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At NASA, “CuPID” and “CUTE” aren’t just Valentine’s Day buzzwords – they’re the names of two satellite missions launching this fall.
The Cusp Plasma Imaging Detector, or CuPID, will study the boundaries of Earth’s magnetic field, to see how energy from the Sun can break through our planet’s magnetic shield. The Colorado Ultraviolet Transit Experiment, or CUTE, will train its telescope on planets outside our solar system to study how quickly their atmospheres are escaping.
Both CuPID and CUTE are CubeSats, a class of very small research satellites. CubeSats are relatively inexpensive to build and launch, in part because they can easily hitch rides with larger satellite missions. CuPID and CUTE will carpool with NASA and the U.S. Geological Survey’s Landsat 9, taking flight from Vandenberg Space Force Base in California.
Both CuPID and CUTE are smaller than microwave ovens, but from their vantage points in low-Earth orbit, they will address questions about enormous questions in space.
Cusp Plasma Imaging Detector (CuPID)
CuPID is equipped with the first wide field-of-view soft X-ray camera to be placed in orbit. The camera observes “soft” or lower-energy X-rays, which are emitted during a phenomenon called magnetic reconnection.
Near Earth, magnetic reconnection starts with the solar wind, which is made up of fast-moving streams of charged particles coursing out from the Sun. Those particles would slam into Earth if not for our planet’s magnetic field, which carves out a protective bubble in space called the magnetosphere. The magnetosphere is strong and large – extending 6 to 10 times Earth’s radius on the Sun-facing side and hundreds of times the length of Earth’s radius on the back side.
Scientists know that the solar wind can sometimes pelt the magnetosphere enough to force it to temporarily reconfigure, a process called magnetic reconnection.
Magnetic reconnection is common in space where two magnetic fields encounter one another and occurs frequently at the edge of Earth’s magnetosphere. When it does, energy from the Sun can flood toward Earth. That’s when astronauts and satellites may face danger.
“There are two big questions we have about magnetic reconnection at Earth’s magnetosphere that we hope CuPID will address,” said Brian Walsh, assistant professor of mechanical engineering at Boston University and CuPID’s principal investigator. “The first is: Does energy flood into one big continuous region, or lots of little patches? The other is: Is it occurring all the time? Or does it occur in bursts?”
This is where CuPID’s wide field-of-view camera comes in handy. Previous NASA instruments have traveled through the edge of the magnetosphere, where charges are exchanged between the Sun and Earth. The most recent of these missions is NASA’s Magnetospheric Multiscale Mission, launched in 2015.
“That mission does great work with the microphysics, but we don’t have a wide field of view because we’re flying through the event,” Walsh said. “With CuPID, we're going to zoom out and get a big picture of the solar wind and the magnetosphere interacting from a vantage point close to Earth.”
CuPID has a long history at Goddard. Three NASA Goddard scientists flew the first wide field-of-view soft X-ray camera back in December 2012. It launched on a suborbital sounding rocket and spent only a few minutes in space. But that was enough time to prove that it could do its job. In 2015, a miniaturized version of the original camera was shown to be successful, and a full satellite with avionics was funded.
Now, that satellite is ready for launch.
Colorado Ultraviolet Transit Experiment (CUTE)
As the first NASA Astrophysics-funded CubeSat to conduct exoplanet science, CUTE will lend new insights about the atmospheres of planets beyond our solar system.
Many planets undergo atmospheric escape, meaning they lose mass from their atmosphere over time. Scientists know that planets in our own solar system, such as Mars, experienced this loss in the past, shaping their climate and evolution into the planets we know today.
“We don’t see extreme atmospheric mass loss on planets in our solar system today, so extrasolar planets can serve as a laboratory for studying those conditions,” said Kevin France, associate professor in the Department of Astrophysical and Planetary Sciences at the University of Colorado Boulder and principal investigator of the CUTE mission. Understanding this process, he says, can offer more insight into how a planet evolves and if planets can develop and maintain habitable conditions – in our own solar system, but also beyond it.
CUTE will study planets outside our solar system where this loss is happening in the extreme: hot Jupiters. These are gas giants similar in mass and size to Jupiter, but they orbit their host stars so closely that particles in their atmospheres become superheated and may overcome the planet’s gravity, escaping out into space.
Over the course of about seven months, CUTE will watch at least 10 of these giants transit in front of their stars. Because CUTE focuses exclusively on these planets, and because hot Jupiters orbit their host stars so quickly, the small satellite will be able to capture five to ten transits per planet.
During each transit, CUTE will study how ultraviolet light from the star changes when it passes through the planet’s atmosphere. Key elements in the planet’s atmosphere, such as magnesium and iron, absorb near-ultraviolet light, providing clear evidence of their presence.
By taking repeated measurements of these atmospheric elements for the same planets, CUTE will help us understand how quickly those planets are losing their atmospheres, and how that changes over time.
A learning opportunity
The proliferation of CubeSats in recent years has allowed for more people, especially students, to get their ideas to space.
“From the very beginning, the involvement of students and early-career scientists and engineers has been crucial to CUTE,” France said. Once CUTE and CuPID are in orbit, students will also monitor them from the ground, and help collect and interpret data.
“CubeSats are a great way to offer students learning opportunities while also developing fantastic science instruments and doing really important work,” Walsh said.