Torquemadus

It will be interesting to see what effect this change will have on air breathing engines, such as the turbojet. Jet ISP increases somewhat after take off, but then starts to decline as altitude increases. Presumably, this means that jets will loose thrust at higher altitudes?

Early plans to send astronauts to Mars were based on similar thinking to Apollo. Apollo sends some astronauts to the Moon along with all of the consumables and propellants they'll need for the mission. Two astronauts land on the surface, but with limited consumables and surface mobility, they can't stay long or get much exploration done. The traditional plan to go to Mars does things the same way. You send a huge spaceship (dubbed Battlestar Galactica by critics) that hauls all of the propellants and consumables needed for the mission from Earth. Once you get to Mars, you send down some crew members in a lander to do a short "flags and footprints" visit to the surface. The landing party have limited consumables and surface mobility, so they can't stay long or get much actual exploration done. To avoid having to wait around for the next return window to open up, the mothership is sent on a high deltaV trajectory to get a gravity assist from Venus to get back to Earth. The mothership is far too big to launch from Earth, so it has to be assembled on orbit at massive and insanely expensive shipyard facilities in Low Earth Orbit and/or the vicinity of the Moon. This is handy if you want to justify a space station and/or Moon base programme, as these are considered mission critical to get to Mars. It's also handy if you want to justify massive spending on zero gravity medical research, advanced propulsion systems development, and so on. Of course, it's not a lot of use if you plan on actually exploring Mars, because the mission doesn't do very much of that. You'd be far better off sending probes instead. Since the Apollo missions flew, NASAs crewed spaceflight programme has been kept ticking over in idle mode. The Space Shuttle programme was created to give the astronauts something to do. When it became apparent that the cost of launching satellites via the shuttle was vastly more expensive than launching them on expendables, the shuttle was left without a clear role. Space Station Freedom was therefore conceived to give the Shuttle something to do. With the collapse of the Soviet Union, the Russian space agency also needed to be given something to do to keep them from heading off to build missiles for whoever. Henceforth, Space Station Freedom became the ISS, which was deliberately designed to require the most complex on orbit assembly possible, therefore helping to keep the Shuttle occupied for as long as possible. With the station built, the astronauts can literally go around in circles while doing research on the already well understood effects of radiation and zero gravity on themselves. Meanwhile, hardware orphaned from the cancelled Constellation Programme continues to be very slowly developed in case any of it comes in handy later on. Modern thinking about human space exploration revolves around In Situ Resource Utilisation (ISRU). Most of the propellants and consumables needed for the mission are produced from local resources. This greatly reduces the size and expense of the spacecraft used to get there. In this regard, Mars has a huge advantage over Earth's resource poor Moon. Precursor missions are sent out to establish the best location for a permanent base. All later flights land at the base, which acts as a jumping off point for expeditions to explore the planet on a global scale. The base soon develops into a settlement. A very good example of how this approach would be used is Robert Zubrin's mission plan.

