National Public Radio host Robert Siegel
speaks with Julie Robinson, International Space Station program
scientist, about the Legos, roundworms and squid embryos riding
along on the Space Shuttle Endeavour's last mission to space.
The shuttle program is being discontinued. Monday's launch of
Endeavour is the second-to-last space shuttle voyage.
LMM Status
March 28, 2011 - Operations were successfully completed for the
6 samples sent up on ULF-5.
The c. elegans understudy expresses
a fluorescent gene which provides an excellent means for
monitoring gene expression and protein localization. Processes
Ground data shown above.
February 2011 - The biological samples for the LMM launched on space
shuttle Discovery's STS-133 mission on Feb. 24. They include eight
fixed slides containing yeast; bacteria; a leaf; a fly; a butterfly wing;
tissue sections and blood; six containers of live C. elegans worms,
an organism biologists commonly study; a typed letter "r" and
a piece of fluorescent plastic.
Video of live C. elegans worms viewed through
the Light Microscopy Module on the ISS.
Overview
The Light Microscopy Module (LMM) is planned as a
remotely controllable on-orbit microscope subrack facility, allowing
flexible scheduling and control of physical science and biological
science experiments within the GRC Fluids Integrated Rack (FIR) on
the International Space Station.
Within
the FIR, an initial complement of four fluid physics experiments will
utilize an instrument built around a lightmicroscope. These experiments
are the "Constrained Vapor Bubble" experiment (Peter C.
Wayner of Rensselaer Polytechnic Institute), the "Physics of
Hard Spheres Experiment–2" (Paul M. Chaikin of Princeton
University), the "Physics of Colloids in Space–2" experiment
(David A. Weitz of Harvard University), and the "Low Volume Fraction
Entropically Driven Colloidal Assembly" experiment (Arjun G.
Yodh of the University of Pennsylvania). The first experiment investigates
heat conductance in microgravity as a function of liquid volume and
heat flow rate to determine, in detail, the transport process characteristics
in a curved liquid film. The other three experiments investigate various
complementary aspects of the nucleation, growth, structure, and properties
of colloidal crystals in microgravity and theeffects of micromanipulation
upon their properties. Key diagnostic capabilities include video microscopy
to observe sample features including basic structures and dynamics,
thin film interferometry, laser tweezers for colloidal particle manipulation
and patterning, confocal microscopy to provide enhanced three-dimensional
visualization of colloidal crystal structures, and spectrophotometry
to measure colloidal crystal photonic properties. In addition to using
the confocal system, biological experiments can conduct fluorescence
imaging by using the fiber-coupled output of the Nd:YAG laser operating
at 532-nm, the 437-nm line of a mercury arc, or appropriate narrow-band
filtering of the FIR provided metal halide white light source.
The LMM concept is a modified commercial research
imaging light microscope with powerful laser-diagnostic hardware and
interfaces, creating a one-of-a-kind, state ofthe-art microscopic
research facility. The microscope will house several different objectives,
corresponding to magnifications of 10´, 40´, 50´,
63´, and 100´. Features of the LMM include high-resolution
color video microscopy, brightfield, darkfield, phase contrast, differential
interference contrast (DIC), spectrophotometry, and confocal microscopy
combined in a single configuration. Sample manipulation techniques
also integrated with the diagnostics are laser tweezers. The LMM provides
an enclosed workarea called the auxiliary fluids container (AFC) with
gloveports and an equipment transfer module (ETM) for transporting
experiment samples from stowage to the LMM. The multiport imaging
head on the top of the microscope provides a motorized slider to select
the sensor or sensors to which the images are directed. The AFC is
fastened to the microscope body and is sealed to provide a clean working
space and one level of containment. Gloveports allow access to the
sample area for cleaning before opening the box and experiment sample
changeout or reconfiguration. The ETM can be configured to support
various experiment modules and is located below the AFC which has
a pass-through for the samples. Materials are thus transferred without
the risk of contamination release. The ETM will be loaded with experiment
modules on the ground, and will provide contained storage until the
samples are utilized in the experiment.
Laser Tweezers
Laser tweezers will be implemented using a custom-built
system based upon a 1064-nm Nd:YAG laser, beam-focusing optics, and
two acousto-optic deflectors to steer the trap within the field of view
of the microscope. Laser tweezers simply is the trapping of a colloidal
particle using radiation pressure by focusing a laser beam through a
high-numerical aperture lens and striking the particle. Laser tweezers
will be used to measure the viscosity and viscoelasticity of the fluid.
A particle will be trapped and oscillated at a fixed frequency. When
this is done, the centroid of the trap and particle will not coincide;
the difference in the two positions through the scan provides the driving
force. Using that information along with the motion, both linear and
nonlinear viscoelastic properties can be computed.
Confocal Microscopy
Confocal microscopy will be implemented using a
532-nm frequency-doubled Nd:YAG laser, a confocal scanner, and an 8-bit
digital CCD camera. The scanner will allow 30 frames per second of confocal
images to the CCD camera. The crystal's three-dimensional structure
is reconstructed by assembling the slices with an image analysis program,
from which colloidal growth, structure, and dynamics can be measured.
The confocal module will be attached and aligned to the side of the
LMM and will access the sample through an auxiliary port on the Leica
RXA. The microscope’s reflected light turret will contain a reflecting
mirror to direct the light to and from the sample.
The engineering, design, and development of the LMM is being performed
under NASA contract NAS3-99155 (Federal Data Corporation).
Live C. elegans worms viewed through
the Light Microscopy Module on the ISS.
Picture of OptiCell container loaded with the STS-107 worm descendants
for flight on STS-133
LMM/CVB
Qualification Model #2
Brightfield
image of colloid particles manipulated by laser tweezers.
The particles
are dyed with rhodamine in order to make them visible for confocal
fluorescence microscopy. About 100 image slices are combined to
determine the particle positions in a volume.
Contacts at NASA Glenn Research Center Project Manager:Ronald
J. Sicker, NASA GRC Ronald.J.Sicker@nasa.gov 216-433-6498 Project Scientist: Dr.
David F. Chao, NASA GRC David.F.Chao@nasa.gov 216-433-8320 Principal Investigator: Prof.
Peter C. Wayner, Jr., Rensselaer Polytechnic Institute wayner@rpi.edu
