Code UG Weekly Notes 12-12-01

Physical Sciences Division
Weekly Highlights for Week Ending 12/12/2001

*** Indicates item is appropriate for the HQ senior staff and may appear
on the OBPR Web site: http://spaceresearch.nasa.gov

GENERAL

*** POOL BOILING EXPERIMENT IN DISCOVER MAGAZINE: An article on the Pool
Boiling Experiment is featured in the December 2001 issue of DISCOVER
magazine (page 13). Recently released images of boiling in space and earth
were provided by the Project Scientist, Francis Chiaramonte, who was interviewed
for the article. The article describes how bubbles do not rise, but rest
"listlessly atop the heated surface" when boiling in space.
The Principal Investigator was Professor Herman Merte at the University
of Michigan and the hardware was designed, built and tested by an engineering
team at the NASA Glenn Research Center. The Pool Boiling Experiment was
flown on 5 separate Shuttle missions from 1992 to 1996.

*** FLUID PHYSICS PI ELECTED FELLOW OF ASME: Professor Paul Neitzel (Georgia
Tech), fluid physics PI and discipline working group chair, was recently
elected Fellow of the American Society of Mechanical Engineers (ASME).
Pro. Neitzel has achieved a solid record of accomplishments in educating
undergraduate and graduate students in mechanical engineering, research
in the area of fluid flow in microgravity fields and service to the engineering
community through his extensive contributions to NASA committees. He is
recognized as a creative teacher who spends his time helping his graduate
students attain the high goals that he sets. He publishes only the highest
quality papers in the most prestigious journals. He has volunteered his
time to a number of committees and through this service commitment has
had a large role in directing the scientific content of our future space
effort.

SHUTTLE FLIGHT PROGRAM

COLLISIONS INTO DUST EXPERIMENT-2: COLLIDE-2, a Hitchhiker payload on
STS-108, should have been completed autonomously based on a preset time
line with barometric switch powering the payload. Since there is no data
down link we won’t know much about COLLIDE-2 operations until the shuttle
returns, we did get confirmation that the crew turned COLLIDE-2 BACKUP
PWR – ON 01/03:01:49 MET. The launch delay did shift the crew sleep cycle.
Assuming a nominal baroswitch power-on and the 14 hour timer, the crew
wake-up time coincided exactly with the start of the COLLIDE-2 experiment.
COLLIDE-2 takes 28 minutes to complete.

ISS FLIGHT PROGRAM

MICROGRAVITY RESEARCH PROGRAM OFFICE (MRPO) PAYLOAD OPERATIONS STATUS
ON THE INTERNATIONAL SPACE STATION (ISS) UF1 STAGE: A successful launch
of ISS Flight UF1 took place on 12/5/01. Joint Operations for Increment
4 are now in progress. MRPO payloads dealing with experiments on cell
science, structural biology and plant growth have been transferred to
the ISS. No problems have been encountered to date. Crew attended operations
will be curtailed during the week of 12/9/01 (approx. 6 hrs) due to preparations
for an EVA on 12/10/01, and transfer operations from the Shuttle and Progress.
Undocking of STS-108 is currently scheduled to occur on 12/14/01.

PHYSICS OF COLLOIDS IN SPACE (PCS) ON ISS: A wide variety of measurements
were carried out during EXPPCS’ 120 hrs of operations last week. We attempted
a novel technique for probing the properties of the colloid-polymer critical
point sample to possibly yield information about the interfacial tension
between the de-mixing phases. This measurement involves rotating the sample
to set up a shear, then stopping the motion and taking a time lapse movie
of the sample as it comes back into stationary equilibrium. Also, we continued
to measure the aging of the colloid-polymer gel sample using long low
angle dynamic light scattering, and performed routine monitoring of the
binary colloidal crystals and glass samples. Finally, some measurements
were performed on the slow (polystyrene) fractal gel sample, which has
not had the salt added as of yet (and is therefore not a gel yet), to
prepare for the combining of the salt and colloid which is planned for
January.

