To The Moon!

(Turns out the first ship I want to do isn’t one of the ones anyone asked for. Oh, well.)


Operated by: Spaceflight Initiative
Type: Early exploration vessel.
Construction: Spaceflight Initiative.

Everyone’s heard of the Silverfall-class explorer, the starship that first carried eldrae from Eliéra to its moons. (A surprisingly large number of them have visited the museum out on Seléne where Silverfall Four — Moondancer — rests in state out on the regolith, where she was flown to her resting place by her original crew, and is kept in flight-ready condition by her many admirers.)

The design discussed here is of the Block II variant of the Silverfall-class, which incorporates the modifications made to improve performance and livability after studies performed on Silverfall Zero and Silverfall One, and whose two examples can be considered representative of the class, including as they do the actual craft, Moondancer, which made the first landing on Seléne; later design revisions included a number of specialized variants, but made no further changes to the basic design.

Length: 42.2 m, of which:

  • Mission module: 12.2 m.
  • Engineering frame: 18 m (overlaps with propulsion module)
  • Propulsion module: 12 m
  • Shock absorbers and pusher/ground plate: 12 m

Beam: 12 m (mission and propulsion module); 22m (widest point)
Mass (fueled): 616,200 kg

Gravity-well capable: Yes.
Atmosphere-capable: No.

Personnel: 2 required, as follows:

Flight Commander
Flight Director/Engineer

Accommodates 6 further mission specialists.

Drive: Silverfall-specific fission pulse drive with laser trigger; cold-gas attitude control and landing system.
Fuel: Plutonium coated fuel pellets.
Cruising (sustainable) thrust: 2.4 standard gravities
Delta-v reserve: 16,800 m/s

Drones: Simple automation only.


Star tracker
Inertial tracking platform
Passive EM array
Short-range collision-avoidance and docking radar
Mk. 1 Eyeball

Weapons: None, unless you count the drive.

Other systems:

Thorium pebble-bed power reactor
Omnidirectional radio transceiver
Communications laser
Whipple shield (habitable area only)
Canned (non-regenerative) life support; CO2 scrubbers
Redundant flight control systems
NaK pumped-loop high-power radiators and maneuvering heat-sinks
NH3 low-power radiators

Small craft: None.


The original Phoenix-class orbiter was once described as an explosion in a girder factory, and its smaller cousin, the Silverfall, maintains much of that look, despite at least some improvements in elegance between the designs. That, and that unlike the Phoenix, the Silverfall was designed as a pure space vessel, intended to be built at and operate from Oculus Station in Eliéra orbit, and to land only on airless Seléne and Elárion.

The layout of the Silverfall-class can be divided into four sections: the upper mission module, the engineering frame which sits atop and wraps around the propulsion module, and the shock absorber/pusher plate section at the bottom.

At the top, the mission module is divided into three tail-lander decks with plenum space in between. The uppermost deck, topped by a blunt cupola and surrounded by the various navigational and communications antennae, contains semicircular bridge and mission management sections, surrounded by the ship’s avionics. From it, an axial passage descends through the next two decks, terminating in a small engineering space (housed in an aft projection) where the mission module connects to the primary thrust truss of the engineering frame. A secondary access tube, normally depressurized, runs down from this passage through the engineering frame.

The second deck houses three pie-segment areas; the ship’s laboratory, workshop, and main stowage area. Opposite the stowage area, between the laboratory and workshop, a secondary airlock provides maintenance access while in flight to the exterior of the ship (with a ladder down to the upper levels of the engineering frame), and is the main access point when the starship is docked.

(Opposite this airlock, centered on the mission module’s vertical axis, is the gold plaque bearing the Imperial Star and the stylized rocket-and-crescent-moon of the Spaceflight Initiative, with beneath them the various names and logos of the various contributors making the Silverfall mission possible.)

The third, lowermost deck contains the crew quarters, divided into a number of modular pods, along with the galley, central mess, ‘fresher, and a small medical bay.

