Subject: [IGSMAIL-2669]: LEO Call for Participation
From: Katrin Weisse <[email-masked]>
To: [email-masked]
Date: Wed, 12 Jan 2000 17:22:33 +0100

******************************************************************************
IGS Electronic Mail      12 Jan 08:26:13 PST 2000      Message Number 2669
******************************************************************************

Author: Christoph Reigber

                    INTERNATIONAL GPS SERVICE
                     CALL FOR PARTICIPATION
                         In support of

                   LOW EARTH ORBITING MISSIONS

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  This Call for Participation will also be available on the CBIS,
                   http://igscb.jpl.nasa.gov
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TABLE OF CONTENTS

- Letter of Invitation to Participate from Professor Christoph
  Reigber, Chair IGS Governing Board
- Executive Summary
- Call for Participation Details
    - IGS Mission and Objectives
    - LEO Recommendations
    - Call for GPS Network Stations
    - Call for High Performance IGS Subnetwork
    - Data Formats
    - Call for Data Centers
    - Call for Associate Analysis Centers
    - Call for Coordinators
    - IGS Analysis Centers
- Letter of Intent
- General Proposal Information
- Proposal Evaluation and Selection
- Schedule of IGS LEO Activity
- Proposal Preparation Details

******************************************************************

International GPS Service - The Chairman of the Governing Board

Potsdam, January 11, 2000

Dear Colleague:

with the forthcoming Low Earth Orbiting Missions CHAMP, SAC-C, GRACE and
others we will soon enter a new era of developments in the fields of
solid Earth, oceanography and atmosphere sciences and applications. The
IGS was extremely successful in organizing the resources of the
international GPS community in the development of GPS science and
applications. The pooling of resources led to a highly efficient and
rapid development of the IGS global network, the development of support
centers for analysis and data archiving, and the rapid advancement of
GPS technique for science and applications. This was achieved because of
the open nature of collaboration while maintaining friendly and
supportive competition among the participants in the IGS.

The establishment of a space network of orbiting GPS receivers could be
developed as an extension of the ground network while utilizing many of
the resources which the IGS currently has in place. Therefore with a
Call for Participation, detailed in the attachment to this letter, the
IGS solicits support in the establishment of an enhanced subset of IGS
infrastructure targeted at supporting Low Earth Orbiting missions.

It is clear that the IGS ground network will be a cost effective element
to most applications of space-based GPS measurements. Recommendations to
this effect were made by the IGS LEO Working Group, chaired by Mike
Watkins in 1998. Furthermore, several participants in the IGS are also
key players in the development of spacebased GPS applications.  The IGS
has a ‘de facto’ role in the development and applications for orbiting
GPS receivers and the stage is set for the IGS to now play a significant
role in the development of spacebased GPS receiver applications.  With
the development of a significant role in the arena of orbiting space
receivers, the IGS will serve the broader geoscience community as well
as potentially provide services for commercial interests.

The operation of a space network of GPS receivers in service to the
broader geoscience community will place special requirements upon the
acquisition and distribution of data from the ground network, new
requirements on the analysis centers, expanded capacity for the
archiving centers, or creation of new ones, and a broader representation
of scientific disciplines and agencies on the IGS governing board.
Therefore, the IGS will need to develop and extend its current
organization in the near future.

It is for these purposes that the IGS is soliciting this Call for
Participation.
Participation in this IGS activity is open to government agencies,
educational institutions and other organizations whose financial
resources allow a firm commitment to be made in support of these new and
demanding activities.  Proposals may be submitted at any time during the
period ending April 3, 2000.
The enclosed document provides information on the participation
solicited, where components will assume expanded roles and functions,
and where new groups or components may be interested in contributing.
Proposals may address any aspect or multiple aspects of the IGS LEO
activity for which the proposing organization has the capability and
capacity to support.

Those organizations interested in participating in the IGS LEO activity
should submit a letter of intent by February 11, 2000, expressing their
interest. IGS will offer full cooperation to groups involved in the
development of support capabilities for LEO missions, and thus will
enhance their effectiveness.  For this reason, participants in current
activities are also strongly encouraged to respond to this solicitation.

