Jump Temp – Entering and Exiting Star Systems

If a ship’s pilot wants to leave a solar system, there’s a navigation challenge to plot a course out. A common misconception is that you’d simply point the ship away from the star and start the engines.

In reality it’s not that simple. If you look at the Cassini space craft’s flight path, it actually takes a dive toward Venus before heading into the outer solar system. Looking at any space probe’s flight path thats been launched, we see a spiral flight path. Why is this? Isn’t a straight line the shortest distance between two points?

Theoretically a straight line might be the shortest, but unless you have an unbelievably powerful drive system, it’s wasteful and likely impossible to do.

For another example, if you watch a rocket launch, you ‘ll see the vehicle curve as it flies upward. This was more evident in old space shuttle launches. The roll and the curve of the take off was easier to notice. Why not just fly straight up? For one, if the rocket went straight up it would not enter orbit. It would launch up into the air, possibly making it into space but would then fall back to the earth once it’s fuel ran out. By moving sideways on it’s ascent, when it starts to fall it misses the earth and thereby enters orbit.

If the target is another planet in the star system, it must be moving fast enough to miss falling into the star it is near. This falling toward and missing is how things orbit.

In a similar way, we are orbiting the sun. If a spacecraft were to fly straight away from the sun, it would start to fall back towards the sun as soon as it’s engines were shut off. The further out the space craft traveled, the slower it would fall but it would none the less fall.

Another reason to follow an indirect path is to intersect with planets and other large gravitic bodies that the craft can steal a little momentum from and use it to speed the vehicle up without using its fuel. This gravity assist is crucial for any vessel that has a fuel supply that isn’t infinite. Although it seems strange that Cassini should move away from Saturn so it can get to Saturn faster, flying in an indirect path is the faster and more efficient.

My one player commented how flying out of a system isn’t rocket science (no really, those were his words). I laughed and answered “It absolutely is rocket science. It’s more complicated than it sounds.”

Ships in Jump Temp would never fly directly away from a star, and might occasionally drop toward the star to get a gravity boost from planets. Falling closer to the star in the middle of a system cannot be used for a gravity assist but can be used for an Oberth effect which is a little complicated but if you’re curious, you can check out  on Wikipedia.



Reverberations of the Singularity

I’ve been thinking about resurrecting a very old game. It was, and now I can’t remember, either the second or third game I designed and played. I love the feel of the world but I think it got away from me in the original version.

I also need to find a new name for it. It was originally called Aftermath, but that’s been taken. The original version would probably be labeled as a poor rip off of Numinara if I published it today (Even though I wrote it in the 90s). I recently had a little spark of an idea that would pull it away from that.

So what is it? It’s a post apocalyptic world, there was a war with weapons that a modern day person would still not really understand. So technology was once really really high. Society has recovered to the level of medieval times in most places but there are a few cities that make high tech items.

A main technology that is being reproduced is called a KAF (Kinetic Abatement Field) unit. They dampen kinetic energy, making projectiles drop out of the air after a few feet. There are personal versions and big versions that protect armies or cities. This means that any combatant has to be ready to drop their gun and pick up a sword if a KAF is activated.

There are laser guns, but they are hard to find, expensive and usually can only fire once (think of fighting with muskets).

The thing that got away from me was the big bad threat. I have some ideas about what would work as an improved concept. I’m thinking the big apocalyptic war was caused by getting close to a computational singularity and people fought over it.

There are however computer cores that house AIs that are left in old server rooms buried in military bunkers and deep basements. They are valued as oracles, objects of power for the knowledge they hold. Finding them can reveal old knowledge, powerful knowledge.

However reviving the AIs revives the threat of the singularity. One or more cores were activated that corrupted others an now they have taken rulership of the largest city state in the known world.

The Energy System, Jump Temp and Character Creation

When putting together Jump Temp character creation and looking at space opera fiction, I felt that most characters showed a kind of specialization. They have something they’re good at, a job or proficiency that make them useful. This often means that they are not very good at other types of tasks.

The question was raised at DriveThruRPG about the cost of adding traits and equipment to an Augment character. Augments are very good at the thing they’re augmented to do. Even without any added equipment or traits they’re formidable characters.

We had one Augment that had a Strong attribute which he used to stop a car. We had one Augment with a Tough attribute that carried around a grenade. In a bad situation he would just pull the pin hold it in his hand and he could shrug off the damage.

