#boiloffs

[jenakuns]

Starship HLS performance hole

Hey so, Artemis is pretty cool. SpaceX bid a modified variant of the Starship upper stage to act as the lander that is currently manifested to take US astronauts back to the Moon. I mean schedule wise it is completely screwed, but that was obviously from the day it was selected. The problem here isn't whether it happens in 2030 instead of 2026, rather how it happens at all.

Now with the protests that followed the sole sourcing of SpaceX, we got a bid launch count of 16 for Starship HLS; 1 depot, 1 lander and 14 tanker (to the depot). This is a large number that has continuingly generated arguments about it's largeness not aided by the napkin math of Musk. It does represent architecture complexity and in currently reasonable world would represent a not small expense (at $2B a year, with 50 launches of Starship, that would still have a cost share of $640M).

But this is just what they bid in 2020 December, how is it going in 2023? Not good. Because of the nature of the architecture; Starship has an extra 3km/s to travel as a single stage; which really tightens the belt on the supposedly large margins it should have as a 1300 ton stage. + Raptor is a large high thrust engine, good for launch vehicles fighting Earth gravity; bad for in space stages where throttling gimps your ISP and thus performance. So launch count hasn't gone down from 16 like people wanna say; it's actually floating even a little up. Now exact launch numbers I don't believe in, because there's a lot of TRL numbers that aren't 7-9.

Launch count isn't only thing; margins are just straight tight. No ZBO + high delta V gives low remaining %s after doing it. Architecturally you can do thing to plug the hole kinda, but fairly large increases launch count and complexity with multiple refillings of Starship in various orbits.

Also reusing a cryogenic stage without zero boiloff in NRHO and which the Gateway people will riot if you leave attached to their station is hard.

Solutions? Innately I just wanna make the lander a bit smaller. That reduces the launch count; although makes the performance hole bigger; meaning more scuffed positions in the architecture to fix reducing the decrease in launch count. To elaborate, performance hole would increase because dry mass ratio increases as the individual components begin taking up more. But if the lander was like 500 tons wet mass instead of 1200 tons that would be nice. Also a smaller engine that Raptor. Closed expanders may be too small at 100 kilonewtons; unlikable burn times without large engine counts. So maybe you do like a 200 kilonewton full flow staged engine?

But like, 8-9 launches and not nail biting margin architecture is nice.

Any custom built lander will also be expensive and increase cost estimates way beyond what 4 bil was bid on. Will SpaceX persevere? Well if Starlink is the money printer they want it to be; expending the resources to develop their lunar capabilities is reasonable. (and also the right thing to do!)

There this thing where like people who dislike SpaceX like their cancelled plans, or at least hypothetical versions of it. I don't think I'm falling into that category.

I really don't like the tumblr post editor. Give me the entire screen please.

[kristsune]

There certainly was an abundance of silliness that happened while the brothers were in the same room for Cooking Simulator, some of that silliness includes: Introducing Alan Dente, and Alan Fresco, heat and chopy-chop, clump, too bad chat, dootdidoot, betrayed, special mouth, for the alans, little iron friends, milk the mato, something something poll tax, coward, flip fopper, prime slime, move it child, yes I trust you!, think of the planet, each individual grain of spice cannot be rendered, las ana, HOOOOO settings, you sure? yes, you became worth it, missed it mate, griddle pan, ROTATE THE BOARD (screenshot included), hope it’s not recorded, Alan is here to make friends, but Alan is here to make enemies, little bit of boil off, Pepper Boiloff, where’s the garlic?, A Perfect Soup, mass spectromite, guest is pleased, lemon time!, balan, parsleeeeyyy, technique: lemon quarters, and to hear more cooking with the Alans look for Silliness part 2!

art by ereubusodora, screenshots by me

[tenaciouschildengineer]

In-Situ Resource Utilization Capabilities, Sustainability

“Advancing in Situ Resources Utilization Capabilities To Achieve a New Paradigm in Space Exploration”, defines In-Situ Resource Utilization “(ISRU) as involving any hardware or operation that harnesses and utilizes ‘in-situ’ resources to create products and services for robotic and human exploration. (page 1) “In Situ” refers to resources found at the site of the exploration which are not carried to the site by spacecraft. Some of the main advantages of  ISRU resources is reducing the cost of launches by optimizing propulsion, reducing launch/landing mass, to create new products, improve our infrastructure, and decrease crew health related mission risks. ISRU products do not require resupply missions, are more efficient, self sustainable, and extend the range for NASA’s missions to the Moon and Mars. Table 1 from the article illustrates the impact of ISRU in terms of propulsion, life support, habitat, mobility, and power.   

Why is this a big deal? Sustainability practices are the future for Earth, Mars, and the Moon. Using Regolith, we can improve our life on Earth by utilizing our resources in a variety of uses. Regolith can be used to make a radiation shield for the ROV, and allow the ROV to fix its own damages with the help of 3D printing mechanisms. 

ISRU can be used to improve existing propulsion systems. As the propulsion system relates to ISRU, ISRU can provide the ability to generate propellants using either sent materials or utilizing space resources. If we could 3D print propellants and generate pressure vessels, we can conceivably manufacture rocket propulsion devices on the Moon. The greatest challenge in 3D printing propellant is that it’s highly flammable. The use of other processes in the production of propellant would be much safer, because it is easier to avoid overheating propellant. 

The article, “System Architecture Design and Development for a Reusable Lunar Lander” exhibits the propulsion design in Gateway. In the design of Gateway, the propulsion system is reusable, using liquid propellant. A pressure-fed system and a pump-fed system uses nitrogen or helium to create movement using the pressure. It works by pushing “the propellant down to the combustion chamber, where it is ignited and exhausted. These types of systems are very reliable for small changes in velocity due to the simplicity of the design.” The design would have to be able to handle extreme amounts of pressure. Also the propellant design could greatly support in situ transportation operations, as mentioned in the Advanced ISRU article: ”Making propellants and establishing surface and potentially orbital propellant depots can also support and enable surface hoppers, reusable landers, and cis-lunar transportation systems,” thus reducing the amount of flight trips, and providing a tremendous reduction in life cycle costs. 

Life Support: Human Explorations and Operations Mission Directorate HEOMD focuses on the “Moxie” Mars Oxygen Isru Experiment, which can convert oxygen using Mars’ atmosphere. This would result in a reduction of the mass of the rocket, due to the decrease in oxygen tank requirements. Understanding how to create oxygen from Mars' atmosphere also makes us more independent in our conquest of Mars. The Resource Prospector mission (RP), uses a land rover, with ISRU capabilities. RP helps attain a further goal of spending more time on Mars/Moon to “perform a low cost mission to a near-permanently shadowed location at a lunar polar location to perform the first ‘ground-truth’ measurement of water and other volatile resources.”(page 7) The RP mission helps us better understand future explorations in the conquest of regolith. 

Habitat: Using regolith as a way to manufacture and construct elements to create radiation protection, also known as radiation shielding used in infrastructure. Using ISRU resources, radiation shielding can be created to help with maintenance and repair of other systems that need the protection. Advancing situ article points out the advantage of using this for habitat “ in case(s) of life support system or logistic delivery failure, radiation shielding not possible with Earth delivered options, feedstock production for in situ manufacturing of replacement parts, and propellant production to eliminate leakage or increased boiloff issues.”(page 3) This is a clear advancement in situ feedstock manufacturing (proving this may be difficult).

Mobility:  “Hoppers” are an important part of extending surface travel. The “Advancing in Situ” article states, “ these hoppers could be one-way, i.e. refueling the original delivery lander to hop to another location, or two-way where hoppers could be fueled to travel to a destination, perform science and take samples, and return to a centralize base location (Hub-and-Spoke surface architecture).” thus allowing more mobility, and providing a redundant base for resources and energy storage. In the event of a catastrophic failure, the operation can continue and it's not a complete loss in scientific exploration. 

Power: storage and regeneration using thermal cycling (energy) or radioisotope power systems is a better alternative to solar power. Operations cannot be dependent on solar energy. The difficulties of solar energy do not allow operations to be done in the shadow condition. In advance, relying on thermal or radioisotope power would avoid the troubles of worrying about dust storms blocking up solar arrays. Solar panels can be used for redundant power supply. Supplementing a solar array but a backup battery use would be more beneficial in more difficult climates. 

The “Ionic Liquid Facilitated Recovery of Metals and Oxygen from Regolith” article shows the importances of retaining regolith. Regolith is made up of useful material such as Oxygen, Silicon, Aluminum, Iron, Magnesium, and Calcium. Elements that are needed for ISRU utilization. The process of recycling these metals is done by using the process of  electroplating. 

For example, a metal-like substance called Nickel Chromium Alloy (can be found in iron meteorites), is used for heating elements’. This substance is temperature resistant, and can be used to create structures. Nickel Chromium Alloy can be recycled and can be electroplated, to form as a sheet and be used as a thermal protection against the sun, to avoid corrosion. Bulk electroplating is used to recycle the metal by using electrolysis. The disadvantage of this process is the energy needed to perform needs full heat capacity, meaning it can not perform as well in shadow regions. These metals are dependent on this process. Luckily, we can use Ionic liquids(organic salts) as a potential source to shape metals in room temperature. The challenges that come from collecting regolith as stated in the presentation is that “these materials are found in highly stable oxides.” To process regolith, it would require recovering the elements back into their original and pure elemental form, and  require “processing these oxides to recover high purity materials.”The disadvantages that come with this process can be highly abbassive to RP because they require lots of chemicals in use, heat, and a tremendous amount of energy to achieve final pure substances.

The article “Lunar Prospecting: Searching for Volatiles at the South Pole”,  demonstrates the challenges from the Resource Prospector (RP) mission. The RP mission includes “a rover for mobility, prospecting instruments to locate and characterize volatiles, a drill to collect regolith samples, and an in-situ resource utilization (ISRU) payload for analysis.” in the lunar polar location in order to deposit measurements of water and volatile sources. The RP main goal is to prospect, acquire or gather, then process the feasible materials found. The Impact of RP is the reduced risk of human exploration. Some of the mission strategic knowledge gaps include, lunar cold traps, detecting volatile species, inconsistent irregular patterns of water, and  “the mineralogical, elemental, molecular, isotopic makeup of the volatiles” as well as 

“ the lunar surface trafficability”(page 1). The RP poses an uncertainty in real time science. The article states “uncertainty introduced by the communications networks and the DSN make this infeasible” (page 4), making it harder to complete “real time” science.  Improving antenna signals, could do so much more with ISRU, as well as adding an antenna to the “hub of the hopper” using the shielding material of lunar regolith. 