Your interest and cooperation in participating in this international
effort are welcomed and appreciated.  Please feel free to contact the
IGS Central Bureau or myself with questions or comments regarding this
call.

Sincerely yours,

Christoph Reigber
Chair, IGS Governing Board

******************************************************************

EXECUTIVE SUMMARY

Soliciting proposals in support of enhancing a subset of the
infrastructure of the International GPS Service (IGS) in support of Low
Earth Orbiter (LEO) Missions.  This support is for precise orbit
determination (POD) of LEO satellites and high rate (~1Hz) GPS ground
tracking data to support LEO space-based GPS applications.  GPS data
from these LEO platforms will be used for IGS POD solutions of the LEO
and of the GPS constellation as well.  Additional space applications
plan to use onboard GPS receivers coupled with the high rate ground data
to produce temperature and water vapor profiles in the neutral
atmosphere and ionosphere imaging products.  The POD will be assessed
for potential improvement to overall IGS analyses.

PARTICIPATION IS REQUESTED IN THE FOLLOWING CATEGORIES

• GPS Stations
- Globally distributed set of stations observing in the ‘classic’
  (30 second) sampling and reporting data at the hourly and eventually
  rapid sub-hourly schedule for IGS rapid processing and product
  generation.
- High rate tracking stations capable of sampling up to a 1 Hz rate
  with rapid (hourly to <15 minute, near real-time or data streaming)
  data delivery, operating according to standards established by the
  IGS (in concert with LEO mission requirements).

• Data Centers
- Organize and provide access to classic hourly and eventually rapid
  subhourly data for Precise Orbit Determination (POD)
- Organize and provide access to high rate ground station data for
  science applications
- Organize and provide access to GPS flight receiver data for POD and
  science applications

• Associate Analysis Centers (AACs) for LEO Project
Analysis centers that propose to incorporate the GPS flight receiver
data into their processing stream for:
- Generating scientific POD for the LEO satellites within a one-year
  phased pilot demonstration project:
    - Phase I - utilizing data from the currently operational GEOSAT
      Follow On satellite (GFO).
    - Phase II – utilizing data from the CHAMP and SAC-C satellites
      scheduled for launch in April 2000.
- AACs will demonstrate POD for these satellites as data is made
  available by mission responsible entities.
- AACs will investigate and assess potential improvement of the suite
  of IGS classic products (orbits, EOPs, etc.)

• Coordinator(s)
- Coordination of the AACs for development, comparison and quality
  control of the new products.
- Assess the overall impact of meeting LEO requirements and
  incorporating LEO GPS into the IGS processes. Assess impact on IGS
  products.

• IGS Analysis Centers (ACs)
- A general call to IGS ACs to develop the capabilities for hourly
  processing.  It is expected that the established ACs will follow
  the agreed upon recommendations of the La Jolla AC Workshop, June
  1999, by developing and demonstrating sub-daily processing.
  (See IGS Mail Message # 2359 from IGS AC Coordinator, Tim
  Springer).

******************************************************************

DETAILS ON LEO CALL FOR PARTICIPATION

The Mission of the International GPS Service
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The IGS clearly has the interest, experience and infrastructure to
become involved in LEO mission support activities.  The following
extract from the IGS Terms of Reference (located at
http://igscb.jpl.nasa.gov) reveals that these activities are certainly
within the stated mission of the IGS.

"The primary objective of the IGS is to provide a service to support,
through GPS data and data products, geodetic and geophysical research
activities. Cognizant of the immense growth in GPS applications the
secondary objective of the IGS is to support a broad spectrum of
operational activities performed by governmental or selected commercial
organizations. The Service also develops the necessary standards and
specifications and encourages international adherence to its
conventions.

IGS collects, archives and distributes GPS observation data sets of
sufficient accuracy to satisfy the objectives of a wide range of
applications and experimentation. These data sets are used by the IGS to
generate the following data products:

- High accuracy GPS satellite ephemerides
- Earth rotation parameters
- Coordinates and velocities of the IGS tracking stations
- GPS satellite and tracking station clock information
- Ionospheric information
- Tropospheric information.