I use piloted fly-back boosters. A big drawback of that is that in the case of a crewed mission, I'm actually launching two crewed spacecraft linked together. A LES would only save the crew from the upper stage. I play on very hardcore custom difficulty, but I still have revert and quicksave enabled because of the ever present risk of bugs, which can and do wipe out my missions from time to time. Reverts allow me to try out simulated launch mishaps, where I deliberately cause a failure and then see if there's a way to save the crew. Even if I deliberately try to screw up the launch, both piloted spacecraft almost always survive. However, I can't land both craft safely while they're still linked. This wouldn't be a problem if I could somehow separate them and fly them down individually, after all, both spacecraft have a competent pilot at the controls. This is partially a drawback of KSP and partially a drawback of the way I design my launch vehicles. I've had a number of real launch mishaps, caused by mistakes during the design of new launch vehicles (sooner or later you have to launch the thing and see if it works). I'm currently trying to phase in a new heavy lifter, and it's given me some trouble keeping the thing on course during ascent as it drains fuel. So far, my mishaps have resulted in wildly sub-optimal ascents that have resulted in a number of successful aborts to orbit. Because of the difficulty settings I use, it takes me quite a while to earn back enough money to cover the cost of a failed heavy lift launch, so I play through the scenario long enough to confirm that all crew members successfully aborted to orbit and would have recovered safely to the KSC runway in due course had I not reloaded. I could decide to be ultra hardcore and earn back enough money to cover the cost of a launch failure. This is completely achievable on the difficulty settings I use, and could be seen as a fitting punishment for failure. I use difficulty settings where completing a contract earns back enough funds to cover the cost of the launch, but only if my launch vehicle design is very efficient. I earn my money by launching extreme capability missions that can complete contract after contract from a single launch. There's no denying that playing KSP in it's current form on extreme difficulty is grindy, but it's not impossible. I'm playing extreme custom difficulty to explore ways to overcome the engineering challenges it imposes. I could grind funds to rebuild after a successful abort to orbit, but doing so would be time spent for the sake of spending time.

What we need is a small nuclear reactor that can be used to power bases. Reactors of this kind have been proposed that weigh roughly three to four tons. The need for nuclear power in KSP hasn't become apparent yet, since we don't have anything in the game that creates the kind of power demands that it would be needed for. ISRU should change this, as most ISRU methods require the running of chemical reactors to manufacture rocket fuel and life support consumables. It's worth bearing in mind that solar power isn't going to be much use in Kerbol's outer solar system. This is something to bear in mind when planning an ISRU base in the vicinity of GP2!

Early space flights provided the crew with a finite supply of breathing oxygen and drinking water. In the case of Apollo and STS, waste water from the hydrogen-oxygen fuel cells was also used. Urine was dumped overboard, to create the famous "Constellation Urion" of frozen ice crystals outside the ship. This approach would be completely realistic in early Career Mode. Present day closed loop life support systems are able to recycle most, but not all, of the oxygen and water used by the crew. In practice, water used for washing doesn't need to be of the same quality as drinking water, so this makes recycling a little more forgiving. Another trick that can be used is to supply some of the rations as fully hydrated whole food instead of dehydrated food. These weigh more than dehydrated rations, but obviously don't have to be rehydrated before consumption, this reduces the amount of drinking water needed by the crew and is beneficial to crew morale on long duration missions. Much of the water content of the hydrated food is then recovered through recycling, which helps to make up for losses in the system. Advanced life support systems have been proposed that use plants to recycle 100% of the oxygen, water, and food. The "recycling" of food has so far been shown to be problematic, due to the biohazards inherent in using human waste as fertiliser while simultaneously trying to harvest edible food from the same plants! Growing food requires either greenhouse agriculture, or artificial sunlight. Greenhouse agriculture is a lot easier if conducted on a planet with an atmosphere. Even a thin atmosphere can protect plants from solar flares. A greenhouse on an unprotected moon or asteroid would require very thick walls to protect the plants within, which in turn imposes a heavy mass penalty on the mission. A lunar greenhouse has the added disadvantage of lacking a 24-hour day/night cycle to keep the plants alive. Generating enough artificial sunlight to grow enough plants to feed the crew indefinitely requires enormous amounts of electrical power, which has to come from somewhere. Simulating life support in KSP would also need to be tied in with ISRU. Providing enough water and oxygen for the crew is a lot easier if you can obtain water and oxygen locally instead of lifting all of the supplies you need from Kerbin. One approach that might be interesting would be to give different capsules different life support efficiency and consumables capacity. It might therefore be more efficient to bring a heavy crew hab which has excellent life support efficiency on a long duration mission, because it saves consumables in the long run. Conversely, a lightweight lander on a short duration mission might benefit from an inefficient life support system that offers a lower dry mass. Consider the difficulty current players have in deciding whether to emphasise TWR or ISP when choosing which engine to use for a particular mission. A long duration hab might have LV-N performance for life support efficiency, but would weigh far too much to make it a viable choice for short duration missions that require low parasitic mass. The other question would be whether interplanetary missions should bring all of their life support consumables from Kerbin, or replenish their supplies via ISRU. I personally think that the issue of growing food should be dealt with in a future expansion of KSP that deals with base building and colonisation, both of which are far beyond the scope of KSP's 1.0 release, but are both fair game for future updates post 1.0. In conclusion, KSP should be simulating open loop and close loop life support, with varying cost, tech tree requirements, and mass penalties. Players should be offered the engineering dilemma of whether to bring lots of supplies from Kerbin, try to use supplies efficiently, or resupply in deep space via ISRU. A mission to a distant interplanetary destination would need to either bring enough supplies, or produce enough supplies offworld to keep the crew alive long enough to get them home. Failure to do either could doom the crew.

