Atmospheric entryPassage of an object through the gases of an atmosphere from outer spaceMars Exploration Rover (MER) aeroshell, artistic renditionAtmospheric entry (sometimes listed as Vimpact or Ventry) is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite.
Heat shieldIn engineering, a heat shield is a component designed to protect an object or a human operator from being burnt or overheated by dissipating, reflecting, and/or absorbing heat. The term is most often used in reference to exhaust heat management and to systems for dissipating frictional heat. Heat shields are used most commonly in the automotive and aerospace industries.
ParachuteA parachute is a device designed to slow an object's descent through an atmosphere by creating drag or aerodynamic lift. It is primarily used to safely support people exiting aircraft at height, but also serves various purposes like slowing cargo, aiding in space capsule recovery on Earth, landing spacecraft on other planets, and stabilizing vehicles or objects.
Inertial measurement unitAn inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the orientation of the body, using a combination of accelerometers, gyroscopes, and sometimes magnetometers. When the magnetometer is included, IMUs are referred to as IMMUs.
AtmosphereAn atmosphere is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. The name originates from Ancient Greek (atmós)'vapour, steam' and (sphaîra)'sphere'. An object acquires most of its atmosphere during its primordial epoch, either by accretion of matter or by outgassing of volatiles.
Rocket engineA rocket engine, also known as a rocket motor, is a reaction engine, producing thrust in accordance with Newton's third law by ejecting reaction mass rearward, usually a high-speed jet of high-temperature gas produced by the combustion of rocket propellant stored inside the rocket. Space vehicles carry their own oxidizer, unlike most combustion engines such as pulse engines or jet engines, so they can be used in a vacuum.
VenusSecond planet from the SunSurface absorbed doserate2.1×10 μGy/hSurface equivalent doserate2.2×10 μSv/h0.092–22 μSv/h at cloud levelApparent magnitude−4.92 to −2.98Absolute magnitude (H)−4.4Angular diameter9.7″–66.0″AtmosphereSurface pressure93 bar (9.3 MPa)92 atmComposition by volume96.5% carbon dioxide3.5% nitrogen0.015% sulphur dioxide0.0070% argon0.0020% water vapour0.0017% carbon monoxide0.0012% helium0.0007% neonTrace carbonyl sulfideTrace hydrogen chlorideTrace hydrogen fluoride^Defining the rotation as retrograde, as done by NASA space missions and the USGS, puts Ishtar Terra in the northern hemisphere and makes the axial tilt 2.64°.
MarsFourth planet from the SunSurface absorbed doserate8.8 μGy/hSurface equivalent doserate27 μSv/hApparent magnitude−2.94 to +1.86Absolute magnitude (H)−1.5Angular diameter3.5–25.1 arcsecondsAtmosphereSurface pressure0.636 (0.4–0.87) kPa0.00628 atmComposition by volume95.97% carbon dioxide1.93% argon1.89% nitrogen0.146% oxygen0.0557% carbon monoxide0.0210% water vaporMars is the fourth planet from the Sun.
Drag (physics)In fluid dynamics, drag, sometimes referred to as fluid resistance, and also known as viscous force, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, or between a fluid and a solid surface. Drag forces tend to decrease fluid velocity relative to the solid object in the fluid's path. Unlike other resistive forces, drag force depends on velocity.Orbital speedIn gravitationally bound systems, the orbital speed of an astronomical body or object (e.g. planet, moon, artificial satellite, spacecraft, or star) is the speed at which it orbits around either the barycenter (the combined center of mass) or, if one body is much more massive than the other bodies of the system combined, its speed relative to the center of mass of the most massive body.
Kinetic energyIn physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of massm traveling at a speedv is 12mv2{\textstyle {\frac {1}{2}}mv^{2}}. The kinetic energy of an object is equal to the work, or force (F) in the direction of motion times its displacement (s), needed to accelerate the object from rest to its given speed.
RetrorocketRocket engine providing negative thrust used to slow the motion of an aerospace vehicle Descent of a Martian lander halted by retrorockets (computer-generated impression) Soyuz space capsule retro-rockets cushion the landing impact A retrorocket (short for retrograde rocket) is a rocket engine providing thrust opposing the motion of a vehicle, thereby causing it to decelerate. They have mostly been used in spacecraft, with more limited use in short-runway aircraft landing.*As an Amazon Associate I earn from qualifying purchases.