The accuracies of these products are sufficient to support current
scientific objectives including:

- Realization of global accessibility to and the improvement of the
  International Terrestrial Reference Frame (ITRF)
- Monitoring deformations of the solid earth
- Monitoring earth rotation
- Monitoring variations in the hydrosphere (sea level,
  ice-sheets, etc.)
- Scientific satellite orbit determinations
- Ionosphere monitoring
- Climatological research, eventually weather prediction."

One can further see that specific to the IGS mission are the scientific
objectives of a support capability for “scientific satellite orbit
determination and climatological research, eventually weather
prediction.”  These objectives clearly drive this Call for Participation
in support of LEO missions.

LEO Recommendations
~~~~~~~~~~~~~~~~~~~
In March, 1999 an IGS/GFZ/JPL workshop was conducted in Potsdam, Germany
to explore the relationship between the IGS and an array of LEO missions
planned for the next decade.  A summary session of the workshop resulted
in the proposal of four recommendations made by the LEO Working Group
(WG). These recommendations are:

R1: The standards for ground stations in the LEO subnetwork be
    codified and distributed.

R2: The IGS Analysis Centers should develop a new rapid analysis
    product (orbit, clock, EOP, and predictions) with a latency of
    less than 3 hours. This would be demonstrated through voluntary
    participation in a pilot project initiated in late 1999.

R3: A new efficient format should be developed for the 1 Hz ground
    data.

R4: A Pilot Project for the use of flight data for POD purposes
    (including effect on the GPS AC products) should begin as soon as
    possible. The WG further recommends that for the duration of the
    Pilot Project, the 1 Hz ground data be handled by the network
    operators and data centers in the new format (as yet not defined)
    described in R3. The Call for Participation will also request
    additional LEO ground sites following the standards of R1.

These recommendations were accepted by the IGS Governing Board at its
11th meeting in La Jolla, in June 1999.

Call for GPS Network Stations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A globally distributed set of stations observing in the ‘classic’ (30
second) sampling and reporting data at the hourly and eventually
sub-hourly schedule for IGS rapid processing and product generation is
required. The IGS has made great progress in this area in terms of
hourly network operations and data collection. One can see from the
attached map of current hourly stations that there are many stations
operating in this mode. This Call specifically targets those areas where
there are gaps in the hourly network, most notably due to the lack of
communications or stations in areas of Africa, Asia, China, India,
Russia and Southeast Asia.

Call for High Performance IGS Subnetwork
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A subset of uniformly distributed stations within the IGS ground network
capable of high data rate (up to 1 Hz sampling) operations and near
real-time data availability is required.  These stations are expected to
operate according to standards and interfaces established by the IGS in
concert with LEO mission operation requirements.  These stations should
also be referenced to hydrogen maser clocks wherever feasible.  The data
from this subnet needs to be made available to the data centers and
hence analysis centers on a subdaily schedule.  This places requirements
of very high reliability upon the operation of the subnet, which
probably is best achieved through redundancy either at the subnet sites
themselves or through a doubling of the size of the subnetwork.  The
ground communication links to support these data acquisition
requirements will need to be evaluated and upgraded in certain
locations.

Currently, there are two groups within the IGS who are closely linked to
upcoming missions CHAMP, SAC-C, GRACE, the GeoForschungsZentrum Potsdam
and Jet Propulsion Laboratory.  With respect to ground support, a set of
stations has been jointly identified (and in parts newly established)
for CHAMP mission support, as shown in the attached map. It is expected
that these stations and augmentations by other agencies would constitute
the initial high-rate IGS ground subnetwork.

It is important to note that the IGS must be prudent in the operation of
high-rate stations.  The proposed data rate of 1 Hz is a factor of 30
over current station data files; however, special formats and
compression should reduce this to a factor of ~17.  This is still a
significant amount of data for transfer and for data centers and
analysis centers to manage.

In this regard, proposed high rate stations will be evaluated based
mostly on location, performance and redundancy.

Note that the 1 Hz rate requirement is to be evaluated by the LEO
Working Group.  Also, the eventual elimination of Selective Availability
(SA) on the GPS satellites should greatly relax the requirements for the
high-rate ground network.

Data Formats
~~~~~~~~~~~~
The standards and data formats for the high rate ground data are yet to
be explicitly defined within the IGS. The CHAMP mission team is
currently implementing a form of compressed Turbo-binary developed by
GFZ. This takes advantage of the data stream from the Allen Osborne
TurboRogue or ACT receivers and compresses the large data quantities for
more efficient data transfer.  JPL has developed a method of emulating
the Turbo-binary compressed formats for the Ashtechs in the CHAMP
mission network. The IGS Network Coordinator and Central Bureau will be
involved in reviewing various high rate data formats employed in both
global and regional arrays with the help of a subcommittee.  A resulting
recommendation for the adoption of a format extensible to all receivers,
and hopefully all missions, will be forthcoming at the IGS Network
Workshop in Norway, July 2000, or shortly thereafter.  A preliminary
standard or tools will be available by March for those organizations
interested in contributing ground data to the CHAMP and SAC-C missions.

