SpaceX Falcon 1e Lunar Capability Guide

[Danderman]

http://www.spacex.com/FalconLunarCapabilityGuide.pdf

Maybe I missed this, but this is new to me, the official guide to how much mass the new Falcon 1e can send to the Moon, presuming the customer adds their own upper stage. With the upgrades, Falcon 1e can put over 1000 kg into a low orbit, so Lunar Prospector-class orbiters could be accommodated, and the Google Prize people could send small landers as well, using the 1e when available in 2010  .

I noticed that Falcon 1e is now on the margins of being able to orbit Mercury capsules, so there may be some fun to be had there. 

[Patchouli]

Falcon 1e probably could launch a mercury type mission since a modern version of the mercury capsule would be much lighter then the 1962 version.

Though on the subject of lunar probes I'd prefer to use ion propulsion for all the delta V needed to go from LEO to escape velocity since 1000Kg isn't much when you start talking about chemical upper stages.

[Comga]

This is identified as Rev 2 on the cover page.

The most salient difference is an increase in stated TLI mass capability from 1300 kg to 1925 kg, an increase of almost 50%.  It also says, curiously, that the transfer trajectory is 48 hours instead of 72 hours.  Scaling in the same manner as was done in the Rev 1 document would increase the capability to 1967 kg on a 72 hr trajectory.  They use the same illustration and give no indication of how the increase is obtained, although the us of regenerative Merline 1-C engines is likely the answer.

Note that both mass-vs-C3 graphs list the capabilities for injection into a Mars transfer solar orbit, one of Musk's original goals.  This too has increased substantially, from 904 kg to 1200 kg.  There have been Mars missions developed with less injected mass.

Of less significance, the document properties have a new author, J Hofeller, and list it as being a "Responsive Small Spacelift (RSS) Request for Information Response".

Pardon me: Those masses were for Falcon 9 to TLI, and therefor off-topic for a discussion of Falcon 1e (as was the light-weight Mercury capsule discussion before it got its own thread.)

[Comga]

I noticed that Falcon 1e is now on the margins of being able to orbit Mercury capsules ...

The launch mass of a Mercury capsule (MA-6) was 1935 kg.  The Falcon 1-e maxes out at ~1100 kg for a minimal 200km orbit,  so there is still a big difference.

and Patchouli, ion engines are not compatible with being launched into LEO.  Solar panels sufficient to collect power to run ion engines would experience many times more drag than the engine could generate.  IIRC, the ESA lunar mission started its ion engines in a pretty high orbit.  Given that the orbit has to be circularized to avoid atmospheric drag at perigee, one has to carry some chemical propulsion to the apogee of the injection orbit, so the benefits of ion engines are expensive to obtain.  Simplicity drives low cost missions to chemical engines and miniaturized payloads.  We don't need to send Lunokods (1814 kg landed mass on the lunar surface) or Surveyors (269 kg).

[Patchouli]

On the modern mercury I was thinking using composites and Al-Li alloys where possible and use of PICA and ceramic TPS which weigh a lot less then what was used in 1962.
Plus the airbag used during the 60s can be dispensed with.
As for control just use three redundant industrial control computers these can weigh less then a kilogram each.

Plus the original shape doesn't have to be used instead more mass efficient shapes such as the discoverer capsule shape could be used or some of the concepts from the Convair 7969 project.

As for ion if it can't be used in LEO it can at least be used maybe a little higher up lets say around 1000km up.
I feel 200Kg TLI isn't enough to actually land something on the moon but could put a small probe in orbit or a crasher probe.

Well maybe a surveyor type probe with extensive use of composites and lots of integrated modern electronics also remember surveyor's TLI mass was more then 269Kg as it used a crasher stage.

[kkattula]

ESA Smart-1 actually used a Hall effect thruster (Snecma PPS-1350-G) with a thrust of 68 mN and ISP 1640. 

