Satellite - Blog Posts
Counting Down to ICON's Launch
In October 2018, we're launching the Ionospheric Connection Explorer, or ICON, to study Earth's dynamic interface to space.
The region of Earth's atmosphere on the edge of space plays a crucial role in our technology and exploration. This is where many of our satellites — including the International Space Station — orbit, and changing conditions in this region can cause problems for those satellites and disrupt communications signals.
This part of the atmosphere is shaped by a complicated set of factors. From below, regular weather on Earth can propagate upwards and influence this region. From above, electric and magnetic fields and charged particles in space — collectively called space weather — can also trigger changes. ICON's goal is to better understand this region and how it's shaped by these outside influences.
10-mile-per-hour sensitivity
Though the ICON spacecraft zooms around Earth at upwards of 14,000 miles per hour, its wind-measuring instrument, named MIGHTI, can detect changes in wind speed smaller than 10 miles per hour. MIGHTI measures the tiny shifts in color caused by the motion of glowing gases in the upper atmosphere. Then, by making use of the Doppler effect — the same phenomenon that makes an ambulance siren change pitch as it passes you — scientists can figure out the gases' speed and direction.
97-minute orbital period
ICON circles Earth in just over an hour and a half, completing nearly 15 orbits per day. Its orbit is inclined by 27 degrees, so over time, its measurements will completely cover the latitudes scientists are most interested in, near the equator.
8 1/3-foot solar panel
ICON doesn't carry any onboard fuel. Instead, its single solar panel — measuring about 100 inches long and 33 inches wide, a little bit bigger than a standard door — produces power for the spacecraft. In science mode, ICON draws about 209-265 Watts of power.
7 years of teamwork
Now getting ready for launch, the ICON team has been hard at work ever since the idea for the mission was selected for further study in 2011.
634 pounds
How much does good science weigh? In ICON's case, about as much as vending machine. The observatory weighs 634 pounds altogether.
5 snapshots per minute from FUV
Because ICON travels so fast, its Far Ultraviolet instrument takes eight snapshots per second of passing structures. This avoids blurring the images and captures the fine detail scientists need. But available bandwidth only allows FUV to send 5 images per minute, so the instrument uses a de-blurring technique called time-delay integration to combine 12 seconds' worth of data into a single image.
Image credit: Mark Belan
4 types of instruments collecting data in tandem
ICON carries four distinct instruments to study Earth's boundary to space.
2 MIGHTIs (Michelson Interferometer for Global High-resolution Thermospheric Imaging): Built by the Naval Research Laboratory in Washington, D.C., to observe the temperature and speed of the neutral atmosphere. There are two identical MIGHTI instruments onboard ICON.
2 IVMs (Ion Velocity Meter): Built by the University of Texas at Dallas to observe the speed of the charged particle motions, in response to the push of the high-altitude winds and the electric fields they generate. ICON carries two, and they are the mission’s only in situ instruments.
EUV (Extreme Ultra-Violet instrument): Built by the University of California, Berkeley to capture images of oxygen glowing in the upper atmosphere, in order to measure the height and density of the daytime ionosphere.
FUV (Far Ultra-Violet instrument): Built by UC Berkeley to capture images of the upper atmosphere in the far ultraviolet light range. At night, FUV measures the density of the ionosphere, tracking how it responds to weather in the lower atmosphere. During the day, FUV measures changes in the chemistry of the upper atmosphere — the source for the charged gases found higher up in space.
360 miles above Earth
ICON orbits about 360 miles above Earth, near the upper reaches of the ionosphere — the region of Earth's atmosphere populated by electrically charged particles. From this vantage point, ICON combines remote measurements looking down along with direct measurements of the material flowing around it to connect changes throughout this region.
2 missions working together
NASA's GOLD mission — short for Global-scale Observations of the Limb and Disk — launched aboard a commercial communications satellite on Jan. 25, 2018. From its vantage point in geostationary orbit over Brazil, GOLD gets a full-disk view of the same region of space that ICON studies, helping scientists connect the big picture with the details.