Six meters below the mission module is the propulsion module, a heavy steel capsule containing the guts of the nuclear-pulse drive that powers the Silverfall. For the most part, however, it is hidden by the engineering frame which wraps around and atop it, a mesh of trusses containing, most notably, the six pellet silos, evenly spaced around the ship, containing the plutonium fuel pellets, and the spherical tanks of cold-gas propellant and life-support supplies.

The lower surface of the engineering frame (along with that of the propulsion module) is the solid sheet of the protective shadow shield, protecting the upper sections of the craft from radiation produced by the pulse drive. The secondary access tube descending from the base of the mission module connects to the primary airlock, located directly above the edge of the shadow shield vertically beneath the secondary airlock, and from which a descent ladder can be lowered once the drive shroud is in place.

At its edges, laser modules extend past the edge of the shield to trigger the explosive coatings of the fuel pellets; just within those edges, sealed slots permit the segmented drive shroud to be lowered after landing, surrounding the mechanics of the shock absorbers and pusher plate, to protect disembarked astronauts from residual drive radiation.


Project Silverfall – First Steps

Calria Adae-ith-Adae: Depressurizing… pump-down complete.  Pressurization amber.  Opening outer door.

Wow.  Sky’s foamy with stars out here.  Are they getting the picture groundside, Airin?

Airin Muetry-ith-Mirari: Communications check, video and audio; blue and blue.  Opscon has us 8/12.

Calria Adae-ith-Adae: Attaching tether.  Moving to the ladder…  Surface is as white as it looked from orbit, only brighter at this angle.  Looks like one of the beaches at Cenval, almost.  Okay.  Everything looks in order on the ship.  I’m getting the wand out, doing radiation check.

There’s a little leakage around the base of the shroud, well under safety range.  Nothing showing above the plate or around the radiators.  Ship is clean.  Looks like there’s some disturbance under the thrusters, but only shallow.  Gear hasn’t sunk much, maybe a couple of inches.

Stepping off the ladder now… and down.  Tether is slack.  Not much give in the ground, but it’s powder, finer than that sand.  Scatters at a touch.  Shifting to the dorsal tether, and –

Airin Muetry-ith-Mirari: Ah, Calry?

Calria Adae-ith-Adae: …ha.  As a representative of the Imperial Couple and the Spaceflight Initiative, I claim this new world for the Empire and her people.  We’ve taken the first step on the road to the stars, and while we two must return, from now we will always be a people of two worlds.  The future is here.  Let’s build it.


Shifting to the dorsal tether, and proceeding around the ship.

– Spaceflight Initiative transcript of Silverfall Four mission, MET +4:17:22 – +4:17:39

“I didn’t remember myself, either; Beran [Beran Irithyl-ith-Issarthyl was in charge of flight communications at OPSCON during the Silverfall Four mission] had to prompt me from the ground.  We’d both been training for this mission for so long, and dreaming about it even longer, that… well, we were concentrating hard on our procedures to resist the urge to leap out of the airlock and just roll around in the regolith, you know?  Embrace the world we’d fought to get to.  That’s enough to make anyone forget her speech.”

– Airin Muetry-ith-Mirari, interviewed at the centennial of the Seléne landing

Project Silverfall – The Landing

OPSCON: Silverfall Four, confirm your intent to land this orbit?  Over.

Pilot (Calria Adae-ith-Adae): The window’s not broadening just sitting here, and this periseléne’s still in the band, even at the high side for burn.  We’ll take this window, Opscon.  Over.

OPSCON: Communications check.  Over.

Pilot: Do you have us, Eyeball?  Over.

Oculus Control: 12/12 on the whisker, 7/12 on the omni.  Over.

Pilot:  Good enough, Eyeball.  Four, clear.

OPSCON: Four, you are go for deorbit preliminary.  Confirm systems, over.

Pilot: By threes, call the checks.  I show mains, accumulators, radiators; blue, blue, blue.

Co-pilot (Airin Muetry-ith-Mirari): Check, check, check.

Pilot: I show fuel, cold-gas, life; blue, blue, blue.

Co-pilot: Check, check, check.

Pilot: I show telemetry, computer, radar; blue, blue, blue.

Co-pilot: Check, check, check.