They will often wear out if they’re trying to do things like figure out technical problems. We did have an augment that had an Intelligent attribute and he was very good at technical tests but had a hard time in survival situations.

If a more versatile character is desirable, then the Augment specialty might not be the best choice. Going with another specialty, possibly the Survivalist, and then adding the desired traits and equipment might be more along the lines of what the player wants.

If the GM is agreeable, a character that wants something very specific can simply start out with 10d of energy and then build their character from scratch.


Jump Temp – The EM Drive

The EM Drive is highly controversial. Many say it’s impossible that such a drive could work but testing so far says that it does. This experimental evidence is usually dismissed as error or an unintended side effect that would not produce thrust.

Why is this drive so controversial? Because it uses no propellant. This makes it seem like it violates Newton’s third law of motion.  If you throw nothing out the back, there can be no momentum pushing the vehicle forward.

The very fact that it needs no mass to chuck out the back is exactly why this system is so exciting. Instead of giant fuel tanks all you need is to generate electricity. It’s usually the propellant mass that runs out long before the ability to generate electrical power is exhausted. With this drive and some solar panels you’d practically have an infinite (infinite over time that is) amount of thrust available.

There’s a new explanation of what might be happening with these experiments that involves pilot wave theory. Although discounted for a long time in favor of the Copenhagen interpretation, it has been gaining popularity in physics circles lately.

Amazingly this sounds to me exactly like the “aether drive” like the ones used in Space 1889.

There is a dark side to this. Because the drive can produce thrust for very long periods of time, they could be used to push relativistic kill vehicles. A relativistic kill vehicle is basically, a very fast moving mass that can be pointed at a planet or some other target. As a vehicle reaches something like 20% of the speed of light, it has accumulated a really large amount of energy.

How large? Planet killing large. No death star required. Just a rock with a nuclear reactor and an EM Drive attached. Give it a few light years to get it up to speed and a few dozen years to make the trip.

The really scary part is that if you’re traveling at a significant fraction of the speed of light, it might be nearly impossible to see the weapon coming.

So a working EM drive is exciting, but also terrifying.

Jump Temp – No FTL Communication

In Jump Temp, there is no FTL communication. That is, aside from a starship. Starships in the process of jumping can send and receive radio signals on both ends of the jump. This makes data channels between star systems possible but only when there’s a constant and unbroken stream of ships traveling in between systems.

It might be practical for planets to have small fleets of jump drones that communicate with nearby star systems. This would help to get vital information in between systems. Commercial endeavors may even deploy their own arrays of jump drones and rent out their communication bandwidth to the highest bidder.

However, there’s another wrinkle to light speed communication. Even at the speed of light, radio takes minutes to travel between earth and the perimeter of where a jump drive can start to deliver the ship faster than light.

That means that when a ship enters a system it could take several minutes for anyone to hear their communications.

That makes Star Trek style video chat impractical except at distances of less than 400,000 kilometers (about 1 light second). The vast majority of communications would likely be similar to text messaging.

Jump Temp – Drive Signatures

Every starship has drive systems that propel it through space. The drive energy is noticeable because of the photons that are emitted. Not only can it be seen, just by measuring the light and it’s spectrum, the model of drive system can be identified. If a drive is modified, it may give off a unique signature but even then a guess could be made as to what the original model was.

Just by observing the drive’s output and the vessel’s speed, a skilled observer can calculate the mass of a ship. Just knowing the mass of a ship can give away what model of vessel it is, whether it is carrying cargo and possibly how many crew are on board.


Some feel that any ship that enters a system would automatically detected and there would be no way to hide in space. Personally I don’t see evidence for this thinking. Despite having many telescopes at their disposal, NASA could not see the Cassini space craft or it’s thrust plumes even though it’s the size of a small school bus. If they could have, in any way, recorded the probe’s decent into Saturn’s atmosphere they would have gladly showed them. This included a 100% thruster burn as it entered the atmosphere.

The problem is resolution and luminosity. The distances in a star system are enormous and that makes imaging a object smaller than a large moon difficult. The more powerful the drive, the further away it could be observed because of the light it emits. Some drives, like plasma drives may be harder to observe. Chemical and especially nuclear drives would be observable from much further away but at eight light minutes away (1 Astronomical Unit) a telescope would still have a hard time picking these drives up.

In the Jump Temp universe, a large portion of the outer solar system is easily accessible via jump drive. A ship jumping around the outer regions of the solar system could be easily hidden by jumping behind various stellar bodies.

