# Could a cubesat be self propelled to the moon from LEO?

Is it possible with current technologies to propel a cubesat, which is launched from Earth, to the moon?

If current propulsion systems are able to do so, how do I continue the research in this topic and what calculations do I have to do to to continue?

• It may be helpful to change the title to reflect your question better. Do you mean for the cubesat to be carried by a larger rocket, or for the cubesat to propel itself? If the latter, would it be from low Earth orbit? You've gotten answers that address both possibilities but clearing the title up would help future viewers of this question. – ben Mar 13 at 4:11

Let's look at some possible examples, building on @ben's answer and @ Knudsen's answer.

We know that the MarCo cubesats were able to navigate from Earth to Mars, with

• attitude control via reaction wheels and cold gas thrusters
• science data and image collection
• communication directly with Earth via a unique pop-up flat high gain antenna
• 70W of solar power at 1 AU via two deployable solar panels plus battery storage
• standard 6U form factor

So let's adopt the MarCo design. They didn't provide their own propulsion, so let's add a propulsion system directly to MarCo's 6U, 14kg initial configuration, and call it 10U and 22 kg. The extra 4U volume is mostly for engines and extra propellant, the extra 8 kg mass budget is for engines and additional solar panels for more electric power, especially out near Mars and a whole bunch more propellant!

Looking for at least apparently existing cubesat electric propulsion systems that you could put in a 3U cubesat today (or soon), the first one that came up in my search is the IFM Nano Thruster for CubeSats. I am sure thee are other options out there, let's just use this as an example. According to that page:

Dynamic thrust range        10 μN to 0.5 mN
Nominal thrust              350 μN
Specific impulse            2,000 to 5000 s
Propellant mass             250 g
Total impulse               more than 5,000 Ns
Power at nominal thrust     35 W incl. neutralizer


Our cubesat will have enough electric power for two engines at 1 AU, since we've expanded the form factor by 4 U and mass budget by 8 kg will allow for larger solar panels.

Our two off-the-shelf engines with 250 g propellant tanks each can provide a total impulse of as much as 10,000 Newton seconds. With an average mass of about 20 kg, that only provides a delta-v of 500 m/s. But how much do we need?

Luckily there's an existing mission that addresses this already! Answers to Going from LEO to lunar using only low-thrust ion propulsion - can it be done? say that the SMART-1 mission has done this already!

According to that article the propulsion system used to provide a trajectory from GTO to the Moon (crash landing) demonstrated a total delta-v of about 3,900 m/s.

Luckily we'd added 8kg to our mass budget, so if we'd added an extra 5 kg of propellant we'd have a total impulse of 100,000 Newton seconds and a delta-v of about 5,000 m/s.

Conclusion:

A back-of-the-envelope calculation starting with a MarCo-like cubesat with demonstrated capability of going from Earth all the way to Mars, augmented from 6U 14 kg to 10U 22 kg with two existing engine designs and another 5 kg of propellant, we can get from GTO to the Moon using solar-electric propulsion.

The extra delta-v allows for maneuvering near the Moon and doing a bit of sight-seeing and selfie-taking.

Alternatively you could use the extra delta-v to boost yourself from LEO to GTO, allowing for a more standard cubesat deployment option as long as the inclination were not too high. That would probably need another few kg of propellant, so it's marginal. Best way to proceed would be to piggy-back on one of the many existing launches to GTO in a similar way to how the MarCo's piggy-backed to the transfer orbit to Mars.

Source: MarCO: Mars Cube One

below: Source: Emily Lakdawalla's Planetary Society blogpost MarCO: CubeSats to Mars!

MARCO SPACECRAFT: Engineer Joel Steinkraus stands with both of the Mars Cube One (MarCO) spacecraft at NASA's Jet Propulsion Laboratory. The one on the left is folded up the way it will be stowed on its rocket; the one on the right has its solar panels fully deployed, along with its high-gain antenna on top.

An alternative, future propulsion system with even higher Isp and therefore needing less propellant mass:

An encouraging video:

• Excellent answer! I did not want to venture into the math but my guess was the required size would be much larger than 10U. Turns out this is a really attainable mission for a group with a (relatively) small grant. – ben Mar 13 at 4:07
• @ben I think it's at least a few million \$US just to buy all of the parts, put them together, and do some basic tests. Maybe you can save some if you build every component from scratch, but that's not going to be so reliable. There's also significant expense in making them spaceworthy and to do all of the logistics of preparing them for launch, obtaining all of the permission. This doesn't include an actual launch, which for such a large cubesat would require special arrangements. If that's still considered (relatively) small, then you're good to go! – uhoh Mar 13 at 4:11
• Oh no doubt this is a subjective statement. No one is doing this in their garage for instance. It's just cool to think that we are at a point where for instance a small university research group could actually attain enough funding to send a mission to the moon. Of course this would also require hitching a ride (like you say, a bit complex with the size) or securing NASA or equivalent support for launch. It's cool to watch space become more accessible. Even if they are baby steps they are steps in the right direction. – ben Mar 13 at 4:25
• @ben absolutely! This answer is base on a proven design. No doubt if you started here and went back to the drawing board you cold find lower cost solutions. Comms would be easier to implement since the Moon is a lot closer than Mars. Remember that the radiation is higher than in LEO, so all of the electronics will have to be somewhat radiation resistant and tolerant to regular faults and crashes, but that's doable with redundancy which is probably cheaper than top-of-the-line rad-hard electronics. The triple-junction solar cells are really pricey, lower efficiency silicon will lower cost. – uhoh Mar 13 at 4:38
• "hey alexa, what's the energy density of pu-239" – tedder42 Mar 13 at 23:28

Very Possible

Cubesats are small - typically the base cube is 10 cm square and under 1.5kg and larger cubesats can be made of combinations of this base size. Much larger spacecraft have been sent to the moon, and I imagine there are any number of possible launchers and propulsion systems to allow this. In fact, multiple groups are currently working on it:

Cubesats have already been to Mars, as part of the InSight lander mission.

Self Propelled

It's not clear from your question if you are asking about a self propelled cubesat, possibly starting at LEO? If so, check this recent paper out. A lot of the necessary equations are explained within. The concept of cubesats with significant propulsion capabilities is newer, but presumably one could add modules containing enough fuel for a cubesat to get itself to the moon.

What Do You Need To Study?

Maybe start with the vis viva equation and the rocket equation and their respective formulations. This is a decent primer on orbital mechanics if you are starting completely from scratch.

• One significant problem is not so much delta-V as radio control. Moon isn't that far so it's not insurmountable, but a good radio to cover a long distance and both receive signal from Earth and transmit it at power receivable on Earth tends to be big and power-hungry. Not much good sending the fanciest satellite if it loses contact and nobody gets to know what it discovered and what is it doing. – SF. Mar 13 at 11:20
• @SF. very true, and something I left out in my answer. The selected answer covers this exact issue in basing a hypothetical design on the MarCo cubesats. – ben Mar 13 at 23:48

Yes, but it has not been done yet.

NASA is currently sending three CubeSat missions I know of to the moon on EM-1 sometime in 2020 (according to current estimates of the SLS timeline). I believe they are all 6U spacecraft. http://exploredeepspace.com/news/the-cubesats-of-slss-em-1/

The three missions are:

All three will use solar-electric propulsion to change orbits. Only LunaH and Lunar IceCube will actually establish orbits around the moon though.

Further study of orbital mechanics will help in evaluating the trade-offs between the delta-v provided by the launch vehicle, solar power systems, and low thrust trajectory optimization.