Re: Risposte alle pagine lunari
Inviato da Trystero il 14/4/2008 1:36:07
Visto che questo è un punto importante preferisco citare tutto il messaggio di James Van Allen e non solo la frase finale che ho inserito nel messaggio precedente:
Dear Mr. Lambert,
In reply to your e-mail, I send you the following copy of a response that I wrote to another inquiry about 2 months ago --
Ø The radiation belts of the Earth do, indeed, pose important constraints on the safety of human space flight.
Ø The very energetic (tens to hundreds of MeV) protons in the inner radiation belt are the most dangerous and most difficult to shield against. Specifically, prolonged flights (i.e., ones of many months' duration) of humans or other animals in orbits about the Earth must be conducted at altitudes less than about 250 miles in order to avoid significant radiation exposure.
Ø A person in the cabin of a space shuttle in a circular equatorial orbit in the most intense region of the inner radiation belt, at an altitude of about 1000 miles, would be subjected to a fatal dosage of radiation in about one week.
Ø However, the outbound and inbound trajectories of the Apollo spacecraft cut through the outer portions of the inner belt and because of their high speed spent only about 15 minutes in traversing the region and less than 2 hours in traversing the much less penetrating radiation in the outer radiation belt. The resulting radiation exposure for the round trip was less than 1% of a fatal dosage - a very minor risk among the far greater other risks of such flights. I made such estimates in the early 1960s and so informed NASA engineers who were planning the Apollo flights. These estimates are still reliable.
Ø The recent Fox TV show, which I saw, is an ingenious and entertaining assemblage of nonsense. The claim that radiation exposure during the Apollo missions would have been fatal to the astronauts is only one example of such nonsense.
James A. Van Allen
Dunque Van Allen dice che per poter avere dei danni dall'esposizione a quelle radiazioni bisognerebbe passarci dentro una settimana. E aggiunge che già all'inizio degli anni '60 lui aveva stimato che il passaggio veloce di un veicolo spaziale (15 minuti per attraversare la zona più pericolosa, 2 ore per attraversare anche le zone più deboli) avrebbe provocato solo l'1% della dose fatale di radiazione sugli astronauti. Un rischio molto minore di qualunque altro legato a quel tipo di viaggio. Dice anche che quelle sue stime sono ancora attendibili.
Dear Mr. Lambert,
In reply to your e-mail, I send you the following copy of a response that I wrote to another inquiry about 2 months ago --
Ø The radiation belts of the Earth do, indeed, pose important constraints on the safety of human space flight.
Ø The very energetic (tens to hundreds of MeV) protons in the inner radiation belt are the most dangerous and most difficult to shield against. Specifically, prolonged flights (i.e., ones of many months' duration) of humans or other animals in orbits about the Earth must be conducted at altitudes less than about 250 miles in order to avoid significant radiation exposure.
Ø A person in the cabin of a space shuttle in a circular equatorial orbit in the most intense region of the inner radiation belt, at an altitude of about 1000 miles, would be subjected to a fatal dosage of radiation in about one week.
Ø However, the outbound and inbound trajectories of the Apollo spacecraft cut through the outer portions of the inner belt and because of their high speed spent only about 15 minutes in traversing the region and less than 2 hours in traversing the much less penetrating radiation in the outer radiation belt. The resulting radiation exposure for the round trip was less than 1% of a fatal dosage - a very minor risk among the far greater other risks of such flights. I made such estimates in the early 1960s and so informed NASA engineers who were planning the Apollo flights. These estimates are still reliable.
Ø The recent Fox TV show, which I saw, is an ingenious and entertaining assemblage of nonsense. The claim that radiation exposure during the Apollo missions would have been fatal to the astronauts is only one example of such nonsense.
James A. Van Allen
Dunque Van Allen dice che per poter avere dei danni dall'esposizione a quelle radiazioni bisognerebbe passarci dentro una settimana. E aggiunge che già all'inizio degli anni '60 lui aveva stimato che il passaggio veloce di un veicolo spaziale (15 minuti per attraversare la zona più pericolosa, 2 ore per attraversare anche le zone più deboli) avrebbe provocato solo l'1% della dose fatale di radiazione sugli astronauti. Un rischio molto minore di qualunque altro legato a quel tipo di viaggio. Dice anche che quelle sue stime sono ancora attendibili.
Messaggio orinale: https://old.luogocomune.net/site/newbb/viewtopic.php?forum=13&topic_id=4284&post_id=116051