For the second time in history, a human-made object has reached the space between the stars. Our Voyager 2 probe now has exited the heliosphere – the protective bubble of particles and magnetic fields created by the Sun.
Comparing data from different instruments aboard the trailblazing spacecraft, mission scientists determined the probe crossed the outer edge of the heliosphere on Nov. 5. This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium. Its twin, Voyager 1, crossed this boundary in 2012, but Voyager 2 carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.
Voyager 2 now is slightly more than 11 billion miles (18 billion kilometers) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.
We sent the first humans to land on the Moon in 1969. Since then, only of 12 men have stepped foot on the lunar surface – but we left robotic explorers behind to continue gathering science data. And now, we’re preparing to return. Establishing a sustained presence on and near the Moon will help us learn to live off of our home planet and prepare for travel to Mars.
To help establish ourselves on and near the Moon, we are working with a few select American companies. We will buy space on commercial robotic landers, along with other customers, to deliver our payloads to the lunar surface. We’re even developing lunar instruments and tools that will fly on missions as early as 2019!
Through partnerships with American companies, we are leading a flexible and sustainable approach to deep space missions. These early commercial delivery missions will also help inform new space systems we build to send humans to the Moon in the next decade. Involving American companies and stimulating the space market with these new opportunities to send science instruments and new technologies to deep space will be similar to how we use companies like Northrop Grumman and SpaceX to send cargo to the International Space Station now. These selected companies will provide a rocket and cargo space on their robotic landers for us (and others!) to send science and technology to our nearest neighbor.
So who are these companies that will get to ferry science instruments and new technologies to the Moon?
Here’s a digital “catalogue” of the organizations and their spacecraft that will be available for lunar services over the next decade:
Astrobotic Technology, Inc.
Deep Space Systems
Firefly Aerospace, Inc.
Cedar Park, TX
Intuitive Machines, LLC
Lockheed Martin Space
Masten Space Systems, Inc.
Moon Express, Inc.
Cape Canaveral, FL
Orbit Beyond, Inc.
We are thrilled to be working with these companies to enable us to investigate the Moon in new ways. In order to expand humanity’s presence beyond Earth, we need to return to the Moon before we go to Mars.
The Moon helps us to learn how to live and work on another planetary body while being only three days away from home – instead of several months. The Moon also holds enormous potential for testing new technologies, like prospecting for water ice and turning it into drinking water, oxygen and rocket fuel. Plus, there’s so much science to be done!
The Moon can help us understand the early history of the solar system, how planets migrated to their current formation and much more. Understanding how the Earth-Moon system formed is difficult because those ancient rocks no longer exist here on Earth. They have been recycled by plate tectonics, but the Moon still has rocks that date back to the time of its formation! It’s like traveling to a cosmic time machine!
Join us on this exciting journey as we expand humanity’s presence beyond Earth.
There’s a whole universe of mysteries out there to put some fun—and maybe a touch of fright—into your All Hallows Eve festivities. Here are a few:
1. Universe of Monsters
Mythical monsters of Earth have a tough time of it. Vampires don’t do sunlight. Werewolves must wait for a full Moon to howl. Now, thanks to powerful space telescopes, some careful looking and a lot of whimsy, NASA scientists have found suitable homes for the most terrifying Halloween monsters.
At Halloween, engineers at NASA’s Jet Propulsion Laboratory craft dramatic creations that have as much in common with standard jack-o’-lanterns as paper airplanes do with NASA spacecraft. The unofficial pumpkin carving contest gives engineers a chance to flex their creative muscles and bond as a team. The rules are simple: no planning, carving or competing during work hours.
In this October 2014 Solar Dynamic Observatory image, active regions on the Sun combined to look something like a jack-o-lantern’s face.
The active regions appear brighter because those are areas that emit more light and energy—markers of an intense and complex set of magnetic fields hovering in the Sun’s atmosphere, the corona. This image blends together two sets of wavelengths at 171 and 193 angstroms, typically colorized in gold and yellow, to create a particularly Halloween-like appearance.
Cassini ended its extended mission at Saturn in 2017.
