Construction of the Space probe for NASA's Psyche Mission

Real Spacecraft
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Hello everybody,

admittedly, it took me a while to figure out what these small gold-colored pyramids are for, and I studied some [Conference proceedings() from the biennial International Electric Propulsion Conference (IEPC) that were published during the preparation phase for NASA’s Psyche mission.

These are mechanical locks, so-called Hold-down & Release Mechanisms (HDRMs), which securely lock the solar array wings, each consisting of five panels, in their stowed position during launch until the space probe is separated from the Falcon 9 Heavy Rocket, in order to withstand the enormous vibrations during the launch and flight, which are secured this way by special mechanisms (tie-downs) and prevent premature unfolding.


Source: NASA (flickr.com)

During the analysis of some of the videos already mentioned, I repeatedly came across Lindy Elkins-Tanton from Arizona State University,

whom I then contacted via email regarding some specific questions, and she subsequently explained, among other things, the function of these HDRMs.

David Y. Oh from Jet Propulsion Laboratory (JPL) is the Lead Systems Engineer and engineering authority for the Psyche Mission. He has been part of the Psyche Team since 2014 and, together with Lindy Elkins-Tanton, played a key role in developing the original concept design for NASA’s Psyche Mission.

And this is the entire Psyche Mission Team, with the two main participants in the center.

This image shows the unfolding of a Solar Array,


Source: NASA

and here one can see the eight HDRMs on the right sidewall (-Y Panel) of the probe.


Source: NASA

Unfortunately I won’t be able to scratch-build them as pyramids, but I can at least simulate it with gold-colored beads (Ø 2,3 mm x 1,5 mm).

To do this, I first need to determine and mark the footpoints of these HDRMs on both sidewalls of the probe.

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163

Hello everybody,

although I’m already at the target level, I still have to make a few changes.

This is because only in the final photos taken shortly before the completion of the space probe and its transfer to the SpaceX facilities at the Kennedy Space Center one can see what certain details of the probe ultimately looked like, as some assemblies were finally covered with blanket foil, including the Cold Gas Thruster (CGT), which is how it should now look on my model.

While the two thrusters, CGT1 and CGT8, are unfortunately not visible behind the covered rod system due to the oblique perspective,


Source: NASA (flickr.com)

however, in the corresponding zoomed-in section, you can see all six CGTs covered with blanket foil on the underside (-Z Panel) with their labels.


Source: NASA (flickr.com)

And now to the front (+X Panel) with the two thrusters CGT7 to the left of the DSOC and the somewhat obscured CGT2 on the opposite side,


Source: flickr.com

which can be seen better in this zoomed-in section, especially the slightly protruding CGT7 with the silver blanket covering of its mount to the left of the DSOC.

In the following side view images, the parts of the covered CGT7 can be seen more clearly,


Source: NASA

which I have marked in this zoom excerpt.

This top view shows the CGT7 completely covered with blanket foil from above.


Source: NASA

And now to this image of the right side (-Y Panel) of the space probe with a direct view of the underside (-Z Panel) and the thrusters CGT3, CGT11/12, CGT9 located there.


Source: flickr.com

Besides these thrusters and the thrusters CGT4, CGT5/6, CGT10 located on the left side (+Y Panel), there is also another Low-gain Antenna that I still need to scratch.

With that I want to say goodbye for today, but not without wishing you all Happy Easter.

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164

Hello everybody,

in the meantime I have made the missing three inner struts on the right side of the DSOC, which one can see in the following pictures.


Source: NASA (flickr.com)

While the two middle struts are covered with silver blanket foil, the upper strut is covered with black foil, which can be seen more clearly in the linked zoom section.


Source: NASA

Then I’ve prepared the struts,

which I then glued with UHU CA.

Then I turned back to the delicate Hall-effect Thrusters, which was quite stressful to recreate one year ago and took a lot of time.