The format for the GPS space receiver data will be documented and made
available to the IGS through the CHAMP and SAC-C mission representatives
in the LEO Working Group.

Call for Data Centers
~~~~~~~~~~~~~~~~~~~~~
Data Centers are solicited to fulfil three functions:
1) Organize and provide access to the hourly classic data.
2) Organize and provide access to high-rate ground station data.
3) Organize and provide access or links to the sets of GPS flight
   receiver data.

Currently a number of IGS data centers are developing or operating to
provide access to hourly 30-second data.  A goal over the next year and
a focus of the planned IGS Network Workshop, July 2000, in Oslo, Norway,
is the standardization of data center structures to facilitate common
access processes by users.

Data centers interested in handling high rate ground data and/or the
flight receiver data will have to operate according to agreed upon
standards to initiate these common access procedures, file and directory
naming conventions, etc.

Access to mission data will be coordinated between the mission network
managers and the IGS Central Bureau Network Coordinator with assistance
of the IGS LEO Working Group.

Call for Associate Analysis Centers (AACs)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
• Associate Analysis Centers (AACs) for LEO Project
Analysis centers that propose to incorporate the GPS flight receiver
data into their processing stream for:

- Generating scientific POD for the LEO satellites within a one-year
  phased pilot demonstration project:
    - Phase I - utilizing data from the currently operational GEOSAT
      Follow On satellite (GFO).
    - Phase II – utilizing data from the CHAMP and SAC-C satellites
      scheduled for launch in April 2000.
- AACs will demonstrate POD for these satellites as data is made
  available.
- AACs will investigate and assess potential improvement of the suite
  of IGS classic products (orbits, EOPs, etc.)

Phase I of the pilot project will concentrate on GFO.  The LEO WG has
identified a test data set that uses the GPS data collected onboard GFO
that can be used to investigate POD of GFO and provide an initial
assessment of LEO data inclusion into the IGS OD processes.

Call for Coordinator(s)
~~~~~~~~~~~~~~~~~~~~~~~
- Coordinate the AACs for development, comparison and quality control
  of the new products
- Assess the overall impact of meeting LEO requirements and
  incorporating LEO GPS into the IGS processes. Particularly assess
  impact on IGS products.
Coordinator(s) will be intimately involved in the activities of the new
Associate Analysis Centers for the LEO Project.  This role assumes
responsibility for the coordination of technical developments necessary
for inclusion of the LEO data into the POD estimation processes.
Through comparison and communication with the participating centers the
analysis systems will be improved and measures of quality control will
be defined.

The experience gained during the one-year pilot project phase will
enable an assessment of the impact on IGS meeting LEO requirements.
Close cooperation with the IGS Analysis Center Coordinator is expected.

