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As with most NASA projects in space, the Chandra X-ray Observatory is a very complex machine with many technical and engineering innovations. Our Chandra Lego project shows a few key features of this telescope that has performed remarkably in space for over two decades. This activity page also includes a 3-D model of supernova remnant Cassiopeia A based on the actual science data that you can build brick by brick, as well as some simple at-home spacecraft and explorers to design that you can be as creative with as you like. Enjoy building your universe with bricks!


Brick by Brick:
Building the X-ray Spacecraft

Other Spaceceafts

Brick by Brick:
Building More Explorers


Brick by Brick:
Building Cassiopeia A

Brick by Brick: Building the X-ray Spacecraft

NASA's Chandra X-ray Observatory is a telescope specially designed to detect X-ray emission from very hot regions of the Universe such as exploded stars, clusters of galaxies, and matter around black holes. Because X-rays are absorbed by Earth’s atmosphere, Chandra must orbit above it, up to an altitude of 139,000 km (86,500 mi) in space. Learn about Chandra, and assemble your own mini-craft with the suggested instructions below.

The Chandra Observatory has three major parts:


• the X-ray telescope, whose mirrors focus X-rays from celestial objects

• the science instruments which record the X-rays so that X-ray images can be produced and analyzed

• the spacecraft, which provides the environment necessary for the telescope and the instruments to work. Part of the spacecraft, Chandra’s electrical power comes from its solar arrays. Located at the front of the spacecraft where radiation enters the telescope, the sunshade blocks light from our Sun.

To learn more about Chandra, visit

Step by Step


Lego Group

Exploded views


Head, Body and Tail


Suggested parts to create your own mini X-ray spacecraft

(Please note: These links are provided as samples only. Chandra/SAO does not endorse any commercial product.)

Brick by Brick: Building More Explorers

Brick-building projects can be a fun activity to do at home. You don't have to limit the activity to just the Chandra spacecraft shown here, however. Try using the bricks you have handy to make different kinds of spacecraft, from low-Earth orbiters, to rovers that explore other planets, to deep space voyagers.  Here, we've provided example specimens of each of those types of spacecraft.

Wartian Rover

Martian Rover
What might a vehicle need to explore the dry surface of our next-door neighbor Mars, or some other planetary body in our solar system?  Would it need rugged wheels? An arm to mine samples from the local soil? A camera to photograph the geology? Something else? This example rover was inspired by NASA's Curiosity and Perseverance rovers. We've had decades of exploration of the surface of Mars through a series of rovers helping us learn about past habitability of the red planet. Learn more about Curiosity and Perseverance.

Low-Earth Orbiter

Low-Earth Orbiter
If you're staying relatively close to home in a low-Earth orbit, what sort of instruments might you need?  Depending on the information you want to collect, you might have to build sensors to study precipitation changes, sea-ice thickness, or forest loss. Collecting accurate and timely information about our planet's changing climate is incredibly important. Low-Earth orbiters can also be built for communications purposes, imaging capabilities, and other uses as well.  This example spacecraft was inspired by NASA's fleet of Earth science missions. Learn more at NASA Science.

Deep Space Voyager

Deep Space Voyager
In 1977, NASA launched two twin spacecraft to explore our solar system.  The deep space probes are now traveling well beyond Pluto into interstellar space, or the region between stars.  What would you need to build in order to create spacecraft that would be resilient enough for such a distance, and be able to store enough power to last so long? How would they communicate all the way back home from so far away?  What else would you need to consider for such a journey? Learn more about the Voyager mission.

Brick by Brick: Building Cassiopeia A

CasA 3D
CasA Lego

Digital model of Cassiopeia A (left) and Lego model of Cassiopeia A (right)

Cassiopeia A (Cas A for short) is a supernova remnant, the aftermath of a star that exploded over three centuries ago. Scientists can study supernova remnants like Cas A in three dimensions to better understand the cycle of stellar death and birth that creates most of the elements essential to life here on Earth. This buildable version of Cas A in 3D shows where some of these important elements are as they expand into interstellar space, where they will one day be swept up in the next generation of stars and planets.

Download PDF Maps
Download Supply List

This document contains maps for building a scientific model of the supernova remnant Cassiopeia A with Legos. The Lego model is derived from actual multiwavelength data collected by various telescopes and mimics the irregular, organic shape of the actual supernova remnant.

The map pages in this document contain grids for a layer-by-layer model, totaling 14 layers of Lego bricks on top of a flat platform. Start with 2 large, flat, 32x32-stud plates connected together with a 1x12 brick at the top and bottom (Could use anything from a 1x8 to a 1x16 brick) and note the grid square 33P, which corresponds to the stud in the first column on the right-most plate, 16 studs up from the bottom edge. A yellow star symbol shown on each layer at 33P is a reference point for the supernova remnant’s interior neutron star and its X-Y position. The actual Z position of the neutron star is marked using a round 1x1 brick at Layer 7, 33P and is roughly central to the model.

The maps include color information which corresponds to the different elements dominating each area of the supernova remnant. This color information can be ignored or modified for various reasons.

Start with Layer 1 and work your way up to Layer 14. See video below and/or download the text-based instructions.

-Get a Lego Brick Separator tool.
-Start by collecting entire inventory of bricks, plus some extras in case some get lost. Each layer map lists inventory specific to that layer. Sorting necessary bricks by layer makes things easier. Each layer’s inventory will fit into a 32 oz. yogurt cup or similar, so you can line up your cups in order before beginning the build.


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Developed by the Chandra X-ray Center, at the Smithsonian Astrophysical Observatory, in Cambridge, MA, with funding by NASA under contract NAS8-03060   |   Privacy  |  Accessibility
Disclaimer: The Chandra X-ray Center does not endorse any commercial product.