Wilkinson Microwave Anisotropy Probe - In the beginning...

[Retired_for_now]

Continuing my obsession with significant, but un-modelled, space probes I've started on the Wilkinson Microwave Anisotropy Probe (WMAP).

In 1965, Penzias and Wilson (later awarded the Nobel Prize) discovered the cosmic microwave background radiation (CMB) while trying to find out why they were getting constant interference in their microwave receiver. The CMB is a constant radio "hiss" visible from earth in all directions. The signal is the remnant of the "first light" of the universe. It dates from a time when matter condensed from the initial particle "soup," allowing light to travel freely for the first time. The existence of the CMB is strong evidence for a hot, dense origin of the universe and its subsequent expansion. The WMAP satellite has been hovering at the Earth-Sun L2 libration point (outside Earth's orbit) since 2001 observing the CMB. WMAP is looking at the intensity, spectrum and polarization of the CMB to allow competing theories of creation (Big Bang, higher-dimensional brane collisions, multiple episodes of vacuum inflation, etc.) to be evaluated.

WMAP is a more sensitive and precise follow-on to the pioneering observations of the cosmic background explorer (COBE) that first detected unevenness in the CMB. This unevenness (anisotropy) provided the seeds for the formation of the macro-structure of the universe (galaxies and galactic clusters).

The spacecraft is composed of fairly simple shapes - but a fair number of them as the electronics boxes are mounted external to the central column of the spacecraft bus. The shade, which blocks radiation from the earth, moon, and sun is the dominant feature. It's a two sided disk with additional copies of the solar panels glued over the graphics to provide some 3-D.
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The lower deck glues over thick card on top of the shade to provide thickness.
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Then, the central hexagonal bus column is glued up and attached to the center of the lower deck. The black part on the bottom of the shade (battery cable run-to be used later) and the three little circles are parts that wandered into the picture.
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Keeping the bays in alignment is a constant task with all the two-sided parts.

Yogi

[Retired_for_now]

It's time to make the little bits now that we have a basic structure to attach them to. The electronics boxes are folded up and glued - I modelled them as open boxes to avoid another folding step as well as the dreaded out-of-square that results from the overlap of the final seam. At this scale, edge gluing the boxes in place is plenty strong.
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The momentum wheels and brackets are likewise assembled with printed faces sandwiching thicker card.
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With a sufficient supply of bits, it's time to glue them in place. I provided outlines on the bus column to aid in positioning the parts.
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The struts that connect the upper and lower decks were a challenge. At 1:24 they should be modelled as thin cylinders with a fitting to provide the correct angles at the top junction. At 1:48 they are simple card outlines. The long leg glues to the lower deck at the base of the central column, then the remaining legs are glued to the outer edge of the deck. If I got the lengths correct, the top of the strut tripods will be even with the top of the bus column.
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Yogi

[jparenti]

I'm getting there myself. So far, keeping everything aligned properly seems pretty simple. I'm in the middle of populating the central bus column now. I'm happy to report that I haven't seen any fit problems at all so far.
EDIT: I tried to show a picture of my progress, but the system keeps kicking me out. I'll try it again later. By then I should have even more built anyway.

[Retired_for_now]

Outstanding J - always good to have some feedback on my sometimes obscure design/build process.

With the struts in place, the battery cable run goes in with two bends to make the turn under the strut, then to the edge of the top deck.

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The top deck has a few bits attached to the underside - another alignment challenge to keep my head straight as I flip things over. The star tracker on the underside of the top deck goes in bay 6 (hopefully marked correctly).

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The moment of truth - fortunately paper is flexible enough to take up .5-1mm gaps (not that I would ever tolerate such - HAH). A drop of glue on the top of each strut tripod and the top of the bus and ...

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Also watching the alignment so the star tracker mounted to the underside of the bus ends up in bay 6 with the black battery box.

Now for the business end. WMAP has two large oval microwave reflector sets that scan the sky at high resolution and focus down on four sets of waveguides leading to the instruments.

The structure on the satellite is an insulation covered truss. On the model, an outer support structure (insulation) and an inner truss-box. The support structure is a somewhat flimsy part until assembled. It's an irregular "canoe" with two sides and a connecting bottom. The end of the bottom needs to be pre-folded to make the attachment lip for the secondary reflector, then the rest of the bottom is curved/glued in place.

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With the two supports done, the inner box is slipped halfway into one and glued in place. The thermal shield/radiator will be mounted next, before adding the second support structure.

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Yogi

[Bomarc]

Great stuff Yogi.

I feel compelled to tell you your space science projects always spark a special fondness in me, having grown up around such things in the '60's and '70's. My dad is a retired aerospace engineer with Hughes Aircraft (Space and Com group), and I remember many a "Summer Vacation" to the Cape as a kid, since dad had to participate in launches of Hughes vehicles (he was Sr. Test Engineer on "Surveyor"). Saw a lot of launches in those days.

Mike

[jparenti]

Good to see more build pics -- I know I'm at least on the right track.
I've got the support struts in place myself and all three reaction wheel assemblies in place now, but this was where I was a short while ago.
And I think my fancy camera has a resolution too high to post the pictures. I'm working on it. :o

[jparenti]

Progress so far:

[Retired_for_now]

Thanks for the words, Mike (I'm still not worthy, O master-modeller).

Looks great J! You are the puzzle-miester.