One thing that irks me somewhat about the current capsules and cockpits in KSP is that none of them are designed for the long duration missions we in fact use them for. If you want to simulate an Apollo or Gemini mission, then there's nothing unrealistic in cramming a few kerbals onto a command module for a couple of weeks. However, it's clear that for interplanetary missions, as well as space stations and bases, that proper living quarters are required. I simulate these with the Hitchhiker Can and it's spaceplane equivalents, even though the Hitchhiker doesn't really seem to be outfitted for this purpose. There should be a small compartment taking up a corner of the Hitchhiker with a closed door marked bathroom.

The most forgiving approach would be to have life support consumables used in a similar way to electricity for probes. If you launch a probe with batteries but no solar panels (or forget to deploy them), it will use up it's supply of electric charge until it eventually "dies". However, this only happens if the probe is focused. If life support worked the same way, it would only be possible to kill the crew of a ship while focused. This would be the simplest approach. Probes have a resource that they need to stay alive, so Kerbals could have their own resource(s) to stay alive in the same manner. This negates any need for alarm clocks and reduces the likelihood of new players being hit with nasty surprises! It would be a simple enough matter for Kerbals on EVA to have a life support resource, they already have EVA fuel as a resource. This should be quite forgiving, lasting quite a long time, and easily replenished by returning to a ship in the same way as EVA fuel. It would probably be a good idea to allow kerbals to draw life support from a vehicle while in a command chair. This would represent the kerbal connecting a suit umbilical to the vehicle to use whatever life support capability it has. This would ensure that command chair equipped vehicles, such as open rovers, can be used without unduly punishing the player for not using an enclosed capsule.

You get a high ISP from a rocket by maximising exhaust velocity. There are practical limits to how much you can heat up the exhaust gas without melting the engine. Using an exhaust gas with a very low molecular weight, such as hydrogen, produces a higher exhaust velocity than heavier molecules. Unfortunately, chemical rockets can't use hydrogen on it's own as an exhaust gas, since they need to burn it with an oxidiser to heat it up. This means that the absolute lowest molecular weight obtainable in a chemical rocket comes from burning hydrogen with oxygen to produce water. Nuclear and solar thermal rockets don't need to use an oxidiser, they can heat up the hydrogen on it's own as an exhaust gas. This is why they obtain better ISP. Thermal rockets can use water as a propellant, heating it up and expelling it as steam to produce thrust. This would produce the same ISP as a chemical engine using hydrogen and oxygen. This might be desirable if planning a mission to a place where water or ice was easily obtainable, as the water could be used to refuel. Other gases can be used instead if the ease of obtaining them matters more than ISP. The performance of the KSP LV-N suggests that it uses hydrogen. It's never been made clear whether the liquid fuel used by engines in KSP is actually hydrogen. The ISP produced by some of the chemical rocket engines in the game suggests this, but the same liquid fuel that they use is also used in jet fuel fuselages, which are thought to contain kerosene. If the liquid fuel used in KSP is not hydrogen, then changing the LV-N to use liquid fuel only still wouldn't be realistic. It's worth noting that hydrogen is difficult to store long term in space because of the need to keep it extremely cold to avoid boil off. To allow the LV-N to be used realistically, players should either be able to use hydrogen to get a high ISP, or use other propellants for easy deep space refuelling. Depending on how ISRU is implemented, there might be an advantage to having an engine that doesn't require oxidiser, especially if fuel and oxidiser can't be mined from the same places.

