A Terrier-Improved Malemute sounding rocket. Credits: NASA Wallops
A NASA rocket mission, launching May 26,
2021, will study radio waves that escape through the Earth’s ionosphere
impacting the environment surrounding GPS and geosynchronous satellites, such
as those for weather monitoring and communications.
Launching from NASA’s Wallops Flight Facility, a
Terrier-Improved Malemute suborbital sounding rocket will carry the Vlf
trans- Ionospheric Propagation Experiment Rocket,
or VIPER. The mission is scheduled for 9:15 p.m., Wednesday, May 26. The launch
window is 9:15 p.m. to midnight EDT and the backup days are May 27-28. The
launch may be visible in the mid-Atlantic region.
VIPER is studying very low frequency radio, or VLF,
waves that are produced by both natural (e.g. lightning) and artificial means.
During the day these waves are trapped or absorbed by the Earth’s ionosphere.
At night, however, some of the waves escape through the ionosphere and
accelerate electrons in the Van Allen Radiation Belt.
“At night, the lower layers of the ionosphere are much
less dense, and more of the VLF can leak through, propagate along the Earth's
magnetic field lines, and end up interacting with the high energy electrons
trapped in the Van Allen Radiation Belts,” said Dr. John Bonnell, the project’s
principal investigator from the University of California, Berkeley.
“Those belts of intense energetic electron fluxes
cover a range of distances from the Earth, from as close as 14,300 miles
altitude (~4.4 Earth radii) out to 23,500 miles altitude (~7 Earth radii). GPS
satellites orbit at around 4.4 Earth radii, and geosynchronous satellites at
about 6.6 Earth radii. So, satellites in those orbits are often engulfed by the
Van Allen Radiation Belts and have to tolerate the effects those energetic
particles have on electronics and materials,” said Bonnell.
In addition to the in-situ measurements made by VIPER
as it flies through the area of interest, the mission also will employ numerous
ground-based systems, including those in Maine, North Carolina, Georgia,
Colorado and Virginia.
This plot shows altitude
profiles of VLF absorption, proportional to the local plasma density times the
electron-neutral collision frequency. The blue profiles show the nighttime
conditions relevant for VIPER, and the red profiles show daytime conditions.
Credits: University of
Colorado Boulder/Robert Marshall
By making accurate measurements of the VLF electromagnetic fields
and the properties of the ionosphere below, at, and above the absorption and reflection
layers in the ionosphere, VIPER provides a novel data set for comparison with
existing numerical models of the fields and the ionosphere, as well as
observations made in the past of the escaping VLF radiation at higher altitudes
and on the ground.
“It was surprising to find that while lots
of ground-based and orbital observations of the VLF
absorption/reflections/transmission had been made, there's not been any
measurements right in the region where all the action happens. While we
have good models of what to expect in such regions, actual measurements
are key to pin down the details of those models, as well as to develop the
instruments required to explore more challenging regions,” said Bonnell.
The two-stage Terrier-Improved Malemute rocket will
carry the VIPER payload to an altitude of about 94 miles before descending and
landing in the Atlantic Ocean. The payload will not be recovered.
A NASA team has found that organic salts are likely present on Mars. Like
shards of ancient pottery, these salts are the chemical remnants of organic
compounds, such as those previously detected by NASA’s Curiosity rover. Organic
compounds and salts on Mars could have formed by geologic processes or be
remnants of ancient microbial life.
Besides adding more evidence to the idea that there once was organic matter
on Mars, directly detecting organic salts would also support modern-day Martian
habitability, given that on Earth, some organisms can use organic salts, such
as oxalates and acetates, for energy.
“If we determine that there are organic salts concentrated anywhere on
Mars, we’ll want to investigate those regions further, and ideally drill deeper
below the surface where organic matter could be better preserved,” said James M. T. Lewis, an organic geochemist
who led the research, published
on March 30 in the Journal of Geophysical Research: Planets. Lewis is based at
NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Lewis’s lab experiments and analysis of data from the Sample Analysis at
Mars (SAM), a portable chemistry lab inside Curiosity’s belly, indirectly point
to the presence of organic salts. But directly identifying them on Mars is hard
to do with instruments like SAM, which heats Martian soil and rocks to release gases
that reveal the composition of these samples. The challenge is that heating
organic salts produces only simple gases that could be released by other
ingredients in Martian soil.
