Nasaicon - Blog Posts

Our New Satellite to Study the Edge of Space

We're about to launch a new satellite called ICON — the Ionospheric Connection Explorer — to study our planet's boundary to space.

The overlap between Earth's upper atmosphere and outer space is complicated and constantly changing. It's made up of a mix of neutral gas (like the air we breathe) and charged particles, where negatively charged electrons have separated from positively charged ions. This charged particle soup reacts uniquely to the changing electric and magnetic fields in near-Earth space, while weather conditions from here on Earth can also travel upwards and influence this region. This makes Earth's interface to space a dynamic, hard-to-predict region of the atmosphere.

Understanding what causes the changes in this region and how to predict them isn't just a matter of curiosity. Earth's boundary to space is home to many of our Earth-orbiting satellites, and it also plays a role in transmitting signals for communications and navigation systems. Unpredictable changes here can garble those signals and even shorten the lifetime of satellites.

ICON, launching on Nov. 7, will study this region with a unique combination of instruments. Orbiting about 360 miles above Earth, ICON will use its cameras to measure winds near the upper edge of Earth’s boundary to space and track atmospheric composition and temperature by studying a phenomenon called airglow. ICON also carries an instrument that will capture and measure the particles directly around the spacecraft, or in situ. 

ICON is launching aboard a Northrop Grumman Pegasus XL rocket. On launch day, the Pegasus XL is carried out over the ocean by Northrop Grumman's L-1011 Stargazer aircraft, which takes off from Cape Canaveral Air Force Station in Florida. About 50 miles off the coast of Florida, the Pegasus XL drops from the plane and free-falls for about five seconds before igniting and carrying ICON into low-Earth orbit.

NASA TV coverage of the launch starts at 2:45 a.m. EST on Nov. 7 at nasa.gov/live. You can also follow along with the mission on Twitter, Facebook or at nasa.gov/icon.

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. 

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

Meet Our ICONic New Satellite

The boundary between Earth and space is complicated and constantly changing. Unlike the rest of the atmosphere, the upper atmosphere near the edge of space has a mix of both neutral particles similar to the air we breathe, as well as electrically charged particles called ions. Changes in this region are unpredictable, but they can affect satellites and garble signals, like GPS, that pass through this region. That’s why we’re launching ICON (the Ionospheric Connection Explorer) to get our first-ever comprehensive look at our interface to space.

About 60 miles above Earth’s surface, Earth’s atmosphere gives way to space. The change is gradual: The gases of the atmosphere get steadily thinner the higher you go. On the edge of space, the Sun’s radiation cooks some of those thin gases until they lose an electron (or two or three), creating a population of electrically charged particles swarming alongside the neutral particles. These charged particles make up the ionosphere.

Because the particles of the ionosphere are electrically charged, they respond uniquely to electric and magnetic fields. Dynamic conditions in space — including shifting fields and surges of charged particles, collectively called space weather — induce shifts in the ionosphere that can have far-reaching effects. The ionosphere is where space weather manifests on Earth, and it’s inextricably connected with the neutral upper atmosphere — so distortions in one part affect the other.  

Changes in the ionosphere and upper atmosphere — including sudden shifts in composition, density, temperature, and conductivity — can affect satellites, building up electric charge that has the potential to disrupt instruments, and garble signals like those used by GPS satellites. Predicting these variances is hard, because the causes are so complex: They’re driven not only by space weather — usually a product of solar activity — but also by regular weather down near Earth’s surface.  

Differences in pressure caused by events like hurricanes, or even something as simple as a sustained wind over a mountain range, can ripple upwards until they reach this region and trigger fluctuations. Weather’s influence on the upper atmosphere was only discovered in the past ten years or so — and ICON is the first mission designed specifically to look at that interaction.

ICON carries four types of instruments to study the ionosphere and upper atmosphere. Three of them rely on taking far-away pictures of something called airglow, a faint, global glow produced by reactive compounds in the upper atmosphere. The fourth type collects and analyzes particles directly.

MIGHTI (the Michelson Interferometer for Global High-resolution Thermospheric Imaging) uses Doppler shift — the same effect that makes a siren change pitch as an ambulance passes you — to precisely track the speed and direction of upper-atmosphere winds.

FUV (the Far Ultraviolet instrument) measures airglow produced by certain types of oxygen and nitrogen molecules on Earth’s day side, as well as oxygen ions on Earth’s night side.

EUV (the Extreme Ultraviolet instrument) measures shorter wavelengths of light than FUV. Airglow measured by EUV is produced by oxygen ions on Earth’s day side, which make up the lion’s share of Earth’s daytime ionosphere.

The two identical IVMs (Ion Velocity Meters) make very precise measurements of the angle at which ionized gas enters the instruments, helping us build up a picture of how this ionized gas around the spacecraft is moving.

We’re launching ICON on June 14 Eastern Time on an Orbital ATK Pegasus XL rocket from Kwajalein Atoll in the Marshall Islands, which will deploy from Orbital’s L-1011 Stargazer aircraft. NASA TV will cover the launch — stay tuned to nasa.gov/live for updates and follow the mission on Twitter and Facebook.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.