I don't think cubesats ever did make much sense for interplanetary use. They are extremely volume limited, and tend to be built out of low quality short lived components. Interplanetary spacecraft usually require multi-year missions to reach their targets, and the radiation environment in deep space is worse than in LEO. Short lived components don't work. Communications over the vast distances is also a challenge. A decent sized parabolic dish antenna is neither complex nor expensive, but it doesn't fit inside the ridiculously small volume limits of a cube sat. Making a communications system fold up adds cost and complexity, which is not what you want.
Interplanetary spacecraft also tend to be very fussy about launching at a specific time to hit a specific trajectory. This is incompatible with rideshare.
Cubesats have had some success for missions where multiple spacecraft are needed, for instance LICIACube took good pictures of the DART impact, and Comet Interceptor plans to use several cubesats for close flybys of their target comet because they might lose one due to dust impact.
NASA should look at building small missions around the Electron rocket - Photon spacecraft platform. That would allow a cheap dedicated launch and more available volume while still being mass and cost constrained. An alternative approach might be standardized buses bought in batches which could be customized with different instruments for different missions. Instruments would have to fit within strict and inflexible interface requirements.
I don't think cubesats ever did make much sense for interplanetary use. They are extremely volume limited, and tend to be built out of low quality short lived components. Interplanetary spacecraft usually require multi-year missions to reach their targets, and the radiation environment in deep space is worse than in LEO. Short lived components don't work. Communications over the vast distances is also a challenge. A decent sized parabolic dish antenna is neither complex nor expensive, but it doesn't fit inside the ridiculously small volume limits of a cube sat. Making a communications system fold up adds cost and complexity, which is not what you want.
Interplanetary spacecraft also tend to be very fussy about launching at a specific time to hit a specific trajectory. This is incompatible with rideshare.
Cubesats have had some success for missions where multiple spacecraft are needed, for instance LICIACube took good pictures of the DART impact, and Comet Interceptor plans to use several cubesats for close flybys of their target comet because they might lose one due to dust impact.
NASA should look at building small missions around the Electron rocket - Photon spacecraft platform. That would allow a cheap dedicated launch and more available volume while still being mass and cost constrained. An alternative approach might be standardized buses bought in batches which could be customized with different instruments for different missions. Instruments would have to fit within strict and inflexible interface requirements.
Not every mission needs to last for years. With cubesats, you can spend very small amounts of money (a few 10s of millions) to complete a specific mission. This is much better than a discovery mission.
Sure they carry risk, but the budget allows these chances to do something.
In an ideal world, we'd have 2x the discovery missions instead, but that world won't come.
Not every mission needs to last for years. With cubesats, you can spend very small amounts of money (a few 10s of millions) to complete a specific mission. This is much better than a discovery mission.
Sure they carry risk, but the budget allows these chances to do something.
Name a planetary destination you can get to in less than six months?
1/The Moon.
2/ Venus
3/ That's about it.
Multi-year lifetime is pretty much unavoidable for planetary missions. Also, the deep space radiation environment is much worse than low Earth orbit.
Another thing cubesats lack is delta-v. Discovery missions typically have a fuel fraction of 0.5.
Cubesats might be marginally acceptable for a low Earth orbit observation mission, but the technology is fundamentally unsuited to planetary exploration.
What would a low cost generic planetary exploration spacecraft look like? Start with fuel tanks and a propulsion system. Aim for a fuel fraction of 0.5 or better. The first planetary probes, the Mariner series, were about 260kg. The probe could be that size or smaller, with a dry mass of 100kg or less. Add a 50-100cm parabolic dish for communications. Design for at least a 3 year lifetime in deep space. If using rideshare, have multiple back-up plans including launches to GTO. Electron is a little too small for planetary launches, but it is cheap and reliable so maybe you would try to find a way to make it work.
I agree with your statements here but will just add one contrary point. LICIAcube succeeded very nicely in what it needed to do by following a sort of hybrid approach. It was carried to its destination and deployed close to the target. So the need for propellant was much less than if it flew the trajectory alone. This might suggest that cubesats to Mars or a main belt asteroid could piggyback on another mission and still succeed nicely. An example might be a Lucy-type flyby of an asteroid with a cubesat deployed on approach to image other parts of the target, or a Deimos observation cubesat deployed from a lander on approach. Larger is still better but there might be some utility in this.