Studies during the previous week were aimed at early stages of aging
of the colloid-polymer gel sample. Once the gel network spans the sample
cell and the fluid no longer flows (i.e., gelation is complete), aging
of the gel occurs. Aging refers to the evolution of the gel’s structure
and to its internal motions during that time. This gelation and aging
scenario is much like the hardening of jello here on Earth – it takes
time for the gel structure to set up, and then a little later on the gel
network has become stiffer (it has aged). The study of aging of gels and
viscoelastic fluids attempts to understand how small stresses built in
during formation relax over time. This type of behavior has been observed
in a variety of "soft" systems including gels, compressed emulsions,
multilamelar micelles and complex viscoelastic fluids. The changes in
the structure of the gel during aging are either too miniscule in amplitude,
or are on length scales too long to observe with static scattering – but
the motions of the network are detectable with Low Angle Dynamic (LAD)
light scattering. As the aging process proceeds, the speed of these motions
slows. Interestingly, the colloid-polymer gel is exhibiting behavior very
similar to what is expected to be observed from the fractal gels when
they are studied in Increment 4.

SCIENCE HIGHLIGHTS

CROSS DISCIPLINE:

FLUID PHYSICS:

FLOW VISUALIZATION IN EVAPORATING LIQUID DROPS AND MEASUREMENT OF DYNAMIC
CONTACT ANGLES AND SPREADING RATES: Principal Investigator, N. Zhang,
OAI, and Co-Investigator, D. F. Chao, GRC, reported that a new hybrid
optical system, consisting of reflection-refracted shadowgraphy and top-view
photography, is used to visualize flow phenomena and simultaneously measure
the spreading and instant dynamic contact angle in a volatile-liquid drop
on a nontransparent substrate. Themocapillary convection in the drop,
induced by evaporation, and the drop real-time profile data are synchronously
recorded by video recording systems. Experimental results obtained from
this unique technique clearly reveal that thermocapillary convection strongly
affects the spreading process and the characteristics of dynamic contact
angle of the drop. Comprehensive information of a sessile drop, including
the local contact angle along the periphery, the instability of the three-phase
contact line, and the deformation of the drop shape is obtained and analyzed.
It has been found that evaporation can induce Marangoni-Bénard
convection in sessile drops. The fluid flow in the drop is attributable
to the surface-tension mechanism from local variations in the surface
temperature. The effect of convection in the drop on the wetting and spreading
processes, however, is not clear. Flow in a small sessile drop takes place
on a microscopic scale and cannot be viewed by eye. Optical methods are
the only non-intrusive means of visualizing flow in small fluid volumes.
Both the Schlieren method and Mach-Zehnder interferometry, however, are
unsuitable for visualizing flow motion in an evaporating sessile drop.
By using the proposed Laser Shadowgraphic method, the whole periphery
of the drop can be viewed simultaneously and instantaneous drop size,
including the contact diameter, the maximum height of the drop, and volume-time
history, can be determined. The equations for calculating the contact
angle and rate of evaporation of the drop are readily derived. These results
were published in the following paper:
N. Zhang and D. F. Chao, "Flow Visualization in Evaporating Liquid
Drops and Measurement of Dynamic Contact Angles and Spreading Rates,"
Journal of Flow Visualization and Image Processing, Vol. 8, No. 2&3,
November 2001, pp. 303-312.

COMBUSTION SCIENCE:

*** FIRE SAFETY ARTICLE IN THE NEW MEXICAN NOVEMBER 27, 2001: Future
spacecraft might one day be equipped with laser-based fire detectors developed
right here in Santa Fe. Southwest Sciences, Inc., caught the attention
of NASA scientists when it proposed building a more sensitive and reliable
fire alarm that uses the same diode lasers found in CD players and other
common devices. The lasers are simple, dependable and cheap, and the concept
is fairly simple, says Alan Stanton, Southwest Sciences co-founder and
president.

Each gas is unique in the way that it absorbs small quantities of light.
Once you know which gases are present during fires, you can determine
what kind of light wavelengths, or colors, those gases absorb. Then you
should be able to set up a laser and a device that measures just how much
and what kind of light is being absorbed to see if these gases are present.

"The trick," Stanton said Monday, "is trying to do that
with very high sensitivity, very high accuracy."

The National Aeronautics and Space Administration awarded Southwest Sciences
a $600,000 grant to figure out a way to do just that. If all goes well,
NASA might employ the new fire detectors in its space program. They could
also be used in large office buildings, Stanton said, but will likely
be too expensive for average homeowners.

The Johnson Space Center in Houston administered the grant through the
Small Business Innovation Research Program, according to U.S. Rep. Tom
Udall, D-N.M., who announced the grant on Monday. Udall credited the program
with helping spur the economy by providing much-needed capital investments
to help small companies pursue new products and technologies.

