MEP Flight Director
Job Description

To figure out when to launch the space craft and how it will arrive at Mars.

Key Words

launch window
orbit
ellipse
speed of sound (Mach number)
aerobraking
decelerate
G-forces ("gees")
relay satellite

Materials

pencil or pen, paper
"Launch/Arrival Date" card
"Arrival" cards
scissors to cut out the cards
tape

Procedure

1.
Look at the list of Earth to Mars launch windows below. What is the average number of months from one launch window to the next? Why can't we send spacecraft to Mars between launch opportunities? (Hint, Earth orbits the Sun faster than Mars).

2.
Talk to the Engineer to find out how many rovers, balloons, and science instruments were selected for the mission. The more of these components there are, the longer it will take to prepare for launch. Use the first table below to figure out your launch window.

3.
Write your probe's launch and arrival dates on the "Launch/Arrival Date" card, and be ready to place it on the Mission Planning Board on the final day.

4.
Choose how the spacecraft will arrive at Mars. The two possibilities are described in the second table below.

5.
Choose the "Arrival" card that shows your decision. Be ready to place it on the Mission Planning Board on Presentation Day.

6.
Tell the Launch Director the spacecraft's mass. Add the cost of your spacecraft arrival scheme to the cost to prepare the spacecraft and give this number to the Project Administrator.

Number of Components Launch Window Arrival Cost to Prepare
4 or less February 1999 August 1999 $10M
5 or 6 April 2001 October 2001 $20M
7 or more May 2003 November 2003 $30M

Method of Arrival Comments Mass Price
The spacecraft goes into orbit around Mars, then sends down one or more landers. The orbiter carries mapping cameras and a Mars-to-Earth Antenna, so it can act as a relay between the entire Martian surface and Earth (be sure the Engineer knows about this!). However, this option adds a lot of mass to the space craft because it takes a lot of fuel to go into Mars orbit. 400 kg $10M
The spacecraft, with lander, goes straight into the Martian atmosphere. This requires aerobraking, using the atmosphere of Mars to slow the space craft down. When it hits the Martian atmosphere, it will be moving at Mach 20 and decelerate at 30 "gees." Aerobraking is much more risky, but it saves a lot of weight, since you don't need to carry as much fuel. However, it leaves you with no orbiter to act as a relay satellite to Earth. 200 kg $5M

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