Call for IGS Analysis Centers (ACs)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
• IGS Analysis Centers (ACs)
- A general call to IGS ACs to develop the capabilities for hourly
  processing.  It is expected that the established ACs will follow
  the agreed upon recommendations of the La Jolla AC Workshop, June
  1999, by developing and demonstrating sub-daily processing.  (See
  IGS Mail Message # 2359 from IGS AC Coordinator, Tim Springer).

Any AC which does not plan to follow these recommendations should send a
message to the IGS AC Coordinator with copies to the IGS Governing Board
Chair and the Central Bureau.

******************************************************************

LETTER OF INTENT

Those organizations interested in submitting a proposal in response to
this Call for Participation should send a one-page non-binding Letter of
Intent, due by February 11, 2000.  The Letter of Intent should state
that you intend to submit a proposal. This letter should be sent to the
IGS Central Bureau:

        Ruth Neilan, Director
        IGS Central Bureau
        Jet Propulsion Laboratory
        M/S 238-540
        4800 Oak Grove Drive
        Pasadena, CA  91109 USA
        Telephone Number:  (818) 354-8330
        Fax Number:  (818) 393-6686
        Email:  [email-masked]

This letter should include the following information:

• Organization name and address
• Name, address, and telephone and fax numbers of the principal point
  of contact
• Specific areas of support which will be addressed in the proposal.

Letters of intent must be received on or before February 11, 2000.
Material in these letters is for information purposes only and is not
binding on the signatories.  Those organizations responding will receive
additional documentation and information in the future.

******************************************************************

GENERAL PROPOSAL INFORMATION

Proposals submitted in response to the Call for Participation must
include specific details on the technical support that will be offered
by the organization and a management plan.  These two main proposal
sections will be used for proposal evaluation and to facilitate
comparative analysis.  Proposal must be signed by an official authorized
to certify institutional support, sponsorship and management of the
proposed activities.

Proposals are due on or before April 3, 2000, at the address provided
above.  The IGS Governing Board reserves the right to consider proposals
received after this deadline if such action is judged to be in the
interest of the IGS; however, there is no guarantee that such late
proposals can be considered.

******************************************************************

PROPOSAL EVALUATION AND SELECTION

The principal elements considered in evaluating any proposal are its
relevance to the IGS objectives, intrinsic merit, and its overall
contribution to the service when compared to  potential contributions
available through other proposals.  In addition to these criteria,
management factors will be considered separately in the selection.

If the IGS Governing Board decides to accept only a portion of the
proposal, the submitting organization will be given the opportunity to
accept or decline such partial acceptance.

Organizations responding to this Call for Participation will be notified
by the Chairman of the IGS Governing Board of the outcome of the
proposal selection process in June 2000.

******************************************************************

SCHEDULE OF IGS LEO ACTIVITY

February 11, 2000    Letters of intent due
February 18, 2000    LEO preliminary standards outline
April 3, 2000        Proposals due
April/May            Evaluation/Selection
Pilot Demonstration  LEO WG will propose dates for one year project
July 26, 2000        Meeting at the Network Workshop in Norway

******************************************************************

PROPOSAL PREPARATION DETAILS

The Proposal should be structured as follows:

- Cover Page (details below)
- Proposal Summary
- Description of Proposed Activities
- Management Proposal
- Financial Arrangements

The Cover Page should contain the following information:

- IGS LEO component referred to
- parent/funding organization
- name and title of authorizing official
- name and title of primary point of contact
- mailing address
- phone/fax/email
- cooperating organizations/institutes
- signatures (the cover page should be signed both by the Authorizing
  Official committing the organization/institution to the IGS
  activity and the primary point of contact involved)

Please send your proposal via postal mail to the IGS Central Bureau at
the above address. For easier distribution to the reviewers, an
additional e-mail version should be made available (in ASCII or attached
Word or WordPerfect file). Please send the email version to
[email-masked].

Proposals should not exceed 15 pages.

******************************************************************

Append:

Map IGS hourly network - available at:
ftp://igscb.jpl.nasa.gov/igscb/resource/hrmap.ps

Map CHAMP mission H/R network - available at:
ftp://igscb.jpl.nasa.gov/igscb/resource/champmap.ps

******************************************************************