[NASA is full of crap] Space experts warn Congress that NASA’s “Journey to Mars” is illusory

This is just plain out false. Cosmic radiation comes from multiple directions - you are exposed once you are outside the atmosphere - the magnetic field is the only protection Kelly gets.

No, 9 months to a year. It doesn't change the argument I am making. You still need to store the fuel for

1. The time it takes to build the spaceship in Earth's LEO.
2. The 9 months until you get to Mars so that you can slow the ship down the right way so it can be "captured" by Mars orbit.

But you ignored all the other points. Keep talking about ESL and how things with most mass than a metric ton can use a parachute.

 

?????

We're talking about the 9 month trip to MARS not even once you get there!

That's 18 months of radiation exposure. Mars doesn't have the magnetic field and atmosphere earth does either but that's a different story.

 

You are running away from your errors - are you capable of admitting you are wrong.

 

Yes, I got my degree in physics and part of that was Hoffman's transfers - I actually did an assignment on a mission to mars - of course that was in 1997. But classical mechanics hasn't change since then surprisingly.

There are many ways to get to Mars - but only a few that are time efficient and energy efficient. I can't comment on a 6 month time frame and I don't know if that involved using gravitational assist or not.

 

Link (yes, this is the Hoffman's transfer orbit Sweet Low ref)

 

That chart is in a log scale - so the differences between the ISS and the trip to mars are actually 3x. Combine a 500 day stay on mars with the round trip and you get 9x which puts you close to 1 Sv. If you got exposed to 1Sv in a short timeframe you would get radiation sickness and probably vomit. Now over a year probably not. But it's not that your cancer rate goes up by 5%, it's that you have a 5% chance of getting cancer later in life related to the exposure. That's right, 1 in 20 people exposed to 1 SV will develop a cancer attributable to the radiation. And cancer isn't the only harmful effect - cosmic radiation kills brain cells, so the astronauts would lose cognitive function over the course of the trip.

You still need to carry fuel with you to get out of the transfer orbit into Mars orbit. Not to mention getting back but of course you don't care about that.

That is a honmann transfer - it is the most energy efficient way to reach mars and yes it is 8.5 months. anything less requires more energy.

neither of us said that protons can travel through a planet. they can travel through a spaceship quite easily though. Not sure why you are talking about the planet's surface when we are talking about space TRAVEL.

The exposure on mars is primarily from solar radiation as well as cosmic radiation which is still higher than what you get on earth. Your own chart shows it is 3times what you get on ISS

 

You keep on bringing up the Earth, presumably as a mass, yet ignore the magnetosphere when your own source cites the magnetosphere as the primary defense.

Now granted the mass of a planetary body does block out radiation but radiation is coming from all directions in the sky. Scott Kelly in space get some protection is from radiation because of the mass of the earth but that is like saying that we don't get sunburned on the soles of our feet while standing on the ground. If we didn't have a magnetosphere or atmosphere we would probably be getting around the same radiation dosage as if we were out in space. The mass helps but even if I lie flat on the planetary body I will still get dosed just like if I like flat on the beach I will still get sunburned.

Yes on Mars there is a thin atmosphere that provides some protection. No one is saying that you would get the same dosage of radiation on Mars as you would in interplanetary space. If so cite the post where we said that. We are specifically talking about the radiation dosage that an astronaut would get on an interplanetary voyage which is substantially greater, much more than the two times level that you cited.

Back to the specific point. Radiation shielding is a major issue with getting to Mars. Scott Kelley's mission will answer a lot of questions about long term exposure to microgravity and a confined environment but won't really answer a lot of questions about long term exposure to the amount of radiation in interplanetary environment.

 

You do know that in Astronomy "omnidirectional" refers to the whole sky and the Earth as a sphere is getting hit omindirectionally. Yes granted the soles of your feet are protected from cosmic rays and your back when you sleep. If not for the atmosphere and magnetic field you would still get heavily dosed even in the shadow of the earth.

So yes the mass of the Earth mostly blocks radiation from the Sun. That is called "night". Cosmic rays though still come from all directions in the sky.

Huh?

What is your argument that mass of the earth is the primary protection and why Scott Kelley only gets half the dosage he would from interplanetary space because the mass of the Earth? Sources including the one you linked too say it is the magnetic field (magnetosphere) that is providing most of the protection.

Again from your own link:
https://en.wikipedia.org/wiki/Health_threat_from_cosmic_rays
[rquoter]Missions beyond low Earth orbit leave the protection of the geomagnetic field. [/rquoter]

Seriously you are in some major denial.

 

To add one more counter point to Bandwagoners' argument. I will grant him that yes mass can block radiation. When considering dosages though just because you are dosed from one side doesn't mean that you are safer. If you stand with your back to a 10 ft thick concrete wall and someone holds an unshielded chunk of plutonium to your face you will still get a lethal dose of radiation. That is the same as if you lie on the beach with no sunscreen you will still get sunburned. It's not that you are getting half of the amount of solar radiation. You are getting the full dose just on half of body.

Without the magnetosphere Kelly would get a full dose of cosmic radiation. Just protecting his back, side, feet or whatever part of his body is facing the Earth doesn't prevent a full dose from hitting the rest of his body since cosmic rays are coming from all directions in space.

To add another point.
Because most planets are spherical you can't just walk around a planet with no atmosphere and magnetic field to avoid cosmic rays or only get the half the dose. You would get the full dose no matter where you went. In LEO microgravity this is more so. Unless Kelly stays anchored in one direction the whole time he can't just limit his dosage by relying on the Earth to shield him. Since he is free falling he is being dosed omnidirectionally in the absolute sense. As the ISS orbits around the Earth with him free floating in it rays are hitting him from all directions. Maybe not at the same time but he is essentially rotating like a roast on a spit.