I found that my science and reputation were outpacing my funds, so I invested a small amount of funds to buy the tier two Administration Building. I run the Patents Licensing and Fundraising Campaign strategies at 10% each. I have high hopes that in the very distant future, these strategies will eventually earn back the funds I spent on upgrading the Administration Building!

I'm playing Career Mode on extreme hardcore custom difficulty. It's not for everyone, but the challenges I face trying to make progress force me to constantly innovate. Playing Career Mode on Hard is grindy. Playing on drastically harder difficulty makes the game seem almost impossible...until you learn to play better. Most of my innovations have focused on reducing launch costs, recovering as much hardware as possible, and maximising the number of missions that can be performed from a single launch. Most of my contracts barely cover the cost of the launch of the spacecraft needed to complete them, but in most cases, I've been able to perform multiple missions. I've shamelessly re-tasked most of my satellites to perform temperature scan contracts from low polar orbit of Kerbin's moons. Most of the others have been recovered by parachute. My Kerbals perform multiple visual survey contracts in a single launch. Reaching all of the surface locations requires the use of fuel efficient "surface mobility". My latest innovation is re-useable space stations and bases. These are used to perform outpost contracts and are then recovered intact to the KSC. Once I've got a few more parts unlocked, I'm going to design a winged "space station" that can land on the KSC runway.

There have been fears voiced in the past that in the event of a launch failure, nuclear material would be released into the atmosphere. Compared to the amount of material released during nuclear bomb tests, civil nuclear accidents, the accidental sinking of various cold war era nuclear submarines, the release of radioactive substances found naturally in many types of coal, and so on, the amount of material present in an RTG is quite negligible. In the event of an actual launch failure, an RTG would remain intact and sink like a brick into the ocean downrange of the launch site, burying itself deep in the subseabed. The amount of material used in a Nuclear Thermal Rocket or a small space nuclear reactor would be more than an RTG, but would still be quite small. As long as it can be ensured that the material will remain intact and sink, there shouldn't be a problem.

SRBs need to be thrust limited to increase their burn time. I usually set mine to 70%. This allows the rocket more time to climb out of the soupy lower atmosphere to altitudes where the atmosphere no longer holds back the acceleration of the rocket. This means that at the point when the SRBs are low on fuel and giving their best TWR, their thrust is being used to rapidly accelerate the rocket, not push against the atmosphere. This in turn increases the altitude and speed the rocket is able to reach before staging, which leaves less work for the second stage to do. While great as first stages, I've never liked the performance of solids in upper stages, so I prefer to use re-useable liquid fuelled upper stages instead.

With the demise of the Saturn 5, NASA lost the ability to send astronauts beyond Low Earth Orbit. The nuclear rockets needed for interplanetary departure stages were orphaned. The political decision was made to keep NASA ticking over in idle mode. The Space Shuttle Program was conceived to give NASA something to do. The Space Shuttle lacked a clear role, so Space Station Freedom was conceived to give the Space Shuttle something to do. Check out the plan.

I was reloading back to a point in space in Kerbin's SOI. I was returning from a highly elliptical orbit and had saved prior to making a course correction burn to fine tune my re-entry. I tried a number of re-entry profiles, some where I attempted direct entry, some where I aerocaptured into a circular orbit first before re-entering. In each case, I was fine in orbit and on aerobraking passes. I had no problems until I was on final approach to the runway. I tried different approach angles to see if they made any difference. Reloading normally clears the problem, so I was surprised that I managed to get the same outcome five times in a row.