Jump Temp – Crew Compartment

A lot of thought has been put into what the crew compartment of a space ship would need to look like. This is no simple puzzle, because a ship that tumbles end over end to produce artificial gravity has strange requirements. The crew compartment would likely have the floor, where the crew’s feet point, be where you would traditionally think of as the front of the ship. But when the vessel was accelerating, the floor would have the occupants looking up in the direction the ship is headed.

Unfortunately it’s nearly impossible to get enough acceleration out of a realistic drive system to simulate anything more than a tiny fraction of earth’s gravity. This would require a ship to tumble or spin on it’s drive axis as it travels. Only larger ships can spin on their axis, because rotating a small ship would not have a large enough rotational radius to properly simulate gravity. With too small a radius, a passenger’s head would experience less gravity than their feet, causing blood to pool in the legs.

A small ship might only tumble when it was jumping, allowing for a period of artificial gravity in between long trips. In this time, a passenger would have to exercise to mitigate bone loss.

It might also be possible for the drive system to pulse on and then shut off as the ship tumbles, allowing for artificial gravity while flying and giving the drive system a duty cycle time to shed waste heat. This would give the passengers longer exposure to artificial gravity and reduce bone loss.

In this way, the nose of a ship would frequently be seen as “down” to the crew, even as they flew in the direction the nose points when the drive fires.

The crew cabin itself is likely to be an open area with sleeping bags arranged on the “floor” but could also function as a restraint system in the event of dangerous accelerations or times when the ship isn’t spinning or tumbling.

There would be one small room that could provide some privacy. The bath room would probably be the only private place on the ship. It would probably also serve as a radiation bunker that the whole crew would have to cram themselves into during radiation storms. Heavy radiation shielding around the whole cabin would be expensive and would require more fuel because more mass means more fuel is expended to accelerate the ship.

As such, the ship would need to be piloted at times from the bathroom. Just in case you were wondering.

Larger ships would likely spin on their axis. Down would become the exterior of the ship. As such, climbing toward the center of the ship on a ladder would cause a quick reduction in the apparent strength of the artificial gravity. Climbing all the way to the center of a vessel might result in severe disorientation for some.

For a ship with “Comfortable Quarters” a small room, big enough to house a small bed and a possibly a tiny desk and chair are all that is implied here. Walls are heavy and an actual bed is a luxury that requires fuel to move.

Jump Temp – Electronic Lockpick

So I made a bunch of pre-gens characters for the con game at Queen City Conquest this past weekend and one of the characters had a piece of equipment that isn’t in the book, an electronic lock pick device. My son said “Whoah! Where did they get that?” I chuckled and replied that you can make any kind of equipment you like with agents. But examples are nice so here it is.

Electronic Lock Pick
Cost 3d
Pool 1d
Technical trait Unlock Doors 2 Steps

It’s really that easy!

Jump Temp – AI Proliferation

The question comes up frequently, can an AI simply copy itself a billion times and make itself more powerful?

By necessity, there would have to be a system in place that keeps this from happening or malicious AIs would just take over everything, just because they could means someone at some point would make one that did.

It’s possible that AIs are actually constellations of programs that really do copy themselves all the time and that’s just how they function.

But how would one prevent an AI from copying itself onto billions of computers? Maybe they operate like crypto-currencies that can be transferred but not copied.

It may be that there are special requirements to copy an AI. It could be that the program simply won’t allow itself to be copied. If that were the only safeguard though, someone would make an AI that would turn itself into a virus.

There has to be something about the architecture of the AI that will not allow it to copy itself. A blockchain validation would fit this bill. There could be something in the neural network that prevents copying too.

Jump Temp – Proc Coins

In Jump Temp there are dozens if not hundreds of currencies. Shady governments may offer payment in their own currency that they know is almost worthless anywhere else due to bad credit.

One solution is to use a crypto-currency, of which there are many. These currencies are data packages that can be transferred but will not allow copying. Forging a crypto-currency is very difficult and most competent AI’s can sniff out a fake in short order. This makes them very handy for independent operators without a reliable data connection.

One feature that some crypto-currencies have is that they can be traded for a real world thing. Proc Coins are one such currency. They can be traded for the use of a distributed net of AIs. For every money agent die, a character can “rent” time on this AI net to solve or help solve information based challenges. Each money die spent in this way becomes 1d of an AI assistant.

Using Proc Coins this way requires a working data connection and the AI cannot be influenced to do anything illegal. The AI assistant is available until it’s dice deplete.