Early Days of VLBI in Space

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Early Days of VLBI in Space

• Bernard F. Burke
• MIT
• Sagamihara 3 Dec 2007

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• 1. Success has many fathers, and the same is
  true of Space VLBI.
• In 1975 Bob Preston presented a paper to
  the AAS on the possibilities of space VLBI, I
  submitted a Proposal to Marshall Space Center for
  a Space Shuttle Experiment, and Leonid Matveenko
  wrote a memo about that time for the Soviet Space
  Program. This started the machinery moving in
  both the USA and in the USSR.
• First steps in the U.S.
• Bobs paper led to no immediate action at JPL.
  He was attached to the Deep Space Network, who
  had little interest in the project. I proposed
  to mount a 10 meter K-band telescope on the Space
  Shuttle, and Marshall Space Center thought it
  might be interesting. Those people thought big,
  and the project was transformed into mounting a
  50-meter telescope on the Shuttle, a dramatic
  thought, even though it would not perform well at
  K-band.

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• The 50-meter project
• Somewhere, lurking in the background, some
  unidentified government agency had an interest in
  such a beast, and the project, supervised by
  Marshall Space Center, took shape. Bob Preston
  joined in Sam Morgan was the MSC leader, and
  Lester Sackett of Draper Lab came in to help with
  the mechanical analysis. The antenna dwarfed the
  shuttle, looking like a big umbrella, and would
  be pointed by orienting the shuttle. It was
  important to get the dynamics right, because the
  large floppy antenna coupled to the shuttle could
  be very unstable. Lester showed that it could be
  done, and over the years of study the project
  began to look good. Then, suddenly, about 1978,
  the shadowy agency that had been supportive, lost
  interest, and over a weekend the project
  vanished.

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• Space VLBI gains interest and support
• Although the fantastic 50-meter umbrella for
  the Space Shuttle was a dead issue, there was now
  a wider group who saw that space VLBI, even from
  the Shuttle with its low orbit, could be
  interesting. VLBI arrays on earth were sparse,
  and the progressive marching of the projected
  baseline family across the earth on successive
  Shuttle orbits could fill the u,v-plane nicely,
  especially at low declinations. Accordingly, in
  late 1978, a proposal was made to NASA to fly a
  3.7-meter dish, for the 1981-1983 missions of
  Spacelab, the experimental module for the
  Shuttle. The proposers were BFB from MIT as PI,
  Alan Rogers and Irwin Shapiro (also MIT), Jim
  Moran (formerly at MIT, now Harvards CfA)
  Marshall Cohen (CalTech), Bob Preston (JPL), Ken
  Johnston (USNO), Ken Kellermann (NRAO), and Tom
  Clark (GSFC).

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5. The Space Shuttle fades, and a free flyer
appears. The project obtained support from
NASA as a study project, with Frank Jordan from
JPL as the Project Manager. It now began to
gain momentum, as the group began to work
seriously. The more explicit the study became,
the lower the level of interest became within the
Spacelab group inside NASA. I think they found
the science too abstract, the engineering too
difficult, and besides they might have been
worried about the safety issue of having a 3.7
meter dish, unfolded from the Shuttle Bay.
Also, it may have cost too much. At any rate, it
eventually became a former Shuttle proposal, one
more failure of the Spacelab to do real science.
By this time, though, there was real momentum
behind the concept, and it morphed into a
free-flying satellite study, based at JPL.
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Frank Jordan was a wonderful source of support
for the project. He understood how both NASA and
JPL worked, and he is a strong scientist in his
own right. He received the Newcomb Medal of the
American Philosophical Society for his
leadership in developing differential VLBI for
spacecraft navigation the whole group worked
well under his guidance. 6. Space VLBI goes
global The international VLBI community was a
very close-knit social organization. There were
no secrets among us (or at least very few) and
we had all worked together that was an essential
part of the VLBI pioneer culture. We knew that
the Soviets were seriously engaged in the early
stages of a space project, led by Leonya
Matveenko and Kolya Kardashev, and in Europe
there was also activity starting, with Richard
Schilizzi being the central figure, along with
many colleagues. Morimoto-san had also
stirred up interest in Japan.
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• 7. The Bologna Symposium
• IAU Symposium No. 110, VLBI and Compact Radio
  Sources, was held in Bologna in the early summer
  of 1983, and it was at this meeting that a
  special gathering was held to explore the
  international possibilities of VLBI in space.
  This, I believe, marks a key moment in the
  development of space VLBI. We all knew that
  international collaborations are complex, that
  science in space is expensive, and that there are
  always delicate negotiations to determine who
  will be the lead agency. We all knew, though,
  that all the large radio telescopes on the ground
  would be essential, and we knew how to work
  together. By that time, we understood what the
  main technical problems would be, and the system
  architecture had reached an advanced stage in
  both Europe and the US.

