The Van Allen Belts

Came across a video on youtube outlining the the new Orion spacecraft mission and the guy seems to be alluring to the fact that there are still problems pertaining to travel through the the Van Allen Belts regarding radiation and communications.

Don't get me wrong i believe we went to the Moon in 1969 with the Apollo program, im just wondering why this seems to be an issue for a spacecraft designed almost 50 years later, given the advances we have made with materials?

Because the people building today's rockets have nothing on their Nazi predecessors.


We'll get back there eventually though.

a reply to: andy06shake

If they were re-using the same craft as was used in Apollo, and the same flight paths, there would be no issues. Proven technology that works.

However: Orion is a completely brand new craft, built with materials and very sensitive electronic equipment that did not exist in the 1960s.

The belts have always been an issue. But there are answers to those issues: testing shielding, limiting the amount of time for exposure, and finding out how well our newer tech will work.

This means lots of testing (like the space shot they did with it over a year ago, unmanned), and making sure that any astronauts that do get in it are going to be okay.

a reply to: Hazardous1408

One would have thought they would have summarized and/or recorded there production techniques and procedures from the Apollo missions through. I'm sure they did really so why the issue now, whats changed up there?

a reply to: andy06shake

This is the answer to your questions. Nothing has changed up there.

www.abovetopsecret.com...

Its impossible to avoid the radiation belts entirely, the idea is to plot a trajectory that avoids them, reducing exposure as much as possible. The apollo missions accomplished this making earth escape trajectory inclined to avoid most of the radiation. They would have to do it again just so. Sooo, whats the problem again? Cost.

Graph

a reply to: andy06shake

You'll have noticed that he doesn't list 'and the people die of radiation poisoning', he's saying that the electronics need to be protected.

Apollo used magnetic core memory and a processor made out of RTL running instructions at about 100kHz. Things are a bit different now.

You will also have noticed that the video is played up to be super dramatic.

a reply to: eriktheawful

I relies why they are doing the tests and that the Orion design is somewhat more advanced and designed for multiple different mission scenarios. I just find it strange the guy seems to imply the belts being a major problem when Apollo already encountered them and even went further than they extend.

a reply to: Bedlam

So its really just an issue as to them hardening there electronics and other key systems from the radiation that's the issue. That makes a whole lot more sense.

Thanks Bedlam.

A while ago, I ran the numbers for Apollo 11's trajectory using Robert Braeunig's numbers ( www.braeunig.us... ) and an areal density of 7~8 g/cm^2 for the Apollo spacecraft. I used Spenvis to calculate the expected dose, using a 2-body approximation of Apollo 11's outbound trajectory over half the mission duration (lunar gravity not accounted for, so it just lingers out in cis-lunar space for the simulation, with no shielding from the moon itself).
h.dropcanvas.com...
The result was less than a rad of expected radiation. Not dangerous at all, even if you double it for a full mission duration with a return leg (and again, not accounting for any shielding the moon itself may provide while in lunar orbit). Here's a diagram showing a slice view of Apollo's trajectory:
www.youtube.com...

I compared this to the trajectory of Orion EFT-1's 3600 mile orbit. In the video you posted OP he says "we need to learn more about this region of space before we send people through it." Well here is the expected dose if you were to send Apollo astronauts in an Apollo command module on the same trajectory as Orion EFT-1's final orbit:
h.dropcanvas.com...
Nearly 30 rads of radiation, almost entirely from trapped proton radiation in the inner Van Allen Belt. It's not lethal, but at that dose you are approaching the threshold at which you may start to exhibit mild symptoms of radiation poisoning according to the CDC:

"Mild symptoms may be observed with doses as low as 0.3 Gy or 30 rads."
www.bt.cdc.gov...

