When I did my PhD in the late 80s we were simulating Kelvin-Helmholtz Instabilities on supercomputers with application to solar dynamics. It is very nice to see that they exist and behave like predicted. There are plenty of other plasma instabilities that were predicted at that time and have now been confimed by space probes.
Given that video is 7.5 hours start to finish, and Parker is moving at several hundred thousand mph relative to that vortex, is it on the order of the diameter of the sun?
430K miles per hour is obviously a big number. And I have previously heard of this slingshot approach to increase speed so I am familiar with it.
However, I believe energy is constant (it can be transformed but unlikely to be created or destroyed). For some object to gain a speed of 430K miles per hour, it must come from elsewhere, obviously it did not burn its own fuel (and I am assuming the slingshot theory). So the Sun transferred it a bunch of energy. I presume that is gravitational energy and to my mind it implies Sun gave away that energy. However, isn't that based on mass? But I do not think the mass would have changed.
ELI5 please in terms of energy exchange. Who gained and lost and how?
That's correct, the energy comes from the body the spacecraft is slingshotting around (the Sun in this case). It's not mass or gravitational energy or anything weird like that, it's actually just a momentum transfer, the same as if the two objects had collided and bounced off each other elastically (i.e. without loss of energy to heat). So a (miniscule amount) of momentum (velocity x mass) is being transferred from the Sun to the spacecraft, and that's where the energy comes from.
(source: I studied physics and had a grandparent at NASA who worked on Voyager II and talked about this issue with me; but it's been a while since both of those things, so anyone with more fresh experience feel free to chime in!)
I'm studying physics right now, I can say I agree with everything you said.
One thing I'd like to expand on to those who don't know how greater energy means greater speed.
The kinetic energy equation is 1/2massvelocity^2=KE
Since the KE increases from the momentum transfer, and mass of the object stays constant, the only thing that can change is velocity, where it has to go up.
ex: KE=2, m=1
2=1/21v^2, v=2
Now if some momentum were transferred, and the kinetic energy increased to KE=8,
8=1/21velocity^2, velocity=4, since the mass can't change
i was wondering too! Do you think it might be because of citing family as a source? I barely ever post here, so don't have a good muscle memory for norms and best practices.
(also both scared and curious of what might result from dropping below 0 karma)
Is it though? A vehicle can't use a gravity-assist slingshot around the Sun to maneuver inside the solar system because the sun is at rest with respect to the rest of the solar system.
hey icehawk -- so you can use any celestial object in the solar system to maneuver; all you're doing is basically changing your direction. But you're right, there's something strange going on here. The original article doesn't actually have any information about what this spacecraft is doing, but it links to another one about the speed. I'm looking at that now, gonna add an addendum (or edit the old comment if i can figure out how to do that)
sorry kshacker, I may have thrown you off the scent here. My explanation of the slingshot effect is right, but it doesn't look like slingshotting is what the spacecraft is using to increase its speed:
tl;dr:
the spacecraft is just falling into the Sun, which is why it speeds up. It isn't gaining speed relative to anything else, and it loses that speed again once it flies away from the Sun. It is using Venus to get closer to the sun each time around by damping its angular momentum, which works but I don't know how to explain that in an ELI5 way.
so it's actually a little anticlimactic.
BlarfMcFlarf and pfdietz got this right below in their comment thread:
"What the Venus flybys did was not add energy so much as remove angular momentum. The hard part about getting close to the Sun is that conservation of angular momentum prevents it."
...and icehawk and vl correctly point out that you can't really use the Sun to increase your within-solar-system speed. Thanks to them for prompting me to look into this further. The cool slingshot maneuvers all involve planets, not the sun.
...but I think the key answer that none of us quite articulated to your question:
How is the spacecraft using the slingshot effect to increase its speed each time around?
...is that it isn't!
...the article dramatically describes it as "picking up speed" each time it goes around the sun, but that is misleading. It is just getting closer to the sun every time around, so of course it goes faster the closer it gets.
the cool part if any is how it uses Venus to get closer to the sun (by sapping angular momentum), but that's hard to explain in a nutshell and doesn't really relate to your energy question.
so that is hopefully now a better answer to this mystery that brings together what some of the other commenters have pointed out.
