Parker Solar Probe Launch Scrubbed
ULA Delta IV Parker Solar Probe Heavy Scrub Statement
“The launch of a United Launch Alliance Delta IV Heavy carrying the Parker Solar Probe spacecraft was scrubbed today due to a violation of a launch limit, resulting in a hold. There was not enough time remaining in the window to recycle. The launch is planned for Sunday, Aug. 12 from Space Launch Complex-37 at Cape Canaveral Air Force Station. The forecast shows a 60 percent chance of favorable weather conditions for launch. The launch time is 3:31 a.m. ET.”
Congratulations! It was a very spectacular launch based on the videos. Better understanding of the Sun will improve solar weather predictions which are important to a society as dependent on electronics as we are.
Get used to such bland or empty pronouncements as more & more spaceflight goes to commercial providers. One provider had a delay/postponement a number of months ago and not even NASA was informed of exactly what caused it…for a booster that NASA uses (and will use) for vital missions.
The details came out later.
As I unsettle (oh dear! Understand, of course!) the mission- why is the corona so much hotter than the solar surface.
The devil is in the details, as usual, but I think the big picture is that there are strong magnetic fields in and below the surface, entangled with the turbulent plasma, as we see from videos of the boiling motions around sunspots.
But a conductive plasma, moving in a magnetic field, induces strong electric fields. These strong moving, changing, EM fields carry energy upwards from the photosphere (the visible surface) to regions where the density is lower and lower, so the plasma conductivity is lower and lower. Yet the changing EM fields remain strong, and induce currents that violently heat the plasma, as its resistivity rises with altitude, while the currents try to force their way through a plasma medium that is rapidly becoming a vacuum.
The energy being dumped into the thinning plasma inevitably raises the plasma temperature, until the kinetic energy of the charged particles — protons, electrons, H+ & He+ ions, along with higher Z atoms and ions — is enough that they are able to escape from the tremendous gravitational field into space, traveling along open magnetic field lines.
(The plasma cannot cross the closed B field lines, which run from one point near the surface, up into the corona, and then return to the surface in the huge magnetic arches we see so beautifully in motion pictures, which show the hot plasma streaming down from above.)
My expertise is too feeble to allow me to give a more detailed, quantitative picture, or even to describe the shortcomings of the above sketch, so I caution all with the misfortune of knowing as little as me. And I welcome corrections and adjustments from our experts, who have drunk deeply of Parker’s works since the 1960s. I hope it is at least true that the missing energy heating the corona must be carried up by the magnetic and electric fields, the EM field lines being whipped around by the boiling conductive inferno below.
If the above is at all correct, the power in the turbulence of the magnetized plasma in the outer layer of the Sun ought to bear some relation to the power radiated as the solar wind. Does anyone know these, quantitatively? As “the coronal heating problem” has been around for decades, I must suspect that the quantitative data on these two exists, and more or less demolishes my fantasy….
Note added: I see that the power in the Solar Wind is fairly well known (cf Wikipedia, of course). The turbulence seems more difficult.
I don’t think there is anything fundamentally wrong with you description. The problem is that there are many ways it could work. The plasma convection could generate waves (most likely Alfven waves) which break as they propagate into the corona. Or the convection could twist magnetic field lines until reconnection sets in. A few other possibilities have been suggested. Unfortunately, the details (and therefore where heat is deposited and how efficiently) aren’t well constrained by observations. The corona isn’t dense enough to see well, at least not on the small scales these processes involve. The answers require local, in situ measurements, and that’s what the Parker Solar Probe is about.
This isn’t at all unusual. Someone noticed something odd during the August 11 launch attempt, and wanted extra time to make sure there wasn’t a problem (or to fix it if there was a problem.) Earlier there had been a longer hold due to “EGSE” (which doesn’t mean much unless you know that’s electronic ground system equipment, and still doesn’t mean all that much if you do.) They only had a 65 minute launch window on that day, and there wasn’t time to address the issue and launch. So they put the launch off until the next day.
As far as explaining the details, that’s rarely done. But that’s also normal in other situations. At an airport, how often do you hear, “25 minute delay for maintenance”? How often do you hear, “25 minute delay because the hydraulic fluid in the port landing gear is low and needs to be topped off”?
Yep, folks have been spoiled by a space agency that used to even tell you what the astronauts had for breakfast. The professionals in charge believe it’s safe and that is all you need to know.
Well, I’m not sure if you would agree, but some of those professional in charge should probably be government regulators. That’s one reason civil aviation is so safe. The FAA sets standards and makes sure they are followed. It isn’t purely a matter of trusting private companies to do the right thing and assuming they won’t cut corners. But those regulations are based on facts and the companies who build and operate the aircraft have a fair amount of input. That’s probably a good model for spaceflight. We’re currently too far from optimal in one direction, but going too far in the other direction is potentially just as bad.
True, but it’s a self adjusting process and a balance will be found in space flight as with aviation. The increased tempo of launches will also help in moving the process forward.
EGSE – Electrical Ground Support Equipment