mit.edu
Fluxgate Magnetometer Core Technology Demonstrator
Proposed by the Columbus Space Program, a co-curricular science and engineering organization
housed at Columbus High School
CubeSat Mission Parameters
Mission
Name
FluxDemon
Sat
Focus
Area(s) (e.g.
science,
technology,
education)
Technology,
Education
Mass
Cube
Size
1.3kg
1u
Student
Involvement
Yes or No
Yes
Desired Orbit
Altitude
Inclination
600km
50 deg
Acceptable
Orbit Range
550km –
650km
400 km @
51.6 degree
incl.
Acceptable –
Yes or No
No
CubeSat Project Details
NASA Funding
Sponsoring
Organization(s)
Yes or No Organization
No
Columbus
Space
Program,
AMSAT
Readiness
Date
Desired
Mission
Life
July 2017
5 years
Collaborating
Organization(s)
List
International
– Yes or No
Prime
Photonics
No
Points of Contact
Mission PI (Overall Systems Engineering, Science & Education Plan)
Organization
Name
Title
Address
Phone
Fax
Email
Columbus Space Program / Columbus High School / AstroSystems, LLC
Luther Richardson
Program Manager of CSP / Science Teacher / Chief Scientist
1700 Cherokee Ave, Columbus GA 31906
706-888-3124
706-748-2546
astro@mit.edu
Engineering POC
Organization
Name
Title
Address
Phone
Fax
Email
AMSAT
Jerry Buxton
Payload Technical POC
Organization
Name
Title
Address
Phone
Fax
Email
Organization
Name
Title
Address
Phone
Fax
Email
Spatial Microsystems
Keith Warren
Chief Engineer
John Klingelhoeffer
Proposal Abstract:
FluxDemonSat proposes to advance the TRL level for NASA research class magnetometers with a new
type of core material. Besides being a technology demonstration mission, this satellite will also have an
education plan that uses an existing network of schools and teachers sponsored by NASA.
Proposal Detail:
The proposed FluxDemonSat mission has a technology and education prime focus area and a secondary
focus area in science. The focus areas are outlined below in the mission objectives table with alignment
with NASA Strategic Goals (FY2014) in orange text.
Primary Focus Area Objectives
M1 (Technology)
Advancing the TRL level for the new type of core for fluxgate magnetometers
will increase availability of research class magnetometers. (NASA SBIR
Proposal #11-2 S1.06-8828 copy in Appendix)
Objective 1.7: Transform NASA missions and advance the Nation’s
capabilities by maturing crosscutting and innovative space technologies.
Objective 2.3: Optimize Agency technology investments, foster open
innovation, and facilitate technology infusion, ensuring the greatest
national benefit.
GSFC Strategic Goal 1: Goddard Space Flight Center both enables and
conducts science research from space.
M2 (Education)
Implement a wide spread education plan that will facilitate a network of data
stations and opportunities for students to analyze data
Objective 2.4: Advance the Nation’s STEM education and workforce
pipeline by working collaboratively with other agencies to engage
students, teachers, and faculty in NASA’s missions and unique assets.
Objective 3.1: Attract and advance a highly skilled, competent, and diverse
workforce, cultivate an innovative work environment, and provide the
facilities, tools, and services needed to conduct NASA’s missions.
M3 (Science)
Secondary Focus Area Objectives
Contribute to investigation of the Earth’s magnetic field and its response to
solar activity
Objective 1.4: Understand the Sun and its interactions with Earth and the
solar system, including space weather.
Objective 2.2: Advance knowledge of Earth as a system to meet the
challenges of environmental change, and to improve life on our planet.
Each objective will be addressed in the next section using its M-designation from the focus area table.
M1.
NASA has been using fluxgate magnetometers to measure magnetic field throughout the history
of space exploration. The best magnetometers for space research have been coming from the
Goddard Space Flight Center (GSFC) with support for missions like the Voyager spacecraft,
Mars Global Surveyor, and current missions like Messanger. These flagship missions have
relied on the low noise high precision fluxgate magnetometers from the Mag Lab at GSFC. In
recent years, there has been a shortage of the permalloy metal cores used at the heart of these
fluxgate magnetometers due to diminishing supplies and a loss of the exact fabrication process.