The slingshots used to deorbit were around Venus, so it slightly gained velocity while the Parker probe lost it to get closer to the sun without expending as much fuel.
As for its velocity around the sun, it’s intuitively like pendulum. When far away, it’s like the raised pendulum, and when near the sun, it’s like the pendulum at the bottom of its swing. Its a strained metaphor, but if you look at the orbit, it’s a very deep swing and a very large object it’s swinging towards, so it ends up quite fast at the bottom.
What the Venus flybys did was not add energy so much as remove angular momentum. The hard part about getting close to the Sun is that conservation of angular momentum prevents it.
Related to this: a minimum energy transfer between two circular orbits is normally the two-burn Hohmann transfer: an elliptical orbit that is tangent to each circular orbit. But if the radii of the two circular orbits have a sufficiently large ratio, it takes less delta-V to use three burns: go into an elliptical orbit that goes out to very large distance, do a small burn to lower (or raise) the periapsis to be at the other orbit, then circularize with a third burn. This is because doing a burn at large distance adds or removes a very large amount of angular momentum.
Flybys to boost speed take a tiny tiny tiny part of a planet’s orbital kinetic energy and exchange it with a spacecraft.
The silliest way to describe it is kind of like stepping in front of a bus, but instead of actually getting hit you just get close enough for gravity to pull you along with the planet. Orbital mechanics is really just not intuitive so you can’t get an easy explanation as one doesn’t exist, your life experience with momentum and gravity is just too different for it to make sense easily.
Potential energy was converted into kinetic energy, not unlike when an apple falls to the ground. So the sun doesn’t really give away this energy, but its the system including these two masses.
It's same as for everything: something is going into lower energy state, while something else going into higher energy state via some energy transfer mechanism.
We are 100% sure for one side of energy transfer: both spacecraft and Sun are going to higher energy level first, then to lower energy level.
Other part of equation is unknown. It's called "Gravitational potential energy", but it's unknown what stores this energy. However, we have few hints: objects creates gravitation waves, gravitational waves are propagated at c (speed of light), there is Higgs field (nature unknown), which is presented everywhere and gives mass, Higgs boson connects objects to Higgs field, gravitational force is proportional to 1/d^2. So, we have a medium (Higgs field), to which objects are connected via Higgs bosons. We can assume that energy can be transferred to/from the medium via bosons, so medium can store the energy and release it. We can speculate that when bosons somewhat connects to medium, it may create a tension in the medium, like bubbles on water, via unknown physical process. As result of that tension, bosons which are closer are spending less energy to create same tension, which makes closer position energetically favorable, so any random motion (because of noise in the medium) in direction of another boson will release some energy, while any movement in opposite direction will require to apply some energy.
>there actually is no objective answer as to which body gained and which lost energy! Energy is always conserved, but which way the transfer happened depends on your reference frame!
this isn't too difficult to demonstrate: pick an inertial reference frame A such that the spacecraft is at rest following the "collision" (aka the slingshot). In this frame, the spacecraft has 0 kinetic energy post-slingshot; therefore, it lost energy in the slingshot, which was transferred to the Sun. Likewise, pick a frame B such that the Sun is at rest after the slingshot (this would be the more usual frame to pick). In this case, it's the Sun that lost energy, and the spacecraft that gained it.
(depending on one's mechanics background this might appear anything from obvious to very weird and unintuitive)
Increasing speed with slingshot works because you leave vicinity of the planet in the same direction planet travels. Basically this allows you to add planet’s speed to your own.
Within solar system you cannot increase speed by slingshotting around the sun.
Total energy within system stays the same, some energy is transferred from the planet to the spacecraft.
>To characterize the spatial scales involved (e.g., radial size, width, and separation of the eddies) we use exclusively observations from WISPR-I, the only instrument where the eddies were discernible.
>From the GCS reconstruction, we estimated that the CME propagated radially in a direction with a Carrington longitude of 20° and latitude of 10°.
>Since all the features exhibited a rather elliptical shape, to characterize the typical scales involved, we measured the length of the major and minor axes (the major axis is along the propagation direction, while the minor axis is perpendicular to this direction).
> From the time-lapse considered, we estimate that the lifetime of the eddies (i.e., the temporal period) is less than 30 minutes.
