|
Aerobraking
|
A method of decreasing speed by increasing air-resistance. In a lander, this is accomplished by opening plates that increase
the air-resistance.
|
|
Apogee
|
The farthest point from the center of the orbit in an elliptical orbit.
|
|
Communication Package
|
The Communication Package will carry 3 satellites to Mars to establish
a communications network. There will be one satellite per Proton, giving a total of 3 Proton rockets.
This package will be launched on a pre-mission flight much before the IPP is launched.
|
|
DARTS
|
Acronym for Delivery And Return Transport System.
|
|
Delta IV Rocket
|
The Delta IV is a type of EELV rocket. See EELV.
|
|
Delta V
|
Pronounced "Delta Vee," not "Delta Five," it means the change in velocity required to change orbits. Two delta Vs are
required to go from LEO to LMO. The first delta V corresponds to the change in orbit from LEO to an orbit around the
sun. The second delta V corresponds to the change in orbit from an orbit around the sun to LMO.
|
|
EELV
|
Acronym for Evolved Expendable Launch Vehicle. It is a new type of rocket
that will likely be the most common rocket of the future. We will be using these rockets (instead of
Titan IVs) to get to LEO.
|
|
Falcon
|
The Falcon is the name of the ascent vehicle on the Nuclear Propulsion Lander. It will be the only vehicle
to leave the Martian surface. The crew will carry all samples with them on the Falcon and return to Low
Mars Orbit to rendezvous with the Transfer Habitat.
|
|
Free-return Trajectory
|
A free-return trajectory is a transfer trajectory that allows the spacecraft to return to Earth even if
it fails to land on Mars. It ensures that if the propulsion system
fails, the spacecraft can still return to Earth without any extra thrust.
|
|
Hohman Transfer
|
A method of inter-orbital transfer. This transfer requires two burns, first to leave the current orbit and enter
an orbit around the Sun, then another burn to change from solar orbit to the desired planetary orbit. It is the
most efficient transfer method in terms of cost of fuel and time of flight.
|
|
Ion Propulsion
|
A relatively new propulsion technology that shoots
plasma ions out of the back of the ship, and thereby moves the ship forward. It is most commonly used in thrusting
small payloads, but has potential use with large payloads as well. (also see VASIMR.)
|
|
IPP
|
Acronym for Ion Propulsion Package.
|
|
Isp
|
Notation for specific impulse. See Specific Impulse.
|
|
LEO
|
Acronym for Low Earth Orbit.
|
|
LMO
|
Acronym for Low Mars Orbit.
|
|
LMRs
|
Acronym for Little Martian Rovers.
|
|
NPP
|
Acronym for Nuclear Propulsion Package.
|
|
Nuclear Propulsion
|
Nuclear propulsion is a very new propulsion technology currently being developed and researched. The propulsion system
uses nuclear fission to generate energy to heat up a propellant, usually hydrogen gas.
It is an extremely efficient method of propulsion.
|
|
On-orbit Docking
|
This is a completely automatic method of docking in planetary orbit. No human control is necessary
for the two modules to join together in space.
|
|
Pathway
|
A mission structure used to get from one place to another.
|
|
Perigee
|
The point closest to the center of the orbit in an elliptical orbit.
|
|
Proton Rocket
|
The Proton is the most commonly used type of Russian rocket. It is used to launch satellites
and equipment and is commercially available. One rocket costs around $20-$50M, but the cost is offset slightly by
the high reliability of this model of rocket. Payload capacity is around 4.5m in diameter and 15m in length.
|
|
SL-12/SL-13
|
The SL-12 and SL-13 are Proton rockets with payload capacities of 20,000kg.
|
|
Soyuz
|
The Soyuz is a Russian manned shuttle. It is commonly used to send astronauts into space. It can carry
a maximum of three astronauts per flight.
|
|
Specific Impulse
|
A measurement of performance of a rocket. It is the ratio of Thrust (N) to the weight flow rate (mg/s) of the propellant.
The units are expressed in seconds. When the thrust and the flow rate are constant, the specific impulse is the time for which
the rocket provides a thrust equal to the weight of the propellant consumed. The greater the specific impulse, the better
the rocket. Specific Impulse is denoted by Isp.
|
|
Spiral Transfer
|
A special type of orbital transfer in which the ship spirals slowly out of orbit until it is
basically free from the original gravitational pull and flies towards the destination, where
it will engage in another spiral motion as it is pulled inwards into the destination orbit.
This transfer is used mainly with ion-propulsion systems, which produce a small but constant thrust.
The transfer is very slow, but the delta V for the transfer is minimal.
|
|
Surface Habitat
|
The surface habitat is the living quarters for the six-member crew during the stay on
Mars. During the transfer to Mars, the Surface Habitat will be connected to the Falcon and the Transfer Habitat,
creating a huge living space. The Falcon and the Surface Habitat will land on Mars, and the coupled system will
serve as the living quarters for the crew.
|
|
Titan IV
|
A very big rocket that uses liquid propellant. It accommodates payloads up to 4.5m in diameter and
20m in length. There are only four left in the world, all of which have been taken.
It is an extremely expensive rocket to make (about $270M per rocket) and is not as reliable as a Proton Rocket.
In the next few years, Titans will become obsolete and will most likely be replaced by the EELV.
|
|
Transfer Habitat
|
The Transfer Habitat is the living quarters inside the Nuclear Propulsion Package for the six-member crew. During the transfer to
Mars, the Falcon, the Surface Habitat, and the Transfer Habitat will all be connected, thus creating a large living space for
the astronauts. On the transfer back to LEO from Mars, the Falcon will be connected to the Transfer Habitat.
|
|
VASIMR
|
Acronym for Variable Specific Impulse Magnetoplasma Rocket. It is a modified ion rocket that
uses magnetic fields to increase the exit velocity of the ions. It is still under construction and testing at NASA. Read the NASA technology release here.
|
Copyright
© 2000 Massachusetts Institute of Technology