A-Train Science Mini-Workshop, March 8, 2013

A-Train Operations and Coordination
Angelita C. Kelly
Mission Operations Manager (MOM)
Earth Observing Constellations
NASA Goddard Space Flight Center

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Overview
Introduction to the technical and operations aspectsof the current Earth observing constellations at the705 km orbit• Afternoon Constellation (e.g., the A-Train)• Morning Constellation

TOPICS• Constellation Overview• Mission Operations Working Group (MOWG)
Coordination• Challenges• Coordination Agreements & Procedures• Constellation Coordination Benefits2

Why Fly Constellations?
Science is key!

Constellations form single “virtual” platforms which enable near-coincident
observations, thus providing enhanced science3International
Earth Observing Constellations• NASA and other space agencies have satellites flying in two Earthobserving constellations.
– The two constellations include instruments from North America,
South America, Asia, and Europe.
Morning Constellation

Afternoon Constellation(Around 10:30 MLT‡)(Around 13:30 MLT‡)

Landsat-5

March 1, 1984

Landsat-7

April 15, 1999

Terra

December 18, 1999

EO-1

November 21, 2000

SAC-C

November 21, 2000

Landsat-8 (LDCM)

February 11, 2013

EOS Aqua
EOS Aura
PARASOL
CloudSatCALIPSO
OCO
Glory
GCOM-W1
OCO-2

May 4, 2002
July 15, 2004
December 18, 2004
April 28, 2006
April 28, 2006
February 2009*
March 2011*
May 18, 2012
February 2014
* Failed to reach orbit• All satellites are at 705 km altitude in sun-synchronous orbits
with a 16-day / 233 orbit repeat cycle
4Current On-Orbit A-Train Missions

Aura(HIRDLS, MLS, OMI, TES)
Launch: July 2004

Aqua
(CERES, MODIS, AMSR-E,AMSU-A, AIRS, HSB)
Launch: May 2002

CloudSat(CPR)
Launch: April 2006

PARASOL(POLDER)
Launch: December 2004

CALIPSO(CALIOP, WFC, IIR)
Launch: April 2006

GCOM-W1(AMSR-2)
Launch: May 2012
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Science Principlesof Constellations• Science requirements drive constellation flying requirements• Combined science exceeds the sum of all individual science• For maximum benefit, scientists/Science working groups
collaborate to enable cross-mission or joint products• Constellation/A-Train science results are shared via
presentations at conferences such as the AGU, IGARSS, etc.
 Two International A-Train symposia have been held:• October 2007 in Lille, France• October 2010 in New Orleans, Louisiana
 Next International Conference—20146

Afternoon Constellation (A-Train)
The A-Train satellites fly within seconds to minutes of each other to enablenear-coincident observations of the land, atmosphere, oceans, and clouds.
• Passive and active sensors• Horizontal and vertical views of the atmosphere“The whole is greater than the sum of its parts”

7Mission Operations
Working Group (MOWG)
The Afternoon Constellation MOWG was officiallyformed in 2003 to coordinate safe flying of constellation
satellites, primarily for the A-Train– Members include Operations and Science teams– Face-to-face Meetings are held twice a year;
extensive use of e-mail and telecons

To enable nearly simultaneous science observations bykeeping the constellation satellites safe.
The MOWG members work together in a spirit ofmutual respect, trust, and cooperation.
8Mission Operations
Working Group (MOWG)

MOWG MeetingNASA Goddard Space Center
October 15-17, 20129

Constellation Flying
Challenges• SAFETYSatellites fly within seconds to minutes of each otherSatellites fly near many other satellites around the 705-km orbit
Constellation configuration must be monitored and communicatedto Mission Teams to ensure SAFETY
Advanced warnings of potentially unsafe situations must beprovided
Orbital Debris Monitoring (see next slide) must be included• Multiple organizations (U.S. and InternationalPartners) — different cultures, different concepts, variedapproaches• Widely separated locations (multiple control centers, timezones)• Data Sharing, i.e., Open Data Policy

10Constellation Flying
Challenges• Concern: SAFETY Satellites fly within seconds to minutes of each other• Approach: Teams must agree on an orbital configuration thatensures safety.
 Close approaches/collisions must be avoided.

• Solution: To simplify operations, A-Train teams implemented a“control box” concept that meets science requirements
 Each satellite can move anywhere within its designated control box, butshall not drift outside without a valid reason.

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Constellation Flying
Challenges• Multiple organizations (U.S. and International Partners) — different cultures,
different concepts, varied approaches• Widely separated locations (multiple control centers, time zones)

12MOWG OperationsCoordination• The MOWG established guidelines for safe constellation flying• Constellation coordination system– Monitors the constellation configuration and status (based on daily orbit datafrom the missions)– Provides advance warning of predicted control box violations– Enables teams to exchange orbital data products

KEY:Orbit product exchange
Status flags, web displays, &e-mail alerts
13Constellation Agreements
The Constellation mission teams abide by the agreementsthat they negotiated, documented, and signed.

