UVSC Path Finder Experiment to Investigate the Origins of Solar Energy Particles – the Sun’s Most Dangerous Form of Radiation

Close-up of a solar flare including a solar flare, coronal mass ejection, and solar energetic particle event. Credit: NASA’s Goddard Space Flight Center

A joint ">Nasa– The experiment of the American naval research laboratory dedicated to the study of the origins of solar energetic particles – the most dangerous form of radiation from the Sun – is ready to be launched.

UVSC Pathfinder – short for Ultraviolet Spectro-Coronagraph Pathfinder – will hitchhike in space aboard STPSat-6, the primary spacecraft for the Department of Defense’s Space Test Program-3 (STP-3) mission. STP-3 is scheduled to take off from a United Launch Alliance Atlas V 551 rocket no earlier than December 5, from the Cape Canaveral space station in Florida.

Solar energetic particles, or SEPs, are a type of space weather that poses a major challenge to space exploration. A solar particle storm, or SEP event, occurs when the Sun hurls energetic particles into space at such high speeds that some reach Earth – 93 million kilometers away – in less than an hour. Bursts of powerful particles can wreak havoc in spaceships and expose astronauts to dangerous radiation.

UVSC Pathfinder will scan the lower regions of the Sun’s outer atmosphere, or corona, where the SEPs are believed to originate. While the Sun flares up almost daily when it is most active, there are only about 20 disruptive solar particle storms in an 11-year solar cycle. Scientists cannot reliably predict which of them will produce MS, or their intensity. Understanding and possibly predicting these solar storms is crucial to enable future space exploration.

“It’s a pioneer because we’re demonstrating new technology and a new way of predicting this kind of space weather,” said Leonard Strachan, astrophysicist at the US Naval Research Laboratory in Washington, DC, and principal investigator for the mission. “At this time, there is no real way to predict when these particle storms will occur.”

Understand and predict PES

The UVSC Pathfinder is a coronograph, a kind of instrument that blocks the bright side of the Sun to reveal the surrounding darker corona. Most coronographs have a single opening with a series of occultors that block out the Sun and reduce stray light. New to UVSC Pathfinder is that it uses five separate apertures, each with its own occluder, dramatically increasing the signal from the crown.

In the crown, scientists expect to find the special group of particles that will eventually become solar energy particles. Not just any ordinary particle in the Sun’s atmosphere can be supplied with SEP. Instead, scientists believe that SEPs originate from swarms of seed particles residing in the crown that are already about 10 times hotter and more energetic than their neighbors. These could come from bright bursts of energy, called flares, or from regions of strong magnetic fields in the corona, called current sheets.

Pathfinder UVSC

UVSC Pathfinder is a spectro-coronagraph, which is an instrument that blocks the bright side of the Sun to reveal the dimmer of the surrounding corona. It is shown here being inspected after thermal vacuum testing at LNR. Credit: Courtesy of Leonard Strachan

It takes a prior solar energy activity to ignite the seed particles. Every now and then, the Sun releases massive clouds of solar matter, called coronal mass ejections. These explosions can generate a shock in front of them, like the wave that culminates in the front of a boat at high speed. “If a coronal mass ejection is fast enough” – at least 600 miles per second – “it can produce a shock, which can sweep away these particles,” Strachan explained. “The particles receive so much energy from the shock that they become SEPs.”

Unlike most coronographs that take visible light images, UVSC Pathfinder is unique in that it is combined with a spectrometer that measures ultraviolet light, a kind of light invisible to the human eye. By analyzing the light in the crown, the researchers hope to identify when the seed particles are present.

Scientists have regularly observed SEPs from a near-Earth perspective, 93 million kilometers from their origin. Since the seed particles are only present in the crown, it was not possible to measure them directly. UVSC Pathfinder aims to observe elusive particles by remotely sensing their signatures in ultraviolet light. “We know relatively little about them,” said Martin Laming, a physicist at the US Naval Research Laboratory and scientific lead at the UVSC Pathfinder. “It really is a revolutionary observation. “

The impacts of MS swarms are severe. When it comes to spacecraft, they can burn out electronics, corrupt a satellite’s computer programming, damage solar panels, and even disorient a spacecraft’s star tracker, used for navigation. The effect is like driving through a blizzard and getting lost: the SEPs fill the star tracker’s view, and losing its ability to orient itself, it spins out of orbit.

Composite FMC

Images from NASA’s STEREO satellite show coronal mass ejection followed by a burst of solar energetic particles. Credit: NASA / STEREO

For humans, MS is dangerous because it can pass through a spacecraft or an astronaut’s skin, where it can damage cells or DNA. This damage can increase the risk of cancer later in life or, in extreme cases, cause acute short-term radiation sickness. (On Earth, the protective magnetic field and the atmosphere of our planet protect humans from this evil.) series of huge solar flares in August 1972 – between Apollo 16 and 17 missions – serves as a reminder of the threat posed by solar activity and radiation.

The UVSC Pathfinder experience marks a major step towards understanding where SEPs come from and how they evolve as they travel through the solar system. The data will help scientists predict whether a solar explosion could generate problematic SEPs in the same way we predict severe weather events on Earth. The forecasts would allow spacecraft operators and astronauts to take action to mitigate their impacts. “If our thinking is correct, the seed particles will be a very important signature of radiation storms to watch out for,” Laming said.

Join the NASA heliophysical fleet

UVSC Pathfinder is the latest addition to NASA’s fleet of heliophysical observatories. NASA’s heliophysics missions study a vast system interconnected from the Sun to space surrounding the Earth and other planets, and to the furthest limits of the Sun’s constant flow of solar wind. UVSC Pathfinder provides key information on SEPs, enabling future space exploration.

The observations of the mission will complement those of two other solar observatories. The new coronograph will approach 865,000 miles from the Sun, while NASA’s Parker Solar Probe and the European Space Agency and NASA’s Solar Orbiter will directly sample space up to a distance of 3.8 million miles and 26.7 million miles from the Sun, respectively. . “We hope that coordinated observations will be useful in determining the evolution of SEPs as they move away from the Sun,” Strachan said.

“NASA’s science program has a long history of obtaining space weather forecasting tools from the results of pure research missions,” said Daniel Moses, chief technologist of NASA’s heliophysics division. “The collaboration between the Scientific Mission Directorate of NASA, the Naval Research Laboratory and the Department of Defense STP program has been particularly fruitful in this area. UVSC Pathfinder continues this proud tradition of fundamental research collaboration with the potential to develop a new high impact tool with predictive capability.

UVSC Pathfinder is a NASA and United States Naval Research Laboratory payload aboard the Department of Defense Satellite-6 Space Test Program (STPSat-6). It flies alongside NASA’s Laser Communication Relay (LCRD) demonstration, which tests improved communication capability with the potential to increase bandwidth 10 to 100 times more than radio frequency systems – enabling space missions send more data home.

UVSC Pathfinder was designed and built at the US Naval Research Laboratory. It was funded by the NASA Heliophysics Program and the Office of Naval Research. It is managed by the Heliophysics Technology and Instrument Development for Science, or H-TIDeS, program office at NASA Headquarters. STP is operated by Space Systems Command of the United States Space Force.

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