During the launch of the Falcon 9 Heavy, the thruster arms with both thrusters are folded and securely docked onto special Hold-down brackets, which are covered by the two small red caps, whose contact points are located between and below the red Remove Before Flight caps of the thrusters, as can be seen in this image section (see first image).


Source: NASA (flickr.com)

As I learned from Lindy Elkins-Tanton, this is the Hold-down bracket for the electric propulsion gimbals, where the Thruster arm is docked during launch.

This mechanism features a low-shock release unit, covered in white foil, which is fired in space and undocks the arm for thruster movement.

At my model, I will depict the thrusters in their extended position as seen during the probe’s long journey through space to the Psyche asteroid.

On the NASA model of the space probe one can see the contour of this Hold-down bracket, which is covered with black blanket foil.

However, for their scratch-building you need clarity about their structural design as well as detailed original images from which one can determine the dimensions, so again the well-known song …

In this picture one can see the bracket on the model a little more clearly,

but it was only through various original images from different perspectives like this one that I gradually recognized and understood its construction.

That’s it for today. Then I watched the totally impressive live broadcast of the Orion capsule landing.

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165

Hello together,

and thus after the successful Artemis II mission return continue with the Psyche space probe and the search for images to determine the dimensions of the Thruster hold-down brackets.

These pictures were initially very helpful to me, as they show and better illustrate the construction of the bracket in its uncovered state, where the thruster arm is locked in the folded position.


Source: NASA


Source: NASA

In the covered final state everything appears a little more diffuse,


Source: NASA

which you just have to get used to over time.


Source: NASA (flickr.com)

Although dimensions cannot yet be determined from this, unlike the NASA model, the following image shows that under the covered rear section of the bracket are two struts for supporting the mount, covered with black blanket foil, which can certainly be depicted.

That’s why I took another look at the NASA videos and came across this clip, which shows both the decoupled thruster arm and its hold-down bracket from the side.

On it you can see the two support sockets (red arrows) of the decoupled thruster arm, which sit on the bracket covered with white foil and outlined in red.

And with this image, I was able to determine some dimensions of the bracket, using the dimensions of my prefabricated Hall-effect thrusters as reference dimensions (yellow),


Source: NASA

which have been ready for final assembly for some time.

And with the help of the following detailed views from the same video, I finally determined the remaining dimensions of the bracket,

including the dimensions of the struts.

Besides this time-consuming and quite stressful scaling process, I also started installing the mechanical hold-down mechanisms for the solar arrays on the two side walls, the so-called Hold-Down and Release Mechanisms (HDRMs),


Source: NASA

for which I wanted to use these gold-colored jewelry beads (Ø 2,3 mm x 1,5 mm).

To do this, I first had to determine the base points of the eight HDRMs on the probe’s side walls, for which I used this image rotated by 90°.


Source: NASA

Next steps will follow later today.

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166

Hello everybody,

then let’s go on with the HDRM beads for the solar arrays on the two [color=blue]sidewalls[/color] of the probe.

The beads were glued to the marked foot marks with UHU CA. To do this, I first dabbed the foot marks with small CA droplets on an acupuncture needle and then carefully grasped the beads with tweezers and placed them on the wall.

The two HDRMs at the bottom edge I haven’t glued yet, as I occasionally still need to place the probe on the ground for attaching further details and therefore have to fix it laterally.

Otherwise, I think that the small HDRMs are actually quite well suggested by the gold-colored beads.

And then it went to the other side,

where the HDRM beads were glued in the same way.

Next time I’ll attach the two Star Trackers to the front before I still lose them,

which have also been prepared for some time.

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167

Hello friends,

and now to the two [Star Trackers() that were glued to the front.

These sensors are used for precise attitude control and navigation and act as the “eyes” of the space probe by detecting star constellations on the way to the asteroid and using this data to determine the exact position and orientation in space.

And so back to the Hall-effect Thrusters, which are just waiting to be attached to the front and back,

which I want to show in the unlocked state, in which they then serve as the drive for the space probe.

That’s why I had to take a closer look at the delicate Hold-down brackets and thought about how I could best scratch-build them.