Operations Coordination Plan
“The A-Train Bible”

Contingency Procedures

These are “living” documents and are the primary source for information about
the Afternoon Constellation configuration, agreements, and procedures.
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Operational Benefits ofConstellation Coordination• SAFE operations – The mission teams are committed tomaintaining a SAFE Constellation configuration• Constellation configuration is monitored and communicated toMission Teams
Mission teams have 24x7 access to the constellation status
Advanced warnings of potentially unsafe situations are provided
Orbital Debris Monitoring (see next slide)• Data Sharing, i.e., Open Data Policy• Responsiveness to changing science requirements
All teams are aware of proposed changes and have a chance to provide
comments/impacts before a change is implemented• Sharing of “Best practices” and “lessons learned”
Assistance is provided to new and existing missions, for example toensure safe insertion into (and exit from) the Constellation
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Constellation Benefit
Orbital Debris Monitoring• Orbital debris is a cause for concern by all space missions.
• NASA has an agreement with the US Air Force to provide
notification of predicted conjunctions between Constellationsatellites and other maneuverable and non-maneuverable space
objects (e.g., orbital debris).
• This is implemented by the Robotic Systems Protection
Program at Goddard.

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Questions/Discussion Items
1. Are there NASA and JAXA satellites that would begood candidates for constellation flying?
a) Current missionsb) Future missions
2. Are there scientists in Japan who are using or areinterested in using A-Train or constellation data?
3. A-Train Constellation Science Contacts — see next
slide
The MOWG teams will provide consultation and analysis support
for any mission wishing to join the Morning or AfternoonConstellation or wishing to form another Earth observing
constellation.
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Constellation
Science Contacts• Morning Constellation:
 Terra: Dr. Kurt Thome Landsat Scientists at GSFC: Dr. Jeremy Irons, Dr. Jeff Masek
 EO-1: Dr. Elizabeth (Betsy) Middleton
 SAC-C: Dr. Sandra Torrusio• Afternoon Constellation:
 A-Train Program Scientist: Dr. Hal Maring/NASA HQ A-Train Project Scientist: Dr. Steve Platnick Aqua: Dr. Claire Parkinson
 Aura: Dr. Anne Douglass; Dr. Bryan Duncan
 CALIPSO: Dr. Dave Winker, Dr. Jacques Pelon/
 CloudSat: Dr. Graeme Stephens, Dr. Deborah Vane
 GCOM-W1: Dr. Taikan Oki; Dr. Haruhisa Shimoda
 OCO-2: Dr. David Crisp
 PARASOL: Dr. Didier Tanre18

Summary• Coordination has been the key to the success of the A-Train• There is some effort required to develop and operate aconstellation, but the opportunity for enhanced science makes it
all worthwhile.

CALIPSO shows ash cloud at 1,500m~7,000m altitude
Credit: NASA/Kurt Severance & Tim Marvel

Aqua/MODIS provides a natural color view
Credit: NASA Goddard / MODIS Rapid Response Team

Aura/ OMI shows sulfur dioxide concentrations
Credit: OMI Science Team19

Additional Information20

Ocean and Ice Convoy study:
Preliminary Convoy Mission Concepts

The Preliminary
Workshop Objectives• To identify and discuss science and application opportunities
from Earth observation constellations across all Earth science
domains including the interactions between these domains.
– The key science accomplishments of existing constellations.
– Identification of observational gaps, novel observations, enhanced EarthObservation products and science questions across all Earth sciencedomains, which can be effectively addressed by satellite convoys andconstellations.

• To present existing experience of Earth Observation convoys andconstellations e.g. international considerations, orbital aspects anddata management• To present the results of the ESA Convoy studies.
– Ocean and Ice Convoy Study: science and derived concepts.
– Land Convoy Study: science and derived concepts.
– Atmosphere Convoy Study: science and derived concepts.

The Preliminary
Workshop Objectives
4. To discuss the challenges of convoys and constellations e.g.
international cooperation, sensor and measurement considerations,orbital aspects and data management.
5. To discuss future Earth observation convoy and constellation
concepts and satellite coordination options in relation to identified
science questions and observational gaps.
6. To collect recommendations for a future constellation studies
and activities development roadmap.

Workshop Information• ESA is co-organizing the workshop with NASA
• Dates: 9 – 11 October 2013
• Location: ESA-ESTEC in the Netherlands• Abstract deadline: Extended until Monday,
April 29
• Registration is free. Space will be limited:

http://congrexprojects.com/13M12

A-Train website(http://atrain.gsfc.nasa.gov/)

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Thank you.
Dōmo arigatōgozaimashita
Questions?

