IERS Message No. 13

central_bureau at central_bureau at
Tue Aug 21 09:40:35 UTC 2001

IERS Message No. 13                                         August 21, 2001

Invitation to a Reception Honoring
John Bosworth  --- Tom Clark
during the venue of the
IAG Scientific Assembly 2001

Hosted by the IAG Services: IERS, ILRS, IVS, and IGS

Dear colleagues,

In June of this year two people retired from long-held leadership
positions in the development and evolution of space geodesy - John
Bosworth and Tom Clark of NASA's Goddard Space Flight Center.
John was a central figure in the Crustal Dynamics Project and follow-on
activities for the last 20 years. With this retirement he will also be
vacating his position as the first Director of the Central Bureau of the
International Laser Ranging Service and Chair of the CSTG Sites
Tom Clark is widely recognized as the 'Guru' of VLBI, and has an
impressive 32 year involvement in its development. Both Tom and John are
have had influence on GPS: John's pursuing the multi-technique
collocation site ties, and Tom's operations of the GPS equipment at
GSFC, his totally accurate clock (TAC), and phase center measurements of
the GPS antennae. 
An interesting review of their professional careers is planned with your
help. We invite you to attend and if you have a particular memory that
you will share, it will contribute to a memorable evening! Please join

Honors Reception
John Bosworth  --- Tom Clark
Monday, September 3, 20001
6:00 - 9:00 PM

Taverna Hotel - Budapest Rooom
1052 Budapest, Vaci utca 20.
Phone: +361 485 3100
Fax: +361 485 3111

* Excellent Hors D'Oeuvres will be served, cash bar.
* Bring your memories and enjoy an evening with friends.

** Please RSVP ** reply to this message or send a message to
ruth.neilan at with the word 'Reception' in the Subject.

Additional Detail

John Michael Bosworth, Associate Chief of the Laboratory for Terrestrial
Physics and Head of the Space Geodesy and Sensor Calibration Office
(Code 920.1), retired from GSFC on June 1 following almost 40 years of
federal service, all but two years with NASA. Mr. Bosworth was honored
by many individuals or organizations at his retirement dinner on June
12. John had a long and successful career as a Project Manager at
Goddard but is perhaps best remembered for his past two decades of
effort on behalf of space geodesy - first as Deputy Manager under Dr.
Bob Coates, and then later as Manager, of NASA's Crustal Dynamics
Project (CDP). The CDP scored many scientific firsts in making precise
contemporary measurements of tectonic plate motion, regional crustal
deformation, Earth orientation parameters (spin axis orientation and
spin rate or length of day), Earth gravity field, etc. Following the
termination of CDP in 1993 and the movement of space geodetic network
responsibilities to GSFC's Laboratory for Terrestrial Physics, John
retained primary responsibility for the management of NASA's SLR and
VLBI networks and served as head of the CSTG Sites Subcommission and as
the first Director of the International Laser Ranging Service (ILRS)
Central Bureau, which is located at GSFC.

Dr. Thomas Arvid Clark retired from GSFC on June 1, 2001. Tom received
his B.S. in Engineering Physics and his Ph.D. in Astro-Geophysics from
the University of Colorado in 1961 and 1967 respectively. From 1966 to
1968, he served as Chief of the Astronomy Branch at NASA Marshall Space
Flight Center and as Project Scientist on the Spacelab Coronagraph.
Since arriving at GSFC in 1968, Dr. Clark has received numerous NASA
awards for his pioneering work on Radio Astronomy Explorer 1 and 2 and
several generations of Very Long Baseline Interferometry (VLBI) systems.
Since the beginning of the NASA Crustal Dynamics Project in 1979, a
global network of approximately 30 VLBI stations have been used to
define the Celestial reference Frame and to measure global plate
tectonics, Earth orientation parameters, and Universal Time. In recent
years, he developed the Totally Accurate Clock (TAC), an inexpensive GPS
timing receiver that has found widespread use in a number of global
networks. Tom was named a Fellow of the American Geophysical Union (AGU)
in 1991 and a Fellow of the International Association of Geodesy (IAG)
in 1999. Tom was also a pioneer in amateur and digital radio; he
designed and flew several low cost satellites for relaying amateur radio
messages around the globe and is a past president of AMSAT. In May 2001,
he was one of only 50 initial inductees into the CQ Amateur Radio Hall
of Fame, a list which included such engineering luminaries and inventors
as Guglielmo Marconi (radio), Samuel Morse (telegraph), Nikola Tesla (HF
generators and radio), and John Bardeen and William Schockley
(transistor). Dr. Clark has applied for GSFC Emeritus status.

Ruth Neilan & Carey Noll

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