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Subject: Of Solar Sails And Glory rss

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Raoul Duke
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What do you do with a solar sail?
What do you do with a solar sail?
What do you do with a solar sail?
Early in the morning!

This is what I’ve been considering in the past week, in response to questions asked at a game I was playing last Saturday.

Solar sails (defined here as the Photon Kite and Photon Heliogyro thrusters) can be tricky to use, but are potentially quite powerful. Here are some advantages and disadvantages:

Advantages:
Mass 0 means they cost nothing to boost and don't add to the dry mass of a rocket stack.
Fuel Consumption 0 means you don't need to carry lots of fuel.
Immune to radiation hazards and solar flares.
No supports required.

Disadvantages:
Base Thrust 0 means that they're only good for very lightweight missions (Wet Mass <4⅔), where the wet mass modifier is positive.
Solar Power means that they're virtually useless past the orbit of Mars.
Solar sails are immediately decommissioned upon attempting an aerobrake maneuver.


How do you maximize the advantages and minimize the disadvantages? There are several elements to consider. The first is that solar sails are most effective when used to achieve Glories instead of prospecting or industrialization. This is because Glories can often be achieved with just a crew card (Mass 1, no supports) instead of requiring a Robonaut, Refinery, and their respective supports.

There are six Glory cards, each worth 3 VP:

Messenger of the Gods: First to land humans on Mercury and return safely to Earth's surface.
God of War: First to land humans on Mars and return safely to Earth's surface.
King of the Gods: First to land humans in the Jupiter zone or beyond and return safely to Earth's surface.
Father Sky: First to land humans on a site in the Uranus zone or beyond [note that you need not return them to Earth!]
Doomsayer of the Gods: First to land humans on a science site and return safely to Earth's surface.
Heroism: Horrifying bad luck, usually resulting in human deaths [my words, not the card's].

The second element is that at the beginning of your rocket's movement, if there is more than one thruster present, you can choose which one to use. This means that you can choose on a turn by turn basis which thruster will give you the most benefit.

The third element to consider is the Slingshot bonus provided by various planets, most importantly Mercury (+1), Venus (+2), and Jupiter (+4). These bonuses can dramatically extend the range of a solar sail mission, allowing operations into the Ceres and Jupiter zones that would be otherwise impossible.

Once you decide to attempt to achieve Glories, the main challenge is target selection. Ideally, you want to be able to get multiple Glories with one mission.

Father Sky is out of the question, as you can't get that far out with a solar sail, even with a Jupiter slingshot.

God of War isn't a good choice because there are no science sites on Mars, and it'll be hard to take off again (impossible if you're playing as the Shimizu or UN with lower powered crew thrusters).

Mercury's low hydration makes it impossible to ISRU refuel there with a crew card alone. This complicates an attempt to achieve Messenger of the Gods and Doomsayer of the Gods in one go by landing at Mercury: Discovery Rupes. For a treatment of this mission plan, see TokMor's post below.

This leaves King of the Gods and Doomsayer of the Gods.

Fortunately, there are several sites which potentially could satisfy both King of the Gods and Doomsayer of the Gods simulaneously:

Elatus (2D, 4 Hydration)
Chiron (4C, 4 Hydration)
Comet Neujmin I (1D, 4 Hydration, Blue Synodic)
Io: Gish Bar Mons (9M, 1 Hydration)
Io: Loki Patera (9S, 0 Hydration)
Europa: Subsurface Ocean (8C, 4 Hydration)
Comet Schwassmann- Wachmann I (2D, 4 Hydration)

As always in High Frontier, not all options are created equal. Elatus, Chiron, Io, and Europa are all impossible to reach with a solar sail alone. This leaves Comets Neujmin I and Schwassmann- Wachmann I. Schwassmann- Wachmann I is very slightly closer, and is non-synodic, which makes it the optimal choice, though if time is not a consideration, Comet Neujmin I would also work.


Here's what a mission to Comet Schwassmann- Wachmann I might look like, using only a crew and either the Photon Kite or Photon Heliogyro:

Mission Turn 1: Boost Operation to put the Crew and Solar Sail into LEO. Using your solar sail, move down the orange path [Net thrust = 2 (0 Base, +2 Wet Mass, +0 Solar)], stopping at the intersection immediately following the Sol- Mercury L4 .

Mission Turn 2: Using your solar sail, [Net Thrust = 4 (0 Base, +2 Wet Mass, +2 Solar)] move to Mercury Flyby (+1 Free Burn), Venus Flyby (+2 Free Burns in in Blue portion of solar cycle, though this is not necessary to complete the mission), Earth-Sol L2, Earth-Luna L5, follow the green path to Jupiter (+4 Free Burns!), turn left from the green path, going between Ganymede and Callisto, right at the first intersection, right again at first circle, then land on Comet Schwassmann- Wachmann I. Site Refuel Operation [1 Tank (4 Hydration -4 ISRU +1)].

Mission Turn 3: Site Refuel Operation [1 Tank (4 Hydration -4 ISRU +1)]. This is necessary to get enough fuel on board for one burn with your crew thruster. Using your crew thruster [Net thrust ≥ 7 (6, 8, or 10 Base depending on specific crew, +1 Wet Mass)], move to circle, then left, stopping at intersection between Ganymede and Callisto.

Mission Turn 4: Again using your crew thruster, [Net thrust ≥8 (6, 8, or 10 Base depending on specific crew, +2 Wet Mass)] move towards Jupiter (+4 Free Burns!), than follow the green route back to Earth, stopping at radiation hazard between HEO and GEO. Take any Operation.

Mission Turn 5: Switching back to your Solar Sail, [Net Thrust = 2 (0 Base, +2 Wet Mass, +0 Solar), move back to LEO. Decommission crew in LEO to claim King of the Gods, Doomsayer of the Gods and 6VP. Take any Operation.


The huge advantage to this plan is speed. Potentially, this can start on Game Turn 2, assuming that you've researched either the Photon Kite or Photon Heliogyro on Game Turn 1. In fact, it can be made even faster. If you find yourself in a race to complete this mission, and the free market value is 4 or higher, decommission your solar sail on Turn 4, take a Free Market Operation, and use the money to pay for Failure Is Not An Option on the aerobrake route between the radiation hazard between HEO and GEO and LEO.

There are two downsides to this mission plan though. Despite the fact that this mission only requires ~3 WT (~2 to buy the sail, 1 to boost) to get off the ground, there is a significant opportunity cost associated with the high number of operations necessary to carry out the mission. The first three turns each require an operation, which imparts an additional opportunity cost of 6 WT compared to taking three income operations. This means that the mission has a combined cost of ~9 WT.

Secondly, this mission is not guaranteed to succeed. Two risks in particular stand out.

1) You have to run through the hazard near Comet Schwassmann- Wachmann I twice, once outbound, once on the return. Even if you choose not to pay for Failure Is Not An Option, you have a 69.4% chance of completing the mission successfully. Given the minimal investment, this is one of the few times where I recommend throwing the Hate Cubes dice, at least on the outbound leg.

2) If you are playing as the UN, the radiation hazard between the Mercury flyby and the Sol-Mercury L4 could potentially be a problem. Your crew only has Rad-Hard 3, which means that rolling a 6 for this radiation hazard will prematurely end your mission. Overall mission success rate for the UN (assuming no Failure Is Not An Option) is 57.8%.
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Patrick Schifano

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Good guide, but I must mention that during the game you missed Friday night we saw two different players use Solar Sailing to get refineries out to prospected sites in a Basic game. The first site was Hertha via that little elbow intersection that utilizes both Venus-Sol Lagrange points. The other was one of the Greek camp Jovian Trojans. It started with a Wet Mass bonus of +1. Then it utilized the +2 Solar bonus, the Mercury, Venus, and Mars flyby to setup a Jupiter flyby which put it in place to rendezvous with a crew near the final site. Puzzlemaster won(Hertha player) and I came in second(Jovian Trojan player).
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Raoul Duke
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sir_schwick wrote:
Two different players use[d] Solar Sailing to get refineries out to prospected sites in a Basic game.


I can see the appeal of that approach. In my opinion, sails are not nearly as powerful in the basic game because nothing requires a support, and everything has a generally higher Mass. The key supposition here though is that you can have a thruster of some sort already at your destination to use as a landing vehicle.

sir_schwick wrote:
Hertha via that little elbow intersection that utilizes both Venus-Sol Lagrange points.


Can you be more specific about which L points are involved? Sol-Venus L1, L2, L3, and L5 are all on the board.

sir_schwick wrote:
The other was one of the Greek camp Jovian Trojans. It started with a Wet Mass bonus of +1. Then it utilized the +2 Solar bonus, the Mercury, Venus, and Mars flyby to setup a Jupiter flyby which put it in place to rendezvous with a crew near the final site.


That's one way to do it. I've found that when heading for Jupiter from the Mercury / Venus flyby route, I prefer to use the Sol-Earth L2 and Earth-Luna L5 points to transition to the green path. By my count, it's a burn cheaper than the blue Mars flyby path.
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Dom Rougier
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Good stuff. An addition:

Uncle Duke wrote:
The downside is that it’s a little risky.


One of the advantages of sails are that they are so cheap, that you can usually afford to take more risks than you can with a larger rocket.

Boosting a Project Orion-powered stack into orbit costs a lot more than a sail+ component, but the risks of failure can be the same. That means that the Orion stack will by necessity spend time and energy to avoid risk, since you want to get as much use out of that vehicle as possible, ideally only boosting it once, and keeping it in space.

A sail-stack can be chucked into danger relatively easily - it's one of the most cost efficient way to send mass to the surface of Mars, for example, even though you're likely to lose half of the missions getting there.

***

In general terms, sails are one-shot, disposable thrusters. They're useful for getting mass *out*, and saving the expensive inner solar system burns.

If you're looking at doing long-range missions with them, then the basic plan would be to dive in towards the Sun, then boost out, preferably picking up a Mars/Venus/Jupiter flyby on the way to your destination. In that sense, it's a 0 mass thruster that saves several mass points of fuel in one direction, accepting some compromises, such as limiting the total mass of your ship.
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Matt B
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I think you're too quick to rule out Mercury as a destination. Here is something I posted in a previous thread. Sure you can't ISRU there, but you can bring your own fuel with you.

TokMor wrote:
Assuming you have the sail and 3 WT loaded on your ship, I think there is a much more efficient glory run you can do in the same time. (As long as your crew thruster has 10 thrust, if not you are SOL for this)

Starting mass is 4, so net thrust of 1. I'll put the net thrust in parenthesis after each year.

Year 1 (T1): HEO, coast to Rad hazard between HEO and Sol-Venus L4
Year 2 (T2): Enter Sol Venus L4, coast through Sol Mercury L4, Continue in straight line and enter burn (the right most one of 3 that are over the text "Mercury Flyby")
Year 3 (T3): 3 more burns to Polar Assist, coast to L1
Year 4 (T11): Switch to crew thruster, enter landing burn and land on Discovery Rupes
Year 5 (T11): Take off, enter landing burn, coast to L1
Year 6 (T4): Switch back to sail (we are now Wisp class), enter 4 burns and coast to Sol Mercury L4
Year 7 (T4): Enter Sol-Venus L4, through the rad hazard to HEO, and coast to LEO for two simultaneous glory completions (Science and Mercury landing)

If I got anything wrong though please someone let me know.
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Raoul Duke
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TokMor wrote:
I think you're too quick to rule out Mercury as a destination. Here is something I posted in a previous thread. Sure you can't ISRU there, but you can bring your own fuel with you.


You are correct, I was too quick to rule out a Mercury landing. I have edited my post above to link to your proposed mission plan.

As I see it, a mission to Mercury: Discovery Rupes has the following advantages and disadvantages compared to a mission to Comet Schwassmann- Wachmann I:

Advantages:
No hazards to cross means a theoretical 100% success rate.
Less operation intensive, meaning that other objectives can be simultaneously achieved.
Lower overall cost (6 WT for components and fuel to LEO + 2 WT opportunity cost for 1 boost operation for Mercury vs 3 WT for components and fuel + 6 WT opportunity cost for 1 boost and 2 site refuel operations for Comet Schwassmann- Wachmann I. The cometary mission could be even more expensive if paying for Failure Is Not An Option).

Disadvantages:
Impossible when playing as UN or Shimizu.
More expensive to launch (6 WT for Mercury vs 3 WT for Comet Schwassmann- Wachmann I, assuming that the solar sail was researched for 2 WT in both cases).
Slower mission overall.
Vulnerable to CMEs. To reduce this vulnerability, it is necessary to launch between the turn immediately preceding the second red event and the turn immediately preceding the second blue event.

Both missions have their uses. In the early game, I would probably try to run the Mercury mission, as it would require fewer operations to pull off, allowing me to continuing to research other technologies. In the late game, where time would be more of a factor and the CME launch window would be more difficult to achieve, I would rather attempt the Comet Schwassmann- Wachmann I mission to try to beat the clock.

Of course, to the Shimizu or the UN, with their lower powered thrusters, the distinction is purely academic.
 
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Francisco Colmenares
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And if you have a C Factory and produce the Mag Sail (it starts 1-0), Thanks to the Rad boosts, with a bit of creative alignment, you can one-shot all the way to Saturn.
 
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Todd Pytel
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andrewdoull wrote:
I haven't checked, but is everyone including the opportunity cost of 2 WT per boost operation? This is a massive tax on the value of boosting multiple times.

I think the assumption is that you'd already be boosting something else anyway. In that case, it's nice to have the flexibility of decommissioning the sails and boosting them back up with the new rocket at no cost.
 
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Raoul Duke
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andrewdoull wrote:
I haven't checked, but is everyone including the opportunity cost of 2 WT per boost operation? This is a massive tax on the value of boosting multiple times.


Thank you for catching that. I had not been applying an opportunity cost for operations spent as part of the mission. This was particularly important for the Comet Schwassmann- Wachmann I plan, which uses 3 operations over the mission duration.

I have revised my above posts to incorporate the opportunity costs of each mission.
 
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Bill Gustafson
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I think the Mercury mission doesn't work because you have to afterburn to land and take off. You need thrust of 11, so fuel cost for each burn is 10 steps (8 + 2 afterburn), and there are only 17 steps between mass 4 and mass 1. Am I missing something?

Ah I see - you are probe class and have +1 thrust already. nevermind!
 
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