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Comet Busters

This adventure was originally posted to the pre-magazine Freelance Traveller website in 2002 and reprinted in the October 2015 issue.


The adventurers must have their own ship with a cargo space of at least 3 tons, and vacc suits for all of the PCs plus three. If the vacc suits prove to be a major problem, let the players find extra vacc suits in the local starport repair shop. The PC team must have at least one person with engineering skill, preferably two, and at least one with mechanical skill.


The PCs have the only ship presently in-system. While technologically limited, the world is sufficiently advanced to have astronomical interests. Recently, a large new comet has been detected, and calculations have just shown that it will collide with the planet in a matter of days. The planet’s government will send a pair of generals and a squad of troops by helicopter to request the ship’s captain to come with them to a nearby military base where he will meet the supreme leader. This leader will inform the captain of the situation his planet faces, and will (firmly) ask him to take on board several nuclear weapons and a nuclear weapons team and to deliver them to the comet, where they hope to to break it up. Should the captain or the other PCs prove less than altruistic the government will offer the following as incentives: land holdings planetside, 1 million credits, large business-oriented interest-free loans, and lifetime tax- and duty-free status, for each PC. This is the “Planetary Hero” monetary award, and has been awarded by this planet only a few dozen times in its history.

Should the PCs demand further payments the government will agree to anything while the crisis is pending, but will then defer payment authorization to the proper bureaucracy, which will deny any payment greater than that listed above. “This is not constitutionally authorized, …”, etc.

The nukes are primitive and bulky, and will require manual detonation. Any member of the weapons team will volunteer as necessary to make the devices work.

All payment agreements will be verbal, with the government chief executive. Any payments made will be on mission success, not before.

The general population will not be notified of the impending catastrophe.

Beginning the Mission

If the PCs’ captain agrees to this mission he will be immediately helicoptered back to his vessel, along with several generals, a squad of soldiers, and three wooden-crated nuclear devices. The cases have simple manual control panels on the outside, with connector jacks and hand-held pushbutton actuators. They are escorted by a weapons team, two young lieutenants and a tough-looking sergeant, who are volunteering to deliver these devices and detonate them. On arrival at the ship the nukes will be loaded into the cargo space immediately and the PCs will be asked to begin their mission without delay since time is short. If the adventurers insist on inspecting the cargo before it is loaded aboard they will be permitted to do so. If there are not enough vacc suits then someone should bring up this issue now, and a frantic general search should ensue.

Maneuvering to the Comet

The weapons team will have sidearms and combat knives, both visible and concealed, as a matter of policy. “We can’t allow transportation of nuclear weapons without an armed escort. Would you?” Their mission is to blow up the comet, and they’ll do anything to accomplish that. If their sidearms are demanded of them while aboard ship they will comply immediately but reluctantly, handing over their visible pistols. If pressed they will then give up their visible knives. If the concealed weapons are located and confiscated then the team will begin quietly noting common gear that can be used as weapons in an emergency, such as fire extinguishers, wrenches, pliers, and the like. The sergeant has Brawling-3, and each lieutenant has Brawling-2, meaning they will be formidable hand-to-hand opponents. The team will make no attempt to stand guard directly over the nuclear devices but rather will stick together at all times, believing they have a better chance against any treachery if they work as a unit.

The approach will take about 20 hours and will be uneventful. Most free time will be spent helping the weapons team learn how to use the ship’s vacc suits and how to function in a zero gravity environment, which skills they will need in order to move the weapons on the comet’s surface. Also all three weapons team members will express great interest in learning how the ship flies through space, making comments such as “I always wanted to be a pilot, but I never thought I’d fly in outer space” and “I hope my world learns to do this some day”. All will ask to sit in the pilot’s seat and maneuver the vessel at least once. Both officers, if engaged in conversations, will show pictures of their families. If asked about his family the much older sergeant will only comment that he is not sentimental. If pressed he will simply insist on concentrating on the mission: “I want to go over the vacc suit again. Please show me how to deal with an air leak.”

If there is any serious confrontation between the adventurers and the weapons team then the weapons team will make absolutely every effort to get the mission back on track.


On arrival at the comet the weapons team will gather on the bridge with the PCs to see what they’re up against. The arrival will be very rough. The comet will be surrounded by debris, some of it capable of damaging the ship, bubbling up in the turbulent atmosphere boiling off of the comet’s surface and escaping into space. Visibility to the surface will be poor. Intelligent adventurers, in the face of this obvious hull-breach hazard, will go to general quarters, all hands donning vacc suits and depressurizing major spaces. If the adventurers have not yet thought to ask then the weapons team will now inform them that they need to find a crack or depression in the comet large enough to allow manual insertion of the weapons and deep enough that a weapon detonation there will cause the comet to pop apart, thus diverting the majority of the comet mass around the inhabited planet in a large ring and minimizing the size of the pieces that do hit.