Pilot: Attitude is six, zero, zero.  Inertials are aligned within point zero zero three, within parameters.  Clock drift is fourteen micro, within parameters.

Co-pilot: Check, check, check.  All systems check out for deorbit and landing.

Pilot: Opscon, systems check out, navigation variances are point zero zero three, fourteen.  Window’s coming up – do we have a go?  Over.

OPSCON: Four, our telemetry matches yours.  You are go for deorbit burn.  Opscon, clear.

Pilot: (loud breath) Okay, here we go.  By the numbers… mains to capacitors for charge.

Co-pilot: Capacitors charging.

Pilot: Stow the radiators, switch to heatsink.

Co-pilot: Radiator stow, check… cooling pumps to internal, no flow in the vanes.

Radiators inboard, four blues.

Pilot: Coming up on window in… two minutes.

Co-pilot: Capacitors show charged and ready.  Clock is running.

Pilot: Opscon, initiating burn in 36.  Four, clear.

Run up the pellet launcher.

Co-pilot: Pellet launcher to burn speed.

Speed nominal.

Pilot: Nominal, check.

Co-pilot: Burn in twelve, eleven, ten, nine, eight, seven, six, five, four, three, two, one, mark.

Pilot: Ignition.  Throttle at nominal-high, acceleration two point seven.

How’re the sinks?

Co-pilot: Heat flow is within parameters, about point five above predicted, no worse.

Pilot: Got some oscillation here…

Co-pilot: Standing by to cut.

Pilot: …trying the dampers.  There, it’s planing out.

Co-pilot:  Very well.  Pellet feed is steady.  Groundspeed 1600, height 490, range 475.  In the grid.

Coming up to inflection.  Standby for pitch-up maneuver.

Pilot: We’re coming in a little short.  I’ll take it to pitch four; compute me a second inflection.  Initiating.

Co-pilot: Pitch five point five, five, four point seven, four point four, four… steady at pitch four.  Pitch-up complete.

Second inflection point on the glass.

Groundspeed eight.  Delta-A in the slot.  Coming up to second inflection.  Standby for pitch-up maneuver.

Pilot: Pitching to zero.  Take the throttle down to thirty.

Co-pilot: Pitch three point five.  Throttle eighty.  Pitch three.  Throttle fifty.  Pitch two point one.  Throttle forty.  Pitch one point five.  Throttle thirty.  Pitch zero…

Attitude zero, zero, zero, throttle steady at thirty.  Range point three eight.  Vertical 28.  Glass to landing configuration.

Heatsinks at half capacity.

Range point one three, vertical fourteen.

Pilot: A little more throttle now.  Throttle to sixty.

Co-pilot: Range point zero seven, vertical one point nine two.

Pilot: Throttle to eight five.

Co-pilot: Range point zero five, vertical point one four five.  Starting to get some ground pushback.

Pilot: Throttle back to three zero.

[expletive] Looks like there’s a crater under us.  Hold us on the throttle; switching to manual lateral maneuvering.

A little more.  A little more…

Co-pilot: Range point zero three, vertical point one eight.  Kicking up the regolith.

Pilot: Stand by to switch to cold-gas thrusters.  Terminate pellet feed in six, five, four, three, two, one, mark.


Co-pilot: Range point one three, vertical point one.  Point zero eight.  Point zero five.  Point zero four.  Point zero two.  Point zero one.  Point zero zero five.  Point zero zero two.  Contact.

Pilot: Thruster shutoff.

Co-pilot: Gear holding, stress shows in the blue.  Internal pressure, blue.  Hull integrity, blue.  Attitude, zero, one point two, point three.

Pilot: Capacitors, cycle to discharge.  Radiators deploy and push.

Co-pilot: Capacitors to discharge, check.  Vanes deploying in ground configuration…

Check.  Pumps running, flow in the vanes.  Heatsinks show two-thirds capacity.

[laugh] We did it!  We’re here!

Pilot: I believe we did, at that.

Opscon, this is Silverfall Four.  We are down safe at White Plains.  I repeat, Four has made landing on Seléne. Over.

OPSCON: We read you down safe, Four. [swallowing]  Good to hear it from you.  Congratulations!

[sound of cheering]