Question: What compound, known as aqua fortis or spirit of niter is used in rocket propellant?

Context paragraphs:
ALICE (propellant): ALICE is a rocket propellant which consists of nano-aluminium powder and water.  After mixing, the material is frozen to keep it stable.  Hence, the name ALICE, for ALuminium ICE rocket propellant.

Niter: Niter, or nitre (chiefly British), is the mineral form of potassium nitrate, KNO, also known as saltpeter or saltpetre.  Historically, the term "niter" was not well differentiated from natron, both of which have been very vaguely defined but generally refer to compounds of sodium or potassium joined with carbonate or nitrate ions.  Three related minerals are soda niter (sodium nitrate), ammonia niter (ammonium nitrate), and strontium nitrate.  Niter was used to refer specifically to nitrated salts known as various types of saltpeter (only nitrated salts were good for making gunpowder) by the time niter and its derivative nitric acid were first used to name the element nitrogen, in 1790.

Hydroxylammonium nitrate: Hydroxylammonium nitrate or hydroxylamine nitrate (HAN) is an inorganic compound with the chemical formula NHOHNO.  It is a salt derived from hydroxylamine and nitric acid.  In its pure form, it is a colourless hygroscopic solid.  It has potential to be used as a rocket propellant either as a solution in monopropellants or bipropellants.  Hydroxylammonium Nitrate (HAN) based propellants are viable and effective solution for future green propellant based missions, as it offers 50% higher performance for a given propellant tank compared to commercially used Hydrazine.

Nitric acid: Nitric acid (HNO), also known as aqua fortis and spirit of niter, is a highly corrosive mineral acid.

BATES: BATES is an acronym for BAllistic Test and Evaluation System, which is a standardized system for measuring solid rocket propellant performance developed by the United States Air Force Research Laboratory in the early 1960s, used for almost forty years thereafter, and again beginning in 2010.  According to this reference, a single propellant grain was used in the original AFRL BATES motor design.  An AFRL BATES propellant grain is inhibited on the OD, burning only on the 2 outer ends and the central bore, and is dimensioned so the burning area does not change significantly (< 3% in the original BATES motor) through the burn, generating a flat-topped thrust curve (neutral burn) to minimize propellant characterization costs and simplify the data analysis.

Rocket engine: A rocket engine is a type of jet engine that uses only stored rocket propellant mass for forming its high-speed propulsive jet.  Rocket engines are reaction engines, obtaining thrust in accordance with Newton's third law.  Most rocket engines are internal combustion engines, although non-combusting forms (such as cold gas thrusters) also exist.  Vehicles propelled by rocket engines are commonly called rockets.  Since they need no external material to form their jet, rocket engines can perform in a vacuum and thus can be used to propel spacecraft and ballistic missiles.

Able (rocket stage): Able rocket stage was a rocket stage manufactured in the United States by Aerojet for the Vanguard rockets used in the Vanguard project from 1957 to 1959.  The rocket engine stage use as a rocket propellant Nitric acid and UDMH.  Able rocket stage was the second of three stages on the multistage rocket Vanguard.  The Able rocket stage was discontinued in 1960.  A further improved versions were used in the upper stage in the Thor rocket family (Thor-Able).  An upgrade to the Able Stage was the Thor-Ablestar rocket.  The Ablestar second stage was an enlarged version of the Able rocket stage, which gave the Thor-Ablestar a greater payload capacity compared to the Thor-Able.  It also incorporated restart capabilities, allowing a multiple-burn trajectory to be flown, further increasing payload, or allowing the rocket to reach different orbits.  It was the first rocket to be developed with such a capability and development of the stage took a mere eight months.

Asteroid mining: Asteroid mining is the exploitation of raw materials from asteroids and other minor planets, including near-Earth objects. Minerals and volatiles could be mined from an asteroid or spent comet then used in space for in-situ utilization (e.g. construction materials and rocket propellant) or taken back to Earth.  These include gold, iridium, silver, osmium, palladium, platinum, rhenium, rhodium, ruthenium and tungsten for transport back to Earth; iron, cobalt, manganese, molybdenum, nickel, aluminium, and titanium for construction; water and oxygen to sustain astronauts; as well as hydrogen, ammonia, and oxygen for use as rocket propellant.

Monomethylhydrazine: Monomethylhydrazine (MMH) is a volatile hydrazine chemical with the chemical formula CH(NH)NH.  It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide (NO) and nitric acid (HNO).  As a propellant, it is described in specification MIL-PRF-27404.

Rocket candy: Rocket Candy, or R-Candy, is a type of rocket propellant for model rockets made with sugar as a fuel, and containing an oxidizer.  The propellant can be divided into three groups of components: the fuel, the oxidizer, and the additive(s).  The fuel is a sugar; sucrose is the most commonly used.  The most common oxidizer is potassium nitrate (KNO).  Additives can be many different substances, and either act as catalysts or enhance the aesthetics of the liftoff or flight.  A traditional sugar propellant formulation is typically prepared in a 13:7 oxidizer to fuel ratio.

Supporting paragraphs: Able (rocket stage) Nitric acid
Answer: Nitric acid (HNO), also known as aqua fortis and spirit of niter