The problem with studying the solar wind from Earth is distance. In the time it takes the solar wind to race across the 93 million miles between us and the Sun, important clues to the wind's origins -- like temperature and density -- fade. "You're constantly asking yourself, 'How much of what I'm seeing here is because of evolution over four days in transit, and how much came straight from the Sun?'" said solar scientist Nicholeen Viall, who advised Di Matteo during his research at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Helios data -- some of which was collected at just one-third the distance between the Sun and Earth -- could help them begin to answer these questions.
Then, Di Matteo searched the data for specific wave patterns. They expected conditions to alternate -- hot and dense, then cold and tenuous -- as individual blobs engulfed the spacecraft and moved on, in a long line.
Parker Solar Probe performs its second solar flyby on April 4, which brings it 15 million miles from the Sun -- already cutting Helios 2's record distance in half. The researchers are eager to see if blobs show up in Parker's observations. Eventually, the spacecraft will get so close it could catch blobs right after they've formed, fresh out of the Sun.