Inside the outer corona of the sun: The Parker Solar Probe
Three years ago, a small spacecraft set off for what must be one of the most surreal places in our solar system: The Sun. The goal of the mission was to make observations of the outer corona of the sun. For this purpose, the spacecraft approached the sun at a distance of fewer than 7 million kilometers, diminishing the previous record of 42.7 million kilometers.
On its way to the sun, the small probe also visited Venus. It not only detected natural radio emissions in Venus’ atmosphere but also took some stunning pictures:
Picture taken of Venus by PSP on July 11th, 2020 Source
Picture taken of the Milky Way by PSP in 2018 Source
Now PSP has reached its destination: It was the first human-made object to pass through the Sun’s outer corona. In the process, it took not only pictures, but also a breathtaking video (see tweet below):
When you consider that this video from more than 100 million kilometers away shows what makes life on our planet possible in the first place, it’s mindblowing.
PSP will now remain in orbit around the Sun for several years, with multiple flybys of Venus. It is impressive to see what technical feats humankind is capable of, especially when you consider that the first powered flight by the Wright Brothers will only mark its 118th anniversary in a few days.
We can look forward to discovering what other achievements await us from the world of aerospace.
I still think one of the most incredible things about this mission is the speed. On this last pass it was going 364,621 mph (586,000 kph) at it’s aphelion (lowest point in it’s orbit). That’s 101 miles per second. I’m at a bit of a loss for how to put that into perspective, but maybe the best way is with distances on earth. New York to London, the route Concord could famously do in 3 hours, ya it would take PSP just a bit over 30 seconds. New York to LA would be about 20 seconds, London to Paris just a bit over 2, and even a full circumnavigation of the earth at the equator would take a mere 4 minutes.
But this isn’t even the fastest the probe will go. By the end of it’s life, on it’s lowest, fastest, and final pass in late 2024 it is expected to pass by at a mind numbing 430,000 mph. It is my some margin the fastest thing humans have ever made, blowing past Voyager 1 at the opposite extreme of solar system exploration which is traveling just 38,000 mph.
Another interesting fact is the temperature: The probe has to withstand temperatures of up to 1377°C. Its isolation is so good, that the payload will be near room temperature. That’s like throwing a box in something hotter than lava and the inside of the box won’t heat up at all. That’s remarkable technology.
In both cases it’s the coasting speed of their orbits around the sun. An object in a circular orbit always maintains the same coasting (orbital) speed, with the speed depending on distance to what you orbit around. So of course Venus orbits faster than Earth and a Starlink satellite orbits faster than a geostationary satellite.
When the orbits are elliptical, the coasting/orbital speed has to change as you move through the orbit, and it can be a massive difference between the min and max speed of the orbit.
For any elliptical orbit you might choose around the Sun, closest approach will have to be fast (the closer the faster). But when Parker passes Venus in its ellipse it will have slowed significantly as it has had to climb against the gravity well of the Sun, only to fall back down again speeding up as it does.
The Parker orbit is very egg shaped with it’s high point near the orbit of Venus. So actually it’s a very low energy orbit. It’s orbital energy around the sun is less than our own orbital energy around the Sun sitting in a chair on Earth!
I understand that, and it is a more relevant method of comparing their orbits from a scientific point of view, but the speed relative to the sun stands best I can tell. To a scientist it isn’t exactly the most relevant number in all cases, but it is true that in a sun relative perspective at aphelion the PSP is the fastest thing humans have ever made by some margin.
Thanks, I hope I didn’t come off as argumentative or anything. Everything you said is very true, and very important context for that number, but just wanted to throw out the counterpoint that the context doesn’t inherently change the meaning of the number, at least in this case.
No, everything you said is great. We definitely need different windows on how we look at the natural world. The answer often changes unexpectedly depending on how the question is asked. I’m constantly blown away by that, like the Parker speed being that high. I couldn’t see that puzzle piece until I saw your post.
It further led me to compare these two graphs: how the midpoint of Voyager 2’s velocity was maybe around 20km/s, and the Parker probe repeatedly goes between about 20km/s and to around 120km/s: