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The propulsion maturation is a partnership between NASA and the U.S. Air Force. iSat's iodine propulsion system consists of a 200 watt Hall thruster (BHT-200-I) developed by Busek Co, a Dancing cubesats
Debra Werner. ''Aerospace America'', July 2017. it may be stored in the tank as an unpressurized solid, and it is not a hazardous propellant. 1U with 5 kg of iodine on a 12U vehicle can provide a change of velocity of 4 km/s ΔV, perform a 20,000km altitude change, 30° inclination change from
Iodine Satellite (iSat) is a technology demonstration satellite of the
, and was initially planned as a secondary payload for launch in mid-2018, but launch was delayed to allow for the propulsion system development to mature. The mission is planned to last one year before deorbit.
CubeSat
A CubeSat is a class of small satellite with a form factor of cubes. CubeSats have a mass of no more than per unit,, url=https://static1.squarespace.com/static/5418c831e4b0fa4ecac1bacd/t/5f24997b6deea10cc52bb016/1596234122437/CDS+REV14+2020-07-3 ...
format that will undergo high changes in velocity (up to 300 meters/second) from a primary propulsion system by using a Hall thruster with iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...
as the propellant
A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...
. Glenn Research Center
NASA John H. Glenn Research Center at Lewis Field is a NASA center within the cities of Brook Park, Ohio, Brook Park and Cleveland between Cleveland Hopkins International Airport and the Rocky River Reservation of Cleveland Metroparks, with a s ...Spacecraft
Electrically powered spacecraft propulsion
Spacecraft electric propulsion (or just electric propulsion) is a type of spacecraft propulsion technique that uses electrostatic or electromagnetic fields to accelerate mass to high speed and thus generating thrust to modify the velocity of a ...
uses electricity, typically from solar panels
A solar panel is a device that converts sunlight into electricity by using photovoltaic (PV) cells. PV cells are made of materials that produce excited electrons when exposed to light. These electrons flow through a circuit and produce direct ...
, to accelerate the propellant and produce thrust
Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...
. The technology can be scaled up to be used on small satellites up to . iSat will also demonstrate advanced power management and thermal control capabilities developed for spacecraft of its size.
The satellite is a 12U CubeSat
A CubeSat is a class of small satellite with a form factor of cubes. CubeSats have a mass of no more than per unit,, url=https://static1.squarespace.com/static/5418c831e4b0fa4ecac1bacd/t/5f24997b6deea10cc52bb016/1596234122437/CDS+REV14+2020-07-3 ...
format, with dimensions of about 20 cm × 20 cm × 30 cm. Its solar arrays aim to produce 100 W.
Propulsion
The propulsion maturation is a partnership between NASA and the U.S. Air Force. iSat's iodine propulsion system consists of a 200 watt Hall thruster (BHT-200-I) developed by Busek Co, a cathode
A cathode is the electrode from which a conventional current leaves a polarized electrical device such as a lead-acid battery. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. Conventional curren ...
, a tank to store solid iodine, a power processing unit (PPU) and the feed system to supply the iodine. The cathode technology is planned to enable heaterless cathode conditioning, significantly increasing total system efficiency.
A key advantage to using iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...
as a propellant is that it provides a high density times specific impulse, it is three times as fuel efficient as the commonly flown xenon
Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
,Debra Werner. ''Aerospace America'', July 2017. it may be stored in the tank as an unpressurized solid, and it is not a hazardous propellant. 1U with 5 kg of iodine on a 12U vehicle can provide a change of velocity of 4 km/s ΔV, perform a 20,000km altitude change, 30° inclination change from
LEO
Leo is the Latin word for lion. It most often refers to:
* Leo (constellation), a constellation of stars in the night sky
* Leo (astrology), an astrological sign of the zodiac
* Leo (given name), a given name in several languages, usually mas ...
, or an 80° inclination change from GEO
Geo- is a prefix derived from the Greek word ''γη'' or ''γαια'', meaning "earth", usually in the sense of "ground or land”.
GEO or Geo may also refer to:
Arts, entertainment, and media
* ''GEO'' (magazine), a popular scientific magazi ...
. During operations, the tank is heated to vaporize the propellant. The thruster then ionizes the vapor and accelerates it via magnetic and electrostatic fields, resulting in high specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine, such as a rocket engine, rocket using propellant or a jet engine using fuel, generates thrust. In general, this is a ratio of the ''Impulse (physics), ...
. The satellite has full three-axis attitude control
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, ...
capability by using momentum wheels and magnetic torque rods to rotate. iSat also counts with a passive thermal control system.
Mission
In the early 2010s, there was an emerging and rapidly growing market for small satellites, although they are often significantly limited by primary propulsion. In 2013, NASAMarshall Space Flight Center
Marshall Space Flight Center (officially the George C. Marshall Space Flight Center; MSFC), located in Redstone Arsenal, Alabama (Huntsville, Alabama, Huntsville postal address), is the Federal government of the United States, U.S. government's ...
competitively selected a project for the maturation of an iodine flight operational feed system. This demonstration flight will address not just propulsion, but the process to integrate commercial off the shelves components as well as custom designed components, opening affordable options of utilizing iodine propulsion systems for national security and for NASA's Discovery class missions.
The iodine thruster will allow iSat to alter its orbital inclination and elevation, opening up a wider range of mission objectives than previously possible with spacecraft of this size, such as transferring from a geosynchronous orbit
A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital ...
to geostationary orbit
A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular orbit, circular geosynchronous or ...
, enter and manage lunar orbits, and be deployed to explore near Earth asteroids
A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (Apsis, perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orb ...
, Mars
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...
and Venus
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...
. As a demonstration, the spacecraft will use its propulsion to lower altitude from its initial orbit of about 600 km to a circular orbit of about 300 km. Then it will perform a plane change maneuver, complete any final operational maneuvers and continue to lower its closest approach to Earth, and de-orbit the spacecraft in less than 90 days following the end of the mission.
See also
*List of spacecraft with electric propulsion
In chronological order, this is a partial list spacecrafts that are equipped with electric space propulsion. This includes both cruise engines and/or thrusters for altitude and orbit control. It is not specified whether the given engine is the so ...
References
CubeSats Ion engines Hall effect Proposed NASA space probes Technology demonstration satellites Proposed satellites {{spacecraft-stub