Space Station investigation called BCAT-CS studies dynamic forces between
sediment particles that cluster together.
For the study, scientists sent mixtures of quartz and clay particles to the space
station and subjected them to various levels of simulated gravity.
Conducting the experiment in microgravity makes it possible to separate out different forces that act on sediments and look at the function of
Sediment systems of quartz and clay occur many places on Earth, including rivers,
lakes, and oceans, and affect many
activities, from deep-sea hydrocarbon drilling to carbon sequestration.
sediments behave has a range of applications on Earth, including predicting and mitigating erosion, improving water
treatment, modeling the carbon cycle,
sequestering contaminants and more accurately finding deep sea oil
It also may provide insight for future studies of the
geology of new and unexplored planets.
We’re set to launch ICESat-2, our most advanced laser instrument of its kind, into orbit around Earth on Sept. 15. The Ice, Cloud and land Elevation Satellite-2 will make critical observations of how ice sheets, glaciers and sea ice are changing over time, helping us better understand how those changes affect people where they live. Here’s 10 numbers to know about this mission:
One Space Laser
There’s only one scientific instrument on ICESat-2, but it’s a marvel. The Advanced Topographic Laser Altimeter System, or ATLAS, measures height by precisely timing how long it takes individual photons of light from a laser to leave the satellite, bounce off Earth, and return to ICESat-2. Hundreds of people at our Goddard Space Flight Center worked to build this smart-car-sized instrument to exacting requirements so that scientists can measure minute changes in our planet’s ice.
Sea ice is seen in front of Apusiaajik Glacier in Greenland. Credit: NASA/JPL-Caltech/Jim Round
Two Types of Ice
Not all ice is the same. Land ice, like the ice sheets in Greenland and Antarctica, or glaciers dotting the Himalayas, builds up as snow falls over centuries and forms compacted layers. When it melts, it can flow into the ocean and raise sea level. Sea ice, on the other hand, forms when ocean water freezes. It can last for years, or a single winter. When sea ice disappears, there is no effect on sea level (think of a melting ice cube in your drink), but it can change climate and weather patterns far beyond the poles.
ICESat-2 will measure elevation to see how much glaciers, sea ice and ice sheets are rising or falling. Our fleet of satellites collect detailed images of our planet that show changes to features like ice sheets and forests, and with ICESat-2’s data, scientists can add the third dimension – height – to those portraits of Earth.
Four Seasons, Four Measurements
ICESat-2’s orbit will make 1,387 unique ground tracks around Earth in 91 days – and then start the same ground pattern again at the beginning. This allows the satellite to measure the same ground tracks four times a year and scientists to see how glaciers and other frozen features change with the seasons – including over winter.
532 Nanometer Wavelength
The ATLAS instrument will measure ice with a laser that shines at 532 nanometers – a bright green on the visible spectrum. When these laser photons return to the satellite, they pass through a series of filters that block any light that’s not exactly at this wavelength. This helps the instrument from being swamped with all the other shades of sunlight naturally reflected from Earth.
Six Laser Beams
While the first ICESat satellite (2003-2009) measured ice with a single laser beam, ICESat-2 splits its laser light into six beams – the better to cover more ground (or ice). The arrangement of the beams into three pairs will also allow scientists to assess the slope of the surface they’re measuring.
Seven Kilometers Per Second
ICESat-2 will zoom above the planet at 7 km per second (4.3 miles per second), completing an orbit around Earth in 90 minutes. The orbits have been set to converge at the 88-degree latitude lines around the poles, to focus the data coverage in the region where scientists expect to see the most change.
All of those height measurements come from timing the individual laser photons on their 600-mile roundtrip between the satellite and Earth’s surface – a journey that is timed to within 800 picoseconds. That’s a precision of nearly a billionth of a second. Our engineers had to custom build a stopwatch-like device, because no existing timers fit the strict requirements.
Nine Years of Operation IceBridge
As ICESat-2 measures the poles, it adds to our record of ice heights that started with the first ICESat and continued with Operation IceBridge, an airborne mission that has been flying over the Arctic and Antarctic for nine years. The campaign, which bridges the gap between the two satellite missions, has flown since 2009, taking height measurements and documenting the changing ice.
10,000 Pulses a Second
ICESat-2’s laser will fire 10,000 times in one second. The original ICESat fired 40 times a second. More pulses mean more height data. If ICESat-2 flew over a football field, it would take 130 measurements between end zones; its predecessor, on the other hand, would have taken one measurement in each end zone.
And One Bonus Number: 300 Trillion
Each laser pulse ICESat-2 fires contains about 300 trillion photons! Again, the laser instrument is so precise that it can time how long it takes individual photons to return to the satellite to within one billionth of a second.