Not every mission needs to last for years. With cubesats, you can spend very small amounts of money (a few 10s of millions) to complete a specific mission. This is much better than a discovery mission.
Sure they carry risk, but the budget allows these chances to do something.
Name a planetary destination you can get to in less than six months?
1/The Moon.
2/ Venus
3/ That's about it.
Multi-year lifetime is pretty much unavoidable for planetary missions. Also, the deep space radiation environment is much worse than low Earth orbit.
Another thing cubesats lack is delta-v. Discovery missions typically have a fuel fraction of 0.5.
Cubesats might be marginally acceptable for a low Earth orbit observation mission, but the technology is fundamentally unsuited to planetary exploration.
What would a low cost generic planetary exploration spacecraft look like? Start with fuel tanks and a propulsion system. Aim for a fuel fraction of 0.5 or better. The first planetary probes, the Mariner series, were about 260kg. The probe could be that size or smaller, with a dry mass of 100kg or less. Add a 50-100cm parabolic dish for communications. Design for at least a 3 year lifetime in deep space. If using rideshare, have multiple back-up plans including launches to GTO. Electron is a little too small for planetary launches, but it is cheap and reliable so maybe you would try to find a way to make it work.
Mars - 4-6 months as well.
Near earth asteroids? There are plenty of those as well.
Even just those, being able to send more missions to:
1. venus
2. moon
3. mars (we HAVE sent cube sats to mars already)
4. near earth asteroids
That would be insane to have more missions to those places. Just cause they are close doesn't mean they are not interesting. I'm sure it would be rather hard to find someone who was bored from ALL the missions to venus in the last few decades that have answered all our questions.
I agree with your statements here but will just add one contrary point. LICIAcube succeeded very nicely in what it needed to do by following a sort of hybrid approach. It was carried to its destination and deployed close to the target. So the need for propellant was much less than if it flew the trajectory alone. This might suggest that cubesats to Mars or a main belt asteroid could piggyback on another mission and still succeed nicely. An example might be a Lucy-type flyby of an asteroid with a cubesat deployed on approach to image other parts of the target, or a Deimos observation cubesat deployed from a lander on approach. Larger is still better but there might be some utility in this.
I expect that we may see continued experiments with cubesats for lunar, near Earth asteroid, Venus, and Mars. "May" because these missions are still tens of millions of dollars. I believe that NASA is seeking funding for one new cubesat mission this decade.
I believe that there will be a period of developing and proving new technologies. It will take time.
A number of people have suggested that the sweet spot for planetary missions (lunar and NEA may be exceptions) may be larger than cubesats because of the requirement for greater propulsive and communications capability (and weaker sunlight than in Earth orbit for some missions). Perhaps something like a hundred or two kilograms.
Carry along cubesats are another possibility. Theoretically, EnVision, VERITAS (if it flies), or the Mars sample return orbiter could carry along cubesats to be released in orbit. I say theoretically because I haven't seen any mention of this being considered.
The MASCOT and other asteroid hoppers are cubesats by most definitions, and even the Chinese manned spacecraft subsatellites (not to mention Apollo Particles & Fields). Whether or not NASA invests, there will be other deep space cubsesats whether for practicality, science or politics.
It may be that people are being a bit too pessimistic about cubesats for lunar science.
There was a time, not so long ago, where the common knowledge was that "No cubesat has ever done real science."
This was disproved by the Colorado Student Space Weather Experiment from LASP in Boulder, CO.
Now lots of bits of science is done with cubesats, and lots of commerce, even with sub-1U cubesats.
These don't replace Hubble, or even WISE level missions, but they do good work.
But these all prioritize their science.
Lunar Flashlight was a grab-bag of technology developments
Green propulsion
Additively manufactured propulsion elements
New radiation tolerant computer
Multi-wavelength lidar
Plus lots of student participation.
Only if all of these elements worked, not just proved they could work, would the real scientific observations be done.
If those observations were really needed by HEOMD's Artemis, they would have split off the lidar onto more proven subsystems, of which there are plenty, and left the rest of the tech dev for the STMD.
Tell me you don't believe that Advance Space could host the Flashlight lidar on a version of the Capstone spacecraft now in lunar NRHO.