Tag: education

Mining Part 2, Mining Colony

by aubreygoodman, posted in Asteroid Mining, Kerbalism, Mission Planning

Vimeo: https://vimeo.com/324381843

YouTube: https://youtu.be/1MprhkvcIaw

Welcome to Kerbalism! I’m your host, Aubrey Goodman. In this episode, we upgrade a manned surface station into a mining colony.

In our last episode, we landed a construction core on Minmus, ready to expand itself to support higher volume resource processing. Now, it’s time to grow our station into our first mining colony. We need a manned presence to enable ongoing mining operations, extracting resources from the surface.

With asteroids, there is a much smaller opportunity for resources. If the asteroid is only one thousand tons, we spend a lot of energy and time with finite benefit, equal to the mass of the asteroid. We must repeat this for each asteroid we wish to harvest. If the asteroids are small, we may use more resources capturing them than they yield from processing.

Moons are different. Resource abundance on the moon surface is effectively limitless, compared to the cache in the asteroid. Once we’re settled in at a good location, we can produce an arbitrary amount of fuel and send it back to orbit. We’ve chosen Minmus because its surface-to-orbit delta-v is very small. The cost of sending resources from the surface to orbit is much lower than Mun or Kerbin. From the surface of Minmus, we can launch into low planetary orbit for about one third the cost of launching from the planet directly.

The construction core is designed for expansion. The goal is to land the bare minimum mining gear and use it to build the rest on-site. Our station core has both radial and vertical expansion options. After we add processing components, we expand outward with more support struts with the same radial and vertical options. These become new expansion points and we repeat as needed.

Of course, expansion comes with its own challenges. Our first expansion of processing equipment was lost when it overheated and exploded. Fortunately, no other nearby parts were damaged. The expansion plan must include increased solar and thermal management. We also need to leave room for ships to land for refueling. These vessels will not be docking in the traditional sense. They simply land near the station and connect via fuel hose. The hoses are limited in length, so ships will need to land close to the hub and wait for colony crew to attach the hose before fuel transfer can begin. Once attached, the station can transfer stored fuel or make new fuel on-demand, until the ship’s reserves are full. Then, it’s simply a matter of detaching the fuel hose and blasting off to Minmus orbit to rendezvous with an orbital fuel station.

Using this technique, we can deliver fuel within our planetary system to support the needs of any ships traveling between the planet and its moons. As we expand to other planets, we create new mining colonies on moons as needed.

As always, thanks for watching Kerbalism!

Mining Part 1, Construction Core

by aubreygoodman, posted in Asteroid Mining, Kerbalism, Mission Planning

Vimeo: https://vimeo.com/314334638

YouTube: https://youtu.be/HvigCivcMvg

Welcome to Kerbalism! I’m your host, Aubrey Goodman. In this episode, we build a manned station on the surface of a small moon using a construction core.

In our series on asteroid mining, we used unmanned probes with mining equipment to extract and process resources from nearby asteroids. We converted them into fuel and metal, the raw materials required to expand the capabilities of an orbital construction platform. Now we must accumulate enough rocket parts to begin building our construction core.

The core itself has an empty mass of about 20 tons, so we’ll need at least 20 tons worth of asteroid just to provide the bare minimum mass. In KSP, there is no waste from the refining process. In reality, this would involve a consideration for waste management. For our purposes, we’ll simply define our threshold as double the empty mass to be safe.

Turns out we need more than we had available in our captured asteroid, so we need to capture another one. After a bit of patience, we find a viable target and proceed with intercept. This time, we find one much larger, so it will be sufficient for this mission and hopefully others. Our patience pays off! We’re fortunate to secure a huge rock with over 2500 tons of viable resources.

Now, we ferry ore back and forth between our harvester and our construction platform, while the processing equipment churns the ore into rocket parts. After many ferry trips, we have enough raw materials, and construction begins.

While the core is being built, we change the focus of the ore processing equipment. We must convert enough fuel to enable the core to execute the transfer orbit maneuvers and land safely. The core has just enough fuel reserves to make the entire trip from planetary orbit to landing. Once we land, we will be able to make as much fuel as we want.

