Satellite how fast

Attitude determination is achieved with the use of two redundant 3-axis magnetometers and two micro sun sensors for coarse information.

For precise determination two miniaturized CMOS star trackers and a 3-axis gyro are being used. Actuation: Attitude control is performed with reaction wheels and with magnetorquers for momentum dumping and coarse control. The four micro reaction wheels are mounted in a pyramid configuration maximizing control effectiveness, and the three magnetorquer rods are mounted in an XYZ configuration. A double-loop NDI Nonlinear Dynamic Inversion technique will be adopted, which allows flexible control of a nonlinear system in different flying modes.

The double-loop NDI technique avoids strong nonlinear feedback which causes unnecessary actuator saturations, and provides flexibility for multiple operational modes by separating rate and angular control.

It is further enhanced through uploading precise GNSS ephemerides from ground. The relative position and attitude information will be obtained by exchanging navigation and attitude data via intersatellite communication.

Orbit control will be implemented by means of a cold gas thruster. EPS Electrical Power Subsystem : Power to the satellite is provided by three body-mounted solar arrays; a central panel is body-mounted to the zenith face of the microsatellite. An orbit average power of 45 W is provided. The electrical power is conditioned, then distributed along a 28 V regulated bus.

The excess solar power generated is stored in a set of lithium-ion batteries with a total capacity of Wh. The microsatellite avionics interface with a lower speed CAN bus. The philosophy behind the CDHS is to develop a highly integrated avionics kernel that manages all the survival functions of the spacecraft.

This architecture consists of computers, data storage, data buses, and the relevant software. They are also hot redundant for each other in case of failure.

The payload data are stored in a radiation tolerant solid state memory with the capacity of 8 GByte. The propulsion subsystem is composed of a cold gas generator developed at TNO and Bradford Engineering , an electronics board, an orbit control thruster, and the associated valves and tubes.

It provides for initial launcher injection corrections and formation maintenance. Hence, no large volume, high-pressured tank and associated valves are needed; no risks for leakage; and the mass and volume of the complete propulsion subsystem are both optimized. For FAST-D, a nitrogen generator has been selected because of its relatively high gas output efficiency each kg of solid propellant can output liters of gas with the pressure range of 0.

RF communications: The onboard subsystem consists of two S-band transmitters, one low power transmitter, one high power transmitter. The low power transmitter is primarily used for telemetry, and the high power one is primarily for payload data downlink. However, for redundancy on the transmit chain, these two transmitters both can be used as the backup of the other one. The two command receivers share two patch antennas, which are mounted on the nadir and the zenith surfaces of the satellite, respectively.

The low power transmitter feeds another two patch antennas. The high power transmitter is connected with a helical antenna. The satellite uplink is performed by a set of 9. The downlink antennas will be operated at 7. The downlink payload date rate is 6. A GNSS receiver is to provide absolute position and velocity data. During FF Formation Flight , the satellites exchange state information, such as position and attitude, between each other through this link.

As payload data are not intended to be exchanged, only a low power transceiver and low-gain antennas are being utilized. The spectropolarimeter is a small, innovative instrument currently under development in the Netherlands. The objective is to measure flux and polarization across a broad wavelength region nm with a spectral resolution of about 2 nm. To achieve this, it has only one detector and no moving parts. The instrument is compact enough to fit on a microsatellite, allowing low-cost and fast access to space.

The instrument is primarily intended for a future planetary exploration Mars mission. The reason for this change is that the spectropolarimeter will focus on characterizing aerosols, leading to a preference for planet-looking FOVs over limb-looking FOVs. Table 1: Key characteristics of the Spectropolarimeter instrument. The viewing angles are chosen such that the scattering angle dependence of the flux and polarization of the scattered sunlight is sufficiently sampled.

The optimal sampling will be obtained for intermediate to large phase angles Figure 8. Figure 8 : Illustration of the scattering angle image credit: TU Delft. The spectropolarimeter has a truly innovative method for doing polarimetry: the degree and direction of linear polarization of the scattered and observed sunlight is encoded as a sinusoidal modulation into the flux spectrum.

Thus, from a single flux spectrum measured in a specific viewing direction , the spectral dependence of the polarization and the flux itself can be retrieved. The spectral measurements in the various viewing directions are thus performed simultaneously. The SILAT design is based on an Europa mission heritage - and can be adapted for an Earth observation mission with an expected decrease in mass. The instrument is an example of a highly integrated payload where three different instruments are combined to create a new instrument with superior characteristics than all three instruments separately.

Thirdly, together with a SCAM Stereoscopic forward looking Camera , this allows the creation of accurate three dimensional maps of the planet's surface.

The SPAD is a particular type of APD Avalanche Photo Diode that can trigger a very fast current switch with resolution times on the order of picoseconds with only the energy of a single photon as a trigger. This type of APD requires an active quenching circuit in order to halt the avalanche breakdown.

The idea of photon counting is to use lasers with high repetition rate 10 kHz or more while the backscattered laser light is detected as efficiently as possible. To maintain an orbit that is 22, miles 35, kilometers above Earth, the satellite must orbit at a speed of about 7, mph 11, kph.

That orbital speed and distance permit the satellite to make one revolution in 24 hours. Since Earth also rotates once in 24 hours, a satellite at 22, miles altitude stays in a fixed position relative to a point on Earth's surface. Because the satellite stays right over the same spot all the time, this kind of orbit is called "geostationary. In general, the higher the orbit, the longer the satellite can stay in orbit.

At lower altitudes, a satellite runs into traces of Earth's atmosphere, which creates drag. The drag causes the orbit to decay until the satellite falls back into the atmosphere and burns up. At higher altitudes, where the vacuum of space is nearly complete, there is almost no drag and a satellite like the moon can stay in orbit for centuries. A launch window is a particular period during which it will be easier to place the satellite in the orbit necessary to perform its intended function.

With the space shuttle, an extremely important factor in choosing the launch window was the need to bring down the astronauts safely if something went wrong. The astronauts had to be able to reach a safe landing area with rescue personnel standing by. For other types of flights, including interplanetary exploration, the launch window must permit the flight to take the most efficient course to its very distant destination. If weather is bad or a malfunction occurs during a launch window, the flight must be postponed until the next launch window appropriate for the flight.

Once the rocket reaches the right location above Earth, it lets go of the satellite. The satellite uses the energy it picked up from the rocket to stay in motion.

That motion is called momentum. But how does the satellite stay in orbit? Not quite. That tug toward Earth--combined with the momentum from the rocket… …causes the satellite to follow a circular path around Earth: an orbit.