1 gigabit of data per day
Together, ICON's instruments produce and downlink about 1 gigabit of data per day — about 125 megabytes. This adds up to about 1 gigabyte per week. ICON produces 10 different data products, ranging from measurements of wind speeds and ionospheric density to more complex models, that will help scientists shed new light on this ever-changing region.
ICON’s launch is scheduled for 4 a.m. EDT on Oct. 26, and NASA TV coverage begins at 3:45 a.m. Stay tuned on Twitter and Facebook for the latest on ICON.
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NASA’s New Planet Hunter Reveals a Sky Full of Stars
NASA’s newest planet-hunting satellite — the Transiting Exoplanet Survey Satellite, or TESS for short — has just released its first science image using all of its cameras to capture a huge swath of the sky! TESS is NASA’s next step in the search for planets outside our solar system, called exoplanets.
This spectacular image, the first released using all four of TESS’ cameras, shows the satellite’s full field of view. It captures parts of a dozen constellations, from Capricornus (the Sea Goat) to Pictor (the Painter’s Easel) — though it might be hard to find familiar constellations among all these stars! The image even includes the Large and Small Magellanic Clouds, our galaxy’s two largest companion galaxies.
The science community calls this image “first light,” but don’t let that fool you — TESS has been seeing light since it launched in April. A first light image like this is released to show off the first science-quality image taken after a mission starts collecting science data, highlighting a spacecraft’s capabilities.
TESS has been busy since it launched from NASA’s Kennedy Space Center in Cape Canaveral, Florida. First TESS needed to get into position, which required a push from the Moon. After nearly a month in space, the satellite passed about 5,000 miles from the Moon, whose gravity gave it the boost it needed to get into a special orbit that will keep it stable and maximize its view of the sky.
During those first few weeks, we also got a sneak peek of the sky through one of TESS’s four cameras. This test image captured over 200,000 stars in just two seconds! The spacecraft was pointed toward the constellation Centaurus when it snapped this picture. The bright star Beta Centauri is visible at the lower left edge, and the edge of the Coalsack Nebula is in the right upper corner.
After settling into orbit, scientists ran a number of checks on TESS, including testing its ability to collect a set of stable images over a prolonged period of time. TESS not only proved its ability to perform this task, it also got a surprise! A comet named C/2018 N1 passed through TESS’s cameras for about 17 hours in July.
The images show a treasure trove of cosmic curiosities. There are some stars whose brightness changes over time and asteroids visible as small moving white dots. You can even see an arc of stray light from Mars, which is located outside the image, moving across the screen.
Now that TESS has settled into orbit and has been thoroughly tested, it’s digging into its main mission of finding planets around other stars. How will it spot something as tiny and faint as a planet trillions of miles away? The trick is to look at the star!
So far, most of the exoplanets we’ve found were detected by looking for tiny dips in the brightness of their host stars. These dips are caused by the planet passing between us and its star – an event called a transit. Over its first two years, TESS will stare at 200,000 of the nearest and brightest stars in the sky to look for transits to identify stars with planets.
TESS will be building on the legacy of NASA’s Kepler spacecraft, which also used transits to find exoplanets. TESS’s target stars are about 10 times closer than Kepler’s, so they’ll tend to be brighter. Because they're closer and brighter, TESS’s target stars will be ideal candidates for follow-up studies with current and future observatories.
TESS is challenging over 200,000 of our stellar neighbors to a staring contest! Who knows what new amazing planets we’ll find?
The TESS mission is led by MIT and came together with the help of many different partners. You can keep up with the latest from the TESS mission by following mission updates.
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Did somebody say space laser?
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.
3-Dimensional Earth
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.
800-Picosecond Precision
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.
Learn more about ICESat-2: https://www.nasa.gov/icesat-2
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Glacier Turns into a ‘Snow Swamp’
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.
Read more: https://go.nasa.gov/2Q9JSeO
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Last Glacier Standing in Venezuela
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.”
Read more: https://go.nasa.gov/2NuYcg6