 How does “real-time science” influence the path and the timing of the planned operation system of the lunar rover, Resource Prospector, to prospect, collect, and process in-situ resources on the Moon?

“Real time science” refers to the ability to make decisions in the moment, near time. Data has a relay. The data from a rover is communicated through orbiters which relay using X band radio waves,  then that information is passed on to the Deep Space Network (DSN) on Earth, which uses antennas to capture the messages. Raw data has to be then translated. The Lunar article shows how data in RP is relayed in space, “Previous testing has shown that a rover can be teleoperated manually with a short round trip delay of up to ten seconds, though even at that delay operators preferred waypoint driving. Delays in the tens of seconds make direct teleoperation driving unsafe, as the rover may crash before the operator sees the crater it is falling into.”, this makes it dangerous to drive using teleop mode, therefore the robot has to use both teleop and autonomous modes in order to travel safely. An advantage of RP, is that it has no sleep times or distance limitations. RP has to find feasible material, gather it, then process in situ. 

In prospecting, RP has to use pre planned navigation, using “ relatively fixed predetermined paths (rails) between the science stations, with adjustments made in near real-time for rover safety.”(page 4), because of this, rover data relays take longer to receive to the Deep Space Network. This is because distance signals take longer to travel in space, rover control takes fatal delays to react to the surrounding environment. In order to complete “real time science”, it requires tactical planning, pre programming in autonomous mode because of the time delay. Developing AI autonomous mode would reduce natural time delay. In autonomous mode, operators must preprogram to avoid collision. For decisions to be made at the moment, the rover must be able to stop when finding the material and wait for the operator to respond. As the voyages become more successful, the rover should be able to drive for itself.  Real time science is better than the alternatives because we waste less time and resources, explore more, and optimize the lifespan of our rovers, making voyages more flexible. As explained in the lunar article “the real-time scientist would have the option to call for a halt and further investigation if they see the rover is driving over a spot that is significantly higher in water concentration than previous areas.” (page 4) From there, the RP creates a known path, more success in RP’s travels will result in RP to meet a closer goal of driving with “real time.”

 Stated in Ionic Liquid Facilitated Recovery of Metals and Oxygen from Regolith, “An Ionic liquid-based process to recover metals and oxygen from regolith has been developed and demonstrated that could make resupply of chemical reagents negligible.” What is the closed-loop ionic liquid (IL) reprotonization process, and what are the benefits of this process to future space exploration?

In oxygen reduction, extreme heat is used to separate materials. In regolith, in order to keep oxygen from reacting, a constant amount of heat is necessary. The oxygen would have to be oxidized, while the metals would get reduced. The benefits of doing this process would be attaining these elements and reusing them on site. When exposed to oxygen, metals will oxidize in the state of metal oxide. The ionic liquid can be liquidized (except for sand) using oxidation reduction, allowing it to retain back to high pure metal by itself. Closed loop refers to recycling the purity of the substance, so that way you can constantly reuse the chemicals. 

Closed-loop ionic liquid (IL) reprotonization is useful for mining and refining tasks in space where either satellites or installations can use a compact system to harvest and refine precious materials. Reducing waste material to optimize space and weight within small satellites and installations, they make the process of  gathering valuable material like platinum, for either furthering the lifespan of an installation or bringing valuable materials back to Earth.

Regolith mentioned in the article, includes sources for solar energy, cement applications for infracture, and life support. Metals are critical for building trusses to support livable structures, resupplying deep space expeditions for maintenance/repair, and oxygen is incredibly useful for sustaining human life far from Earth. Common metal refining processes use heat or fire which is incredibly dangerous in closed ships and pose an expensive refining cost for ship crew. The benefits of this process to help future space exploration, by potentially supplying a limitless and autonomous method of preparing raw material for 3D printers in space. The initial investment of rover engineering durable parts and shipping supplies from Earth can be extremely expensive so having the capacity to manufacture parts outside of Earth can be incredibly lucrative. We can completely recycle the metal-like materials. An important step toward von neumann probes, is self replicating probes. Manufacturing spare parts out of metals found from regolith can extend life span rovers and missions. An alternative to using ISRU resources is sending elements that can be recycled and harder to find in space, elements like Nickel Chromium Alloy, which can be completely recycled. A one time send is required if it's reusable.  In order to make waste material viable again, we can build refinery facilities using RP and situ manufacturing to gather and build recycling systems respectively. Rovers are ideal for resource gathering being deployed in large numbers and with simple autonomous control, they can scour the expanse of space or aboard the same ship for resources. Then these rovers can deliver these materials to CNC machines either to 3D print, mill, assemble, and so forth. These raw materials can be reused back into viable material for use once again.  Waste material can be used to also generate fertilizer, refine vitamin supplements for bone mass supplement. Rovers are ideal in terraforming oxygen, making robots handle the preparation of ready in use oxygen on Mars or the Moon, a tremendous contribution for life support in space. This is also the basic principle behind von neuman probes or self replicating probes which are economical in reducing waste material. ISRU is a step forward toward sustainability goals, benefiting resource utilization here on Earth.

