Nibbles in Space

By the late 1970’s engineers were starting to grasp the risk of the ever-growing space debris population; we have best-practise guidance in place to help avoid the creation of more debris; space debris, much like pollution on Earth is a negative externality; no meaningful space debris legislation, nor enforcement.

Issues relating to the use of space have been dealt with through the United Nations Committee on the Peaceful Uses of Outer Space; five UN Treaties between 1967 and 1979; the Moon and other bodies be used “exclusively for peaceful purposes” but this does not apply to space itself; as we look forward it’s likely that further agreements are required.

Space sickness is experienced by as many as half of people as they adapt to weightlessness; just like on ground, exercise and health checks are vital; as water is the most heavily consumed item for life support it’s vital that as much be recycled as possible; to help reduce the risk of cancer, spacecraft will have areas with increased shielding against space radiation.

The only external source of energy available to a spacecraft with reasonable flight heritage is solar radiation; the use of unfolding solar arrays is common; in a fuel cell, hydrogen and oxygen, or a similar combination, are combined to produce electricity and water; Radioisotope Thermoelectric Generators, or RTGs, convert heat released from the decay of radioactive material into electricity.

The main way of changing the velocity of a spacecraft is to take part of the mass of the spacecraft, and eject it; anything but small plane changes require a lot of energy, which can make such manoeuvres prohibitive; the Earth’s diameter is almost 43km more at the equator than between the poles; Sun-synchronous orbits are used in Earth observation missions to maintain consistent illumination of the ground throughout the year.

Earth’s atmosphere has an effect on all spacecraft up to at least 500km, but on occasions to over 1000km; Electric and magnetic fields exist around most bodies in space, including the Earth and the Sun; Space also contains a number of plasma environments; Trapped radiation and solar particle events are the two major natural radiation sources of concern to spacecraft engineers.

The most valuable service from space is communications; space enables reliable, and high-quality communications far from terrestrial infrastructure; it is estimated that over 13% of the non-financial business economy gross domestic product is supported by GNSS; (US) companies can sell images to anyone down to a spatial resolution of 25cm.

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Space technology has probably contributed more to the pursuit of peace than just about any other technology. Locating all kinds of radio transmissions from Earth is a key form of military surveillance from space. A number of countries have dedicated military communications satellites. Several militaries also operate a Global Navigation Satellite System.

All orbits below 2000km altitude are termed low-Earth Orbits, or LEO. The duration, or period of an orbit increases as altitude increases. A geostationary spacecraft appears stationary in the sky. If you are north of Svalbard, at over 81 degrees latitude GEO satellites are below the southern horizon.

A satellite is an object that orbits something else. An object in orbit is in continual freefall, moving forward so fast it never hits the ground. The closest point of an orbit to Earth is termed perigee, and the furthest point is apogee. An orbit is the path around another object in space.

Space travel became a seriously considered engineering endeavour through the works of Konstantin Tsiolkovsky. To access space a dedicated vehicle is required, a launch vehicle. Multistage rockets are two or more rockets, or stages working in sequence. Once a stage has completed its burn it is jettisoned.

As altitude increases the air gets thinner, that is, atmospheric density decreases. The nominal boundary to space as the von Kármán ellipsoid, a curve, above the surface of the Earth at 100km altitude. A spacecraft is a vehicle or vessel designed to operate beyond the von Kármán ellipsoid. The only thing we all agree on is that space is up.

The basic unit of information is a bit. It has two possible values, “0” (zero) or “1” (one). Eight bits make up a byte. Each hexadecimal digit represents four binary digits, termed a nibble. A nibble is half a byte.

Nibbles in Space is a series of short podcasts, making space more accessible. A nibble is half a byte. A nibble is 4 bits of information, whether you listen to it as a podcast or if want a little more of a Nibble you can read it at SpaceProf.xyz/Nibbles.