Space planes can be landed tail-first on low gravity bodies. I fit landing legs around the tail for this purpose. Once on the surface, I can use frictionless wheels and tiny amounts of propellant to travel long distances over the surface. This is handy if I want to spam surface exploration contracts. When I want to return to Kerbin, I use a hill as a ramp to "ski jump" off the surface. I then manoeuvre the spacecraft conventionally. The wings and landing gear are used to recover to the KSC runway.

What we need to do is figure out a way to land vertically and then deploy wheels for horizontal surface travel...

I play on hardcore custom difficulty. I've been getting by with the engines from the tier 1 R&D building. I use the LV-909 for my crewed spacecraft and the 48-7S for my satellites. The LVT-30 and LVT-45 power my fly-back boosters, while the SRB-KD25k is used as a cheap first stage. In the early game, I used the much less capable BACC booster. Two-stage to orbit launch vehicles are not fashionable in KSP at the moment, because the mighty Turbojet rules supreme. My designs throw away "trash bins full of boom" solids as a first stage, and recover their liquid fuelled second stage to the runway. The crewed upper stage also recovers to the runway, while the satellites can be recovered via parachute. They are more than adequate for the economic demands of the extreme difficulty settings I use. My launch costs consist of a bunch of cheap SRBs, and a small cost for the liquid propellants used by the other stages. No parts other than empty solids are expended. Nonetheless, the launch costs of my Kerboosters are pathetically inefficient compared to Turbojet SSTOs. It's worth bearing in mind that proposed IRL SSTO concepts are only economical because of the low operational costs involved. The NASA Space Shuttle offered far higher payload to orbit costs than the expendables it should have replaced. This was mostly due to the cost of paying the standing army of workers needed to prepare the re-useable shuttle for each launch. The enormously high dry mass of the orbiter didn't help either. SSTOs try to reduce costs by offering rapid turn-around times with a small ground crew, allowing the launcher to spread costs over a very large launch manifest. IRL SSTOs need to have extremely low dry mass to have any hope of reaching orbit, which leaves very little margin for cargo. This means that they either need to launch very small satellites, or deliver small but very frequent service to orbiting stations to deliver parts and consumables for on-orbit assembly or other operations. The economics of launches in KSP don't take ground crew costs into account. We don't have to pay our workers. An enormously large and expensive Turbojet SSTO will give excellent launch costs, because it doesn't really cost anything at all. Provided it recovers to the runway, it costs nothing. Only the propellants are paid for, and most of the propellants were sucked in through the air intakes! Since air-hogged turbojets can place payloads into orbit with only a little help from RCS, Turbojet SSTOs are almost a free lunch!

On this occasion, I reloaded five times and tried different approach angles. I eventually gave up after five quickloads and decided to just put the plane down with the remaining wing parts. Once again, Structural Wing Type B was the only part affected.

I'm looking forward to 1.0 and ISRU. Once I've got ISRU, I can build my own version of in KSP! The idea that humans cannot or should not expand into space is a holdover from geocentrism and should have been discarded long ago.

I actually think that Squad need to go a lot further than adding just one extra gas planet. This will require a fair amount of work, so Squad are quite justified in getting the core features of the game finished in 1.0 first. The extra planets that are needed could be added as part of a Moar Planets update post 1.0. I think that there should be analogues for Saturn, Uranus, and Neptune. These should be placed at appropriate distances from Kerbol. These could then be complimented by analogues for Kuiper belt objects such as Pluto/Charon for end-gamers to visit. The Kuiper Belt has the added advantage of already being spelt with a K! We also need a decent Main Asteroid Belt. There's a lot of potential for interesting and varied places to visit there. Some main belt asteroids have their own small moons. There are also contact pairs, which would be interesting to go EVA on! It would also be interesting if players were able to detect larger versions of the ARM asteroids there. If those aren't considered hardcore enough. How about adding some Oort cloud iceteroids? These orbit a loooooong way from the Sun. If anything, they would serve to educate players about how big our solar system really is.