Sources:

  NCAS Subject Matter Lecture Susan Martinez, Additive Manufacturing Engineer NASA's Marshall Space Flight Center Huntsville, AL (2020).

Advancing in situ resource utilization capabilities to achieve a new paradigm in space exploration.Sanders (2018).

 Lunar Prospecting: Searching for Volatiles at the South Pole Trimble & Carvalho (2016).

 Ionic liquid facilitated recovery of metals and oxygen from regolith. Karr, Curreri, Thornton, Depew, Vankeuren, Regelman, Fox, Marone, Donovan & Paley (2018).

System Architecture Design and Development for a Reusable Lunar Lander.Batten, Bergin, Crigger, & McGlothin (2019).

[isaackuo]

Space Carrier VARUHARA WIP notes

Here's a WIP for a retro C64 video game intro. It's a hard Science Fiction setting, with unabashed retro tropes.

SPACE CARRIER VARUHARA INTRO SEQUENCE

VALHALLA EXTERIOR

Sasaki, flying a small scout Dauber, approaches the Valhalla. Valhalla is slowly spinning for artificial gravity.

Valhalla fires ball ammo from a railgun turret at the Dauber.

The Dauber absorbs the bullets into a large foam shield. This slows down the Dauber for final approach.

The Dauber enters the stern trap.

In the cockpit, Sasaki is exhausted and yawning.

VALHALLA HANGAR

Gori-Lieutenant: Late again, and running on gas! Do you want another demotion?

Sasaki-Lieutenant: Yawn ... Come on, Gori-Lieutenant, no one cares that much. I demoted myself.

Gori: What?

Sasaki: Budget cuts - when did we last _fuel_ the Vallhunds for CAP?

Gori: well, the boiloff...

Sasaki: ch! I can _fly_ in a Dauber ... yawn ... zzz

Gori: So serious. There's nothing out there.

Sasaki: ... my brother is ... zzz

Gori shakes his head, and lets Sasaki nap in the cockpit while he begins mounting boosters.

DEEP SPACE, VALHALLA IN DISTANCE

In the background of stars, a weird gash rips apart. A fleet of alien starships spill from the rip.

VALHALLA BRIDGE

Radar officer: C-Captain! Something is there! Umm ... 190km away?!? Octant 5.

Chiba-Captain: 190km??? How? Stealth? Or ...

Radar officer: Battleships! ... maybe ... Missiles!

Chiba: Battlestations! Condition red! Helm! De-spin, and aim cats for missile intercept!

Helm officer: Yessir!

Chiba: Weapons! N-Beams, target missiles!

Weapons officers: Yessir!

Chiba: Handler! Scramble all Vallhunds! 5 percent fuel!

Aircraft handler: Yessir!

Radar officer: Captain! The budget ...

Chiba: Time! It's _time_ we lack. Missile ETA is 80 seconds. Do you know how long it takes to fully fuel a Vallhund?

Radar officer: I don't know.

Chiba: Our alpha strike drill record is ten minutes.

VALHALLA HANGAR

Pilots and deck officers are scrambling, hurrying into cockpits and fueling the fighters.

Sasaki is still asleep, but Gori is hooking bridle lines to her Dauber. The Dauber already has two quad racks of boosters loaded.

Gori: Oy! Open bridle brakes!

Gori bangs on the Dauber's cockpit.

Gori: Wake up, Sasaki! It's a scramble!

Gori pushes to float back. The airlock door slides shut. The airlock is enormous compared to the Dauber, reflecting its small size compared to the Vallhunds.

VALHALLA BRIDGE

Chiba, looking at screen: What type of ships are they?

Radar officer: Type ... unknown. Radar emissions ... absent. No emissions at all ... wait. UV? UV or something.

Chiba: UV lidar, perhaps?

Radar officer: Maybe ... I don't get it.

Chiba: Damage report!

Damage control officer: Damage reports absent!

Chiba: What? The enemy has no n-beams? No beams at all, maybe? Missiles only?

Chiba: Missile status?

Radar officer: No change. Impossible to assess n-beam effects.

Chiba: Helm! Upward thrust, 30 mps.

Helm officer: Yessir!

Radar officer: Missile maneuvers! Upward ... 30 mps.

Chiba: So ... guidance unaffected by n-beams? No way. But what about the warheads?

Chiba: Weapons! N-beams target enemy battleships!

Weapons officer: ... Where?

Chiba: Identify any promising points at will. Use your own judgment.

Weapons officer: Acknowledged!

VALHALLA CATAPULT TUNNEL

Airlock chamber in the floor rotates to reveal the Dauber. Sasaki is still asleep, with her helmet lolling.

The bridle lines pull the Dauber up into the center of the tunnel, positioned for launch.

In the left side of the tunnel, a large digital count-down display shows 10, 9, -- on 8, the Dauber is accelerated down the tunnel at incredible speed.

In the cockpit Sasaki's helmet slams rearward, instantly waking her; the cockpit is vibrating like crazy.

VALHALLA EXTERIOR

The Dauber silently exits the starboard cat tunnel; the disposed bridle lines glint briefly with reflected sunlight at the same moment that a naval bridle would have splashed into the ocean.

VALHALLA BRIDGE

Handler: Dauber away!

Chiba: So soon!

Chiba holds mic to face.

Chiba: Hailing Dauber. Chiba-Captain.

Sasaki: Dauber here. Sasaki-Lieutenant.

Chiba: 14 missiles at 120km, Sasaki-Lieutenant. You see them?

Sasaki: Yes, I see them on radar ... and visual.

Chiba: Missile guidance seems unaffected by N-beams. We are firing on them with N-beams. Intercept and observe.

Sasaki: Acknowledged!

Chiba: Weapons! N-beams, target missiles!

Weapons officer: Yessir!

VALHALLA HANGAR

Vallhunds are still being fueled and supplied. Two Vallhunds, still attached to fuel lines, are being moved to the airlocks at opposite sides of the hangar. Those two visibly have no weapons mounted on their rocket rails.

DEEP SPACE, VALHALLA IN DISTANCE

The Dauber thrusts back toward the Valhalla with booster packs, first discarding a pair of boosters from the left rack, and then discarding a pair of boosters from the right rack. As the second pair is discarded, the missiles catch up to the Dauber.

Sasaki: Hailing Valhalla. Sasaki-Lieutenant.

Chiba: Valhalla here. Chiba-Captain.

Sasaki: You're firing N-beams at the missiles?

Chiba: Yes.

Sasaki: Neutron signature ... absent. No, minimal. Consistent with N-beam scatter.

Chiba: No way! They're not nuclear weapons? Observe closer.

Sasaki: Acknowledged ... I'm approaching a missile ...

Sasaki: What kind of missile is this? Unknown type. No obvious sensors or thrusters. No emissions. Permission to engage?

Chiba: Engage.

Sasaki: Acknowledged.

Sasaki opens fire with recoilless machine cannon. The missile instantly jinks hard upon impact.

Sasaki: So fast!

Sasaki continues firing upon the jinking missile, but it's very hard to hit

Sasaki: It's dodging! So hard to hit! No ... not dodging. _Reacting_...

Sasaki takes a break from firing. After a couple seconds, the missile thrusts back on course.

Sasaki studies the sensor readings.

Sasaki: What! No way ... 500 KeV gamma signature? Positrons?

Chiba: Positrons? Anti-matter warhead? What is this enemy!

Sasaki: Bullets! Ball ammo! It can work!

Sasaki resumes firing upon missile; it reacts with chaotic thrusts opposite the impact points

Chiba: Weapons! Railguns, target missiles! Ball ammo!

Weapons officer: Yessir!

Chiba: Sasaki-Lieutenant, disengage! We're firing upon the missiles with ball ammo.

Sasaki: Don't mind me! They're too hard to hit from a distance.

Chiba: Understood.

VALHALLA EXTERIOR

Railgun turrets fire streaks of glowing hot ball ammo toward the missiles

DAUBER EXTERIOR

Glowing ball ammo streaks from the Valhalla rain all around.

Sasaki fires upon and chases a missile, finally shattering it to pieces at very short range with a good string of hits.

Sasaki looks up at the Valhalla, having grown larger in view.

Sasaki: Damnit!

Sasaki stops firing and pilots the Dauber to physically grab a missile.

Sasaki: No reaction?

Sasaki thrusts toward another missile and physically throws the missile she's holding at the other missile. Both missiles explode spectacularly on impact.

Sasaki: Got it!

Sasaki flies toward another missile. This time, her Dauber's shield - luckily placed between her and the enemy fleet - glows hot.

Sasaki: Eh? UV? UV laser?

As Sasaki approaches the missile, a spot on the missile glows from laser fire before an explosive reaction thrusting away.

Sasaki: No way! Guidance was unaffected because guidance is absent! The missiles are dumb rocks!

Sasaki chases the missile to try and grab it, but it is dodging too well. The Valhalla is getting larger in the background.

VALHALLA CATAPULT TUNNEL

The airlock chamber rotates to reveal a lightly armed Vallhund. Its large size fills out the chamber.

The bridle lines lift the Vallhund into the tunnel.

VALHALLA BRIDGE

Chiba: Handler! Status?

Handler: We won't make it, damnit!

Chiba pauses in thought.

Chiba (into mic): Sasaki-Lieutenant, disengage. Avoid the blast radius.

Sasaki: No, I can still ...

Chiba: This is my final order, Sasaki-Captain.

Sasaki is shocked.

Sasaki: A-acknowledged.

VALHALLA CATAPULT TUNNEL

Vallhund accelerates down the tunnel.

Before it reaches the end, massive explosions erupt into the tunnel.

DAUBER EXTERIOR

The Valhalla zooms past the Dauber, VARUHARA visible on the hull momentarily as it shrinks into the distance. It is crumbled by massive explosions, albeit smaller than nuclear explosions.

The Dauber turns to face the empty place where the Valhalla was. The imposing enemy fleet becomes visibly apparent.