Still won't kill you, but it might just make you sick if you fly Orion EFT-1's trajectory with the older Apollo capsule. Obviously that's not desirable, and it's also not the same region of space covered by Apollo. Quite literally you can not safely pass through the region of space traversed by Orion EFT-1 using the older Apollo capsules. Apollo took an inclined trajectory to the moon and did not pass directly through the most intense region of the inner Van Allen belt. Orion basically did just that and deliberately passed through the most intense region.

In fact (almost certainly by design), Orion's trajectory placed it near the edge of the South Atlantic Anomaly, an area of higher radiation where the Van Allen Belt dips lower than normal, as it crossed the 1000 km mark to enter the edge of the inner Van Allen belt. Here's a screenshot from Brent Boshart's satellite tracker showing where Orion EFT-1 was as it crossed the 1000 km altitude mark: h.dropcanvas.com... . Given a peak altitude of 3600 miles or about 5800 km, it basically stayed within the inner belt from that time until it came screaming back down towards re-entry in the Pacific. Wiki lists the inner Van Allen belt limits at 1000 km to 6000 km (en.wikipedia.org...). The wiki for EFT-1 also lists this period at 1000 km near the SAA as being the first of two of the highest radiation periods during the mission (en.wikipedia.org... ).

In any case, manned Apollo flights obviously did not use this kind of "worst case scenario" trajectory which spends an entire orbit lingering in the inner Van Allen Belt, and transiting into it near the SAA at the worst possible location. EFT-1 was partly to test the radiation resilience of the new Orion capsule. Its computer systems are vulnerable to "bit flips" and memory upsets in ways that the core rope memory of the old Apollo Guidance Computer would not have been.

I just really hope when they do, that they can record it. And stream it to us. There's nothing more that I want to see right now, than what it's like to sail through space. I want to see it so bad! I've accepted that I'll likely never experience it first hand, so I'm counting on the Astronauts of Tomorrow to help bring my dreams to fruition.

I really hope they can work out the VAB issues.

-Alee

that young NASA guy on the video sounds like he's never heard of, or dealt with, the Apollo systems....bizarre NON-reference to the entire Apollo program...and then they wonder why the landing on the Moon skepticism is still around

originally posted by: andy06shake
a reply to: eriktheawful

I relies why they are doing the tests and that the Orion design is somewhat more advanced and designed for multiple different mission scenarios. I just find it strange the guy seems to imply the belts being a major problem when Apollo already encountered them and even went further than they extend.

Oh no no no no....

Orion is not "somewhat" more advanced. It is MUCH MUCH more advanced than any of the Apollo craft were!

originally posted by: andy06shake
a reply to: Bedlam

So its really just an issue as to them hardening there electronics and other key systems from the radiation that's the issue. That makes a whole lot more sense.

Thanks Bedlam.

Then, too, going to Mars they'll spend a LONG time out of the Earth and Moon's magnetic fields. Even though the Moon doesn't have a BIG field, it's enough to provide SOME protection. In interplanetary space, there's a good bit of radiation over a much longer period of time. I'd be more worried about that, frankly, than a single exposure gotten from the VAB as you dive through it as fast as you can manage.

Is it just me or has this video been posted on ATS at least a dozen times over the years??

a reply to: charolais

Well it's only a couple of years old on YouTube, which is where i came across it.

Possibly it has in the past been posted but if it has i have not came across it.

Can you provide links to these dozen other threads that allegedly contain said video here on ATS?

a reply to: charolais

It's been used in a few Moon Landing Hoax threads as "proof" we didn't go. I believe they are floating around in the Skunk Works forum.

originally posted by: andy06shake
a reply to: charolais

Well it's only a couple of years old on YouTube, which is where i came across it.

Possibly it has in the past been posted but if it has i have not came across it.

Can you provide links to these dozen other threads that allegedly contain said video here on ATS?

OK maybe I exaggerated a little bit, but it's definitely been included in a few threads!

one
two
three
four (it's part of a larger video in OP)

For the same reasons new aircraft models need to be test-flown despite the fact that the Wright brothers figured the flying business over 100 years ago. New materials, new technologies, new safety requirements.