Now that the historic Parker Solar Probe is charging toward the Earth’s sun, scientists are ready to use it to answer decades old mysteries about its core, surface and atmosphere.
“This mission has been the dream of scientists since the beginning of the space age,” says Dr. Gary Zank, director, Center for Space Plasma and Aeronomic Research at the University of Alabama in Huntsville. “To see it finally happening is intensely satisfying. Like all great missions, however, we will learn more than ever imagined and yet will be left wanting to know even more.”
Since the probe launched Aug. 12, the spacecraft and its instruments are going through commissioning to ensure that everything works as designed and planned, Zank says.
“This takes some time,” he said. “There will be a period that data is returned for a first analysis. But once everything is working, and the data begins to flow, that’s when the real mission begins — this is the discovery phase where the probe will begin to spend significant lengths of time in a part of the solar wind, this will occur even before the closest approach to the sun.”
Zank said scientists are “hoping” to see the probe’s first data possibly by the end of October or early November.
“From then on until the end of the mission, there will be a stream of papers describing, discussing, analyzing, relating to theories and models, everything that will be observed,” Zank said. “In fact, we will not have enough people working on this data set to unearth all the gems waiting to be discovered.
“This data will be used during the mission and for decades after, especially because this is a once-in-a-lifetime mission.”
Zank, also an eminent scholar and distinguished professor at UAH, is co-investigator on one of the spacecraft’s investigations: The Solar Wind Electrons Alphas and Protons investigation.
That’s where CSPAR comes into play.
CSPAR and Marshall Space Flight Center formed a consortium with Harvard Smithsonian Astrophysical Observatory, NASA Goddard Space Flight Center, Los Alamos National Lab, University of California Space Sciences Laboratory, University of New Hampshire, and the Massachusetts Institute of Technology to build the SWEAP instruments.
SWEAP instruments will directly measure the properties of the plasma in the solar atmosphere during the probe’s encounters into the sun’s atmosphere over the next seven years. In includes a small instrument that will look around the protective heat shield of the spacecraft directly at the sun. This will allow SWEAP to sweep up a sample of the atmosphere and touch the sun for the first time.
“As fascinating and enjoyable as it is to develop theories and models, unless they’re tested and hopefully validated against observations, it’s about as useful as staring at one’s navel,” Zank said. “So, spacecraft observations are key to ensuring that we can develop testable, quantitative models and theories of the physical phenomena or processes that interest us.”
He said the origin of the solar wind, the high-speed (350 to 800 km/s) flow of charged particles from the solar surface, remains perhaps the outstanding unexplained problem in space physics today. The PSP was built in large part to answer that fundamental question, and basically clear up the mystery that has faced scientists since the start of the space age.
“The Parker Solar Probe is a billion dollar mission so certainly one of the largest heliophysics missions ever flown, and by extension, one of the biggest and most important projects in which CSPAR is involved,” Zank said.
In addition to SWEAP, the other investigations include:
- The Fields Experiment will measure electric and magnetic fields, radio emissions and shock waves in the sun’s atmospheric plasma.
- The Integrated Science Investigation of the sun uses two instruments to monitor electrons, protons and ions in the sun’s atmosphere.
- The Wide-field Imager is a telescope that will make images of the sun’s corona to see the solar wind, clouds and shock waves as they pass by the spacecraft.
Proving a theory?
Then there is Zank’s theories related to how the sun can be hot at its core yet stay relatively cool at its surface, while at the same time super-heating its coronal atmosphere?
“I have developed two theoretical models to explain the heating of the solar corona, which in turn will explain the origin of the solar wind,” Zank said.
Both models, he said, are based on the dissipation of low frequency magnetic turbulence, and the differences reside in certain somewhat technical characterizations of the underlying turbulence.
“Broadly speaking, they’re both turbulence models,” Zank said. “The competing model for heating the solar wind relies on high frequency waves called ion-cyclotron waves, and the damping of these waves is thought to heat the solar corona. PSP will measure directly the coronal plasma using the SWEAP instrument that I’m involved with and the magnetic fluctuations using the Fields instrument.
“The combined results from these two instruments will allow us to infer the nature of the fluctuations and so distinguish between low-frequency turbulence-like and high-frequency wave-like modes. The amount of energy in these fluctuations can be measured as well. From these kinds of measurements, we will be able, if life remains simple and straightforward (not always guaranteed!), we should be able to take the first steps in confirming what the basic heating mechanism is for the solar corona and hence the origin of the solar wind.”