Also, we need to identify an ideal landing zone, where resources are abundant. We do this using a resource surveyor in polar orbit around Minmus. The surveyor satellite provides a map of ideal landing locations. We select a viable equatorial candidate and begin the landing sequence.

Our station does not have landing gear. Instead, it has heavy pads for its base, so we need to set it down very gently on a flat surface. We selected a landing zone in a flat equatorial region with sufficient resource abundance to support our needs. In our next episode, we begin to expand the capabilities of our surface station to support fuel harvesting on a larger scale.

Thanks for watching Kerbalism!

Asteroids Part 2, Capture and Harvest

by aubreygoodman, posted in Asteroid Mining, Kerbalism, Mission Planning

Vimeo: https://vimeo.com/311723008

YouTube: https://youtu.be/628eqhhpV5s

Welcome to Kerbalism! I’m your host, Aubrey Goodman. In this episode, we harvest resources from an asteroid and use them to capture the asteroid in orbit.

In our last episode, we intercepted an asteroid and grabbed onto it. We still need to slow it down in order to capture it into planetary orbit. If we don’t slow down, our harvester will be swept out of the planet’s sphere of influence to solar orbit along with the asteroid. Since the whole point is to use the resources within the asteroid, we need a retrograde burn with the asteroid in tow.

We’ve used most of the fuel to position our harvester. If we’re lucky, we might have some fuel to slow down, but there’s a good chance we’ll need to do a little harvesting before we can perform the maneuver.

This is where we begin to encounter the boundaries of what KSP can do. As sophisticated as it is, the unmodified game supports only one form of resource processing – fuel. We can convert ore into various fuels, but we can’t make metal or rocket parts to build directly in space. There are addons to enable this, and we’ll use them in the next episode.

This is also where we surpass the real world capability. The game allows players to grapple an asteroid and extend drills, all with the click of a button. Clearly, we don’t yet have this level of technology available in the real world.

The reason we use a harvester to capture our asteroid is simple. It would be expensive to bring enough fuel to slow down the asteroid, so we bring harvesting equipment along and use it to make fuel after we arrive. By carrying fuel processing components, we can plan to use most of our fuel to intercept and attach to the asteroid. Then, we can mine resources and process them into fuel to fill our tanks before the return trip.

With adequate fuel in our tanks, we perform a retrograde maneuver to settle into stable planetary orbit. The final altitude of our asteroid’s orbit will affect our orbital fuel harvesting operations, so it’s important to consider the details.

If the asteroid inclination is high, we will need extra fuel to ferry ore between the harvester and the processing facility. However, the asteroid itself is massive, so we would need a lot of fuel to move it to a different orbit. In our example, we settle into a circular orbit around the planet, between our two moons, but in a highly inclined orbit.

With an asteroid in stable orbit around the planet, we can begin to use its resources. In our next episode, we refine these resources into metal and rocket parts to build spacecraft directly in orbit. Don’t miss it!

And thanks for watching Kerbalism!

Stations Part 3, Nearby Planets

by aubreygoodman, posted in Kerbalism, Mission Planning

Vimeo: https://vimeo.com/310704564

YouTube: https://youtu.be/V6dT4-zPk8c

Welcome to Kerbalism! I’m your host, Aubrey Goodman. In this episode, we send a manned station to Duna.

After we have built sufficient infrastructure, we’re ready to take a bold step. It’s time to send a manned mission to orbit around another planet in our solar system. In the real world, we would be going to Mars. For the purposes of our discussion, we’ll go to Duna, which is a lot like Mars.

Just as before, we will construct our station in planetary orbit before sending it on its way. This time, though, we need to use completely different designs for the support craft we’ll be taking with us. The science and tourism landers designed in the last episode were meant for landings on moons.

Duna has significantly more mass than a moon. Its gravity is about twice that of the Moon, so we need extra delta-v to land safely. We do get one huge benefit for free. By landing somewhere with an atmosphere, we can use heat shields and parachutes to slow our descent. This saves a lot of delta-v and reduces the fuel requirements for our landers.

Science landers involving samples will need a reserve of fuel to takeoff and return to the station. For now, we will skip the return trip to save on weight. Until we have a more sophisticated refueling option, fuel is a precious resource. We’re also sending relay satellites instead of tourism landers. Ferrying tourists will have to wait. Besides, the landers are no good if they can’t communicate their findings back to home base.

