The first thing I did when I heard about the Parker Solar Probe’s successful launch (0731 UTC Sunday) was to double-check the spacecraft’s projected velocity when it makes its closest approach to the Sun. I always think in terms of high speed when contemplating operations close to our star, the legacy of the two Helios missions, which at present hold the record as fastest man-made objects. Placed in highly elliptical orbits after their launches in 1974 and 1976, the Helios spacecraft managed a sizzling 70 kilometers per second.
The Helios missions were a joint venture between what was then West Germany’s space agency and NASA, the craft themselves built by German aerospace firm Messerschmitt-Bölkow-Blohm. Helios 2 flew closer to the Sun by about 3 million kilometers, closing to 0.29 AU (43 million kilometers), which took it inside the orbit of Mercury. The Parker Solar Probe ups the ante considerably, with an eventual closest approach of just 6.1 million kilometers.
The spacecraft at that point will be moving at roughly 192 kilometers per second, easily eclipsing the Helios record. Now imagine if we could put a spacecraft at these speeds on a course for Alpha Centauri. Context is everything, and what is truly a blistering pace in comparison to our previous records turns out to be a good deal less than 1 tenth of one percent of lightspeed when pondered in interstellar terms. It gets us to Centauri A/B in 6000 years.
Image: The United Launch Alliance Delta IV Heavy rocket launches NASA’s Parker Solar Probe to touch the Sun, Sunday, Aug. 12, 2018, from Launch Complex 37 at Cape Canaveral Air Force Station, Florida. Parker Solar Probe is humanity’s first-ever mission into a part of the Sun’s atmosphere called the corona. Here it will directly explore solar processes that are key to understanding and forecasting space weather events that can impact life on Earth. Credit: NASA/Bill Ingalls.
We’ll track the Parker Solar Probe with great interest over the course of its seven year mission, which gets interesting quickly as the craft heads toward Venus for the first of seven flybys of that planet, using Venus’ gravity to tighten up its solar orbit. By November, the Parker Solar Probe will be positioned to pass through the Sun’s corona with the first of its projected 24 total passes by the Sun. Bear in mind that the corona is more than 300 times hotter than the Sun’s surface.
We have an 11-centimeter thick carbon-carbon composite shield to thank for making operations in this environment possible, one whose front surface is capable of withstanding temperatures beyond 1300 degrees Celsius. This advanced thermal protection will keep four suites of instruments alive to study plasma and energetic particles, magnetic fields and the solar wind.
That last point has great relevance to our discussions on Centauri Dreams, namely the methods we may one day use for fast transportation around the Solar System by way of building the infrastructure we’ll need for interstellar flight. The more we learn about the solar wind, which can hit 800 kilometers per second, the more we’ll understand the variables that may help us harness it through variously designed magnetic sails. That assumes, of course, that this highly mutable and unpredictable flow is manageable enough to navigate with such craft.
Image: Artist’s impression of the Parker Solar Probe spacecraft leaving Earth, after separating from its launch vehicle and booster rocket, bound for the inner solar system and an unprecedented study of the Sun. Credit: JHU/APL.
I’ve commented before in these pages that there are also interesting implications for future ‘sundiver’ missions in the Parker Solar Probe. In these concepts, a solar sail, perhaps furled behind an occulter such as a small asteroid, would be taken as close as possible to the Sun before being unfurled at perihelion to achieve the highest possible acceleration. If a mission like that is ever to happen, we’ll need the kind of data the Parker Solar Probe delivers as we learn how to operate in an environment as extreme as any spacecraft has ever encountered.
The Parker Solar Probe’s solar arrays have already deployed. Immediately ahead for the spacecraft is deployment of its high-gain antenna and magnetometer boom, as well as the first of a two-part deployment of its electric field antennas. The instrument testing period begins in early September and continues for four weeks, after which science operations will begin.