What do you do if you
have a sample from another planet, and you want to find out if it contains a
certain molecule...maybe even one that will reveal whether the planet can
sustain life? When scientists face a situation like this, they use an amazing
tool: the mass spectrometer. It separates out materials, allowing scientists to
look very closely at a sample and see what's inside.
However, Lewis and his team propose that another Curiosity instrument that
uses a different technique to peer at Martian soil, the Chemistry and
Mineralogy instrument, or CheMin for short, could detect
certain organic salts if they are present in sufficient amounts. So far, CheMin
has not detected organic salts.
Finding organic molecules, or their organic salt remnants, is essential in
NASA’s search for life on other worlds. But this is a challenging task on the
surface of Mars, where billions of years of radiation have erased or broken
apart organic matter. Like an archeologist digging up pieces of pottery,
Curiosity collects Martian soil and rocks, which may contain tiny chunks of
organic compounds, and then SAM and other instruments identify their chemical structure.
Using data that Curiosity beams down to Earth, scientists like Lewis and
his team try to piece together these broken organic pieces. Their goal is to
infer what type of larger molecules they may once have belonged to and what
those molecules could reveal about the ancient environment and potential
biology on Mars.
“We’re trying to unravel billions of years of organic chemistry,” Lewis
said, “and in that organic record there could be the ultimate prize: evidence
that life once existed on the Red Planet.”
While some experts have predicted for decades that ancient organic
compounds are preserved on Mars, it took experiments by Curiosity’s SAM to
confirm this. For example, in 2018, NASA Goddard astrobiologist Jennifer
L. Eigenbrode led an international team of
Curiosity mission scientists who reported
the detection of myriad molecules containing an
essential element of life as we know it: carbon. Scientists identify
most carbon-containing molecules as “organic.
Research scientist Dr.
Jennifer Eigenbrode discusses the discovery of ancient organic molecules on
Mars.
Credits: NASA's Goddard
Space Flight Center/Dan Gallagher
“The fact that there’s organic matter preserved in 3-billion-year-old
rocks, and we found it at the surface, is a very promising sign that we might
be able to tap more information from better preserved samples below the
surface,” Eigenbrode said. She worked with Lewis on this new study.
Analyzing Organic Salts
in the Lab
Decades ago, scientists predicted that organic compounds on Mars could be breaking down into salts. These salts, they
argued, would be more likely to persist on the Martian surface than big,
complex molecules, such as the ones that are associated with the functioning of
living things.
If there were organic salts present in Martian samples, Lewis and his team
wanted to find out how getting heated in the SAM oven could affect what types
of gases they would release. SAM works by heating samples to upwards of
1,800 degrees Fahrenheit (1,000 degrees Celsius). The heat breaks apart
molecules, releasing some of them as gases. Different molecules release
different gases at specific temperatures; thus, by looking at which
temperatures release which gases, scientists can infer what the sample is made
of.
“When heating Martian samples, there are many interactions that can happen
between minerals and organic matter that could make it more difficult to draw
conclusions from our experiments, so the work we’re doing is trying to pick
apart those interactions so that scientists doing analyses on Mars can use this
information,” Lewis said.
Lewis analyzed a range of organic salts mixed with an inert silica powder
to replicate a Martian rock. He also investigated the impact of adding
perchlorates to the silica mixtures. Perchlorates are salts containing chlorine
and oxygen, and they are common on Mars. Scientists have long worried that they
could interfere with experiments seeking signs of organic matter.
This is the first photo
ever taken on the surface of Mars. It was taken by NASA’s Viking 1 spacecraft
just minutes after it landed on the Red Planet on July 20, 1976.
Indeed, researchers found that perchlorates did interfere with their
experiments, and they pinpointed how. But they also found that the results they
collected from perchlorate-containing samples better matched SAM data than when
perchlorates were absent, bolstering the likelihood that organic salts are
present on Mars.
Additionally, Lewis and his team reported that organic salts could be
detected by Curiosity’s instrument CheMin. To determine the composition of a
sample, CheMin shoots X-rays at it and measures the angle at which the X-rays
are diffracted toward the detector.
Curiosity’s SAM and CheMin teams will continue to search for signals of
organic salts as the rover moves into a new region on Mount Sharp in Gale
Crater.