A Small Business Innovation Research grant was awarded to a company called Prime Photonics
to manufacture a replacement core material using a newly developed metallic glass core. These
cores are intended to serve as drop-in replacements for current NASA designs for fluxgate
magnetometers. This CubeSat mission would fly a fluxgate magnetometer in the form factor of a
small NASA design using a metallic glass core. The data would include magnetic field
measurements that would be compared to a solid state magnetometer for verification, and also
diagnostic data to confirm the performance of the metallic glass cores. The end result would be
performance data on the metallic glass cores operating in a fluxgate magnetometer operating in a
space environment advancing this new technology to a TRL-6 or TRL-7 depending on the
results. TRL 7 is defined as: “A high fidelity engineering unit that adequately addresses all
critical scaling issues is built and operated in a relevant environment to demonstrate
performance in the actual operational environment and platform (ground, airborne or space). ”
[NASA, 2007]
Fluxgate Magnetometers work by saturating the core material with magnetic field and using
sense coils to react to changes in magnetic flux and circuitry can act to nullify the external field
(closed loop sensor)
Cubesat FGM will measure Earth’s field to be compared to solid state magnetoresistive
magnetometer reading – this comparison validates overall measurement ability
The FGM circuit will have a op-amp integrator that will output the microsecond time response
of the core to be measured as a data output
Fluxgate Magnetometer Core (Idealized Diagram
Small NASA Fluxgate Magnetometer
from Acuna, 1978)
𝑉𝑠𝑒𝑐
(image taken by proposal PI at NASA
Goddard Mag Lab in 2004)
𝑑𝜇𝑟⁄
)
𝑑𝑡
= 𝑛𝑠 𝐴𝐵𝑒𝑥 (1 − 𝐷)
[1 + 𝐷(𝜇𝑟 − 1)2 ]
(
The equation above describes the electric potential measured by the fluxgate magnetometer.
Three of the terms are directly related to the core material and the noise level dictates the
sensitivity of the measurement:
𝑑𝜇
demagnetization factor (D), relative permeability (𝜇𝑟 ), and rate of change ability ( 𝑟⁄𝑑𝑡).
These performance measures need to be verified on the ground and also in orbit. Ground and
on-orbit measurements would be taken by the fluxgate and a solid state magnetoresistive
magnetometer to verify performance measurements.
In terms of physics, the slope of the hysteresis curve showing the applied field and
magnetization of the core material is equal to the permeability mr. Since the change of
applied field is known electrically, the time also allows for measurements of permeability.
It takes a considerable engineering effort to make a spacecraft magnetically clean. This
mission will take basic steps to minimize stray magnetic fields, but the focus is to obtain
performance data on the coil inside of the fluxgate magnetometer. Stray magnetic field from
electrical currents in the satellite will be filtered out by comparing simultaneous measurements
by an industry standard solid state magnetometer in the payload section of the CubeSat.
M2.
The Columbus Space Program is a co-curricular science and technology organization housed in
Columbus High School. Students from this program have been selected to fly their
experiments on NASA suborbital rockets, balloons, space shuttles, ISS, and at drop towers
numerous times. This group also has worked to develop a high altitude balloon program that
has flown 23 missions to the edge of space with altitudes up to 118,500 feet. This proposed
CubeSat mission would be an ideal central concept for a national outreach program. The goals
of the outreach program would be to involve student groups from around the country in
collecting data directly from the CubeSat and also analyzing it.
The education plan will reach out to students and teachers through the FIRST Robotics
community, and teachers through the Network of Educator Astronaut Teachers (NEAT), as
well as teacher workshops with the Teachers in Space organization. Ten percent population of
undergraduate students at MIT have participated in FIRST Robotics so that this same group of
high school students will become the next generation of scientists and engineers of the caliber
most suited for the challenges of NASA missions.