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• We had been in contact with one another and the
  result was the final paper in the symposium The
  Quasat Project by Schilizzi, Burke, Booth,
  Preston, Wilkinson, Jordan, Preuss, and Roberts.
  This you could call this the ultimate
  post-deadline paper, because it was the result of
  our informal conferences the Quasat mission,
  including its name, was invented at the meeting.
  The author list is made up of those who
  participated in the discussions.
• 8. Getting the agencies involved
• By the close of the Bologna meeting, we had all
  agreed to keep in touch with one another, and to
  start discussions with their various agencies,
  especially their space agencies, to work on the
  next step. NASA and ESA had good channels of
  communication contacting the Soviet authorities
  was not so easy in those days, although there
  were both formal and informal contacts.

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The first order of business was to arrange for a
meeting that would have space VLBI as its
subject. Events moved fast, I think, largely
because ESA and NASA were supportive of the idea.
Charlie Pellerin liked the idea, as did his
counterpart at ESA, Roger Bonnet. At the working
level of the agencies, Henk Olthof and Frank
Jordan were the key actors who made it work.
9. The Gross Enzersdorf Workshop Gross
Enzersdorf is a cozy Austrian town not far from
Vienna, and was chosen as the venue for the
workshop Quasat-- a VLBI Observatory in Space.
On 18 June, 1984, 84 participants gathered from
a wide range of countries many from Europe, the
USA, and Canada, with a significant delegation
from the USSR Sagdeev (director of IKI),
Kardashev, Popov, and Matveenko. Japan was
represented by Morimoto-san.
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The sponsors were the European Science Foundation
and the US National Academy of Science, with the
collaboration of ESA and NASA. The local host
was the Austrian Solar and Space Agency. The
proceedings appeared rapidly, 3 months later, as
ESA publication SP-213. Many papers, both
theoretical and practical, were given. The most
complete presentation was a 92-page description
of both the US and European versions of Quasat.
The 3 brief Soviet papers described a mission
called RACSAS, with a satellite in a dramatic
elliptical orbit, reaching apogee at a million
kilometers, a concept that would return as a
hindrance, not a help, to international
collaboration. The workshop, I would say, was a
huge success, not because Quasat was a success,
because it did not become a mission, but because
it set a general process in motion. We also
enjoyed the fine ambience, and especially the
wine, of Austria.
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10. The Quasat Project The process of converting
international enthusiasm into inter-agency
projects takes time. In the case of Quasat, the
process was relatively smooth. There had been
three years of work, with each agency making its
own studies, but enough interaction so that we
both knew what the other was doing. In 1986, a
more formal step was taken, with ESA and NASA
agreeing to an arrangement where they would work
toward a common goal, an ESA spacecraft with a
NASA scientific package, with the detailed
sharing to be worked out as the project
developed. BFB was the US PI, Frank Jordan was
the PM, and JPL would organize the US part of the
project. Quasat was approved as one of a group
of ESA-approved candidate missions, to undergo
phase-A study with down-selection in 1988. Now
things became real, as significant amounts of
money began to be spent. It was all very
exciting.
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11. RACSAS becomes Radioastron Shortly after the
Gross Enzersdorf meeting, a meeting was held in
Hungary between Soviet and American VLBI people,
with Schilizzi attending, so that the Europeans
would be informed. Their plans for space VLBI
were now becoming more explicit and more public,
the mission was now called Radioastron, and
international collaboration was being invited.
An advisory body, the Radioastron international
steering committee (the RISC) would be convened,
and the official participation of the various
space agencies would be invited. For a while,
the Soviet planning was going faster than the
Quasat effort. Contracts were let with Finland,
ESA, and Australia to build the front ends for K,
C, and L-band, a low frequency LNA to be built in
India, and various elements to be built by
countries within the Soviet bloc. Some of the
meetings were held in exotic places e. g. the
Crimea, and Samarkand.
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I would give Kolya Kardashev and his group high
marks for putting together a collaboration that
had many obstacles in its path. It was agreed
that the meetings would alternate between the
Soviet bloc and the West the invitees would not
be screened by the security people, and only the
invitees would attend. The main US participation
would be for tracking and data acquisition, but
this would be an essential part of the operation.
Information flowed freely, and the operation was
truly collegial. I got to know Roald Sagdeev
well one interesting exchange came when we
discussed Quasat, the parallel project. I asked
why the Soviets did not merge the Radioastron
mission with Quasat. He answered that
theoretically it was a good idea, but the
Europeans didnt have enough money. A prescient
comment. We were able to visit closed institutes
in the USSR Lavochkin, Babochkin, and the
secret 70-m dish in Evpatoria its published
coordinates put it 10 km out in the Black Sea,
even though the US knew its place within a
hundred meters!
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• 12. The TDRSS Experiment
• Toward the close of the Bologna Symposium, Gerry
  Levy of JPL gave a short paper on how the
  Tracking and Data Relay Satellite System (TDRSS)
  might be used as a demonstration experiment for
  space VLBI. Since TDRSS was operated by the Deep
  Space Net (DSN) of JPL and he was part of that
  organization, Gerry was in a good position to
  make that happen. Some of our colleagues were
  most uneasy about the experiment they were
  afraid it might not work, and thus discredit
  Quasat. We all thought differently it will
  work, and will strengthen the case for space
  VLBI. The DSN engineering staff are very good at
  meeting specs. The experiment was carried out in
  1986 and 1987, and it worked! The primary ground
  stations were the DSN 64-meter telescope at
  Tidbinbilla in Austalia and the Usuda 64-meter
  telescope of ISAS in Japan. The experiment was
  complex, because establishing a phase-stable link
  to the TDRSS was not simple, and the skills of
  many were needed