With our station assembled and all its support craft docked, we’re ready to plan an escape orbit! We could simply burn prograde to accelerate out of Kerbin’s gravity, but this would need a lot of fuel. Instead, we rely on the moon to give us a gravity assist. By flying close to the moon’s surface, we take advantage of the moon’s gravity to accelerate us away from the planet.

It works like this. If we encounter the moon on the leading side, in its direct path, its gravity will slow us down. If we find ourselves on the trailing side, in its wake, we will slingshot around it and gain enough speed to escape planetary orbit.

Now that we’re on a solar orbit, outside of Kerbin’s gravitational influence, we can chart a course to Duna. Unfortunately for us, we have chosen our launch timing poorly. We must wait nearly 400 days before our Duna intercept. Clearly, we’ve glossed over the details about planning to sustain a crew for 2yrs until the next resupply mission can be expected to arrive. In the real world, people need to eat.

As we approach the planetary encounter, the station prepares to perform a retrograde burn to settle into a circular orbit. After assessing our fuel status, we determine we have sufficient fuel to deploy our relays before descending into our final orbit to deploy surface landers.

Now that we have stations spreading throughout the system, we need a sustainable way to harvest fuel in space. After watching time lapse video of refueling missions, maybe you’ve started to appreciate the value of finding fuel sources in deep space. In our next episode, we intercept an asteroid and begin to harvest its resources!

And thanks for watching Kerbalism!

Stations Part 2, Lunar Orbit

by aubreygoodman, posted in Kerbalism, Mission Planning

Vimeo: https://vimeo.com/309137882

YouTube: https://youtu.be/YZj6RmCgXJ8

Welcome to Kerbalism! I’m your host Aubrey Goodman. In this episode, we deploy orbital stations to our moons.

In our quest to explore our solar system, we seek new information to help us make sense of the universe, to expand our understanding of physics. Having a manned station in orbit around a moon helps pave the way toward increased traffic to the moon and acts as a support point for missions to its surface.

Just as we did for planetary stations, we first send an unmanned fuel pod into low lunar orbit. This will help prepare for future missions. Deploying a manned science station at the same altitude but on the opposite side of the orbit helps increase utility. The fuel pod acts as a last ditch option for crafts running critically low on fuel. Having both stations on the same orbit at opposite ends effectively doubles the chance a struggling craft can dock with a station.

Orbital science stations act as a staging point for science missions to the surface. We want to make sure we have docking ports of all sizes on these stations, again to maximize utility. Also, since this station will be supporting other smaller craft, it needs a large cache of fuel, monopropellant, and electricity.

After the station is assembled in planetary orbit, with all its supporting craft docked, we’re ready for transfer orbit. With fuel reserves adequately filled, we plan and execute our lunar transfer maneuvers. This means a prograde maneuver from planetary orbit and a retrograde maneuver to settle into a low circular orbit around the moon.

From here, we can send our unmanned support craft to the surface to explore and gather samples. We can also ferry tourists to the surface for a space selfie. Tourism helps generate revenue to stoke the financial furnace to pay for our science missions.

We’ve spent a considerable amount of resources just to deploy stations to our moons. It’s going to take a lot more funding to build and deploy manned stations to other planets. In our next episode, we send a manned station to Duna, which is a lot like Mars. Don’t miss it!

And thanks for watching Kerbalism!

Stations Part 1: Planetary Orbit

by aubreygoodman, posted in Kerbalism, Mission Planning

Vimeo: https://vimeo.com/308821250
YouTube: https://youtu.be/gIWuT522JG4

Welcome to Kerbalism! I’m your host, Aubrey Goodman. In this episode, we deploy a station to planetary orbit.

So far, we’ve only sent small things into space. Now, we’ll start to experiment with larger objects. The best place to start is a station in low planetary orbit. As you may have noticed by now, this will be pretty much the beginning of any mission. The first step will often be stable low orbit. From there, we have options.

One of the most important components of a successful spacefaring society is a system of orbital fuel depots. These unmanned stations act as storage containers for extra fuel. We will use them for future missions, where it makes sense to refuel in space after launch before continuing on a mission.