- - - - - 8< - - - - -

BACKGROUND TECHNOLOGY NOTES

The heavy carrier Valhalla is a solar powered spacecraft with hydrolox fuel and four main engines. It normally operates with spin gravity. In spin mode, only one engine is required for full maneuvering capability - it works like a spinning helicopter rotor with cyclic and collective throttling for maneuvering. When de-spun, it is desirable to have either the upper pair or the lower pair of engines functional.

Valhalla's main armament is six neutron beam turrets. Ion pulses drive neutrons via magnetized plasma wakefield acceleration. These neutron beams can fry guidance electronics and disrupt nuclear warheads, making them potent missile defenses. However, it is difficult to assess how much damage has been done to the target.

In the previous interplanetary war, the proliferation of N-beam defenses outmoded long range missiles. Large fighters armed with short range rockets proved more effective. Their large fuel tanks provided adequate neutron shielding to get past defenses. To improve range and endurance, carriers began incorporating catapults to launch fighters and railguns to brake returning fighters. Valhalla exemplifies late war carrier design.

Valhalla's space wing is dominated by Vallhund fighters - a post-war design. They use the same hydrolox fuel as Valhalla itself, maximizing range and delta-v thanks to high specific impulse. However, Vallhunds were designed for high intensity conflict, lacking insulation to mitigate hydrogen boiloff. Valhalla is currently operating far from supply lines, so the Vallhunds are rarely fueled up for operations. Still, this is not considered a serious problem, because any enemy will be detected from far away.

Another fighter type is the small Dauber scout. It's a pre-war design, dominated by its tail radar. It uses magnesium-aluminum/lox hybrid rocket boosters to maximize endurance, because they don't suffer from boiloff. For extended delta-v, multiple disposable booster packs are used. The Dauber's flexible limbed design has given it the ability to keep up with the times, despite a lack of N-beam protection.

Valhalla's catapults use a bridle line system. The bridle lines suspend the fighter in the tunnel. The shuttles are accelerated by linear motor electromagnets paired in series, guaranteeing that their movement down the tunnel is synchronized. This bridle system is more suitable than a less retro nose gear system, because the desired speed exceed speeds suitable for wheeled landing gear.

- - - - - 8< - - - - -

ADDITIONAL TACTICS NOTES

Captain Chiba's most obvious tactical error was fruitlessly trying to launch Vallhund fighters rather than the small complement of Dauber scouts. However, he's a veteran of an interplanetary war in which "There's No Stealth in Space". The possibility of an encounter without hours of advance notice was inconceivable. Under such unthinkable time constraints, it's natural to stick to practices that one has trained for. Even if Captain Chiba tried to push his crew into novel tactics, it would be unlikely to work as well as doing what they've trained for.

As it was, there was never a possibility of launching all of the Dauber scouts very quickly. They're considered auxiliary support for the strike fighters, so only one was ever launched at a time. As such, only one deck hand was comfortable with prepping a Dauber unsupervised.

Captain Chiba references "alpha strike" drill times, even though an alpha strike consists of fully loading and launching all Vallhund fighters. Why not reference a fast interceptor scramble drill? Simply put, they never drilled for such a thing. Late war carrier tactics revolved around opposing alpha strikes directly pummeling their way through each other. Holding back any of the space wing in reserve would only be a recipe for losing the battle. Concentrating a full alpha strike was the way to both maximize chances of victory and minimize fighter losses.

Conversely, the alien tactics seem puzzling. They only launch about a dozen missiles, and no fighters. Partly, this is because they are testing the capabilities of an unfamiliar enemy with unfamiliar technology. Also, it is because of an internal bet. The mysterious advisor to this invasion mission, Quartz Brooder, has bet the task force's commander that a mere 14 missiles would be sufficient to win the battle. The commander is incredulous, but intrigued enough to see how it goes. She knows full well that her fleet has overwhelming numerical superiority regardless.

Basically, Valhalla was doomed because the enemy had a greatly superior force and greatly superior information. If we include the knowledge of Quartz Brooder, the enemy had a very good idea of the weaknesses of the enemy and how to exploit them. In contrast, the human force had no idea such an enemy was even possible.

[spaceexp]

Microgravity Zero Boiloff Tank experiments provide data for Pressure Control Systems

Cleveland OH (SPX) May 31, 2019 Long-duration cryogenic storage of propellant and life support liquids is an enabling technology within the critical path of nearly all envisioned human planetary missions [1]. The pressurization and pressure control of such propellant tanks will be governed by complicated dynamic interactions amongst forced mixing, the various gravity-dependent transport mechanisms in the vapor and liquid phase Full article

[sciencespies]

Dynetics to use in-space refueling for NASA lunar lander

https://sciencespies.com/space/dynetics-to-use-in-space-refueling-for-nasa-lunar-lander/

Dynetics to use in-space refueling for NASA lunar lander

WASHINGTON — The lunar lander under development by Dynetics for NASA’s Artemis program will make use of in-space refueling of cryogenic propellants and require three launches in quick succession, company officials revealed.