7. The Ghost of Cassiopeia
The brightest stars embedded in nebulae throughout our galaxy pour out a torrent of radiation that eats into vast clouds of hydrogen gas – the raw material for building new stars. This etching process sculpts a fantasy landscape where human imagination can see all kinds of shapes and figures. This nebula in the constellation of Cassiopeia has flowing veils of gas and dust that have earned it the nickname “Ghost Nebula.”
This infrared view of the Helix Nebula reminded astronomers of a zombie eyeball.
9. What Do You See?
The Oct. 26 Earth Observatory’s Puzzler feature offers a spooky shape for your consideration. What is it and what does it look like? You tell us.
10. Space Candy
The trick-or-treat tradition is still—so far—pretty much confined to Earth. But thanks to the men and women who have been living aboard the International Space Station for more than 17 years, we have a preview of what a future space-based trick-or-treater’s Halloween candy haul would look like in microgravity.
Bonus: 11. Want More?
Our education team offers a bunch more Halloween activities, including space-themed pumpkin stencils, costume tips and even some mysteries to solve like a scientist or engineer.
From deep below the soil at Earth’s polar regions to Pluto’s frozen heart, ice exists all over the solar system…and beyond. From right here on our home planet to moons and planets millions of miles away, we’re exploring ice and watching how it changes. Here’s 10 things to know:
1.Earth’s Changing Ice Sheets
An Antarctic ice sheet. Credit: NASA
Ice sheets are massive expanses of ice that stay frozen from year to year and cover more than 6 million square miles. On Earth, ice sheets extend across most of Greenland and Antarctica. These two ice sheets contain more than 99 percent of the planet’s freshwater. However, our ice sheets are sensitive to the changing climate.
Data from our GRACE satellites show that the land ice sheets in both Antarctica and Greenland have been losing mass since at least 2002, and the speed at which they’re losing mass is accelerating.
2. Sea Ice at Earth’s Poles
Earth’s polar oceans are covered by stretches of ice that freezes and melts with the seasons and moves with the wind and ocean currents. During the autumn and winter, the sea ice grows until it reaches an annual maximum extent, and then melts back to an annual minimum at the end of summer. Sea ice plays a crucial role in regulating climate – it’s much more reflective than the dark ocean water, reflecting up to 70 percent of sunlight back into space; in contrast, the ocean reflects only about 7 percent of the sunlight that reaches it. Sea ice also acts like an insulating blanket on top of the polar oceans, keeping the polar wintertime oceans warm and the atmosphere cool.
Some Arctic sea ice has survived multiple years of summer melt, but our research indicates there’s less and less of this older ice each year. The maximum and minimum extents are shrinking, too. Summertime sea ice in the Arctic Ocean now routinely covers about 30-40 percent less area than it did in the late 1970s, when near-continuous satellite observations began. These changes in sea ice conditions enhance the rate of warming in the Arctic, already in progress as more sunlight is absorbed by the ocean and more heat is put into the atmosphere from the ocean, all of which may ultimately affect global weather patterns.
3. Snow Cover on Earth
Snow extends the cryosphere from the poles and into more temperate regions.
Snow and ice cover most of Earth’s polar regions throughout the year, but the coverage at lower latitudes depends on the season and elevation. High-elevation landscapes such as the Tibetan Plateau and the Andes and Rocky Mountains maintain some snow cover almost year-round. In the Northern Hemisphere, snow cover is more variable and extensive than in the Southern Hemisphere.
Snow cover the most reflective surface on Earth and works like sea ice to help cool our climate. As it melts with the seasons, it provides drinking water to communities around the planet.
4. Permafrost on Earth
Tundra polygons on Alaska’s North Slope. As permafrost thaws, this area is likely to be a source of atmospheric carbon before 2100. Credit: NASA/JPL-Caltech/Charles Miller
Permafrost is soil that stays frozen solid for at least two years in a row. It occurs in the Arctic, Antarctic and high in the mountains, even in some tropical latitudes. The Arctic’s frozen layer of soil can extend more than 200 feet below the surface. It acts like cold storage for dead organic matter – plants and animals.
In parts of the Arctic, permafrost is thawing, which makes the ground wobbly and unstable and can also release those organic materials from their icy storage. As the permafrost thaws, tiny microbes in the soil wake back up and begin digesting these newly accessible organic materials, releasing carbon dioxide and methane, two greenhouse gases, into the atmosphere.
