Author Topic: Radiation  (Read 45104 times)

Offline benparry

  • Earth
  • ***
  • Posts: 193
Radiation
« on: March 19, 2018, 01:56:16 PM »
Hey guys I have a question about radiation which stems from a discussion I have had with a guy on a Facebook group. He contends that the daily dose of radiation from a LEO mission should be magnitudes lower than the daily disease of any of the Apollo lunar missions. He comments that with the VAN protecting us etc and the fact that radiation outside of this and on the surface of the moon is much higher than it is inside the VAN for LEO missions why are the daily dose inside the LEO missions not much lower than the moon missions

Offline Northern Lurker

  • Venus
  • **
  • Posts: 77
Re: Radiation
« Reply #1 on: March 19, 2018, 03:21:30 PM »
Which Apollo mission? Compared to which LEO mission? Does he know about radiation in cislunar space? Radiation in LEO? Type, flux and energy distribution of radiation in LEO and cislunar space? How much Apollo craft attenuates radiation? How much craft in LEO attenuates? Are radiation doses to be compared in same units and in lengths of exposure?

If he doesn't have any any clue in any of those questions, he is just handwaving.

If he is comparing ISS dose to Apollo dose, one must remember that ISS makes about 15 orbits every day and each orbit skirts the South Atlantic Anomaly which is low hanging part of Van Allen belts. It adds radiation doses in LEO. Also radiation exposure in LEO is much bigger than under the atmosphere.

Lurky

Offline benparry

  • Earth
  • ***
  • Posts: 193
Re: Radiation
« Reply #2 on: March 19, 2018, 03:23:07 PM »
hey lurky. I think what might be best here is to ask Tim to join this forum and put forward the points himself.

Offline benparry

  • Earth
  • ***
  • Posts: 193
Re: Radiation
« Reply #3 on: March 19, 2018, 03:25:26 PM »
he did however share this pic


Offline Northern Lurker

  • Venus
  • **
  • Posts: 77
Re: Radiation
« Reply #4 on: March 19, 2018, 03:49:04 PM »
Well I'm not an expert in radiation. As an informed amateur I have some idea about the questions to be asked.

I noticed from your attachment that ASTP and Apollo 7 which flew at about 200 km. Skylab was around where ISS is today and I'd quess SAA makes the difference.

Offline benparry

  • Earth
  • ***
  • Posts: 193
Re: Radiation
« Reply #5 on: March 19, 2018, 03:54:11 PM »
I think he was querying the Apollo missions. am I correct in saying 7 and 9 were LEO missions whereas the rest went to the moon. basically he thinks the moon ones should be more

Offline raven

  • Saturn
  • ****
  • Posts: 1378
Re: Radiation
« Reply #6 on: March 19, 2018, 06:04:01 PM »
I think he was querying the Apollo missions. am I correct in saying 7 and 9 were LEO missions whereas the rest went to the moon. basically he thinks the moon ones should be more
And what is he basing that on? Soviet soft lander Luna 9 only measured 30 millirads a day. (see page 12 of this PDF which corroborates with ever other source I've found so far) and the radiation exposure experiments aboard Zond 5 and 7, which, like Apollo, went to the moon and returned to Earth, found that (see page 4 here)  "Seven day flights along´╗┐ the trajectories of the Zond-5 and 7 probes are safe from the radiation point of view." And these are both results from the USSR.

Offline benparry

  • Earth
  • ***
  • Posts: 193
Re: Radiation
« Reply #7 on: March 19, 2018, 06:11:37 PM »
he is basically saying that using logic, if the area outside of the LEO is higher in radiation (this includes the VAB and also the general outer space) then missions in these areas should have a higher daily dose than missions that are withing LEO and lower in radiation

Offline raven

  • Saturn
  • ****
  • Posts: 1378
Re: Radiation
« Reply #8 on: March 19, 2018, 07:26:00 PM »
he is basically saying that using logic, if the area outside of the LEO is higher in radiation (this includes the VAB and also the general outer space) then missions in these areas should have a higher daily dose than missions that are withing LEO and lower in radiation
Well, except in the case of Skylab mission, they did have a lower daily average dose, and Skylab passed repeatedly through the South Atlantic Anomaly, a portion of the VAB that extends lower into Low Earth Orbit. So his logic is flawed because he is not taking a radiation source into account.

Offline benparry

  • Earth
  • ***
  • Posts: 193
Re: Radiation
« Reply #9 on: March 20, 2018, 02:58:55 AM »
Hi Raven. is that also true for the Apollo 7 and 9. did they pass though the SAA too. I think he is saying that they should be magnitudes lower. I have given Tim the link for for this forum and he is going to set up an account so he can put forward his arguments.

