In 1999 two professors, one at Cal Poly and one at Stanford, wrote down a standard for a satellite small enough that a university class could build one and cheap enough that a university could afford to launch it. The unit was a ten-centimetre cube weighing about a kilogram. They called it a CubeSat. The first ones reached orbit in 2003, and since then thousands have flown, built by universities, companies, space agencies and a growing number of high schools.
The Apogee series is four spacecraft, and the CubeSat is the one a student can actually make. This is what it is, how it gets to orbit, and what the other three plates are for.
What a CubeSat is
The standard is the whole idea. One unit, 1U, is 10 × 10 × 10 cm. Stack them and you get 2U, 3U, 6U, 12U. A 6U CubeSat, the one in the Cubesat plate, is 10 × 20 × 30 cm, the size of a shoebox, and weighs around 12 kg with everything in it. Because the outside dimensions are fixed, the deployer that holds it on the rocket can be standard too: a spring-loaded box that opens on command and pushes the satellite out.
That standard box is what made the launches cheap. A CubeSat does not need its own rocket; it rides along in a spare corner of a launch that was going anyway, as one of dozens. And because the form factor is fixed, the parts became catalogue items. Solar panels that fold out, radios, batteries, flight computers, reaction wheels to point the thing: all of it can be bought to fit a 1U or 6U frame. A team's work becomes the mission, the instrument and the software, which is exactly the work worth learning.
Deployed, a 6U with its arrays open makes about 60 watts in sunlight, enough to run a camera, a radio and a computer. It talks to the ground on UHF or S-band, through antennas on university rooftops. A mission that would have taken a bus-sized spacecraft a generation ago, imaging a stretch of coastline every day, say, now fits in the shoebox.
Why students build them
A CubeSat program is a complete engineering project at a scale a team can hold in its head: requirements, design, testing, launch paperwork, operations, and the particular education of watching something you built stop responding and working out why. The first high-school CubeSat was launched in 2013, built by students in Virginia; NASA's launch initiative has since flown dozens from schools and universities, and amateur radio operators around the world relay their signals for free.
If you are a student or a teacher, the entry points are real: the CubeSat design specification is public, the kits exist, and the launch opportunities are competitive but open. The satellite on the shirt is not a fantasy. It is a thing a class can build.
Apogee, perigee, and why the series is named for a point
An orbit is an ellipse, and an object in it is not at a constant height. The farthest point from Earth is the apogee, the nearest the perigee; from the Greek for "away from Earth" and "near Earth". A CubeSat released at 400 km on a nearly circular orbit has an apogee and perigee a few kilometres apart. A deep-space probe leaving Earth has an apogee at infinity. The series is named for the high point because every one of its four spacecraft is defined by how far out it was built to work.
The lander: built to arrive once
A planetary lander is the opposite of a satellite. It does not orbit; it goes down, and it stays. The one in the Lander plate is a four-legged design with gold thermal blanketing, crushable footpads that absorb the last metre of the fall, and an instrument mast on top. At 360 kg with a seismometer as its main instrument, it is built for one job, listening to the interior of a planet: set the instrument on the ground, keep it warm, keep it still, and record for years. The legs are the whole point of the design. They are built for exactly one landing.
The probe: everything serves the dish
A deep-space probe is a radio dish with a spacecraft attached. The one in the Probe plate is built around a 3.7-metre high-gain antenna, powered by a radioisotope thermoelectric generator that turns the heat of decaying plutonium into about 470 watts, because sunlight is useless beyond Jupiter. It transmits on X-band. Everything else on it, the attitude thrusters, the star trackers, the booms that keep the instruments away from the generator, exists to keep that dish pointed at a planet billions of kilometres away. At those distances a signal takes hours to arrive, and the two spacecraft of this pattern launched in 1977 were still sending data nearly fifty years later.
The segment: a mirror that had to fold
The largest space telescopes have a problem the CubeSat solved by being small: they do not fit in a rocket. The Segment plate is a primary mirror made of eighteen hexagonal segments of beryllium coated in gold, 6.5 m across and 25 square metres of collecting area, folded to fit inside a rocket fairing and unfolded in space into a single surface. Beryllium because it is stiff, light and holds its shape at cryogenic temperatures; gold because it reflects infrared almost perfectly. After unfolding, each segment is adjusted by actuators until the eighteen act as one mirror, aligned to a fraction of the wavelength of the light it collects, which at infrared wavelengths means tens of nanometres. The hexagon is the shape that tiles a circle with the fewest gaps.
Why it is a series
Four spacecraft, four jobs, four distances: a shoebox at 400 km, a lander on another planet, a probe beyond the planets, and a mirror looking past all of them. Each plate carries the numbers that define the machine, its mass, its power, its aperture, so the shirt can be checked against the spec sheet.
Every design comes as a tee, a hoodie and a desk mat. The planets those spacecraft visit are the sister series, Orbital. Start with the Apogee series and pick the distance.
