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Xtronaut: The Game of Solar System Exploration» Forums » Rules

Subject: Same gravity assist; mission cancelled rss

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1) Can two of the same gravity assist cards be played? Do you get a delta v bonus from both of them? If yes, does this represent doing two flybys around the same body?

2) When a "mission cancelled" card gets played or after completing a mission, you draw three and keep one as usual. But, at game setup you just get one card with no choice, correct?

3) Thematic questions --

A) On p. 19, I am assuming that 3 instances of "delta-V" in the table should be "delta v per unit payload mass", correct? Otherwise it sounds like small spacecraft need less delta v than large spacecraft for the same mission.

B) I am not sure I understand why the differences in delta v between the small and large spacecraft is so large for first stage and additional boosters. For example, the difference is ~11 km/s for falcon additional booster card. In order to add 11km/s, you need to multiply the mass of your rocket by more than a factor of 10 (for the rocket efficiencies considered in the game) Does the game assume that the actual rocket stages are also smaller for small spacecraft and larger for larger spacecraft?
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Val Ofiesh
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Good questions.
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Dante Lauretta
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Answers to Rus (rebelikov) below:

1) Yes - you can use the same planet twice for gravity assists. This is common in spaceflight where a mission may flyby Earth or Venus more than once to get the needed Delta-V.

2) At game setup the rules call for a single mission card to be dealt to each player. Some players have a house rule where you deal out mission cards equal to the number of players +1 and each player decides on their mission in turn.

3A) Good catch! This is a typo. Delta-V remains constant for a mission and it is the total energy (1/2*mass*Delta-V^squared) that is lower.

3B) Rockets provide a total amount of kinetic energy to the spacecraft. This energy is equal to 1/2*mass*Delta-V^squared. The values on the cards for each rocket represent real performance. For the small spacecraft I used a mass of 1900 kg, medium = 3700 kg, and large = 7500 kg.
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