Classic Traveller
The player group is hired by an ex-Imperial Navy Captain for an expedition. He will tell the players that his father was an itinerant asteroid miner who was lost in a misjump when the Captain was young. His father's ship was recently discovered, and the Captain has the records from the last jump. His father and the crew came out in empty space, only to find a large asteroid-like body. His father and several of the crew went to explore the asteroid, but never came back. The one remaining crew member set the ship on course for the nearest system, but his low berth failed before the ship was found. The Captain wants to travel to the asteroid and find out what happen ed to his father.
MegaTraveller
Set up will be much the same, but the father's ship was attacked when it returned to the system in the middle of a battle of the Rebellion, which killed the remaining crewmember (not the failure of the low berth).
New Era
The Classic Traveller set-up can be used in the Regency. For the RC or a Pocket Empire, the Captain is looking for his grandfather rather than his father.
1) The situation is exactly as it seems. The asteroid is plain rock. The Captain's father and his fellow crew were killed by faulty equipment.
2) As 1, but the asteroid has rich deposits of ore that can be worked.
3) As 1, but the Captain's father was abandoned on the asteroid on purpose by the crewmember. The father left a message explaining what happened.
4) As 3, but the "Captain" is actually the crewmember who left the father for dead, and has returned out of guilt. The players should be given a series of clues to this respect. The asteroid contains nothing valuable.
5) As 4, but the crewmember has returned for valuables hidden on the asteroid.
6) The introduction is all a cover story. The Captain is an active member of a secret service appropriate to the setting and time of the campaign. The asteroid is a secret cache of fuel, parts and weapons maintained by an enemy of the local political ent ity that the Captain learned about during his service. He plans to use the players to discover this and use the cover story to prevent the enemy from learning their codes have been compromised.
7) As 6, but the Captain has gone rogue and plans to kill the players and steal as much as he can from the facility for sale on the black market.
8) The Asteroid is a generation ship and the father is alive aboard. He was abandoned by the crew member on the ship, who panicked when the father didn't return promptly. The people on the asteroid are friendly and interrested in getting to civilization and in trade.
9) As 8, but the asteroid's inhabitants just want to be left alone. They are not interested in trade, but they will return the Captain's father.
10) As 8, but the asteroid's inhabitants are violently xenophobic, and will fight to destroy the player's group. They are technologically less sophisticated than players, however, so the Captain's father can be rescued if things are done right.