At some point during the approach the sergeant (or a lieutenant) will either locate and retrieve the team’s firearms without the PCs’ knowledge or he will find some suitable substitute such as a rivet gun or emergency flare launcher. Whatever he finds he will put it in his vacc suit outer pocket.


In a few hours the comet will be too close to the planet for the nuclear detonation to have any effect on its chances of hitting the planet. A short search will immediately discover two likely-looking canyons. One will be easily and safely approached, but may not be deep enough. The other is definitely deep enough, but will be dangerous to approach. If the ship lands near the first canyon it will immediately be obvious that the canyon is not deep enough and that the second canyon must be attempted. There is no time to look for a third canyon, but if the adventurers insist on trying then they will have to maneuver through debris that might damage their ship. For each turn spent looking roll 8+ on 2D, DM pilot skill, to avoid debris; failure means the ship will be hit by a rock that causes a hull breach. On approaching the second canyon roll 10+, DM pilot skill, to avoid a minor crash landing that will require continuous work by all engineers to fix before a takeoff can be attempted, and roll 10+, DM pilot skill, to avoid a collision with debris that will cause a minor hull breach in a primary living space. In the event of any damage, either from debris or from crash landing, the PCs should act immediately to begin repairs:

To repair hull breach damage:
Every 15 minutes, roll 6+ on 2D, DMs as follows:
+1 for each person with engineering skill working on the repair
+1 for each 15-minute period that has passed

To repair crash landing damage:
Every 15 minutes, roll 15+ on 2D, DMs as follows:
+ mechanical skill of the senior engineer working on this repair
+1 for each other person with engineering skill working on this repair
+1 for each 15-minute period that has passed.

The engineers can work on only one job at a time, and the ship can easily maneuver even with the hull breach, so presumably the adventurers will seek to repair the crash landing damage first.

On A Refusal

If for some reason the PCs refuse to proceed and try to abandon the mission, the weapons team will draw any weapons they can, imprison the PCs in a stateroom, and attempt to land the ship near the comet’s deepest canyon. They will crash-land, automatically doing double the damage specified above (roll every 30 minutes and count 30-minute periods, rather than 15 minutes). The PCs may, of course, attempt to resist this hijacking.

On The Surface

When the ship lands, whether gracefully or not, the weapons team will immediately begin manhandling the nuclear devices out of the ship’s cargo bay. Two of them will only be able to move one weapon at a time, while one remains in the cargo bay door with weapons left there while others are being moved. All of them, having little zero gravity experience, will have to work slowly to make any progress. They will request assistance from the PCs (one lieutenant will release them, if they were hijacked, and then immediately go back outside), with assurances that the PCs will not have to remain behind to detonate the bombs and that they will have time to get away.

Before (if) any PCs move out to assist the weapons team a patch of high-speed debris will strike the soldiers, puncturing their suits. The two lieutenants will die, while the sergeant will succeed in emergency patching his suit but be seriously wounded. The weapons and the ship will be undamaged. If no PCs are moving out to assist the weapons team, or if they retreat, the sergeant will again request assistance, stating that he himself is unable to continue.

If the adventurers refuse to help then the sergeant will arm the weapons and threaten to detonate them immediately if the adventurers do not complete the job. If the adventurers still refuse to assist, he will do so. The detonation will be successful and save the planet entirely on 10+, else save it but with great damage on 8+. The ship and PCs will be destroyed. The PCs will be unable, because of terrain and angle, to bring any ship’s weapons to bear against the sergeant without first lifting off and gaining altitude from the comet, which action will be immediately visible to him.

If the PCs assist involuntarily then the sergeant will supervise them with the recovered gun in one hand and the pushbutton actuator in the other. The referee will have to adjudicate further action. If the PCs succeed in placing the weapons to the sergeant’s satisfaction he will dismiss them, giving them a time limit to get away before he manually detonates the nukes. If the PCs assist voluntarily the sergeant will be unable to help move the nukes but he will be able to supervise weapon placement.