M3
Several spacecraft missions including Cubesats have aimed to investigate the interaction between
the Sun and Earth by measuring the magnetic field from orbit. FluxDemonSat would take data
with as good or better sensitivity than the other missions. This satellite would offer another data
point in time and space.
Measure changes in the Earth field over time with correlating data from ground based
magnetometer measurements.
UC Berkley CINEMA mission to measure
Earth-Sun interaction
Graphic showing source of magnetic source
measurements from space by ESA’s Swarm
mission
Merit Review
Feasibility Review
Need for Collaboration  Prime Photonics, AMSAT
CharBroil manufacturing capability: parts made from student designs using laser cutting sheet metal
machine, Wire EDM, lathe & milling machines
Prime Photonics supplying low noise metallic glass core designed for NASA FGM sensors
Auburn university’s clean room for final production of electrical circuits and integration
Columbus Space Program Robotics Lab (access to 3d printer)
AMSAT FOX satellite program (subsystem support)
Need to put the Prime Photonics NASA sized drop-in cores inside of a quality fluxgate
magnetometer and measure performance while in orbit.
OPTIONS: Build our own fluxgate magnetometer or Obtain a small NASA magnetometer from
Goddard Space Flight Center Mag Lab
Electronics. Designed, Built, & Tested by Columbus students with guidance by electrical engineer
Keith Warren
Prime Photonics has a Small Business Innovation Research grant with NASA to produce quality low
noise fluxgate magnetometer (FGM) cores that can act as drop in replacements for current NASA
FGM sensors
Contact made with company CEO, Steve Poland. Agreement made that a flight on a Cubesat with
relevant performance data would advance the TRL level of the cores. Agreement made that low
noise cores with O.D. of 1.0 inches would be available within a year to us to be integrated into a
FGM sensor for Cubesat flight.
AMSAT has launched multiple small satellite including Cubesats that have served the amatuer radio
community with education programs
Columbus Space Program would fully manage the payload section of the FluxDemonSat mission
Students from Columbus Space Program would work with AMSAT engineers/mentors to use
previously designed subsystems (COM, EPS, CDH, STR)
Skeleton Structure with deployed FGM using a spring loaded or motor deployed Copper Beryllium
“tape measure”
The “V-diagram” from systems engineering illustrates the engineering approach to FluxDemonSat.
Students will gain a full engineering life cycle experience.
This proposal will present a general feasibility, set of requirements, and some elements of high-level
design.
Verification and Validation (V&V) will be accomplished using a set of design budgets:
Power Budget, Link Budget, Mass Budget, Cost Budget, and Schedule
•
23 high altitude balloon launches has built student knowledge:
•
Communication Systems
•
Electronics and Programming
•
Integrated Process Teams
•
DREAMS payloads will serve to test the performance of CubeSat payload prototypes at
altitudes over 100,000 km
•
DREAMS-24 is scheduled for Nov. 15: 16-bit magnetometer will fly and gather data
•
Three or more DREAMS launches in the future dedicated to FluxDemonSat testing
•
Subsystem Costs managed by AMSAT
•
Payload Costs
•
Magnetometer Cores $3000
•
3 axis Fluxgate Magnetometer (1 flight, 1 engineering, several 1-axis versions)
$1000
•
FGM drive circuit (several development versions + 1 flight + 1 engineering) $2000
•
Three Balloon launches (DREAMS) for testing $2500
TOTAL BUDGET (Payload) $8500
Support: Georgia Space Grant $5000, US Army $1500 (Pursuing options for $2000 additional
support – must be documented as letters of support in the proposal)
Costs are for materials and supplies. All labor and site costs are volunteered or donated.
Does the Proposal demonstrate that the CubeSat investigation provides benefits to NASA by
addressing one or more of the goals and objectives of the NASA Strategic Plan?
• Are these the benefits that were reviewed in the merit review?
• Why is an orbital flight opportunity necessary or advantageous for providing these benefits to
NASA?