In a Sept. 15 webinar held by Dynetics in cooperation with the American Institute for Aeronautics and Astronautics, the company discussed the overall architecture for the lander it is developing as part of NASA’s Human Landing System (HLS) program. Dynetics is one of three companies that received HLS contracts from NASA in April for initial design studies of a lander that can transport astronauts to and from the lunar surface.

The Dynetics lander relies on in-space refueling to be able to carry out its mission. “Our lander is unique in that we need lunar fueling to accomplish our mission,” said Kathy Laurini, the HLS payload and commercialization lead at Dynetics, during the webinar. “In the next couple years, we will take in-space cryogenic propellant refueling technologies from the lab to TRL 10 and operational.” TRL, or technology readiness level, is a measure the maturity of a technology, and is usually measured on a scale of one to nine.

That refueling will initially be done by additional launches carrying propellant that is transferred to the lander. The lander will be launched on a United Launch Alliance Vulcan Centaur rocket. For the initial 2024 landing mission, Laurini said that launch will be followed by two additional Vulcan launches. Propellant from those rockets’ Centaur upper stages will be transferred to the lander.

One challenge with this approach is with “boiloff,” or loss of cryogenic propellants as they warm up. To address this, Dynetics plans to carry out the Vulcan Centaur launches on “14 to 20 day centers,” or roughly two to three weeks apart, said Kim Doering, vice president of space systems at Dynetics. “We worked closely with NASA on our concept of operations, and the Orion plans, to ensure that our operational scenario is viable and feasible.”

That would be a much faster launch rate than what ULA’s existing vehicles, the Atlas 5 and Delta 4, have traditionally supported. “We’re all set up and preparing the launch system to support that cadence out of the Cape, and on track to do that,” said Mark Peller, ULA vice president, during the webinar.

That in-space refueling technology will be tested in space prior to a crewed flight of the lander. “We have put together a plan that will demonstrate all of the critical functions of the lander. We will demonstrate in-orbit refueling of the lander,” Doering said. “We’ll check everything out before we put a crew on that lander.”

In the long term, propellant for the Dynetics lander could come from other sources. Laurini said the lander could be a customer for future commercial propellant depots around the moon, or use propellant created from extracting water ice on the lunar surface. “Having the ability to fill our liquid oxygen tanks on the lunar surface could enable new mission classes,” she said, “like hopping around to other parts of the moon to accomplish some key science objectives.”

Dynetics also used the webinar to show a full-scale model of the lander it recently completed. The low-fidelity lander is primarily intended to allow astronauts and engineers to test the layout of the lander’s cabin, including placement of key systems, to determine the best locations for that equipment.

“In this mockup we have volumetric representations of a lot of our different systems,” said Lee Archambault, a former NASA astronaut who now works for Sierra Nevada Corporation, one of Dynetics’s partners on the HLS program. “These volumetric representations can be moved around as we decide on the final placement for these systems in our architecture.”

In addition to the mockup, Dynetics said it has completed both a systems requirements review and a certification baseline review for the lander. Those were among the early milestones in its $253 million HLS contract from NASA.

Blue Origin separately announced Sept. 14 it completed similar reviews of the lunar lander it is developing under a $579 million HLS award, agreeing with NASA on dozens of design and construction standards. Blue Origin is leading a so-called “National Team” that includes Draper, Lockheed Martin and Northrop Grumman. It recently delivered a full-sized mockup of its lander to NASA’s Johnson Space Center for testing like that planned for the Dynetics model.

The third company to win an HLS award, SpaceX, has provided few updates about the progress it is making on its $135 million contract to design a version of its Starship reusable launch vehicle for lunar missions. The company did not respond to questions about the status of reviews and the development of mockups or other hardware associated with the program.

#Space

[homebrewtalk]

Do You Really Ruin Gelatin If You Boil It? Experiment Time.

I have been brewing for some 5 years, 2 of those also as a head-brewer at a local brewery. I don’t have any official education supporting my brewing skills, I gained all of them myself, reading forums, books and articles like this, but most importantly, by experimenting. The information you get from other homebrewers can be useful, but as you probably know, you must take it with a pinch of salt. So many times you read posts from people who are claiming something, but then, after some time, you find out they were completely wrong. Sometimes the wrong information just robs you of your time, sometimes it ruins a brew or two, or slows down your progress. Some of these rumors are so widely spread that the counter-information stands no chance. One of the very common rumors is that you mustn’t boil your gelatin solution (that many of us use as a clearing agent), because you DENATURE the proteins present and it no longer does its job. However, as everybody knows, it is a good idea to sanitize everything that touches the beer in its cold stage, so being able to boil the gelatin would really be convenient. This is the reason for me publishing this article, to bring (what seems to be) true to the masses. Just a little disclaimer, I try not to be a hypocrite, so I admit right now that all you read in this article are just my theorems and information I got from the internet, often simplified, as well as an experiment. There are, however, is some really nice evidence that supports some of them.

What is Gelatin?

It is a protein substance derived from collagen. Collagen is the main structural protein in bodies of animals. It is insoluble in water, but at certain conditions, it can be broken down by water molecules, an irreversible process called hydrolysis. And this is how gelatin is made. Gelatin is to collagen is what dextrins are to starch. The collagen is usually sourced from animal skin, bones, and hoof as these are the most collagen-rich parts. It has to be extracted first to get rid of fat, minerals and other substances, but the actual breakdown into gelatin is then done partial DENATURATION by BOILING it in water. It is then even sterilised by heating to 140°C (375°F) and dried to the solid form.