Time pressure will be very high. The mission is fast approaching a point where it will be too late for the planned detonation to affect the comet’s impact on the planet. The sergeant will be fully aware of that time, having marked it on his watch, and he will goad the PCs as necessary to hurry. If that point is reached before the weapons are fully placed then he will detonate the weapons immediately regardless of any other consideration. If the detonation time is getting very close and it looks as if the weapons will not be fully placed he will stop goading the PCs so as to keep them calm and working until the last possible minute. While moving the weapons under this time pressure each PC must at some point roll 2D for 12+ once, DM +DEX, to avoid injury due to haste in handling large objects in close quarters in zero gravity. Injuries will be pinched limbs. For each injury roll 2D for 12+, indicating a serious injury leaving the PC unable to contribute any further effort towards moving the weapons.

If the engineers finish repairs, they may quickly join the effort to move the nukes down the canyon.

The Find

As the PCs are moving the weapons to the bottom of the canyon, their vacc suit headlamps shining in the darkness, all will notice right away that there are strange shapes frozen into the glass- clear ice in both canyon walls. It soon becomes apparent that the shapes are several non-humanoid aliens, some artifacts, and what appears to be a ship. The aliens strongly resemble praying mantises and are a little smaller than human-size. They wear straps carrying various items of gear, but no clothing. The ends of their “arms” have manipulatory organs with multiple opposing digits. The ship appears to be about two hundred tons or so. The tail section is not in view, and no guess as to the propulsion system can be made. The artifacts are scattered about in the ice near the aliens and near the surface.


After the sergeant recovers from his own amazement he will continue to insist on weapon placement. When this is finished he will dismiss the PCs while he remains behind to initiate the detonation. If the adventurers have fully cooperated with the supreme leader and the weapons team from the very beginning and have otherwise been efficient then they will have enough time to attempt to recover artifacts from out of the ice, should they choose to try. They will be able to reach up to two items per PC present, for up to a total of nine items, before time pressure forces them to abandon further excavation and to head for the surface to escape the planned detonation. If they must choose between objects then the PCs can select from the following: three iridium-colored hollow tubes 3cm diameter 15cm long, two palm-sized saucer-shaped metal disks ringed with buttons, two plain silver balls 5cm in diameter, about half of an alien’s head, and one entire alien arm. If the players ask if they can take pictures then remind them that their vacc suits incorporate videocams and that they can fully record, in high definition digital format, all that they see as they work.


As the PCs return to their ship any repair crew should have had six chances to repair the ship should they have needed to do so. If the ship is not yet repaired and the PCs have been efficient in their use of time then they should have two more chances to repair the damage and resume flight without having to worry about blast from the nukes. If a final roll is necessary (and successful) before flight is possible, the PCs will escape but their vessel will likely take serious damage from fragments of the blasted comet (repeat the damage and repair possibilities listed earlier in Landing). If damaged, the ship must be repaired in two hours or it will burn up in the planet’s atmosphere. If the vessel is still on the surface of the comet when detonation takes place then the ship will automatically take all damage listed in Landing (no roll) and again must be repaired in two hours or burn up in the planet’s atmosphere. In addition to this, each crew member must roll 2D for less than or equal to the lower of STR or DEX or be injured sufficiently to be unable to participate in any repair effort.


If the PCs acted in a timely manner and did not engage in excessive delays then the planet will suffer only minor damage from pieces of the destroyed comet, and they will be paid to the limit previously specified. If, however, they failed to perform expeditiously then upon their return they will find that large pieces of the comet have impacted the planet. Overall damage to the planet’s biosphere and human population will be moderate and temporary. Damage to the government, however, will be fatal—the capital city, governing center, and starport will have been destroyed by a nearby strike. All who knew of the PCs’ involvement in trying to stop the comet, including the supreme leader and senior military officers, as well as all who knew of any payment arrangements made with the PCs, will have been killed in the impact. If they press their case and an investigation is launched they will have little evidence of their role in this matter. Astronomers will report that they did in fact notify the government of the impending collision, but they will have no knowledge of what action the supreme leader took regarding this information. Surviving witnesses may report that an off-world ship did arrive recently at the starport near the capital, and then leave shortly before the comet fragments impacted, but none of them will have any idea who it was or where this ship went after departing. The nuclear scientists will say they received valid orders to hastily assemble the devices and turn them over to the military weapons team, but they have no idea where the weapons went after that. If the adventurers made video records of their activities then the remaining governmental organs may be persuaded that the PCs did in fact contribute to the partial saving of the planet—provided, of course, that these records show the PCs cooperating with the weapons team and not needing to be coerced into taking action.

If the PCs failed to deliver the weapons at all then the planet will be severely traumatized by the comet’s full impact, with tremendous damage to the population and the biosphere.

If any alien artifacts were recovered from the comet, the referee should decide what they are and what the PCs options are for retaining and using them, selling them, or surrendering them to the Imperium, a university, or some other organization for research purposes.