In just four days this summer, miles of snow melted from
Lowell Glacier in Canada. Mauri Pelto, a glaciologist at Nichols College,
called the area of water-saturated snow a “snow swamp.”
These false-color images
show the rapid snow melt in Kluane National Park in the Yukon Territory. The
first image was taken on July 22, 2018, by the European Space Agency’s Sentinel-2;
the next image was acquired on July 26, 2018, by the Landsat 8 satellite.
Ice is shown as light blue, while meltwater is dark blue. On
July 26, the slush covered more than 25 square miles (40 square km).
During those four days, daily temperatures 40 miles (60 km)
northeast of the glacier reached 84 degrees Fahrenheit (29 degrees Celsius) —
much higher than normal for the region in July.
In 1910, glaciers covered at least 4 square miles (10 square
km) of the mountainous region of northwestern Venezuela. Today, less than one
percent of that ice remains, and all of it is locked up in one glacier. The
ongoing retreat of Humboldt Glacier—Venezuela’s last patch of perennial
ice—means that the country could soon be glacier-free.
The glacier is in the highest part of the Andes Mountains,
on a slope at nearly 16,000 feet. A cold
and snowy climate at high elevations is key for glaciers to exist in the
tropics. Most of Earth’s tropical glaciers are found in the Andes, which runs
through Venezuela, Colombia, Ecuador, Peru and Bolivia. But warming air temperatures
have contributed to their decline, including Humboldt Glacier.
The relatively recent changes to Humboldt are evident in
these images, acquired on Jan. 20, 1988, by the
United States Geological Survey’s Landsat 5 and on Jan. 6, 2015,
by Landsat 8. The images are false-color to better differentiate between areas
of snow and ice (blue), land (brown) and vegetation (green).
Scientists are trying to understand how long Humboldt will remain.
One said: “Let’s call it no more than 10 to 20 years.”
human journey to Mars, at first
glance, offers an inexhaustible amount of complexities. To bring a mission to
the Red Planet from fiction to fact, NASA’s Human Research Program has organized some of the hazards
astronauts will encounter on a continual basis into five classifications.
The variance of gravity fields that
astronauts will encounter on a mission to Mars is the fourth hazard.
On Mars, astronauts would need to
live and work in three-eighths of Earth’s gravitational pull for up to two
years. Additionally, on the six-month trek between the planets, explorers will
experience total weightlessness.
Besides Mars and deep space there
is a third gravity field that must be considered. When astronauts finally
return home they will need to readapt many of the systems in their bodies to
To further complicate the problem,
when astronauts transition from one gravity field to another, it’s usually
quite an intense experience. Blasting off from the surface of a planet or a
hurdling descent through an atmosphere is many times the force of gravity.
Research is being conducted to
ensure that astronauts stay healthy before, during and after their mission.
Specifically researchers study astronauts’
vision, fine motor skills, fluid distribution, exercise protocols and response to
Exploration to the Moon and Mars will expose astronauts to five
known hazards of spaceflight, including gravity. To learn more, and find out
what NASA’s Human Research Program is doing to protect humans in
space, check out the “Hazards of Human Spaceflight" website.
Or, check out this week’s episode of “Houston
We Have a Podcast,” in which host Gary Jordan
further dives into the threat of gravity with Peter
Senior Research Director/ Element Scientist at
the Johnson Space Center.
Take a deep breath. Even if the air looks clear, it is nearly certain that you will inhale millions of solid particles and liquid droplets. These ubiquitous specks of matter are known as aerosols, and they can be found in the air over oceans, deserts, mountains, forests, ice, and every ecosystem in between.
If you have ever watched smoke billowing from a wildfire, ash erupting from a volcano, or dust blowing in the wind, you have seen aerosols. Satellites like Terra, Aqua, Aura, and Suomi NPP “see” them as well, though they offer a completely different perspective from hundreds of kilometers above Earth’s surface. A version of one of our models called the Goddard Earth Observing System Forward Processing (GEOS FP) offers a similarly expansive view of the mishmash of particles that dance and swirl through the atmosphere.
The visualization above highlights GEOS FP model output for aerosols on August 23, 2018. On that day, huge plumes of smoke drifted over North America and Africa, three different tropical cyclones churned in the Pacific Ocean, and large clouds of dust blew over deserts in Africa and Asia. The storms are visible within giant swirls of sea salt aerosol(blue), which winds loft into the air as part of sea spray. Black carbon particles (red) are among the particles emitted by fires; vehicle and factory emissions are another common source. Particles the model classified as dust are shown in purple. The visualization includes a layer of night light data collected by the day-night band of the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP that shows the locations of towns and cities.