>Table 1. Average Sizes (in Mm) of the Minor (top row) and Major (lower row) Axis of Observed Eddies
> The misconception that there is no sound in space originates because most space is a ~vacuum, providing no way for sound waves to travel. A galaxy cluster has so much gas that we've picked up actual sound. Here it's amplified, and mixed with other data, to hear a black hole!
> In a recent publication they show that in some cases a sound wave can jump or "tunnel" fully across a vacuum gap between two solids if the materials in question are piezoelectric.
> Helmholtz resonance is one of the principles behind the way piezoelectric buzzers work: a piezoelectric disc acts as the excitation source, but it relies on the acoustic cavity resonance to produce an audible sound.
Outside of sci-fi (as in: in physics based renderings) wormholes look like lenses, and a lens free-floating in space with only point-like stars behind it is hard to notice.
ERBs in particular are unstable in a universe containing literally anything else including a single photon, so you can't ever see one.
Even though they had Kip Thorne as a scientific advisor and he made a scientifically accurate rendering of various environments, if they'd not made it a swooshy tunnel in the middle then the transit would have been somewhat boring (or sudden) cinema.
The Parker Solar Probe has a very eccentric orbit around the sun and mostly operates behind this large head shield which always faces the sun. So imagine it like horse blinders and the instruments are facing in the direction of travel and to some extent 'to the right' away from the sun.
In the video the sun is always to the left and the probe is going through its closes approach of the orbit (aka perigee) which directly correlates to the velocity telemetry in the bottom left. At the highest speed, it's closest to the sun.
So in the video of the vortex the sun is to the left, the axis of the vortex is likely pointing directly at the sun and the probe is flying past it.
It's one of the coolest science images I've seen! I don't understand how one can't be in awe.
Look at the time scale. Look at how big that structure is!
We're traveling at nearly 0.1% the speed of light, at temperatures of 2,500 degrees Fahrenheit. This is an incredible testament to science and engineering.
You know what else might look boring but is actually insanely cool? Emission spectra from exoplanets. Peaks on a graph, but we're sensing atmospheres from worlds our ancestors could never have imagined.
Just think what lies ahead for our species. It's incredible to ponder.
This probe is flying through an incredibly harsh environment, and it’s likely tuned for certain brightnesses/wavelengths to show features better. It’s also why a lot of space probes use false color; your eyes just wouldn’t be able to see features otherwise.
“Cheap” and “first in human history” rarely go together. When Apple offers a mass produced solar probe I’m sure it will have a color camera. Until then you have to be satisfied by the actual achievement instead.
We can send probes to the sun, to Mars, collect samples from asteroids billions of miles away.... but we can't get decent quality colour photos?!? That tech is beyond us? In 2024? .. wtf ...
I really don't get why my original post is downvoted and being disputed. It seems such a basic point.. It such an oversight on the part of NASA, it borders on intentional.
> It such an oversight on the part of NASA, it borders on intentional.
This is why you are being downvoted. You clearly do not understand the difficulty of these achievements. Yet you claim NASA is incompetent for doing something literally nobody has ever done before.
A color camera has no scientific value so they didn’t send one. It’s that simple.
Assuming you know more than NASA is rightfully going to earn downvotes. You don’t know more than NASA.
Approach this with an open mind and some curiosity and you’ll get a much warmer response. You might even learn something.
We already know what color the sun is. Color cameras take worse quality images and use more data to do so. The black and white images are higher fidelity and thus convey more useful information.
> You are telling me that using your visual sense is irrelevant, because of all the data that is being collected.
I’m not telling you that. Black and white pictures are still perceived with the visual sense. The picture is data.
> Ie scientists like spreadsheets of info, databases, rather than imagery that is faithful to the human eye.
Well, no, clearly they value images because they sent a camera. A human eye would be completely obliterated way before reaching the sun’s corona. It’s physically impossible for a person to perceive this environment “faithfully”.
> everyone who can use their eyes to judge information will do so
Yes but there is less useful information in a color image to judge.
> you can do both cos the overhead of a colour camera is so low!
The overhead for a useless instrument is extremely high. There are mass constraints, power constraints, and communication bandwidth constraints. A color camera would be a pointless waste of resources.