Two campaigns, CARVE and ABoVE, study Arctic permafrost and its potential effects on the climate as it thaws.
5. Glaciers on the Move
Did you know glaciers are constantly moving? The masses of ice act like slow-motion rivers, flowing under their own weight. Glaciers are formed by falling snow that accumulates over time and the slow, steady creep of flowing ice. About 10 percent of land area on Earth is covered with glacial ice, in Greenland, Antarctica and high in mountain ranges; glaciers store much of the world’s freshwater.
Our satellites and airplanes have a bird’s eye view of these glaciers and have watched the ice thin and their flows accelerate, dumping more freshwater ice into the ocean, raising sea level.
6. Pluto’s Icy Heart
The nitrogen ice glaciers on Pluto appear to carry an intriguing cargo: numerous, isolated hills that may be fragments of water ice from Pluto’s surrounding uplands. NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Pluto’s most famous feature – that heart! – is stone cold. First spotted by our New Horizons spacecraft in 2015, the heart’s western lobe, officially named Sputnik Planitia, is a deep basin containing three kinds of ices – frozen nitrogen, methane and carbon monoxide.
Models of Pluto’s temperatures show that, due the dwarf planet’s extreme tilt (119 degrees compared to Earth’s 23 degrees), over the course of its 248-year orbit, the latitudes near 30 degrees north and south are the coldest places – far colder than the poles. Ice would have naturally formed around these latitudes, including at the center of Sputnik Planitia.
New Horizons also saw strange ice formations resembling giant knife blades. This “bladed terrain” contains structures as tall as skyscrapers and made almost entirely of methane ice, likely formed as erosion wore away their surfaces, leaving dramatic crests and sharp divides. Similar structures can be found in high-altitude snowfields along Earth’s equator, though on a very different scale.
7. Polar Ice on Mars
This image, combining data from two instruments aboard our Mars Global Surveyor, depicts an orbital view of the north polar region of Mars. Credit: NASA/JPL-Caltech/MSSS
Mars has bright polar caps of ice easily visible from telescopes on Earth. A seasonal cover of carbon dioxide ice and snow advances and retreats over the poles during the Martian year, much like snow cover on Earth.
This animation shows a side-by-side comparison of CO2 ice at the north (left) and south (right) Martian poles over the course of a typical year (two Earth years). This simulation isn’t based on photos; instead, the data used to create it came from two infrared instruments capable of studying the poles even when they’re in complete darkness. This data were collected by our Mars Reconnaissance Orbiter, and Mars Global Surveyor. Credit: NASA/JPL-Caltech
During summertime in the planet’s north, the remaining northern polar cap is all water ice; the southern cap is water ice as well, but remains covered by a relatively thin layer of carbon dioxide ice even in summertime.
Scientists using radar data from our Mars Reconnaissance Orbiter found a record of the most recent Martian ice age in the planet’s north polar ice cap. Research indicates a glacial period ended there about 400,000 years ago. Understanding seasonal ice behavior on Mars helps scientists refine models of the Red Planet’s past and future climate.
8. Ice Feeds a Ring of Saturn
Wispy fingers of bright, icy material reach tens of thousands of kilometers outward from Saturn’s moon Enceladus into the E ring, while the moon’s active south polar jets continue to fire away. Credit: NASA/JPL/Space Science Institute
Saturn’s rings and many of its moons are composed of mostly water ice – and one of its moons is actually creating a ring. Enceladus, an icy Saturnian moon, is covered in “tiger stripes.” These long cracks at Enceladus’ South Pole are venting its liquid ocean into space and creating a cloud of fine ice particles over the moon’s South Pole. Those particles, in turn, form Saturn’s E ring, which spans from about 75,000 miles (120,000 kilometers) to about 260,000 miles (420,000 kilometers) above Saturn’s equator. Our Cassini spacecraft discovered this venting process and took high-resolution images of the system.