The funds are intended to promote new products, which individual companies
can then commercialize. The two-year grant is the second NASA has awarded
Southwest Sciences; the first phase funded a feasibility study for the
laser technology.

Stanton said he believes the laser technology could make fire detection
much more of a science. The lasers would measure for various kinds of
gases, making false alarms less common, while at the same time speeding
up actual detection.

Carbon dioxide, for instance, is in the air at all times. Its constant
presence would allow for constant performance checks, Stanton said, but
sudden increases would indicate a fire. Carbon monoxide (CO) is more common
when fires smolder, meaning the device could detect fires before they
actually start.

"There might not be an open flame, but just slowly burning, smoldering
fires are likely to produce CO," he said.

Other gases would not be present without fire, Stanton explained. Gases
such as acetylene and hydrogen cyanide are produced when plastics burn,
meaning that any significant level of these gases would indicate a fire.

Stanton and partner Joel Silver moved from Massachusetts to Santa Fe
and set up Southwest Sciences about 15 years ago. Today, the company employs
about 12 people to develop new technologies, which are then licensed for
manufacturing and development through other companies.

Southwest Sciences used similar laser technology in developing a way
to measure trace amounts of water vapor. Stanton said the company then
licensed the technology to measure moisture in gases that are used to
manufacture semiconductors and computer chips.

"Our approach is not to turn ourselves into a manufacturing company,
but instead to license our technology to other companies that would be
our commercial partners and would actually do the manufacturing and selling
of our components," Stanton said.

QUANTITATIVE DETECTION OF COMBUSTION SPECIES USING ULTRA-VIOLET DIODE
LASERS: The objective of this Phase II SBIR, led by J. Pilgrim of Southwest
Sciences, is the development of a robust, wavelength-agile, tunable, sensitive
system for quantitative gas sensing based on diode laser technology, and
to use this system with blue or ultraviolet diode lasers for the detection
of radical species in microgravity combustion experiments. A Tech Brief,
"Wavelength-Agile External-Cavity Diode Laser," appeared in
the November 2001 issue of NASA Tech Briefs magazine. This Tech Brief
is selected as Photonics Brief of the Week (http://www.ptbmagazine.com/articles/brief_of_week.html).
A prototype wavelength-agile external-cavity diode laser (ECDL) is developed
and demonstrated as part of an effort to develop noninvasive laser-based
instruments that would measure absolute concentrations of trace gases.
As envisioned, these instruments would offer a combination of high sensitivity,
versatility, large bandwidth, long-term stability, accuracy, and reliability
– attributes that would make them attractive for use in research on combustion.
The measurement principle implemented in the developmental instruments
is that of wavelength modulation spectroscopy (WMS). ECDLs are useful
for detecting trace gases by WMS because their wavelength-tuning ranges
are greater than those of diode lasers alone, allowing improved opportunities
to match a molecular resonance with an accessible laser source. In prior
ECDLs, wavelength modulation is affected by using piezoelectric actuators
to translate laser optics. This mechanical translation approach limits
achievable modulation frequencies to a few kilohertz, whereas frequencies
of tens or even hundreds of kilohertz are needed to enable the use of
high-sensitivity detection techniques in WMS. In addition, prior commercially
available ECDLs include complex and expensive optical components. The
present prototype ECDL is simple and inexpensive, relative to prior commercial
ECDLs. Its design combines the stability of an external cavity laser with
the wavelength agility of a diode laser. Wavelength tuning and modulation
are done electronically, with the cavity resonance stabilized through
a feedback control. This allows the much higher tuning and modulation
rates that are needed for WMS. The diode laser in the prototype ECDL is
of a room-temperature ultraviolet type that has recently become commercially
available. However, the design principle is just as well adaptable to
other diode lasers, effectively making a wide range of diode lasers into
tunable lasers at minimal cost. The feasibility of the developmental instruments
has been demonstrated by using the prototype wavelength-agile ECDL as
the source of light in a prototype WMS spectrometer for measuring concentrations
of CH radicals in laboratory flames.