Offline raven

  • Saturn
  • ****
  • Posts: 1378
Re: Radiation
« Reply #10 on: March 20, 2018, 03:16:30 AM »
Hi Raven. is that also true for the Apollo 7 and 9. did they pass though the SAA too. I think he is saying that they should be magnitudes lower. I have given Tim the link for for this forum and he is going to set up an account so he can put forward his arguments.
I honestly don't know special, but given how much lower Apollo 7 and 9's orbit was compared to Skylab, the exposure would be at least a little less.  As for it being magnitudes less, I'd like to see what he's basing that on. I am no means an expert on this matter and I know most, if not all, people here know much more about the details of Apollo than I.

Offline benparry

  • Earth
  • ***
  • Posts: 193
Re: Radiation
« Reply #11 on: March 20, 2018, 04:19:01 AM »
I think he is basing it on the fact (his words) that the VAB protect us 10*3 from radiation and the fact that radiation is much higher in outer space than within the confines of the LEO safety

Offline Jason Thompson

  • Saturn
  • ****
  • Posts: 1348
Re: Radiation
« Reply #12 on: March 20, 2018, 08:11:52 AM »
The first question has to be what he understands by the term 'radiation'. Many people, especially those who see it as a relevant concern in the Apollo hoax idea, think of radiation as some big, all-penetrating thing that makes you sick and kills you. What few of them, in my experience, realise is the wide variety of kinds of radiation that exist, and hence that an argument that just talks about 'radiation levels' is meaningless and inconclusive. Light and heat are also forms of radiation.

The VAB, for example, is not actually protecting us. The magnetic field of the Earth does that, and in trapping the particle radiation from the solar wind it creates the VABs. Of course in trapping those particles it makes the VABs a region of high radiation, but it's particle radiation. A lot of that can be blocked, or at least attenuated, by spacecraft hulls and insulation, and as it's a belt it can be avoided almost entirely. Some of the EM radiation can be blocked by a spacesuit. UV radiation, for instance, can't penetrate a white spacesuit or even the clear polycarbonate of the helmet. It doesn't matter what the radiation levels in space are if you happen to be encased in something that can reduce the exposure significantly anyway. His 'logic' is based on a very shaky premise.

He should also consider that we have decades of data about the radiation levels in space, a significant amount of which is important for commercial revenue. Satellites are just as susceptible to radiation as humans (more so, since a human body can repair itself while satellite electronics cannot), and we depend on them these days for communications, GPS, and so on. Does your friend honestly think he's the first person to look at the data and realise it exposes a hoax of the scale of the Apollo program rather than people who understand the subject realising it does no such thing and so maybe he should take that into consideration?
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline benparry

  • Earth
  • ***
  • Posts: 193
Re: Radiation
« Reply #13 on: March 20, 2018, 08:49:19 AM »
Hi Jason thanks for your reply. I have actually given him this link so he can view the thread. I think he's going to open an account so he can discuss directly his concerns.

Offline JayUtah

  • Neptune
  • ****
  • Posts: 2715
    • Clavius
Re: Radiation
« Reply #14 on: March 20, 2018, 11:09:52 AM »
I think he is basing it on the fact (his words) that the VAB protect us 10*3 from radiation and the fact that radiation is much higher in outer space than within the confines of the LEO safety

The Van Allen belts (or more specifically, the interrelated phenomena to which Jason Thompson refers) indeed protect us from radiation when there is radiation.  Specifically they protect us from solar radiation in the form of the various fits it throws from time to time.  A quiescent sun doesn't really put out enough radiation to worry about.  Galactic cosmic radiation is not really attenuated by the Van Allen belts since it is electromagnetically neutral.  The key misconception here is that the radiation environment outside the VAB must be so much greater than inside it, barring an ongoing solar event.  That's just not true.  There is only a marginal increase in radiation exposure outside the VAB, and it is easily shielded for -- especially for short missions.

Ironically for orbital missions it is the VAB, specifically the Southern Atlantic Anomaly, that poses a greater problem.  Because of the difference in alignment between Earth's rotational axis and its magnetic axis, many manned orbital missions take the spacecraft (or space station) through the SAA, which is a low-hanging region of the inner Van Allen Belt.  This can happen several times a week, or even several times a day.  This is actually a more dangerous exposure since it occurs so frequently.  The actual received doses are small, especially behind polyethylene shielding.  But the fact that they occur often mean an organism doesn't have time to heal from each exposure, and the effect accumulates.  it's actually safer to send someone on a two-week mission in deep space because the exposure is a one-time thing.
"Facts are stubborn things." --John Adams