How and Why Gelatin Works?

First, let’s talk terminal velocity of spherical objects in fluid (yes, it’s physics and yes, it’s beautiful). Now this will be very inaccurate due to million kinds of little simplifications here, but still sufficient to give you a point. Imagine two spherical objects (both the same material) of different sizes. In vacuum, they are going to fall at the exact same speed (accelerating, actually, but at the same rate). In fluids, things get much more complicated, as the drag comes into play. The bigger ball obviously has more drag, but it is also heavier, in fact, so much heavier that it counterbalances the drag difference and the bigger ball is falling faster than the small one. At some point (rather quickly) both balls reach their terminal velocity and they no longer accelerate, they fall at constant speed. This terminal velocity is given by this formula:

v=29ρp-ρfμgR2

In the equation, everything except R (which is the ball radius) is constant.

See the power of it? Ball 10 times the diameter is going to fall 100 times faster.

Now the balls are the tiny little particles that make your brew cloudy. Yeast is one kind of these particles and while it is by no means the tiniest, it is still so small that it’s terminal velocity only allows it to fall very slowly. It has, however, one very useful feature, the feature called flocculation. Some strains (Fuller’s for example) flocculate so well, that you can see chunks as big as 10mm in your starter. And as the formula higher up says, the bigger the particle, the higher the settling speed. This is why Belgian powdery strains take ages to settle. A bigger problem, however, comes with particles smaller than yeast (they are usually proteins). They are (and thus their settling velocity is) so incredibly small, that they seem not to settle at all. They don’t even flocculate. What’s more, some particles are even smaller, so small, actually, that they are affected by some really minor molecular forces to such an extent, that they really do not settle. These are called true colloids.

This is why you want to add gelatin. Gelatin has a strong positive charge in acidic solutions, which results in electrostatic attraction between gelatin macromolecule and our tiny little haze particles and voilà, the particles suddenly flocculate.

The Experiment

The experiment was rather straight-forward. I bought three bottles of the same cloudy wheat beer (Hoegaarden). I let them cool in my kegerator for 12 hours to a serving temperature of 4°C. I prepared two solutions of gelatin. I decided to try the two extremes, so I diluted the first portion of gelatin (0,5g) in 40ml of roughly 30°C (86°F) water (a full hour of stirring) and I boiled the second portion (0,5g) in 45ml of water (to make up for the boiloff) for one minute.

I then opened two of the bottles and injected 5ml of one of the solutions to each of them and capped them. I gave all three bottles a good shake, so they have the same starting point.

I put the bottles back to the fridge and decided to wait 48 hours for the magic to happen. After 24 hours I checked the progress. Both bottles with gelatin were visibly less cloudy than the untouched one, but not clear yet.

After the 48 hours, I took the bottles out for sampling.

As you can see, the myth is busted. I tasted them, and I can tell the clear ones were definitely crisper and also seemed to have slightly lighter body and slightly more banana taste to them. The taste difference was similar to hefeweizen vs kristalweizen and I preferred the hazy one. It suited the witbier style better. I should also say that while the beer in the bottle was clear, the sediment was easy to agitate. This applied to both samples.

Conclusion

Boil your gelatin. It is safer, much quicker and makes little-to-no difference. And also, don’t believe everything people say and don’t spread it if you don’t have at least some clues that it is actually true.

by Robert Solarik My name is Robert (but I like to call myself Robko). I was born, and I also live in Slovakia, a small country south of Poland. Ever since I was born, I have been curious how things work, which led to basically all my toys being disassembled at some point of their short lifespan. During high school times, however, I discovered the charm of homebrewing and after graduating, I was not really decided what university to proceed to. I don’t like doing things if I am not sure they make sense, so I got a job as a head-brewer in a small brewery, because that was my biggest passion at the time. After two successful years I finally decided for studies of mechatronics at a technical university in my hometown, and I am enjoying every bit of it. I am still brewing actively at home. It has been five years since I started.

Want to Read Part 2? Check Out This Article »

I decided to do an experiment to bring more light into another commonly discussed, gelatin related topic: “Do you have to cold crash before gelatin fining?” While with the last topic, opinions were quite polarized, some people saying boiling gelatin is a disaster, others being on my side, with this one, most people agree cold crashing is recommended. Let’s look how much of a difference it really makes! What Exactly is a Chill Haze? Every homebrewer knows that sometimes, after putting a warm bottle of apparently clear beer into a refrigerator, the beer becomes hazy as it cools. Generally, some proteins are insoluble in beer, while others are soluble up to a certain concentration if certain…

Do You Really Ruin Gelatin If You Boil It? Experiment Time. was originally published on HomeBrewTalk.com

[livefreeshop]

Abstract: Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASAs future space exploration due to their high specific impulse for rocket motors of upper stages suitable for transporting 10s to 100s of metric tons of payload mass to destinations outside of low earth orbit and for their return. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several months. These losses can be eliminate... from New NASA STI Report Series http://go.nasa.gov/2lOXL2D