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• The 4.9 m telescope on the satellite was
  balanced by the 64-m telescopes on the ground
  (the effective area was that of a pair of 16-m
  telescopes) the Mark III correlator at Haystack
  worked well, and the experiment was a success.
  Gerry deserves great credit for coordinating a
  great team effort (32 authors from the US,
  Australia, and Japan).
• 13. The Down selection at Darmstadt
• By the time that 1988 came along, the Phase A
  study had made great progress, and we were sure
  that we had a strong position. One bad aspect,
  though, was the price--it was alarmingly high.
  As the shootout at Darmstadt approached, the
  word spread that we didnt stand a chance, and
  the night before, we had a disastrous dress
  rehearsal of our presentation. It was truly
  bad--Charlie Pellerin was pacing up and down
  angrily at the back of the room. Henk Olthof and
  Frank Jordan were slumped down in their chairs,
  as Ken Johnston, acting as the hostile
  prosecutor, ripped each speaker apart.

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• Despond and despair gripped us all. Kens
  destruction was so devastating that we agreed
  that the whole thing had to be totally reworked.
  As I remember it, we decided that a fragmented
  bunch of papers would not do the trick, and
  instead one masterful speaker should present the
  case. The unanimous choice was Peter Wilkinson,
  as I remember. The evening, for Peter
  especially, was not convivial, but he turned out
  to be a stellar spokesman, the best of all the
  competing projects. To universal surprise,
  Quasat survived.
• 14. The Outcome at Bruges
• The final selection came a short time later, at
  Bruges. Quasat was done in by high cost and by
  the desire of Europes planetary community to
  have a space project. Cassini/Huygens was
  chosen, to join NASA on a visit to Saturn and
  drop a probe into Saturns atmosphere.

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• There was still one hope. NASA held a
  competition, in which the ultraviolet telescope,
  FUSE, was the only serious competition. Both
  were excellent missions, but there were thousands
  of stellar astronomers who wanted FUSE, and only
  a handful who wanted Quasat. The politics of
  choosing space missions has a populist tinge, and
  the voice of the multitude was heard. Quasat was
  finished.
• 15. VSOP arises, to become HALCA
• My story ends here, because we have left the old
  times in 1988, to enter new times in 1999.
  Morimoto-san had been the only radio astronomer
  from Japan at Gross Enzersdorf, and his brief
  note, saying that they were studying two
  approaches in Japan, but detailed analyses of
  missions still remain to be done. That was only
  the beginning, for our Japanese colleagues
  continued to study progress in the US, Europe,
  and the USSR.

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VSOP appeared as a real mission gradually, and
that story must be told by our Japanese
colleagues. In my notes for a meeting held 15
February 1989, involving Nishimura, Oda, Mishima,
Hirabayashi, Kobayashi, Tanaka, Takano, Hirosawa,
and Morimoto on the Japanese side, and Joel
Smith, Bob Brown, Jordan, Wilshire, and BFB,
Nishimura-san said that the MV rocket decision
was a few months away, and the budget approval
would be given next year that would be when
formal approval would be given. We had heard
that launch might be in 1993, but at this meeting
the launch date was given as 1994 or 1995. I
must make one comment as an American observer.
Charlie Pellerin was in charge of NASA
astrophysics, and he had been mightily impressed
by the Japanese ability to mount missions within
budget and on time, with very modest budgets.
The NASA support depended heavily on Charlie.
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At VSOP Launch
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16. A Last Word At Gross Enzersdorf, Frank
Jordan showed a wonderful computer animation,
starting with the Quasat orbit, showing baselines
to the main ground stations, and then the growth
of uv coverage. Then the movie showed the Quasat
orbit again, much reduced in scale, and suddenly
a small red dot appeared, coming in from a much
higher apogee. That was, of course, Radioastron.
The baselines then were shown, and finally the
growth of uv coverage. The movie was a hit, and
Peter in his wonderful sales pitch at Darmstadt
used it again, to great effect.
Radioastron, at the moment, is going its own way,
with an orbit that no foreign observer likes. It
would be a marvelous thing if Radioastron could
reconsider its singular orbit, and choose an
orbit that would complement and
supplement VSOP-2. Our Russian colleagues would,
I am sure, be applauded by all.
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