After getting an overview of the structural design and determining the most important dimensions,


Source: NASA

I’ve first cut the brackets from an Evergreen strip (1 mm x 2 mm x 6 mm). For the two support sockets of the thruster arm, I used my Punch & Die Set to punch out small discs (Ø 1 mm) from an Evergreen strip (0,75 mm x 2,5 mm), onto which I wanted to glue small discs (Ø 1 mm) punched out of aluminum sheet (0,13 mm).

Gluing these small plates onto the short support stubs was extremely difficult because one can no longer hold them even with the sharpest tweezers.

Only my tried and tested trick 17 helped, for which I placed the small stub on the adhesive surface of a masking tape, dabbed it with a tiny drop of UHU CA using an acupuncture needle, then picked up the small aluminum plate with my pointed tape tweezers and carefully placed it on the small stub while holding my breath.

This is what the first fitting of the plated support sockets looked like.

Then I filed a small curve into the brackets.

Next the support sockets were then glued to the bracket.
.

Now all that’s missing are the three struts that support the bracket,

hoping I can still manage it too.

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Superb detailing as always … nice update :+1:

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Thanks John, https://www.britmodeller.com/forums/public/style_emoticons/default/bow.gif the final countdown is approaching.

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Hello everybody,

since I want to show the Hall-effect Thrusters in their unlocked and unfolded working state, I first need to understand the arrangement of the Hold-down Brackets with their three struts in the unlocked state, in order to determine their distances and dimensions.


Source: NASA (flickr.com)

For the struts, I will use black stranded wire (Ø 0,5 mm) from which I have removed the insulating sleeve, into which I have inserted brass wire (Ø 0,2 mm) for better shape stability of the bending points.

After that, I drew a small sketch of the arrangement of the bracket and its three struts,

whose dimensions I’ve scaled in this image, resulting in the lengths of the three struts (S1, S2, S3),

and from this image, the distance of the Hold-down bracket from the gimbal-stored Thruster socket followed, which is 7 mm.

Here you can see the holding device with the temporarily installed struts,

and next to it the indicated position of the Hall-effect Thruster in its working position,

as well as in the locked position during launch,

which is only intended to demonstrate that the “spectacle-like” bracket on the thruster arm also fits well onto the two sockets of the hold-down bracket.

But there’s one detail I still don’t completely like. And these are the black brackets to which the struts apparently attach.

As can be seen particularly from this picture, these are flat brackets, which are significantly thinner than the blanket-covered struts that I had with the same diameter (Ø 0,5 mm) so far.


Source: NASA

Therefore, for these holders I used my narrowest black masking tape (0,1 mm x 0,5 mm) and glued two strips of it on top of each other, resulting in a thickness of approx. 0,25 mm, which fits better with the round struts (Ø 0,5 mm) and I also like it better this way.

Although these are only minimal differences, with this solution I am somewhat closer to the original, as can be seen from the comparison of the two following images.

For comparison, here is the previous solution, initially with only an angled extension of the strut of the same diameter,

and here is the glued-on double tape holder, which should also be advantageous during the subsequent mounting of the struts to the Hold-down brackets.

In this arrangement, the inserted strip (1 mm x 2 mm) also gives me further options to determine the final required lengths of the struts.

Next comes the mounting of the brackets on the front and back of the probe.

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171

Hello everybody,

in retrospect, I had a lightbulb moment when I saw the struts, which is why I’ve taken another closer look.

First of all, I was impressed by the flat black holders, which are significantly thinner than the struts covered with blanket foil, which so far have the same diameter (Ø 0,5 mm) as I previously described.

When you look at the angled, uncovered part on the strut S3, you can see, especially in the linked zoom shot, that in my opinion it is a support plate that is articulated to the strut.


Source: NASA

And with my now sharpened eagle eye, I discovered an equally uncovered support plate to the right of it, which, although hidden by strut S1, apparently belongs to a further strut S4, which completes the picture.