This technique will be the foundation for all advanced missions. By staging fuel and other components at key locations, future missions can take advantage of pre-staged resources. The goal is to deploy sufficient equipment to extract and refine the natural resources available in space and on the surface of other orbital bodies. But that’s a lot of work!

We’ll start with a simple orbital fuel pod. This needs to have docking ports, some kind of attitude control system, and enough solar panels to keep it powered. Ships docking with this fuel depot may need to top off various different fuels, so keeping a little of everything on hand is helpful. Our example shows only monopropellant and liquid fuel storage.

A fuel pod is a great start, but we need to start sending manned missions now that we have infrastructure in place. This means we’re ready to send science missions! By launching scientists into orbit, we begin to explore the effects of zero gravity on materials and living tissue. This can be a great accelerator, pushing the cutting edge of our technology ever faster.

Still, just as in real estate on terra firma, location is key. There’s only so much to be learned in low orbit. In our next episode, we expand to consider stations in lunar orbit around a moon. So stay tuned!

And thanks for watching Kerbalism!

Satellites Part 2: Lunar Orbit

by aubreygoodman, posted in Kerbalism, Orbital Basics

Vimeo: https://vimeo.com/307753956

YouTube: https://youtu.be/qCvHz1n0qxU

Welcome to Kerbalism. I’m your host, Aubrey Goodman. In this episode, we’ll review the deployment of satellites to lunar orbit.

First, let’s expand to consider the nearest moon. It requires more deltaV to get there, and more still to stabilize in a circular orbit. The good news is our Kerbin orbital satellite is over designed for its task. Its first stage does almost all the work, and we have plenty of fuel left over in the second stage for transfer orbit burns.

Once the craft is in planetary orbit, we need to perform two maneuvers to stabilize into orbit around Mun. If we do a really good job executing the maneuvers, we will settle into a circular orbit.

Orbital transfer between Kerbin and Mun can be done really at any time from a mostly equatorial orbit. This refers to the inclination of the orbital plane relative to the rotation of the body. Kerbin and Mun have very similar inclination, making it convenient to transfer between them. As we’ll find later, Kerbin’s other moon, Minmus, has a different inclination.

While a transfer can be made between Kerbin and Mun at any time, there are optimal points along the orbit where fuel use can be minimized, due to favorable alignment. Sometimes, we can save a huge amount of fuel simply by waiting for 20-30 mins.

Once we find a transfer orbit we like, with a destination periapsis at the desired altitude – that means the periapsis of the resulting orbit around Mun – once we find that periapsis, we can proceed with executing the maneuver at the appropriate time. Even perfect execution will result in slight misalignment with your designed objective. This is expected. If necessary, you can make corrections with RCS, but this is generally not required.

Now, after some time has passed your craft has traversed its path and is now approaching the periapsis of the destination orbit. You must burn retrograde until you slow down enough to stabilize into an elliptical orbit. Then, bring the apoapsis down to around the same altitude as the periapsis, resulting in a circular orbit.

Kerbin has a second moon, called Minmus. Its orbital inclination is about 6 degrees higher than Kerbin, so any craft headed there must also perform a maneuver to align its inclination. This is ideally done during orbital ascent, which reduces the inclination difference.

Our over designed satellite has enough fuel to enter stable orbits of both moons. But it also does very little. As we add capability to our satellite, the payload mass increases, and the first stage fuel requirements increase exponentially.

So that’s it for lunar satellites. In the next episode, we’ll focus on solar satellites; that is, satellites on an orbit similar to a planet. Those will lead us to a place where we will be able to establish a relay network of satellites that allows us to explore a wider part of the solar system. So stay tuned for that and much more!

And thanks for watching Kerbalism!

Satellites, Part 1: Deploying to Low Orbit

by aubreygoodman, posted in Kerbalism, Orbital Basics

Vimeo: https://vimeo.com/307509709

YouTube: https://youtu.be/ZcPy605hAiM

Welcome to Kerbalism! I’m your host, Aubrey Goodman. In this episode, we’ll review the basics of deploying a satellite to low orbit. Let’s get started!

