Do we need manned space flights?

The effects of a long term exposure to radiation

Question: Do we need manned space flights?
Position‹3 of 3: No, space flights are too dangerous
Argument‹2 of 3›: The effects of a long term exposure to radiation

Astronauts will not likely be protected neither in the voyager neither in the trip nor in the permanence on a planet

The argument

So far the only human mission outside low Earrth orbit have been Apollo missions to the moon. Radiation shields on the vessel might not be feasible. Further on planet like Mars there is not a magnetic field that protect us like Earth's Van Allen radiation belt. There is no sufficioent prediction on the amount of radiation to which astronaut will be exposed

Context

During space segments of a mission and also on planet surface (like Mars) astronauts might not be adequately protected from radiation.

Premises

[P1]Beyond low Earth orbit, astronauts lose the protection of Earth's magnetic field, and planets like Mars have no equivalent shield. [P2] Effective radiation shielding on a spacecraft may not be feasible. [P3] There is no reliable prediction of how much radiation astronauts on long missions would be exposed to. [C] Therefore, because of the dangers of long-term radiation exposure, manned space flights are too dangerous.

Counter-arguments

Some reasonable measures can be put in place. Water can be used as a shield on the vessel. On Mars surface astronatus could live in an under-ground habitat and use terrain itself as a shield Some estimation shows radiation to be at an acceptable level.

Rejecting the premises

[Rejecting P1] The premise conflates two things. The Van Allen belts are trapped radiation held by the magnetosphere, not the shield itself, and Mars — while lacking a global magnetic field — does retain an atmosphere and, more importantly, offers its own surface material as mass shielding. [Rejecting P2] The counter-argument on record identifies feasible measures rather than novel ones: water and stored consumables can be arranged as shielding around a crew compartment on the outbound vessel, and habitats on Mars can be placed under regolith so the terrain does the work. Neither requires technology that does not exist. [Rejecting P3] The claim that exposure cannot be predicted is the weakest of the three. Instrumented spacecraft have measured the radiation environment on the transit to Mars and at the surface, so the dose for a reference mission is estimated rather than unknown — which is what the counter means in saying some estimates put it at an acceptable level. [Rejecting C] The conclusion also treats a quantified occupational hazard as disqualifying, which is not how comparable risks are handled elsewhere. Whether the dose is acceptable is a judgement about limits and mission design, and the argument argues from uncertainty rather than from a figure. (The body is also badly typo-affected and is a candidate for replacement.)