Melting Greenland (OMG) scientists are heading into the field this
week to better understand how seawater is melting Greenland’s ice from below. (Yes,
those black specks are people next to an iceberg.) While NASA is studying ocean
properties (things like temperature, salinity and currents), other researchers
are eager to incorporate our data into their work. In fact, University of
Washington scientists are using OMG data to study narwhals – smallish whales
with long tusks – otherwise known as the “unicorns of the sea.”
Our researchers are also in the field right now studying how
Alaska’s ice is changing. Operation
IceBridge, our longest airborne campaign, is using science
instruments on airplanes to study and measure the ice below.
What happens in the Arctic doesn’t stay in the Arctic (or
the Antarctic, really). In a warming world, the greatest changes are seen in
the coldest places. Earth’s cryosphere – its ice sheets, sea ice, glaciers,
permafrost and snow cover – acts as our planet’s thermostat and deep freeze,
regulating temperatures and storing most of our freshwater. Next month, we’re
launching ICESat-2, our
latest satellite to study Earth’s ice!
After traveling for two years and billions of kilometers from Earth, the OSIRIS-REx probe is only a few months away from its destination: the intriguing asteroid Bennu. When it arrives in December, OSIRIS-REx will embark on a nearly two-year investigation of this clump of rock, mapping its terrain and finding a safe and fruitful site from which to collect a sample.
The spacecraft will briefly touch Bennu’s surface around July 2020 to collect at least 60 grams (equal to about 30 sugar packets) of dirt and rocks. It might collect as much as 2,000 grams, which would be the largest sample by far gathered from a space object since the Apollo Moon landings. The spacecraft will then pack the sample into a capsule and travel back to Earth, dropping the capsule into Utah’s west desert in 2023, where scientists will be waiting to collect it.
This years-long quest for knowledge thrusts Bennu into the center of one of the most ambitious space missions ever attempted. But the humble rock is but one of about 780,000 known asteroids in our solar system. So why did scientists pick Bennu for this momentous investigation? Here are 10 reasons:
1. It’s close to Earth
Unlike most other asteroids that circle the Sun in the asteroid belt between Mars and Jupiter, Bennu’s orbit is close in proximity to Earth’s, even crossing it. The asteroid makes its closest approach to Earth every 6 years. It also circles the Sun nearly in the same plane as Earth, which made it somewhat easier to achieve the high-energy task of launching the spacecraft out of Earth’s plane and into Bennu’s. Still, the launch required considerable power, so OSIRIS-REx used Earth’s gravity to boost itself into Bennu’s orbital plane when it passed our planet in September 2017.
2.It’s the right size
Asteroids spin on their axes just like Earth does. Small ones, with diameters of 200 meters or less, often spin very fast, up to a few revolutions per minute. This rapid spinning makes it difficult for a spacecraft to match an asteroid’s velocity in order to touch down and collect samples. Even worse, the quick spinning has flung loose rocks and soil, material known as “regolith” — the stuff OSIRIS-REx is looking to collect — off the surfaces of small asteroids. Bennu’s size, in contrast, makes it approachable and rich in regolith. It has a diameter of 492 meters, which is a bit larger than the height of the Empire State Building in New York City, and rotating once every 4.3 hours.
3. It’s really old
Bennu is a leftover fragment from the tumultuous formation of the solar system. Some of the mineral fragments inside Bennu could be older than the solar system. These microscopic grains of dust could be the same ones that spewed from dying stars and eventually coalesced to make the Sun and its planets nearly 4.6 billion years ago. But pieces of asteroids, called meteorites, have been falling to Earth’s surface since the planet formed. So why don’t scientists just study those old space rocks? Because astronomers can’t tell (with very few exceptions) what kind of objects these meteorites came from, which is important context. Furthermore, these stones, that survive the violent, fiery decent to our planet’s surface, get contaminated when they land in the dirt, sand, or snow. Some even get hammered by the elements, like rain and snow, for hundreds or thousands of years. Such events change the chemistry of meteorites, obscuring their ancient records.
4.It’s well preserved
Bennu, on the other hand, is a time capsule from the early solar system, having been preserved in the vacuum of space. Although scientists think it broke off a larger asteroid in the asteroid belt in a catastrophic collision between about 1 and 2 billion years ago, and hurtled through space until it got locked into an orbit near Earth’s, they don’t expect that these events significantly altered it.