More thrust than a traditional "ion engine", and lower ISP. Therefore smaller power requirements (1200 W max). Total delta v was about 4000 m/s, for 82 kg of xenon propellant and launch mass of 367 kg.

Unfortunately, a lunar lander will need a high thrust chemical engine to do the landing bit.  Assuming the lander separates in very low lunar orbit, 1000 kg of launch mass might allow about a 200 kg (fueled) lander, using this technology.

[Patchouli]

Lets see 367kg+200kg for a lander + an extra 40kg of Xenon because it's hauling the lander so 607Kg total that leaves around 400kg left to use on a chemical stage for getting into a high enough orbit to use the hall thruster.

Maybe just build the entire lunar orbiter/cruise stage around the upper stage and use hypergolic fuels or hybrid rocket technology.

Simple is usually better even if it wastes a little payload.

I guess yes it definitely may be possible to perform a lunar mission with Falcon 1e.

[Giovanni DS]

The idea of a minimal capsule is interesting, would be possible, using modern technology, to build a single/double seat capsule weighting less than 1000kg ?

As requirements:
- Capable to dock to ISS (manned or unmanned) and stay there docked for a long period, much like a sci-fi escape pod.
- Survivable re-entry even with less than optimal trajectory.
- Be able to survive landing in sea or land.
- Launch on demand in a short time.

If not 1000kg, how much such a vehicle could weight ?

[mr.columbus]

As requirements:
1.Capable to dock to ISS (manned or unmanned) and stay there docked for a long period, much like a sci-fi escape pod.
2.Survivable re-entry even with less than optimal trajectory.
3.Be able to survive landing in sea or land.
4.Launch on demand in a short time.

If not 1000kg, how much such a vehicle could weight ?

Requirement 4 doesn't have much to do with the spacecraft, rather with the launcher and your destination (ISS orbit etc.). So for purposes of designing a minimal mass vehicle, we can disregard it.

I do not see why you ask for requirement 3. Except for one Soyuz landing, where the capsule unintenionally landed in a lake, there has never been an unintended water landing or vice verca for a manned vehicle. It would be better to choose one method and stick with it to reduce mass. If you don't care much about whether the capsule does a hard, uncomfortable landing or not, landing on land is better from a mass perspective.

Requirement 2. is of course paramount. A spacecraft that can't survive a reentry under suboptimal conditions from orbit, isn't something anyone needs.

As to requirement number 1, a docking port for docking to ISS + microshields + power systems for long-term stays on orbit alone will burst your 1000 kg mass budget. Thus, for a minimum mass vehicle design I suggest not include either of these requirements. It would make more sense to just build a new kind of docking system: your vehicle could be guided into a depressurized airlock, then the airlock would be closed and pressurized - power down your vehicle and store it inside the station. Of course that would require 1. a small enough spaceship to fit inside an airlock docking port 2. you need to build such an airlock docking module first and launch it to the ISS or a future spacestation and 3. you need storage space inside the pressurized modules of the ISS/any other spacestation that is your destination, if you want to use that airlock docking port for more than just one vehicle.

All that said, it's hard to tell whether an orbital spacecraft with less than 1000 kg could be desgined. Basically, what you would need to do is build a pressurized cockpit for one person (one seat only) and look whether the heatshield, electronics, life support systems, propulsion systems and batteries/solar cells don't blow your mass requirement.

[edkyle99]

I noticed that Falcon 1e is now on the margins of being able to orbit Mercury capsules ...

The launch mass of a Mercury capsule (MA-6) was 1935 kg.  The Falcon 1-e maxes out at ~1100 kg for a minimal 200km orbit,  so there is still a big difference.

A big chunk of that 1,935 kg was for the launch escape system.  On orbit insertion, Mercury weighed 1,354 kg-ish.  Falcon 1-e might be able to lift a modernized Mercury-like spacecraft if no launch escape system were used - but that's probably not a good idea.