Jets of icy particles burst from Saturn’s moon Enceladus in this brief movie sequence of four images taken on Nov. 27, 2005. Credit: NASA/JPL/Space Science Institute
9. Ice Rafts on Europa
View of a small region of the thin, disrupted, ice crust in the Conamara region of Jupiter’s moon Europa showing the interplay of surface color with ice structures. Credit: NASA/JPL/University of Arizona
The icy surface of Jupiter’s moon Europa is crisscrossed by long fractures. During its flybys of Europa, our Galileo spacecraft observed icy domes and ridges, as well as disrupted terrain including crustal plates that are thought to have broken apart and “rafted” into new positions. An ocean with an estimated depth of 40 to 100 miles (60 to 150 kilometers) is believed to lie below that 10- to 15-mile-thick (15 to 25 km) shell of ice.
The rafts, strange pits and domes suggest that Europa’s surface ice could be slowly turning over due to heat from below. Our Europa Clipper mission, targeted to launch in 2022, will conduct detailed reconnaissance of Europa to see whether the icy moon could harbor conditions suitable for life.
10. Crater Ice on Our Moon
The image shows the distribution of surface ice at the Moon’s south pole (left) and north pole (right), detected by our Moon Mineralogy Mapper instrument. Credit: NASA
In the darkest and coldest parts of our Moon, scientists directly observed definitive evidence of water ice. These ice deposits are patchy and could be ancient. Most of the water ice lies inside the shadows of craters near the poles, where the warmest temperatures never reach above -250 degrees Fahrenheit. Because of the very small tilt of the Moon’s rotation axis, sunlight never reaches these regions.
A team of scientists used data from a our instrument on India’s Chandrayaan-1 spacecraft to identify specific signatures that definitively prove the water ice. The Moon Mineralogy Mapper not only picked up the reflective properties we’d expect from ice, but was able to directly measure the distinctive way its molecules absorb infrared light, so it can differentiate between liquid water or vapor and solid ice.
With enough ice sitting at the surface – within the top few millimeters – water would possibly be accessible as a resource for future expeditions to explore and even stay on the Moon, and potentially easier to access than the water detected beneath the Moon’s surface.
11. Bonus: Icy World Beyond Our Solar System!
With an estimated temperature of just 50K, OGLE-2005-BLG-390L b is the chilliest exoplanet yet discovered. Pictured here is an artist’s concept. Credit: NASA
OGLE-2005-BLG-390Lb, the icy exoplanet otherwise known as Hoth, orbits a star more than 20,000 light years away and close to the center of our Milky Way galaxy. It’s locked in the deepest of deep freezes, with a surface temperature estimated at minus 364 degrees Fahrenheit (minus 220 Celsius)!
Earlier this month, the southeastern United States was struck by Hurricane Michael. After the category 4 storm made landfall on Oct. 10, 2018, Hurricane Michael proceeded to knock out power for at least 2.5 million customers across Florida, Georgia, North Carolina, and Virginia.
In this data visualization, you can clearly see where the lights were taken out in Panama City, Florida. A team of our scientists from Goddard Space Flight Center processed and corrected the raw data to filter out stray light from the Moon, fires, airglow, and any other sources that are not electric lights. They also removed atmosphere interference from dust, haze, and clouds.
In the visualization above, you can see a natural view of the night lights—and a step of the filtering process in an effort to clean up some of the cloud cover. The line through the middle is the path Hurricane Michael took.
Although the damage was severe, tens of thousands of electric power industry workers from all over the country—and even Canada—worked together to restore power to the affected areas. Most of the power was restored by Oct. 15, but some people still need to wait a little longer for the power grids to be rebuilt. Read more here.
In 2020, we will launch our next Mars rover. It will journey more than 33 million miles to the Red Planet where it will land, explore and search for signs of ancient microbial life. But how do we pinpoint the perfect location to complete this science…when we’re a million miles away on Earth?
We utilize data sent to us by spacecraft on and orbiting Mars. That includes spacecraft that have recorded data in the past.
This week, hundreds of scientists and Mars enthusiasts are gathering to deliberate the four remaining options for where we’re going to land the Mars 2020 rover on the Red Planet.
The landing site for Mars 2020 is of great interest to the planetary community because, among the rover’s new science gear for surface exploration, it carries a sample system that will collect rock and soil samples and set them aside in a “cache” on the surface of Mars. A future mission could potentially return these samples to Earth. The next Mars landing, after Mars 2020, could very well be a vehicle which would retrieve these Mars 2020 samples.