Soon, scientists will also have an opportunity to study better-preserved
soil below the Martian surface. The European Space Agency’s forthcoming ExoMars
rover, which is equipped to drill down to 6.5 feet, or 2 meters, will carry a
Goddard instrument that will analyze the chemistry of these deeper Martian
layers. NASA’s Perseverance rover doesn’t have an instrument that can detect
organic salts, but the rover is collecting samples for future return to Earth,
where scientists can use sophisticated lab machines to look for organic
compounds.
Banner image: This look back at a dune that NASA's Curiosity Mars rover
drove across was taken by the rover's Mast Camera (Mastcam) on Feb. 9, 2014, or
the 538th Martian day, or sol, of Curiosity's mission. For scale, the distance
between the parallel wheel tracks is about 9 feet (2.7 meters). The dune is
about 3 feet (1 meter) tall in the middle of its span across an opening called
"Dingo Gap." This view is looking eastward. Credits:
NASA/JPL-Caltech/MSSS. More
information here.
May 20, 2021By Lonnie Shekhtman
NASA’s Goddard Space Flight Center, Greenbelt, Md.
A groundbreaking study led by
engineering and medical researchers at the University of Minnesota Twin Cities
shows how engineered immune cells used in new cancer therapies can overcome
physical barriers to allow a patient’s own immune system to fight tumors. The
research could improve cancer therapies in the future for millions of people
worldwide.
The research is published in Nature
Communications, a peer-reviewed, open access, scientific journal
published by Nature Research.
Instead of using chemicals or radiation, immunotherapy
is a type of cancer treatment that helps the patient’s immune system fight
cancer. T cells are a type of white blood cell that are of key importance to
the immune system. Cytotoxic T cells are like soldiers who search out and
destroy the targeted invader cells.
While there has been success in using immunotherapy
for some types of cancer in the blood or blood-producing organs, a T cell’s job
is much more difficult in solid tumors.
“The tumor is sort of like an obstacle course, and the
T cell has to run the gauntlet to reach the cancer cells,” said Paolo
Provenzano, the senior author of the study and a biomedical engineering
associate professor in the University of Minnesota College of Science and
Engineering. “These T cells get into tumors, but they just can’t move around
well, and they can’t go where they need to go before they run out of gas and
are exhausted.”
In this first-of-its-kind study, the researchers are
working to engineer the T cells and develop engineering design criteria to
mechanically optimize the cells or make them more “fit” to overcome the
barriers. If these immune cells can recognize and get to the cancer cells, then
they can destroy the tumor.
In a fibrous mass of a tumor, the stiffness of the tumor
causes immune cells to slow down about two-fold — almost like they are running
in quicksand.
“This study is our first publication where we have
identified some structural and signaling elements where we can tune these T
cells to make them more effective cancer fighters,” said Provenzano, a
researcher in the University of Minnesota Masonic Cancer Center. “Every
‘obstacle course’ within a tumor is slightly different, but there are some
similarities. After engineering these immune cells, we found that they moved
through the tumor almost twice as fast no matter what obstacles were in their
way.”
To engineer cytotoxic T cells, the authors used
advanced gene editing technologies (also called genome editing) to change the
DNA of the T cells so they are better able to overcome the tumor’s barriers.
The ultimate goal is to slow down the cancer cells and speed up the engineered
immune cells. The researchers are working to create cells that are good at
overcoming different kinds of barriers. When these cells are mixed together,
the goal is for groups of immune cells to overcome all the different types of barriers
to reach the cancer cells.
Provenzano said the next steps are to continue
studying the mechanical properties of the cells to better understand how the
immune cells and cancer cells interact. The researchers are currently studying
engineered immune cells in rodents and in the future are planning clinical
trials in humans.
While initial research has been focused on pancreatic
cancer, Provenzano said the techniques they are developing could be used on
many types of cancers.
“Using a cell engineering approach to fight cancer is
a relatively new field,” Provenzano said. “It allows for a very personalized
approach with applications for a wide array of cancers. We feel we are
expanding a new line of research to look at how our own bodies can fight cancer.
This could have a big impact in the future.”
Twenty-five years after the events of Fyra bröllop och en begravning (1994), Charles, Carrie, Fiona, Tom, David, Matthew, Bernard, Lydia and Father Gerald are back in church. But whose wedding is it - and will there be any more familiar faces?