Merit Review, Oct 31st
Feasibility Review, November 7th
Mr. David Rush (confirmed)
Mr. John Klingelhoeffer (confirmed)
Mr. Perry Ballard (USAF) confirmed
Michael Taylor (SpaceX), confirmed
Eryn Maynard (Google) confirmed
Bobby Russell (General Atomics), confirmed
Dr. Chris Spraggins (CHS), confirmed
Taylor Klotz (WTVM), confirmed
Christian Nelson (NASA), confirmed
What was the merit review process?
• Was the merit review competitive or non-competitive?
• What were the qualifications of the merit review committee members (if possible identify by name,
title, and expertise)?
• What factors did the merit review use to assess merit?
• What was the outcome of the merit review?
• How did the Respondent respond to and/or address the findings of the merit review?
What was the feasibility review process?
• What were the qualifications of the feasibility review committee members (if possible identify by
name, title, and expertise)?
• What factors did the feasibility review use to assess feasibility?
• How were the management team roles, experience, expertise, and the
organizational structure of the team assessed?
• How was the technical development risk associated with the overall CubeSat mission assessed?
• If the CubeSat investigation requires critical technology development for flight readiness, how were
the areas assessed, and how were the plans for completing technology development assessed?
• Concerning the development of the CubeSat for flight, how was the probability of success
assessed?
• What was the outcome of the feasibility review?
• How did Respondent respond to and/or address the findings of the feasibility review?
• Is there sufficient financial support for the development of the CubeSat payload and for all other
costs incurred by Respondent to support its participation in the project?
CubeSat primary and, if appropriate, secondary focus area: scientific research question, technology
development/demonstration, or education.
• CubeSat Development: schedule for remaining CubeSat development that supports a launch in
2015-2018.
• Summary of Requirement compliance or required potential waivers.
Funding Commitment Letter(s): letter(s) demonstrating sufficient financial support for remaining
CubeSat development.
• Note for Proposals identified with an Education Focus Area: If the proposed CubeSat includes
outreach components, the proposal must include a description of the education plan.
Compliance checklist and required documents
o Respondent is a NASA center, a U.S. not-for-profit organization, or an accredited U.S.
educational organization
o Proposal includes demonstration of the benefits to NASA based upon the 2014 NASA Strategic
Plan
o Proposal identifies a project focus area
o Proposal includes a description of the merit review process and outcome including review
committee membership
o Proposal includes a description of the feasibility review process and outcome including review
committee membership
o Proposal fully complies with the Launch Services requirements and identifies any potential
waivers
o Proposal includes a completed Mission Parameters Table
o Proposal includes a completed Project Details Table
o Proposal includes a schedule for remaining CubeSat development that supports a launch in 20152018.
o Proposal includes funding commitment letter(s) demonstrating sufficient financial support for
remaining CubeSat development
Importance of Fluxgate magnetometers to NASA
New Cores
AMSAT
Schedule
Education Plan
Merit Review
Feasibility Review
Launch Service Requirements
Financial Plan
Resumes
Plans for Remaining development
Technical Risks & Mitigations
Core Testing with Flux Gate Magnetometer
Magnetic core performance can be measured as shown in the formula below. The slope
of the hysteresis response of the core is equal to the permeability 𝜇𝑟 of the core, which will be
measured through circuity. A physical manifestation of the core performance can be observed in
Figure 1. The alignment of the magnetic domains of the core determine another measure of core
performance, the magnetization factor, 𝐷 . Measuring the magnetic field inside the core itself will
give a direct measurement of the alignment of the magnetic domains inside the core and, thus, a
way to determine the magnetization 𝐷 of the core.
𝑉𝑒𝑥𝑡
𝑑𝜇
𝑑𝑡
= 𝑛𝑠 𝐴𝐵𝑒𝑥 (1 − 𝐷)
1 + 𝐷(𝜇𝑟 − 1)2
Figure 1: The hysteresis curve of a magnetic material driven to saturation.
