> for an actual manned mission so close to Sun you need a huge vessel, which would require proportionately gigantic sail. It will be big, but a lot less so tha

> for an actual manned mission so close to Sun you need a huge vessel, which would require proportionately gigantic sail. It will be big, but a lot less so than you'd think. Solar sails need to be a huge proportion of the mass of the vessel they are moving if you are near earth. However, the thrust provided by the sail scales by 1/(distance to sun)². Near Mercury's perihelion, solar sails are stronger than they are near earth's orbit by a factor of ~10. But that's not where it ends. The plan calls for sundiving, or going <1 million km from the surface of the sun, where sails have tens of thousands of times the thrust they have near earth. > While you can deal easily with heat by reflecting the light, you need to contend with a lot of shielding necessary to deal with solar winds that are much more stronger and frequent so close to the sun. Solar wind is charged, which means it's just extra thrust with the right kind of sail. > It might be possible to run a train of supply missions this way, I would have to check the math but I am too lazy today to do it:) IN general it does not matter a lot how long it takes for a supply mission to reach the planet This would actually be a lot faster than going to Mercury with a traditional Hohmann transfer, assuming you leave earth with a burn towards Venus (you could also slowboat with the sail there, but that would probably take years). The route is circuitous, but the speeds would be much, much higher.