5. It might contain clues to the origin of life
Analyzing a sample from Bennu will help planetary scientists better understand the role asteroids may have played in delivering life-forming compounds to Earth. We know from having studied Bennu through Earth- and space-based telescopes that it is a carbonaceous, or carbon-rich, asteroid. Carbon is the hinge upon which organic molecules hang. Bennu is likely rich in organic molecules, which are made of chains of carbon bonded with atoms of oxygen, hydrogen, and other elements in a chemical recipe that makes all known living things. Besides carbon, Bennu also might have another component important to life: water, which is trapped in the minerals that make up the asteroid.
6. It contains valuable materials
Besides teaching us about our cosmic past, exploring Bennu close-up will help humans plan for the future. Asteroids are rich in natural resources, such as iron and aluminum, and precious metals, such as platinum. For this reason, some companies, and even countries, are building technologies that will one day allow us to extract those materials. More importantly, asteroids like Bennu are key to future, deep-space travel. If humans can learn how to extract the abundant hydrogen and oxygen from the water locked up in an asteroid’s minerals, they could make rocket fuel. Thus, asteroids could one day serve as fuel stations for robotic or human missions to Mars and beyond. Learning how to maneuver around an object like Bennu, and about its chemical and physical properties, will help future prospectors.
7. It will help us better understand other asteroids
Astronomers have studied Bennu from Earth since it was discovered in 1999. As a result, they think they know a lot about the asteroid’s physical and chemical properties. Their knowledge is based not only on looking at the asteroid, but also studying meteorites found on Earth, and filling in gaps in observable knowledge with predictions derived from theoretical models. Thanks to the detailed information that will be gleaned from OSIRIS-REx, scientists now will be able to check whether their predictions about Bennu are correct. This work will help verify or refine telescopic observations and models that attempt to reveal the nature of other asteroids in our solar system.
8. It will help us better understand a quirky solar force …
Astronomers have calculated that Bennu’s orbit has drifted about 280 meters (0.18 miles) per year toward the Sun since it was discovered. This could be because of a phenomenon called the Yarkovsky effect, a process whereby sunlight warms one side of a small, dark asteroid and then radiates as heat off the asteroid as it rotates. The heat energy thrusts an asteroid either away from the Sun, if it has a prograde spin like Earth, which means it spins in the same direction as its orbit, or toward the Sun in the case of Bennu, which spins in the opposite direction of its orbit. OSIRIS-REx will measure the Yarkovsky effect from close-up to help scientists predict the movement of Bennu and other asteroids. Already, measurements of how this force impacted Bennu over time have revealed that it likely pushed it to our corner of the solar system from the asteroid belt.
9. … and to keep asteroids at bay
One reason scientists are eager to predict the directions asteroids are drifting is to know when they’re coming too-close-for-comfort to Earth. By taking the Yarkovsky effect into account, they’ve estimated that Bennu could pass closer to Earth than the Moon is in 2135, and possibly even closer between 2175 and 2195. Although Bennu is unlikely to hit Earth at that time, our descendants can use the data from OSIRIS-REx to determine how best to deflect any threatening asteroids that are found, perhaps even by using the Yarkovsky effect to their advantage.
10. It’s a gift that will keep on giving
Samples of Bennu will return to Earth on September 24, 2023. OSIRIS-REx scientists will study a quarter of the regolith. The rest will be made available to scientists around the globe, and also saved for those not yet born, using techniques not yet invented, to answer questions not yet asked.
Read the web version of this week’s “Solar System: 10 Things to Know” article HERE.
A human journey to Mars, at first glance, offers an inexhaustible amount
of complexities. To bring a mission to the Red Planet from fiction to fact, our Human
Research Program has
organized some of the hazards astronauts will encounter on a continual basis
into five classifications.
The third and perhaps most apparent hazard is, quite
simply, the distance.
Rather than a three-day lunar trip, astronauts would
be leaving our planet for roughly three years. Facing a communication delay of
up to 20 minutes one way and the possibility of equipment failures or a medical
emergency, astronauts must be capable of confronting an array of situations
without support from their fellow team on Earth.
Once you burn your engines for Mars, there is no
turning back so planning and self-sufficiency are essential keys to a
successful Martian mission. The Human Research Program is studying and
improving food formulation, processing, packaging and preservation systems.
While International Space Station expeditions serve as
a rough foundation for the expected impact on planning logistics for such a
trip, the data isn’t always comparable, but it is a key to the solution.
Exploration to the Moon and Mars
will expose astronauts to five known hazards of spaceflight, including distance
from Earth. To learn more, and find out what our Human Research
Program is doing to protect humans in space, check out the “Hazards
of Human Spaceflight" website. Or,
check out this week’s episode of “Houston We Have a Podcast,” in which host Gary Jordan
further dives into the threat of distance with Erik Antonsen, the
Assistant Director for Human Systems Risk
Management at the Johnson Space Center.