Cubesats for Solar System Exploration Options

[vjkane]

[ADMIN NOTE: New topic started using moved posts from Pallas telescopic observation topic. Please read and keep rule 1.9 in mind. Thanks!]


I was hoping that NASA would select the Athena mission to do a flyby of Pallas using a cubesat spacecraft under the SIMPLEx program. It selected the Janus mission to flyby two near Earth asteroid binary systems instead. The Athena team plans to submit again.

[antipode]

That's good news vjkane! Cubesats for initial exploration of interesting NEOs and objects out to the main belt seem like a great way to go.
I think there's a need for an ongoing program that sits well under the Discovery class cost-wise that can take advantage of cubesat architectures with limited but focused payloads,
only solar power, and new cheaper smallsat launchers or rideshare opportunities.

P

[vjkane]

That's good news vjkane! Cubesats for initial exploration of interesting NEOs and objects out to the main belt seem like a great way to go.
I think there's a need for an ongoing program that sits well under the Discovery class cost-wise that can take advantage of cubesat architectures with limited but focused payloads,
only solar power, and new cheaper smallsat launchers or rideshare opportunities.

P

Don't get too excited. While it was ranked Category 1 (fully selectable on science and implementation), NASA didn't select it. There also has to be a launch opportunity. The previous proposal made use of the Psyche Mars flyby and the fact that Pallas is currently close to the ecliptic.

All we know about the new proposal, based on the PI's statements, is that the next version will be much better.

[JRehling]

Given the low mass of cubesats, I wonder about a mission that sends many of them on a Jupiter (or, possibly, Earth) flyby and spreads them out enough, before the flyby, for the gravity assist to scatter them into solar orbits that cross back through the asteroid belt and fly by many different targets from an initially-similar trajectory. There have to be many opportunities for such orbits to intersect the orbits of two targets (out of thousands to choose from) so that the number of asteroids observed could be on the order of 1.5 per cubesat. Thereby, one low-mass mission could give us flyby observations of many asteroids.

The investment in delta-v for the Jupiter flyby would be high if you only wanted to observe a single target, but for the payoff of observing many targets, the science / cost would become more appealing.

The devil is in the details as to what a Jupiter gravity assist can achieve, but a couple of inspiring examples are Pioneer 11, which gained a high inclination en route to its Saturn flyby, Ulysses, which gained a 79° inclination for observing the Sun. Getting to Pallas is easy in comparison to either of those.

[HSchirmer]

Given the low mass of cubesats, I wonder about a mission that sends many of them on a Jupiter (or, possibly, Earth) flyby and spreads them out enough, before the flyby, for the gravity assist to scatter them into solar orbits that cross back through the asteroid belt

It occurred to me that it might make sense to reverse direction first - Venus is closer and IIRC aligns more often for flybys(?) So an initial Venus gravity/Oberth boost might be a faster way to get out to Jupiter. Also, I VAGUELY remember that rockets using RP1 for fuel (kerosene/diesel) are denser, and pack more delta-v for Oberth maneuvers boosts, compared to cryogenics (H2 or CH4) or hypergolics. IIRC problem is, if you fly RP1 past ~1.0 AU it turns into Jello unless you heat and stir it. So, perhaps aim IN towards Venus, use cheap Lox-RP1 and get the Oberth/gravity boost there?

Also seems to me that a cubesat heading towards the asteroid belt could benefit from some sort of solar sail, for course correction on the way out, for station keeping once you get there, and as a solar collector to reflect light back onto the cubesat solar cells to keep the battery charged and the cubesat alive.

Question- how much of an Oberth/gravity boost CAN you get from a sling shot maneuver around the moon?
I have to ask, because years ago, somebody speculated that the GRAIL data and a super accurate lunar gravity map would allow a bonkers "Tors Twillinger"-"REVERSE HOVER-SLAM" massive Oberth & gravity boost from a lunar flyby.
It's essentially the "Thor's Twins" turn from The-Hunt-For-Red-October, (but with a rocket.)
You skim over the surface of the moon around 300 feet/100 meters above the surface, now that you are deep in the Lunar gravity well you light up a high delta-v Lox-RP1 engine, blast across the lunar seas, and then thread the gap through the mountains at the west end of the Ocean of Storms, then make the final course correction that gets you to the outer solar system in a hurry.
Could it work?

[JRehling]

1) Venus does not align more often for flybys; this is easy to lookup and check. The synodic period of Venus is 19 months and for Jupiter, 13 months… not that the difference would matter much in planning a single mission.

2) Adding a solar reflector for two purposes to each cubesat immediately defeats the principle of simplicity. I was suggesting that there might be an affordable, elegant solution and you're proposing an expensive solution; of course, those always exist. That's just an entirely different topic.

3) The magnitude of possible gravity assists depends upon many factors, but they vary with the amount of time that the spacecraft spends within the body's gravity well… time integrated times the acceleration due to gravity at that distance… and Jupiter has a mass 390 times that of Venus. It has easily the greater potential for bending the paths of objects on similar trajectories to different destinations.

[HSchirmer]

2) Adding a solar reflector for two purposes to each cubesat immediately defeats the principle of simplicity. I was suggesting that there might be an affordable, elegant solution and you're proposing an expensive solution; of course, those always exist. That's just an entirely different topic.

Fair points. My points
1) cubesats rely on batteries & solar panels, not plutonium RTGs.
2) A big shiny flat solar sail would allow a cubesat to make course corrections without needing heavy cold gas thrusters.
3) The same big shiny sail, when parabolically curved, would focus dim sunlight onto a cubesat solar panel, allowing a cubesat to survive on solar power much further out that it could otherwise.

and Jupiter has a mass 390 times that of Venus. It has easily the greater potential for bending the paths of objects on similar trajectories to different destinations.

4) Of course, the sun has a mass 333,000 times that of Venus, is only 1 AU away and has NO synodic period, so it's thousands of times better for bending orbital paths.