After making extensive use of my Kerbooster Light to launch a sizeable satellite constellation to Kerbin's moons, I was able to raise enough funds to buy the Tier 3 Launch Pad. This allows me to use the next largest size of launch vehicle from my Kerbooster family. I've built and flown larger versions, but I need to upgrade the R&D building to unlock the parts they use. The Kerbooster Medium is simply an up-scaled version of the Kerbooster Light. It can throw modest sized crewed spacecraft, as well as interplanetary probes. For my first test flight of 0.90, I'm going to use the Kerbooster to deploy my Kestrel lander. The Kestrel was born out of my earliest experiments with "stack shuttle" configurations. The idea was to make a vehicle that worked more like the original Space Shuttle concept, incorporating a re-useable booster and re-useable orbiter. I was also influenced by Buzz Aldrin's Starbooster concept, which he used in his novel Encounter With Tiber. The Kerbooster uses an all-solid first stage. It's not recoverable, but it's cheap. I looked at the value of the solids when empty of fuel and discovered that they are worth so little when empty, that their recovery value is dwarfed by the cost of the parachutes needed to land them safely. This is before the performance penalties of carrying the extra weight and drag of the parachutes are accounted for. The parachutes themselves would be recovered downrange at a percentage of their original value, all to recover a bunch of "trash bins empty of boom". The solids are thrust limited to 70%, which ensures that they burn long enough to lift the stack clear of the dense portion of the atmosphere. The solids are giving their best thrust to weight ratio when the stack is at a high enough altitude not to be hindered by terminal velocity. After first stage separation, the stack already has an apoapsis above 70km, so the fly-back stage is used to finish the job of accelerating to orbital velocity and circularising. The payload is deployed into an eccentric orbit, minimising the amount of fuel that must be expended by the payload spacecraft to reach it's destination. In this case, I'm throwing the Kestrel to the Mun, so I use the Kerbooster to perform the departure burn, taking care to leave the Kerbooster on a trajectory that returns it to Kerbin. I don't usually deplete the Kerbooster's fuel tanks this much, but I'm performing a test flight, so I want to see how far I can push the design. The Kestrel is delivered to the Mun with a near full fuel load. The Kerbooster has an adequate, although marginal, reserve of fuel for orbit change manoeuvres for the return trip. I perform an aerobraking pass, noting that I should actually have performed a course correction burn when I left the Mun, my orbit is slightly inclined, instead of equatorial as I intended. With marginal fuel remaining, I bring the Kerbooster in for re-entry. Through sheer trial and error, I've figured out how to perform reasonably accurate re-entries, which place me within gliding distance of the KSC. I'm conscious as I do this that the new aerodynamic and re-entry heating in 1.0 are going to have a big effect on my designs. Whether my shuttles are still flyable in 1.0 remains to be seen. Worst case, I'll come up with a new design. My approach brings me down from space within reasonable distance of the KSC. My re-entry turns out to be pretty accurate. I still need to turn around and line up with the runway.

Modern mission plans for sending humans to Mars try to avoid the use of space stations altogether. Early mission plans for missions to Mars, such as Werhner Von Braun's Die Marsproject and George Bush Senior's Space Exploration Initiative, required all of the propellants and consumables used on the mission to be lifted from Earth. This required on-orbit assembly of a massive interplanetary spaceship dubbed "Battlestar Galactica" by it's critics. The plan requires a massive Earth orbiting space dockyard. Some variations also factor in a huge Moon base as well, so that oxygen made from lunar material can be used as propellant for the giant spaceship. Due to limited consumables, the mission only allows a stay on Mars of a few weeks for the crew, who also lack significant provision for surface mobility. The SEI version had an estimated cost of 450 billion dollars. The alternative method, known as , is to launch spacecraft directly to Mars on heavy lift boosters comparable to the Saturn 5 (or modern equivalents). In-Situ Resource Utilisation (ISRU) is used to produce propellants and consumables on Mars. The crew are able to stay on the surface for one and a half Earth years. During which time they have access to long ranged surface vehicles, powered by liquid fuels produced on Mars. Total programme cost has been estimated at 30 to 50 billion dollars spread over a ten year programme.NASA have produced design reference missions based on variations of this plan. The upcoming ISRU feature should allow missions of this type to be flown in KSP.