The thermal shield/radiator goes on next - I glued two extra layers of the card stock (not thick card) together to thicken and stiffen the part. Getting the thickness with layers makes a heavy part, but was easier than trying to fold up a very shallow box. The shield/radiator is notched to fit over the inner truss and the arms of the antenna supports are glued on to the vertical face (parallel and straight).

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The other reflector support then slips over the inner truss and is glued to the truss and to the radiator. There is an omni antenna at the top of the assembly, modelled here with graphics on four overlapping tabs. The tabs all get glued on top of one another providing a base for the omni antenna and flexing the vertical supports together.

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The actual reflectors are shallow, oval conics. The primary reflector attaches to the top third of the support arms which are curved to mate with the reflector (the bottom floats or can be attached with a small spot of glue at the bottom edge of the reflector). I gave up trying to capture the entire curvature - this is one of those tasks requiring CAD software.

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The secondary reflector is glued to the forward lip of the support structure (that's why it was folded in when the support structure was built up) and with a small spot of glue on the very bottom edge of the reflector.

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The remaining task is to fold and glue up the optical table underneath the reflector assembly and attach four small struts to the radiator.

Yogi

[Retired_for_now]

With the reciever head and bus complete, all that remains is to connect them with a short cylinder, tabbed on each end for gluing.

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Enhancements:
This one would be a good candidate for enlargement. At 1:24, the reciever truss and feed horns could be modelled in detail. It would also be feasible to roll cylinders for the interdeck struts and the struts stabilizing the radiator.

I do need to texture the antenna support structure - it's tiled together from various primitive shapes so the texture will be a challenge to get even (limitation of my simple drawing software). Then again, if I use a crinkled foil pattern it may look OK, just pieces of insulation taped together ...

At a larger scale, modelling the various thrusters, fuel piping, and some wiring would also be practical (for those of us with big thumbs anyway - I fully expect to see Ray et.al. working on 1:200 scale versions of these spacecraft eventually).

A little experimenting with the plain paper prototype also shows it is possible to fold the sun shield (again, plain paper - not card for this exercise) for stowage - with a little judicious scoring of folds and reinforcing of the solar panels with a layer of card.

Yogi

[Retired_for_now]

Just got a return ping from the Goddard WMAP team, so I sent them a copy for evaluation. Hopefully will post soon - either with the mission site or here and at LHVCC.

[jparenti]

Finished! I didn't notice any fit issues at all, so unless you found something you want to change, I would proclaim this a finished kit.
I'm on to the next one now, which I hope to start a build thread on by tomorrow. :)

[Retired_for_now]

Outstanding work J! I think I got as much satisfaction from seeing your build as from completing the prototype - maybe more. Looking forward to your build thread.

Working odds-n-ends right now, so taking suggestions on the next significant but un-modelled probe.

Yogi

BTW: this is the effect I was going for...

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[jparenti]

...taking suggestions on the next significant but un-modelled probe.

How about this one?

http://i79.photobucket.com/albums/j136/jparenti/International%20Cometary%20Explorer/isee-3.gif

http://i79.photobucket.com/albums/j136/jparenti/International%20Cometary%20Explorer/ICEdiagram1.jpg

Launched in 1978 as the International Sun-Earth Explorer 3 (ISEE-3) for studies of Earth's magnetic field and solar wind interaction, it was repurposed as the International Cometary Explorer (ICE) in 1982 and studied Comets Giacobini-Zinner and Halley. It was abandoned eventually in 1997, but apparently someone didn't turn it off and contact was reestablished with the probe in September 2008. It was waiting for instructions, even after 30 years in space. All but one of its instruments are functional, and it still has propellant left. There is talk of sending it out to chase another comet in 2017 or so.
Interestingly enough, there was the possibility of recovering it in 2014. It's already been donated to the Smithsonian if we get it back, although that would be in the 2040s if it gets used again. :D
About all the reference material I could find is a few photos and line drawings. Maybe someone has more information than I do...?
International Cometary Explorer pictures by jparenti - Photobucket (http://s79.photobucket.com/albums/j136/jparenti/International%20Cometary%20Explorer/)

[Retired_for_now]

Hmnnn - very good story with this one. Inner can, outer cylinder (OK - 16 sides ...), but boy, you sure do like your greebles.

Deep Space One is in similar "storage." Solar powered ion drive with 10% of its reaction mass remaining. But, they intentially left DS1's radio on.

Yogi

[lunger1]

did the Goddard team ever post your wmap or cobe models?

Chris

[Retired_for_now]

Thanks for the reminder, Chris. Been a while since I've heard from them. They have the completed packages (even included instructions).

I guess I'll call times up on the Lambda folks and see if Lower Hudson Valley has room on the disks to host COBE and WMAP.

Yogi (just filling in the blanks ...)

[lunger1]

welcome Yogi. I really enjoy building your models. I'm working on my first scratch build model of NASA'S ACRIMSAT. still working out some of the details because I could not find any scale drawings so Im just working off the artists picture and the drawing in the press kit.

Chris

[Retired_for_now]

Looking forward to your results, Chris. You can resize the pictures to scale on your drawing palette and draw right over them to make parts - probably ends up as accurate as any spacecraft drawing you could FOIA (they're always tweaking something right up to launch it seems).
Post your build or even the kit?
Yogi

[Retired_for_now]

WMAP is posted and available for download in 1:24 and 1:48 scales at the Lower Hudson Valley Challenger Center (jleslie48.com). Take the time to make a donation on the home page if you can.

Yogi