Long before we think about sending people into orbit, we need to send smaller unmanned probes. These serve as opportunities to learn about the perilous environment of low orbit. As we’ll show, they also present a solution to the issue of communication within the solar system. Without relays to boost the signal back to the origin planet, probes must carry heavy radio hardware powerful enough to reach home. Heavy things cost more to send to orbit. Lowering the cost is often a matter of reducing payload mass or using fuel more efficiently. There are many things to consider, even when designing a simple satellite deployment mission.

First, let’s look at the simplest case, deploying to planetary orbit. Here, we use Kerbin as our planet. It is similar to Earth, so it works very well as a learning and planning tool.

The simplest form of an orbital launch vehicle is a single stage configuration. This means the entire vehicle is one single unit ready to fly to orbit, from takeoff through ascent to low orbit. This is both inefficient and expensive for a satellite. There’s really no reason for the heavy lift stage to remain in orbit once the satellite has reached its intended orbit.

Rather than hauling heavy engines and fuel tanks into orbit to live forever awkwardly attached to our satellite, we will consider a more popular two stage configuration. In this case, we use a solid rocket first stage and a liquid second stage for orbital stabilization and precision maneuvering.

Using a solid rocket first stage has some side effects. The most important is they burn until the fuel is gone. There is no in-flight throttle control. Throttle can be achieved by narrowing the nozzle geometry, but this is a design-time decision and significantly impacts the construction cost.

Using a liquid first stage, we would be able to cut throttle on the ascent, and throttle back up at the peak of ascent to circularize the orbit for payload deployment. Then, if we’ve done well, we can burn retrograde to return the first stage back to the surface.

Terms & Concepts

by aubreygoodman, posted in Kerbalism, Orbital Basics

Vimeo: https://vimeo.com/309674273

YouTube: https://youtu.be/pAcyaTRn_JM

Welcome to Kerbalism! I’m your host, Aubrey Goodman. Space is strange and foreign. There are lots of terms and concepts you probably haven’t heard before. We will use this terminology throughout the show, so let’s review the basics!

First, you blast off straight upward until your orbit reaches the desired altitude. The point with highest altitude along your orbit is called the apoapsis. Accelerating upward will raise your apoapsis. This is called a prograde burn; prograde means adding energy to the vehicle. When the craft reaches the apoapsis, we initiate a second maneuver (also a prograde burn) to accelerate sideways and increase our speed.

This raises the periapsis, or point with lowest altitude, up to the same altitude as the apoapsis, resulting in a circular orbit. In a circular orbit, the craft’s velocity doesn’t change very much. If we are orbiting a body outside of its atmosphere, there are no forces to accelerate the craft. This is referred to as a stable orbit.

If we wanted to land from a circular orbit, we would need to slow down, performing a retrograde burn. Retrograde means removing energy from the vehicle. Wherever we are along a circular orbit, burning retrograde will cause the apoapsis to settle at the craft’s location while the periapsis descends toward the planet’s surface on the opposite side of the orbit.

As the craft descends, its velocity increases. To be clear, we slow down now to speed up later at a lower altitude. If the periapsis is inside the atmosphere, we will begin to lose energy to drag forces. As we drop lower into the atmosphere, drag increases and vehicle speed decreases.

If instead we wanted to visit a moon orbiting the planet, we would need to burn prograde to speed up and raise the apoapsis to a higher altitude. This has the opposite effect as before. As the craft ascends, its velocity decreases. This time, we speed up now to slow down later at a higher altitude.

Each of these maneuvers is introducing a change in velocity, known as delta-v. As we compare different aspects of spacecraft design, we will be focused on optimizing delta-v. Many of the tools we use include automatic calculations for delta-v.

At this point, you might feel confused. In an elliptical orbit, the velocity changes along the path, so isn’t that the same as delta-v? Well, not exactly. As the craft moves around the ellipse, it speeds up toward the low point (or periapsis) and slows down toward the high point (or apoapsis). Each time the craft travels around the path, it returns to the periapsis with the same speed as it had the last time. Unless there is some other influence acting on the craft, it must obey the laws of physics and mathematics.

That’s all for this quick review. Stay tuned for satellite deployment!

And thanks for watching Kerbalism!