He only needs to activate the BACC via the staging sequence. It doesn't matter whether the BACC has been used earlier in the flight or not. The staging sequence can be edited in flight to "activate" the already activated part. The contract isn't clearly explained, which misleads a lot of new players into thinking that they have to lift the part to the required situation in an unused state. My method lifts a burned out BACC to the required orbit and then "activates" it to complete the contract.

Don't worry! We're sending you BACC To The Future! This design burns all seven BACC boosters limited to 70% thrust as a first stage. I've tried to avoid using any parts you didn't show in your pic, so I haven't used any struts. BACC boosters burn out too quickly, so I thrust limit them for a longer burn time and add enough to ensure a decent thrust-to-weight-ratio at launch. I use sepratrons to (hopefully) achieve a clean staging event, delaying the ignition of my second stage until the first stage is clear. Six out of seven BACC boosters are dropped, with the last remaining booster carried to orbit as payload. At this point, I've now lifted an empty BACC booster into orbit, with fuel to spare to manoeuvre it into an orbit with the correct parameters to complete the contract, whatever they may be. The next step is to edit the staging sequence so that the BACC booster can be "activated" when the correct parameters are met. The fact that I've already burned out the BACC is irrelevant. By editing the staging sequence, I can "activate" it as many times as I like. You mentioned sepratrons, goo pods and the LV909. I'm not sure what you intend to do with those, but for demonstration purposes, I brought those up as well.

Standard RTGs used on most probes produce 300W and weigh 60kg. Programmes to develop small space nuclear reactors have existed in the past. (As have programmes to develop Nuclear Thermal Rockets). Robert Zubrin's Mars Direct plan shows a mass allocation of 3.5 tonnes for an 80kW nuclear reactor used to provide power for the ISRU chemical reactors used to produce consumables on Mars. By comparison, it also allocates one tonne for a 5kW solar array for each spacecraft used in the plan. In his book Entering Space, he suggests use of a smaller 30kW reactor to provide power and nuclear electric propulsion for an outer solar system probe. He doesn't specify the exact weight of the probe reactor, but he predicts it would allow payload to be doubled and data transmission to be increased one hundredfold, while also powering active sensors that could increase the amount of data that could be gathered by a similar amount. Increasing the science payoff of a mission by one hundred times is not to be sniffed at! NASA's Asteroid Redirect Mission advocates development of a solar electric drive to move the asteroid. This drive would then be used to push large cargoes to Mars. The relative benefits of ARM are currently being debated. This drive is obviously a lot bigger than the ion drive we currently have in KSP. If such a drive were to be developed IRL, and subsequently added to the game, players would have to provide large quantities of electrical power to operate it. Large arrays of cheap and heavy solar panels would suffice in Kerbol's inner solar system, but would be useless in the outer solar system. We don't yet know the precise details of the upcoming ISRU feature, but I'm expecting it to be used to justify the existence of bases and stations in the game. It would make sense if the hardware is heavy and requires a lot of power to operate. A small nuclear reactor might make an ideal power source for a base in the outer solar system. Outer solar system exploration involves covering enormous distances. If Squad wanted to be realistic, they could reduce the transmission rate of antennas in proportion to the distance from Kerbin, meaning that the transmitter would take longer to send the transmission and use more power. This would make it desirable to bring a high power transmitter for outer solar system mission. There could also be scope for adding energy hungry active sensors to the game.