Here’s an overview of the potential landing sites for our Mars 2020 rover…
This area was once warmed by volcanic activity. Underground heat sources made hot springs flow and surface ice melt. Microbes could have flourished here in liquid water that was in contact with minerals. The layered terrain there holds a rich record of interactions between water and minerals over successive periods of early Mars history.
This area tells a story of the on-again, off-again nature of the wet past of Mars. Water filled and drained away from the crater on at least two occasions. More than 3.5 billion years ago, river channels spilled over the crater wall and created a lake. Scientists see evidence that water carried clay minerals from the surrounding area into the crater after the lake dried up. Conceivably, microbial life could have lived in Jezero during one or more of these wet times. If so, signs of their remains might be found in lakebed sediments.
At this site, mineral springs once bubbled up from the rocks. The discovery that hot springs flowed here was a major achievement of the Mars Exploration Rover, Spirit. The rover’s discovery was an especially welcome surprise because Spirit had not found signs of water anywhere else in the 100-mile-wide Gusev Crater. After the rover stopped working in 2010, studies of its older data records showed evidence that past floods may have formed a shallow lake in Gusev.
Candidate landing sites Jezero and Northeast Syrtis are approximately 37 km apart…which is close enough for regional geologic similarities to be present, but probably too far for the Mars 2020 rover to travel. This midway point allows exploration of areas of both landing sites.
How Will We Select a Site?
The team is gathered this week for the fourth time to discuss these locations. It’ll be the final workshop in a series designed to ensure we receive the best and most diverse range of information and opinion from the scientific community before deciding where to send our newest rover.
The Mars 2020 mission is tasked with not only seeking signs of ancient habitable conditions on Mars, but also searching for signs of past microbial life itself. So how do we choose a landing site that will optimize these goals? Since InSight is stationary and needs a flat surface to deploy its instruments, we’re basically looking for a flat, parking lot area on Mars to land the spacecraft.
The first workshop started with about 30 candidate landing sites and was narrowed down to eight locations to evaluate further. At the end of the third workshop in February 2017, there were only three sites on the radar as potential landing locations…
…but in the ensuing months, a proposal came forward for a landing site that is in between Jezero and Northeast Syrtis – The Midway site. Since our goal is to get to the right site that provides the maximum science, this fourth site was viewed as worthy of being included in the discussions.
Now, with four sites remaining, champions for each option will take their turn at the podium, presenting and defending their favorite spot on the Red Planet.
On the final day, after all presentations have concluded, workshop participants will weigh the pros and cons of each site. The results of these deliberations will be provided to the Mars 2020 Team, which will incorporate them into a recommendation to NASA Headquarters. A final selection will be made and will likely be announced by the end of the year.
On Sept. 15, 2017, our Cassini spacecraft ended its epic exploration of Saturn with a planned dive into the planet’s atmosphere–sending back new science to the very last second. The spacecraft is gone, but the science continues!
New research emerging from the final orbits represents a huge leap forward in our understanding of the Saturn system – especially the mysterious, never-before-explored region between the planet and its rings. Some preconceived ideas are turning out to be wrong while new questions are being raised. How did they form? What holds them in place? What are they made of?
Six teams of researchers are publishing their work Oct. 5 in the journal Science, based on findings from Cassini’s Grand Finale. That’s when, as the spacecraft was running out of fuel, the mission team steered Cassini spectacularly close to Saturn in 22 orbits before deliberately vaporizing it in a final plunge into the atmosphere in September 2017.
Knowing Cassini’s days were numbered, its mission team went for gold. The spacecraft flew where it was never designed to fly. For the first time, it probed Saturn’s magnetized environment, flew through icy, rocky ring particles and sniffed the atmosphere in the 1,200-mile-wide (2,000-kilometer-wide) gap between the rings and the cloud tops. Not only did the engineering push the spacecraft to its limits, the new findings illustrate how powerful and agile the instruments were.
Many more Grand Finale science results are to come, but today’s highlights include:
Complex organic compounds embedded in water nanograins rain down from Saturn’s rings into its upper atmosphere. Scientists saw water and silicates, but they were surprised to see also methane, ammonia, carbon monoxide, nitrogen and carbon dioxide. The composition of organics is different from that found on moon Enceladus – and also different from those on moon Titan, meaning there are at least three distinct reservoirs of organic molecules in the Saturn system.