Modern day tech often reaches spaceflight circles decades after it becomes ubiquitous in normal use. For spaceflight purposes it is extremely vital that any and all components and tech is matured amd that takes a long time. Add in a ton of certification and paperwork processes and there you go.
I disagree. There’s an enormous amount of bleeding edge tech in spacecraft. This camera was a totally custom thing. The constraints are simply so limiting that we have to make tradeoffs.
And even if that were the case, do you not think there would be some scientific value to having the photo in colour that it would be worth the risk?
Personally - I think its ridiculous that NASA get so many billions but are unable to put in a decent colour camera. I can't see any acceptable reason for this.
In addition to all the other replies on this topic, monochrome sensors are capable of higher detail and higher sensitivity than color sensors. There's no scientific benefit to using a color sensor. In fact, a color sensor would be detrimental.
Yes, no professional telescope uses a color sensor, because the on-chip filters on those are terrible and doesn't go away when you don't want color. All color images are either done by combining images with different filters or are false color images.
I wish. AFAICT, that's the universal human condition.
One of the great things about ChatGTP is as a framing point — I can now use it as a standard by which to say: "this thing we all keep rolling our eyes at for its mistakes? It's knows more about this than ${person} does" (sometimes I'm that ${person}, helps point me in the direction of intellectual humility).
It's very much not an off-the-shelf camera; it seems to have involved years of custom engineering work.
This article doesn't seem to address the specific question of "why is this camera monochrome?" but you can see that it wasn't trivial to make an instrument that would work well in this difficult environment. So it's definitely not like "and let's throw a commercial digital camera on there too just for fun!".
It's a legitimate question why some kind of color camera wasn't considered worth including, but lots of space missions have sensors that are something other than a simulacrum of human vision. That's why so many astronomical images end up getting published in false color.
In almost all of those cases, the justification for the false color seems to be some form of "true color wouldn't have been possible or appropriate for the scientific purposes of this imagery".
Thank you for acknowledging this is a legitimate question.
I've no issue with all sorts of cameras and scientific instruments being placed on a space craft. I don't expect to get access to all the data that is sent back - though - as it is from the public purse - I think it should be made available.
My point is that the only interaction us great unwashed have with these missions is with the imagery that is provided.. How difficult would it be to have a colour camera?!?! I have a crap mobile and it has 3 cameras! And one on the front! When colour cameras have been available to everyone for so long, its simply inconceivable that NASA can never provide decent imagery! Its 2024 ffs, surely we can have colour by now! No? If not now, when?
> How difficult would it be to have a colour camera?!?! I have a crap mobile and it has 3 cameras! And one on the front! When colour cameras have been available to everyone for so long, its simply inconceivable that NASA can never provide decent imagery!
They do have missions that have great color cameras, like on Mars!
The James Webb Space Telescope also produces great color imagery, but it's normally presented in false color because its camera is biased toward the infrared.
In that diagram you see that the Webb sees more colors than the human eye, but most of them are ones that our eyes don't see. They have various arguments that the colors that it does see are more interesting and useful for seeing very faraway stuff.
As someone whose first programming job was processing multispectral satellite data[0][1]: if you put me in charge of a mission, my first question would be "which specific frequencies provide the most scientific value?", and then focus on that/those. They won't necessarily have anything in common with what you'd normally use for "true colour" (quite a lot of what you see in astronomy falls into this category: even when you see a colourised press-release, it's not what you'd see if you looked at it with your natural eye).
As for "what about a colour camera":
First, look at all the noise in the images, all those slightly curved streaks. That's radiation going through the satellite and hitting the sensor from the side. Normal consumer stuff isn't even trying to cope with that sort of environment.
Second, look at how low the frame rate is. That suggests the data rate is really low, and they probably don't have spare capacity for anything merely decorative.
> Just ask yourself, if you were in charge of the mission, in what world would you decide to use a black and white camera rather than colour to capture the data of what is probably a multi-billion dollar mission?
In this world, where I choose the best tool for the job. Color cameras are worse for this task. I don’t make engineering decisions based on gut reactions to things I know nothing about. I ask questions then make a decision based on facts and objectives.
The camera has to be shielded against various forms of radiation that are emitted from the Sun and that could be a limiting factor for its capabilities.
