The Parker Solar Probe will make its closest approach yet to the Sun

If KSP is to be believed, this is shockingly difficult to do

In order to 'land' on the sun, or any celestial body, you need to get rid of your orbital speed. Higher orbital speed means higher orbit altitude. Landing on earth is comparatively easy, because you can use the atmospheric drag to slow down. It is so difficult to land on Mars because of it's thin atmosphere. Alternatively you need a shitload of fuel to burn to kill that velocity.

Earth's orbital velcity is ~30km/s. So by extension, anything that comes from Earth will at least have that speed. So the probe needs to find 30km/s delta v in order to actually get close to the sun.

>So the probe needs to find 30km/s delta v

I don't understand why we aren't doing solar + ion drive everywhere (except obviously launch), and instead we settle for slow multi-year multi-grav-boosts trajectories. Current ion drives (by NASA and on Starlink) have 2500-3500 Isp. Which means that even 100+ km/s is easy doable with just 2 stages.

I assumed that if I did out the math on this, it would be clear why we don't, but then I did and I now share your confusion.

The Parker Solar Probe mass is 555kg. An achievable amount of ion thrust is around 0.5N. Thus, running that thruster would accelerate the craft at 0.0009m/s2.

Getting such a craft to 30km/s of delta-v would therefore take about 33.3 million seconds of thruster time, or about 13 months.

I don't know what the duty cycle is on ion thrusters. Maybe they aren't robust enough to fire for over a year straight?

>The Parker Solar Probe mass is 555kg. An achievable amount of ion thrust is around 0.5N. Thus, running that thruster would accelerate the craft at 0.0009m/s2.

To be precise for 555kg probe you'd need additional 600-800kg of propellant mass and thus run the thruster(s) at about 1.5N thrust using 40-60KW - 250m2 of solar panels - everything is available at the current state of tech.

https://en.wikipedia.org/wiki/Ion_thruster

"A test of the NASA Solar Technology Application Readiness (NSTAR) electrostatic ion thruster resulted in 30,472 hours (roughly 3.5 years) of continuous thrust at maximum power. Post-test examination indicated the engine was not approaching failure.[75][3][4] NSTAR operated for years on Dawn."