For the first time, Cassini saw up close how rings interact with the planet and observed inner-ring particles and gases falling directly into the atmosphere. Some particles take on electric charges and spiral along magnetic-field lines, falling into Saturn at higher latitudes – a phenomenon known as “ring rain.” But scientists were surprised to see that others are dragged quickly into Saturn at the equator. And it’s all falling out of the rings faster than scientists thought – as much as 10,000 kg of material per second.
Scientists were surprised to see what the material looks like in the gap between the rings and Saturn’s atmosphere. They knew that the particles throughout the rings ranged from large to small. They thought material in the gap would look the same. But the sampling showed mostly tiny, nanograin- and micron-sized particles, like smoke, telling us that some yet-unknown process is grinding up particles. What could it be? Future research into the final bits of data sent by Cassini may hold the answer.
Saturn and its rings are even more interconnected than scientists thought. Cassini revealed a previously unknown electric current system that connects the rings to the top of Saturn’s atmosphere.
Scientists discovered a new radiation belt around Saturn, close to the planet and composed of energetic particles. They found that while the belt actually intersects with the innermost ring, the ring is so tenuous that it doesn’t block the belt from forming.
Unlike every other planet with a magnetic field in our Solar System, Saturn’s magnetic field is almost completely aligned with its spin axis. Think of the planet and the magnetic field as completely separate things that are both spinning. Both have the same center point, but they each have their own axis about which they spin. But for Saturn the two axes are essentially the same – no other planet does that, and we did not think it was even possible for this to happen. This new data shows a magnetic-field tilt of less than 0.0095 degrees. (Earth’s magnetic field is tilted 11 degrees from its spin axis.) According to everything scientists know about how planetary magnetic fields are generated, Saturn should not have one. It’s a mystery physicists will be working to solve.
Cassini flew above Saturn’s magnetic poles, directly sampling regions where radio emissions are generated. The findings more than doubled the number of reported crossings of radio sources from the planet, one of the few non-terrestrial locations where scientists have been able to study a mechanism believed to operate throughout the universe. How are these signals generated? That’s still a mystery researchers are looking to uncover.
For the Cassini mission, the science rolling out from Grand Finale orbits confirms that the calculated risk of diving into the gap – skimming the upper atmosphere and skirting the edge of the inner rings – was worthwhile.
Almost everything going on in that region turned out to be a surprise, which was the importance of going there, to explore a place we’d never been before. And the expedition really paid off!
Analysis of Cassini data from the spacecraft’s instruments will be ongoing for years to come, helping to paint a clearer picture of Saturn.
To read the papers published in Science, visit: URL to papers
One year ago, on Sept. 15, 2017, NASA’s Cassini spacecraft ended
its epic exploration of Saturn with a planned dive into the planet’s
atmosphere–sending back new science to the last second. The spacecraft is
gone, but the science continues. Here are 10 reasons why Cassini mattered…
Cassini and ESA (European Space Agency)’s Huygens probe expanded our understanding of the
kinds of worlds where life might exist.
2. A (Little) Like Home
At Saturn’s largest moon, Titan, Cassini and Huygens showed us one of the most Earth-like worlds we’ve
ever encountered, with weather, climate and geology that provide new ways to
understand our home planet.
3. A Time Machine (In a Sense)
Cassini gave us a portal to see the physical processes that likely
shaped the development of our solar system, as well as planetary systems around
4. The Long Run
The length of Cassini’s mission enabled us to observe weather and
seasonal changes over nearly half of a Saturn year, improving our understanding
of similar processes at Earth, and potentially those at planets around other
5. Big Science in Small Places
Cassini revealed Saturn’s moons to be unique worlds with their own
stories to tell.
Cassini showed us the complexity of Saturn’s rings and the
dramatic processes operating within them.
7. Pure Exploration
Some of Cassini’s best discoveries were serendipitous. What
Cassini found at Saturn prompted scientists to rethink their understanding of
the solar system.
8. The Right Tools for the Job
Cassini represented a staggering achievement of human and
technical complexity, finding innovative ways to use the spacecraft and its
instruments, and paving the way for future missions to explore our solar
9. Jewel of the Solar System
Cassini revealed the beauty of Saturn, its rings and moons,
inspiring our sense of wonder and enriching our sense of place in the cosmos.
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.
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
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’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.