TUNABLE ULTRAVIOLET LIGHT SOURCE FOR COMBUSTION EXPERIMENTS: This research
is being led by Daniel B. Oh and Kristen A. Peterson of Southwest Sciences,
Inc.. A Tech Brief, "Tunable Ultraviolet Light Source for Combustion
Experiments," appeared in the November 2001 issue of NASA Tech Briefs
magazine. The researchers developed a light source that comprises a tunable
diode laser and associated optics to provide the optical excitation needed
for simultaneous wavelength-modulation absorption spectroscopy (WMS) and
laser induced fluorescence (LIF) measurements in experiments on combustion.
These measurements are needed for determining the spatially and temporally
resolved concentrations of molecular and radical species that play important
roles in flames. Other uses for measurements of this type could include
general detection and quantification of trace gases in the atmosphere,
including toxic gases emitted by industrial facilities. In comparison
with prior ultraviolet lasers and with prior WMS and LIF instruments,
this light source and the developmental instruments are compact and rugged
and consume less power. As a result, these instruments are expected to
be suitable for use not only in laboratories, but also in diverse harsh
environments, including drop towers, aircraft, and spacecraft.

FUNDAMENTAL PHYSICS:

FLIGHT INVESTIGATOR DESCRIBES OBJECTIVES AT HOME AND ABROAD: David Goodstein
of Caltech, a flight investigator in the Fundamental Physics program,
has presented the objectives of his experiment at two recent invited talks.
His CQ experiment studies how a heat current changes properties of liquid
helium near a phase transition called the lambda transition. He traveled
a third of the way around the world to present an invited talk at the
Quantum Fluids and Solids Conference in Germany, "The CQ Experiment:Enhanced
Heat Capacity of Superfluid Helium in a Heat Flux". Back at Caltech,
he talked about "A dynamic new look at the lambda transition"
at the weekly Caltech Physics Colloquium in Pasadena.

THEORETICAL PAPER DESCRIBES A NEW PHASE TRANSITION IN AN ULTRA-COLD GAS:
A group led by Pierre Meystre of the University of Arizona has showed
new results of a calculation describing a gas of very cold atoms. In "Ferromagnetism
in a lattice of Bose condensates" the authors show that an ensemble
of spinor Bose-Einstein condensates confined in a one-dimensional optical
lattice can undergo a ferromagnetic phase transition, and spontaneous
magnetization arises due to the magnetic dipole-dipole interaction. This
phenomenon is analogous to ferromagnetism in solid state physics, but
in this case it occurs with bosons instead of fermions. The citation for
this paper is Pu, H., Zhang, W., and Meystre, P., Physical Review Letters
87, 140405 (2001).

THEORY DERIVES PARAMETERS OF RELATIVITY THEORY: Two Russian physicists
working for Project SEE (Satellite Energy Exchange) in the Fundamental
Physics ground research program have succeeded in using what is known
as "brane theory"–which is a generalization of "string
theory"– to calculate the values of some parameters that describe
the difference between Einstein’s theory of general relativity and other
theories that are similar. These parameters are the "Parameterized
Post Newtonian" (PPN) parameters beta and gamma. The PPN scheme was
worked out 30 years ago by physicists Ken Nordtvedt, Kip Thorne, and Clifford
Will to describe the departures from general relativity that might be
observable from experiments in the solar system if Einstein’s theory is
not quite right. This is the first calculation of any of the PPN parameters
from brane theory. This new result is a major step toward testing which
classes of brane theory are consistent with experimental evidence.

The Russian physicists who obtained this result are Vitaly Melnikov and
Vladimir Ivashchuk. Prof. Melnikov, the president of the Russian Gravitational
Society, presented an invited talk at the 2000 Fundamental Physics investigator
workshop.

Citation for this work:
V.D. Ivashchuk, V.S. Manko, & V.N. Melnikov, "PPN Parameters
for General Black Hole and Spherically Symmetric p-Brane Solutions",
Gravitation & Cosmology v.6 No.3 (23), pp. 219-224 (2001).

ATOMIC CLOCK TEAM AT HARVARD-SMITHSONIAN TEST RELATIVITY THEORY: Ronald
Walsworth and colleagues at the Harvard-Smithsonian Center for Astrophysics
recently reported their use of atomic hydrogen masers to perform the most
stringent test to date of Lorentz symmetry of the proton. I.e., the researchers
showed that the physics of the proton is symmetric under rotation. In
a recently published paper, the authors present a new measurement constraining
Lorentz and Charge-Parity-Time (CPT) symmetry violation of the proton
using a hydrogen maser double resonance technique. A search for hydrogen
Zeeman frequency variations with a period of the sidereal day (23.93 h)
sets a limit on violation of Lorentz and CPT symmetry of the proton at
the 10-27 GeV level, independent of nuclear model uncertainty, which improves
significantly on previous bounds.

The paper reporting this test was published in Physical Review D, vol.
63, p. 111101 (2001).