 - Ed Kyle

[Giovanni DS]

Good idea with the pressurized airlock, it would save a lot of mass, there could be contamination issues however if the vehicle uses toxic propellants.

[Jim]

Good idea with the pressurized airlock, it would save a lot of mass, there could be contamination issues however if the vehicle uses toxic propellants.

How do you get out of the airlock while inside the vehicle.  This is not a good idea

[hutchel]

You are thinking in terms of our current manual airlocks - Nothing says the "hatch" to vacume can't be automatically closed and locked/ then the system would be able to repressurize the volume around the capsule allowing egress.

[Jim]

You are thinking in terms of our current manual airlocks - Nothing says the "hatch" to vacume can't be automatically closed and locked/ then the system would be able to repressurize the volume around the capsule allowing egress.

yeah, right.  More hatches, a jettison mechanisms, more complicated and more risk.  a rescue vehicle minimizes risks
This is not a viable idea.

[kevin-rf]

Shouldn't we have a seperate thread for minimal manned capsul on a falcon? Unless we are hoping through the use of unobtainium of sending the passenger to the moon...

I wonder what the lightest shape for a reentry module would be. I so dislike the use of Al and alloys in reentry module. Any TPS failure and well, we know what happens. Ti maybe?

To save weight, how about ...

Ejection seat instead of an escape tower?

Ejection of the passenger(s) instead of a heavier capsul recovery system?

Can a tether be made lighter than a retro pack?

[TrueBlueWitt]

Re-entry "Suit"?

Saw this a while back in Pop Sci or Pop Mech.. Looks like it might be possible to handle re-entry with a suit(given the low amount of mass).. although re-entry energy from LEO or sub-orbital velocities is a different animal than a direct return from the moon!  Anyone want to ride down in a suit strapped to the back side of a small ablative sheild?  That would be a heck of a ride!  Going downhill on a saucer sled. 

Thinking bare minimum re-entry mass.. Then bail off the shield and come down on a chute only big enough for astronaut and suit.  Biggest concern would be landing(land or water).

That's what I call a minimalistic approach.

[aero313]

Re-entry "Suit"?

Sounds like MOOSE from the 1960s.  Also, for minimalist reentry capsules, check out the design for an emergency capsule on the Scout launch vehicle.

[mr.columbus]

You are thinking in terms of our current manual airlocks - Nothing says the "hatch" to vacume can't be automatically closed and locked/ then the system would be able to repressurize the volume around the capsule allowing egress.

yeah, right.  More hatches, a jettison mechanisms, more complicated and more risk.  a rescue vehicle minimizes risks
This is not a viable idea.

Yes, the idea of an airlock docking does not bode well with using such spacecraft as a rescue vehicle. I was suggesting this method of docking in order to keep the mass of the spacecraft down and still keep the ability to dock to a spacestation. After all, the originally question was "how do we get the mass of crewed spacecraft down to 1000kg or less and still have the ability to dock to a space station."

The problem with contamination through toxic fuels would of course need to be dealt with. Non-toxic hypergolic bipropellents could be used: http://www.patentstorm.us/patents/6419771/description.html .

[jongoff]

Of less significance, the document properties have a new author, J Hofeller, and list it as being a "Responsive Small Spacelift (RSS) Request for Information Response".

I met Jonathan Hofeller back at the Next Generation Exploration Conference #2 at Ames in February.  He was in the same working group as I was (along with one of the other regulars here who I won't name for anonymity purposes).  Not only does he spell his first name the right name (always a mark of a smart guy), but last I heard, he's also one of the main people at SpaceX working on selling Falcon for lunar launch. 

~Jon

[Comga]

I met Jonathan Hofeller back at the Next Generation Exploration Conference #2 at Ames in February......
~Jon

Did he happen to mention this RFI?  Do we know of an RFI that included lunar capabilities?

PS  I agree on the correct spelling of his and your name, which is also that of my son.