As a result, all four struts have the same version with support plate, which is why I have adjusted my previous pictures accordingly.

Unfortunately, individual parts are always hidden in the various photos, so you have to look closely,

but that doesn’t change the fact that these are four struts supporting the Hold-down brackets.

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Superb work mate …. the detailing just stays at a brilliant level.

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Thanks John, https://www.britmodeller.com/forums/public/style_emoticons/default/bow.gif I Ialso hope so.

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Hello everybody,

and thus to the tricky struts.

To make my work a little easier, I trimmed my small sketch so I could use it as a template to pierce the base points of the struts and support plates with a needle.

Then it occurred to me that I should also glue the four Sun Sensors on the front at some point, which can be seen here on the NASA model,

as well as here on the original space probe still in its uncovered state.


Source: NASA

I did this first before attaching the Hold-down bracket and the four struts, since the sensors had already been prepared for a long time.

Here one can see the corresponding pierced base points of the struts,

and here all four struts and support plates are already glued to each other, which was a pretty stressful process until the struts had the matching length for the holder.

This would actually complete the front except for the attachment of the Hall-effect thruster.

I now have to repeat the same procedure once more with the Hold-down bracket on the back.

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175

Hello everybody,

on the front, the last little detail missing was this small module on the bottom left corner, which is still covered with silver blanket foil,

and then was glued on.

Before I turned to the back to the Hold-down bracket with its struts and support plates, it seemed advisable to first attach the X-Band Low Gain Antenna mounted on the upper right and the two Multispectral Imagers, as the available places for handholds on the probe were becoming increasingly limited.

Both instruments are marked here,

and can be seen a bit better in the linked video.

To make assembly easier for me, I raised the existing holding device slightly by placing it on a Mon Cheri box.

However, I had to take care that I could no longer place the front of the probe against the steel angle bracket, and therefore had to insert a Balsa spacer to protect the Hold-down bracket as well as the Module from breaking, which made the whole process increasingly difficult.

Then I reattached my template to mark the position of the Hall-effect Thruster and the Hold-down bracket, including the struts.

But somehow I lost confidence in this adventurous holding device with its bulky holding clamp, which seemed too unstable overall.

And since I didn’t want to risk a final crash of the whole probe, I remembered my sheet metal and magnet mount and clamped the probe securely onto the sheet metal by using neodymium magnets and Balsa spacers.

After marking the mounting points for the Bracket and struts and the Thruster and bracket gluing places, I’ll first attach the X-Band Low Gain Antenna and the two Multispectral Imagers tomorrow, and then we’ll see what’s next.

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Hello friends,

by the way, did you notice anything about this picture?

Then let’s go on, first with the missing Multispectral Imagers, for which I used two of these small beads each, which I glued to the end of a needle,

which I’ve then inserted and glued into the pre-drilled holes on the back.

By the way, I’ve also glued a wire into the bead at the back of the X-Band Low Gain Antenna,

which I’ve then glued in the upper right corner.

After that, I’ve glued on the Hold-down Bracket for the rear-mounted Hall-effect Thruster.

After attaching my template, the base points for the struts were pre-drilled again,

which is what I’ll continue with next time.

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Hello friends,

did you really not notice anything about this picture?

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It’s hard to believe that apparently only blind people are at home here, then I should better save myself the trouble of posting, especially since it’s also costing me valuable time …

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What are we supposed to pick up on? Not well versed in the subject.

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Nevertheless, thank you for your answer. You really have to look closely already to see the difference.

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Hello friends,

then I’ll solve the mystery.

One of the two Star Trackers was missing.

That was the unfortunate result of modifying my makeshift Holding device, as I can hardly grip the space probe securely anywhere anymore without breaking something.

I immediately thought, OMG, where did the Star Tracker go?

My first worried glance at the floor didn’t turn up it, so the stressful search began in the jumble of things on the table, and lo and behold, it had thankfully landed unharmed in a small bowl, so all I have to do is glue it back on again. One only needs to be lucky!

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