Project
Manager's Corner: The Next Steps
Gary
Sanders
The
figure shows four copies of TMT on a mountain summit. This arrangement
evokes the placement and setting of the two Keck telescopes in
the Keck Interferometer on Mauna Kea, or the striking array of
four unit telescopes that the European Southern Observatory operates
on Cerro Paranal as the VLTI. These are powerful interferometric
tools for astronomy. The figure suggests a TMTI, a stupendous combination
of four TMT telescopes providing amazing resolution capability.
Alas, while visually exciting, a TMTI would be prohibitively expensive.
The figure, courtesy of M3
Engineering, actually represents something
more mundane but still very important. It is a trade study comparing
four arrangements of summit buildings with varying facility arrangements
and roof heights, placed next to our enclosure with its ventilation
openings. It is input to aerodynamic modeling of the flow across
these structures. What is notable about this is that it marks a
kickoff of the next, and more detailed, phase of TMT design.
Read
more...
TMT Science Workshop
Planning
has begun for a 3-day workshop on "Science
in the Era of TMT" to be held this summer. The workshop
will bring together scientists from the TMT partner countries
and around the world to share and develop concepts and
ideas for science programs enabled by extremely large
telescopes. The workshop will be held at the Beckman
Center on the campus of the University of California
at Irvine, July 23-25. Further details will be posted
on the TMT website. |
|
Science
Nugget—Unveiling a
Supermassive Black Hole at the Center of Our Galaxy
Astronomers
are presently closing in on proof that one of the most enigmatic
objects in our Universe - a supermassive black hole - lurks at
the heart of our own galaxy, the Milky Way. Over the last decade,
near-infrared diffraction-limited imaging with 10 meter class
telescopes has revealed that several of the stars near the Galactic
center (GC) are moving on elliptical trajectories with velocities
as large as 12,000 km/sec, a few percent the speed of
light (see Figure 1). These motions can only be explained if the
stars are orbiting a central dark mass 4 x 106 times more massive
than the Sun, confined within a volume only 45 AU on a side. These
measurements provide the most definitive evidence for the existence
of a supermassive black hole (BH), not only at the center of our
galaxy, but more broadly of any galaxy in our Universe (Ghez et
al. 2003, 2005; Schodel et al. 2002, 2003). Because the center
of the Milky Way is 100 times closer than the next closest galaxy,
the GC presents a unique opportunity to study a supermassive BH
and its environs in much more detail than is possible in any other
galaxy.
Read more...
Technology
Nugget—Controlling all those Segments, Part 2:
Sensors
In
the previous
edition of Technology Nugget we introduced the complex
system responsible for maintaining the overall shape of the TMT
primary mirror which consists of 492 segments. We call segment
assembly with three actuators (illustration)this system the M1
Control System (M1CS) and it consists of 1,476 actuators, 2,772
sensors, thousands of electronic assemblies, and many sophisticated
control algorithms (software). The system that is used to determine
the proper "set-points" for the M1CS using starlight
is known as the Alignment and Phasing System (APS). We can think
of the M1CS as a system that "stabilizes" the 492 mirror
segments and the APS as the system that "aligns" the
492 segments by determining the set-points for use by the M1CS.
In particular, last month we described the actuators that are responsible
for moving the segments. In this edition of Technology Nugget we
will discuss the M1CS edge sensors. The edge sensors provide very
precise measurements of the height differences between adjacent
segments.
Recall
from our discussion on actuators that motions within the plane
of each segment are minimized passively by a complex structure
called a Segment Support Assembly (SSA). The remaining out-of-plane
motions of each segment are controlled by three actuators symmetrically
positioned so as to enable motion of piston, tip, and tilt. The
sensor height measurements and the "set-points" determined
by the APS are utilized by a software control algorithm to generate
actuator commands. The actuator commands are calculated to position
the 492 individual segments so as to imitate a nearly perfect monolithic
mirror.
Read more...
Q & A
with Chuck Steidel
Chuck Steidel is the DuBridge Professor of Astronomy at Caltech,
and has been involved in thinking about science and instruments
for 30m telescopes since 1998; he has served as one of the co-chairs
of the Science Advisory Committee for TMT since the beginning of
the project.
Chuck sat down for an interview with Doug Isbell recently to discuss
the TMT's exciting potential breakthroughs in the understanding
of galaxy formation and evolution.
Download
Chuck Steidel Interview [11:09 min. 10.2 MB MP3]
Focus On - Europe Moves Forward
Our European colleagues are not idle. Indeed, they have just taken
a major stride towards their own extremely large telescope (ELT).
We pointed to news coverage of the start of their project design
(Europe
plans giant eye on the sky) and (Extremely
Large Telescope could reveal secrets of life, the universe and
everything) in our
August Newscast. We were particularly pleased to see many potential
design features that were similar to features of TMT, and we have
looked forward to cooperative development and communication. Now
Europe has moved farther and completed several steps leading to
a design concept that will guide their next steps in development.
See The
Rise of a Giant; ESO Council Gives Green Light to Detailed
Study of the European Extremely Large Telescope.
Partner News
TMT Partner, AURA, Steps Back from TMT and Takes on a New Role
in our Program
The
original TMT partnership was formed between University of California,
Caltech, the Canadian ACURA consortium, and AURA. AURA provided
access to TMT for the US publicly funded astronomy community.
With the release of the NSF Division of Astronomy Senior
Review in October, NSF has asked AURA to take on a new role. NSF has asked
that AURA/NOAO act as NSF's "Program Manager" for the
GSMT Technology development effort at a national level in a manner
similar to the role played by NASA's major Centers for the development
and operations of various space missions. For those of you who
do not follow the acronyms in this field, GSMT stands for Giant
Segmented Mirror Telescope, a generic label used for any very large
telescope being designed to fulfill the goals of the 2001 decadal
survey of astronomy. There are two such programs in the US, the
Carnegie Observatories GMT project, and our own TMT. AURA has been
a partner in TMT, but has supported NSF in managing the parallel
and balanced funding by NSF of both projects. Under the new arrangement,
AURA will take a more management oriented role, coordinating the
continuing support by NSF of both projects. TMT looks forward to
continuing to work closely with AURA and NSF to define the TMT
technology base and design and we appreciate the continued support
of NSF in fulfilling important national needs.
Previous
Issues
View
the TMT Newscast
Archive. |