Source: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/imgsol/hyloop.gif
For the purpose of measuring the performance of the Prime Photonics core, a flux gate
magnetometer will be used, as outlined in the block diagram in Figure 2. The core itself is
wrapped with magnet wire to create a torroidal electromagnet, and this torroid is placed at the
center of a sense coil. The core is magnetically saturated in the positive and negative directions
as driven by an excitation circuit. Since the coil is saturated, any external magnetic field cannot
fit in the torroid’s magnetic field, so it leaks to the sense coil surrounding the torroid. The change
in magnetic field in the sense coil will induce a voltage in the wire, which is demodulated by
circuitry. The sense coil’s output will be tied to circuitry that uses operational amplifiers to detect
the amount of magnetic field through phase demodulation, which both nullifies the external
magnetic field, which makes a closed-loop sensor, and drives a signal to an analog-to-digital
converter (ADC) that sends the high resolution (18-bit or 22-bit) measurement of magnetic field
to the microprocessor, which then logs the data.
Phase demodulation helps the sensor’s noise rejection because only signals that are
exactly in phase with the torroidal excitation will be measured. Furthermore, sine wave phase
demodulation prevents picking up noise or interference from odd harmonics that match the
torroidal excitation phase. To further avoid interference of noisy digital signals in our closed
loop analog circuitry, the signal measurement circuitry, consisting of an ADC and
microprocessor, and other circuitry will be magnetically shielded from the flux gate
magnetometer and its circuitry.
Though monitoring magnetic field measurement itself can measure core performance
over time, a faster, more reliable form of measuring the core responsivity is measured as follows.
To monitor the hysteresis response of the core, a small value resistor is placed in series with the
torroid to measure the excitation response of the core, and the voltage across the resistor, which
directly corresponds to 𝜇𝑟 , can be monitored by the ADC. Another method to measure the coil
performance is to detect the magnetic field inside the core itself, by using a thin Hall-effect
sensor placed inside the core itself. Slots a few millionths of an inch thick can be cut with a
diamond saw and a Hall effect sensor with an analog output, which directly corresponds to 𝐷 ,
can be placed and connected to the ADC.
Figure 2: Block diagram of the flux gate-magnetometer and its circuitry.
Source: Columbus Space Program
Magnetoresistive Magnetomter testing
Jinny van Doorn
By using a Honeywell magnetoresistive magnetometer (HMC2003), an open-loop triaxial sensor
that detects magnetism by registering magnetically-induced changes in resistance of a sensitive material,
we conducted testing of the natural daily periodic variation in magnetic field on the ground. The sensor
itself has a resolution of approximately 4 nT, while the USGS and other agencies have observed the
periodic variation to be approximately 36 nT.
The data collected so far via ground testing includes a full day and night, registered by a single
HMC2003. A sharp increase in magnetic field takes place around sunset, equally offset by a sharp
decrease, most probably owing to the bow shock of the magnetosphere, around daybreak. The precise
circumstance of these drastic increases and decreases , which occur over the duration of less than 30
minutes, was not initially certain. To rectify this issue, times for visible magnetic events were derived
from a calibration that encompasses magnetometer exposure to a magnet (insert magnet type`/strength
here) at a known time.
The exposure and subsequent sensor saturation occurred at 4:25:42 PM, and the magnetometer
was switched off at 12:08:00.AM the next day. There are 67752 data points in between the point of
saturation and the switching off, which indicates a sample rate of approximately once per second.
Sunset occurred 3618 seconds after saturation at 5:41, and sunrise the next day at 7:08, meaning
that roughly 46140 seconds elapsed between sunrise and sunset. The beginning of the increase in
magnetic field readings occurs around 33 minutes after sunset, increasing for 17 minutes until reaching a
20107 counts, the highest reading of the measurement period. There appears to be a lag time between
sunset and the increase in magnetic field, and a lead time between the decrease in magnetic field and
sunrise.
HMC2003 Calibration
C
o
u
n
t
s
time (s)