Scientist Interview: Felipe Ruiz (Parker Solar Probe - Deputy Lead Mechanical Engineer) 

Me too

Yea, what about the sample of the shield?

Here's a good demo of it at the time stamp 5m 30s, but the whole video is good. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Zc4jy_9Wpew.htmlm29s

maybe he is making a special video in ASMR cuddling with that piece of shield. i hope.

I would have been appreciative to have seen the shield parts too. I've been so curious about it.

If not for real life time constraints I'd love to listen to all of those hours form all of those people as well. This is super amazing!

He got his BS in 2014, so probably mid 20s. That is super impressive.

He is 26

"26" Really? that's impressive!

honestly makes me feel sad (but motivated), that i will only start my studies in my mid 20's/ but good on him!

Major hat tip to him, and to the wise souls that invested their time in him. I'm 44 and never finished my B.S. This is motivating.

Robert Trejo it really is remarkable how he is able to put just enough complexity and information in the videos.

Btw, you should have brought your model to the interview so you could point at it when talking about the different components and parts. :)

I don't think the model had been created (Aug 20) when this interview occurred (Aug 11?).

Nym Alous the pressure is different and different distances from the sun and different weather states. You can be sure they thoroughly optimized this!

Idjles Erle How is the pressure different as you get closer except to be more intense and/or have a higher amplitude? (I don't know, but if you know I would appreciate an explanation.) As for the optimization, well, seeing as how this was made by humans, who are fallible, with time and money constraints, I don't think that I can be sure that it was thoroughly optimized, which is why I wondered about it in the first place. Like I said, there is a reason, but it could be anything, from the materials wouldn't balance properly, or the battery casing wouldn't fit that way, or we could have centerlined it but it would have taken another year, to we didn't realize it hadn't been centerlined. Heck, one explanation is that the water and hydrogen that are being carried won't stay aligned as they are expended. I am just interested in what the actual reason is.

Nym Alous very interesting question. I think the expenditure of the water and hydrogen may be the reason, as it is not a constant rate of expenditure

The pressure is generally dropping off by 1/r² as the Faraday Cup guy mentioned but it is not smooth. If everything was perfectly smooth they wouldn't need to go there, but the Corona is a boiling, seething place and they are going to measure this variation. This thing will also be hit "in the face" with coronal mass ejections and it is going incredibly fast to where it is really hot. Even the Kepler Space Telescope that was going "slow" in the cold of space and was well balanced ran out of fuel after many years of momentum dumping was affected by the solar pressure. These guys will be very efficient with their 82 kg of hydrogen. I imagine random magnetic fields will also create minor torques at different times. You can be completely certain that this probe was perfectly balanced - human fallibility plays no role here. My only question is why they didn't put a second Faraday Cup on the other side to be redundant and balance mechanically, but i am sure they worked that all the way through and the 82kg of hydrogen was the best option. Hundreds of people work on these machines for decades and balance mistakes are not made.

Idjles Erle Even with the Faraday Cup you could still adjust centerline and center of mass with center of pressure to be balanced. It is done all the time with aircraft. The Kepler Space Telescope was not intended to face the solar wind head on with a heat shield, and in order for it to accomplish its missions it would need to get hit with the solar wind (and gravity) on different parts of its surface as it rotated to take pictures of different parts of the universe. As for the Corona boiling being the reason we need to go there, that doesn't make any sense, nor is that among the stated reasons for the mission. I also don't understand how human error and fallibility won't play a role. If humans had a hand in something, there is the chance of error. Even the Kepler Space Telescope had reaction wheel failures and also failures to repair those wheels, resulting in a shortened mission life. Saying that hundreds of people working on a machine does not automatically mean that no mistakes will be made, in fact, as more people work on a specific project the odds of an error being made increase. The people who work at NASA are just people, with the ability to overlook things, make math errors, and just assume that someone else is taking care of something. I'm not saying that this is happening or has happened, I just wondered about a particular design and was hoping for someone who had inside information to address it. (You are not wrong about having a second Faraday Cup, though. I wondered the same thing. I also wondered why they didn't just integrate it with the heat shield, though I can think of a number of reasons why they wouldn't.)

The main failure point was not a design flaw in the bearing or manufacture but a failure of materials and an unexpected electrical arcing across the steel balls. The steal balls (or pins/rollers for that matter) and i think raceways have been replaced with non conductive ceramics this should negate the electrical arcing problem and to my knowledge has more or less stopped the failure of these bearings.

You should watch the interview with Dr. Tony Case if you haven't already.

Rhyme Bito it sounded like he said in the main video that it could handle a CME fine, right?

right to the face

This was my question too. It seems a well placed, small weight, or a slight realignment of the TPS could center the C.G. to the C.P.. Perhaps the extra weight of a slightly larger shield or of balancing weights would grater than the weight of the fuel requited for momentum dumps?

It might just be because it can't be infinitely precise in construction. Any small deviation causes this torque.

Watch the other interview video with Tony Case. It addressees why it's off-axis

In the comments, Tony Case said they tried to align the cop and cog.

Other than it’s just hard to be perfect, there is one instrument that has to be exposed on one side and that throws things off because there isn’t a matching one on the other side.

the center of mass is in a different plane than the center of pressure. The slightest change in pressure causes a slight torque which increases the distance from the center of mass causing more torque etc etc. You can't be perfect due to differing pressures as well so adjustments are always required.

yeah, there is some comb filtering. Easy to get if you are trying to align 2 audio sources

I think of it as _shinning a heat light into the void of space._ Thermal radiation is emitted as electromagnetic (infrared) radiation via the radiators. Energy in, energy out. I'm assuming that the solar arrays also reflect much of this thermal radiation before it has a chance to soak in. (?) I still have much to learn myself.

b1aflatoxin i get the physics of it, i just wanted to see it, i want to see how a radiator optimized for pure radiation rather than convection works. I know it’ll be black since it has the highest emissivity, but what else? The fins can’t be parallel since they’d radiate towards each other, so is it a black, corrugated panel with each fold at 90° to the other?

Found it, in case anyone's interested: en.wikipedia.org/wiki/Magnetorquer