A-Train Science Results – Eyjafjallajökull in Iceland (2010)

CALIPSO shows ash cloud at 1,500m~7,000m altitude
Credit: NASA/Kurt Severance & Tim Marvel

Volcanic plumeAqua/MODIS provides a natural color view

Credit: NASA Goddard / MODIS Rapid Response Team

Aura/ OMI shows sulfur dioxide concentrations
Credit: OMI Science Team27

A-Train Data Policy• A-Train mission members agree to abide by a common set of dataexchange and access principles to maximize the use of A-Train
data for public benefit.
• To enable data verification, inter-instrument data comparisons andalgorithm synergy, A-Train member agencies make available thealgorithms for calibration and higher level data products.
• A-Train member agencies establish appropriate mechanisms forproviding data and documents.
• Data will be made available as soon as the initial calibrationand validation has been completed; the goal will be to releasedata in a preliminary form within six months of acquisition after thestart of routine data acquisition.
• A-Train member agencies may require registration of data users.
• Redistribution of A-Train data by users may be limited bymember agencies; redistribution of “value-added” data sets (i.e.,from which original data cannot be extracted) is permitted.
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Types of Constellations

Most constellations are spaced around the Earth
to provide instantaneous, global coverage(e.g., GPS, communications, satellite radio, weather).
GPS Constellation

Terra
SAC-C

In contrast, the 705 Constellations’ satellites orbit
in close proximity so that observations occur atabout the same time over approximately thesame region.

Landsat-7

EO-1

Morning and Afternoon
Constellations
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Constellation Coordination
In practice, there is a range of constellation types in existence withvarying coordination requirements.
Operations
Typical Characteristics
Coordination

Increasing coordination

MinimalModerate• Heterogeneous
satellites• Some orbit parameters
may be similar)• Multiple owners• Multiple organizations• Heterogeneous
satellites• Satellites often in close
proximity (but notrequired)• Multiple agencies• Operations handled byseparate organizations• Homogeneous satellites
Central (singleorganization) • Single agency• Easy Coordination

Coordination

Examples• Operations are notcoordinated• Coincidental science
results can becorrelated• Little negotiation

GPM constellation (including ISRO’s
Megha-Tropiques)• Some maneuvercoordination• Science data sharing• Moderate negotiation• Tightly coupledobjectives and datasharing• Little negotiation

Earth Observing Constellations• A-Train (Afternoon Constellation)• Morning Constellations

GPSGRACEIridium

The coordination sometimes evolves over time as the science community identifies
innovative ways to leverage available data from one satellite with data from another.
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Earth Science Afternoon Constellation
The Earth Observing Constellations are not a homogenous mix of
identical satellites. They comprise several satellites with diverse
instruments that provide complementary observations.

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Afternoon Constellation Challenges
Numerous organizations are involved in this international undertaking
Locations
Affiliation

Project Scientist/
Principal Investigator/ProjectManagement

Control Center

Aqua

NASA

GSFC, Greenbelt, MD

GSFC, Greenbelt, MD

AuraNASA

GSFC, Greenbelt, MD

GSFC, Greenbelt, MD

CloudSatNASA

CSU, Ft. Collins, CO
CloudSat Project, JPL, CA.

Air Force Facility, New
MexicoCALIPSO

NASA/CNES

LaRC, Hampton, VA
CNRS, Paris, France

LaRC, Hampton, VA
CNES, Toulouse, France

PARASOL

CNES

UST de Lille
Villeneuve D’Ascq, France

CNES, Toulouse, France

GCOM-W1

JAXA

Tokyo, Japan

EOC, Hatoyama, Japan

OCO-2

NASA

JPL, Pasadena, CADulles, VA

Mission32

Constellation Agreements:
Conflict Resolution Process
A process exists to resolve conflicts.

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Example
Afternoon Constellation Documentation
Memorandum of Understanding(MOU)
or Interface Agreement (IA)Project Plan
Science and Mission Requirements Document
Mission Operations Concept
On-Orbit Mission Management Plan
Operational Interface Agreement

End of Mission Plan

Orbital Debris
Avoidance Procedure

Afternoon Constellation
Coordination Plan
Afternoon Constellation
Contingency Procedures
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Constellation Agreements:
Change Process
The A-Train has a process for making changes to the constellationto accommodate new science requirements. This process has been
exercised several times.

Configuration
ChangeRequestMissionTeam…………………

………………
………………
………………
……………

MOWG

ScienceTeamsOpsTeams

A Mission Team submits a change request to be considered by the MOWG.
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