Humans in Zero-G

The article at:

http://www.spacedaily.com/reports/Co...g_Nuclear.html

includes the following:

"The Russian data show that the human body very quickly wants to get
rid of processes that cost it energy to maintain all of this bone
strength when there's no load on the bones and the heart doesn't have
to pump against gravity. The one guy who stayed up well over a year was
so badly deteriorated that after the Russians tried to get some of his
processes to restart, they realized they had to put him back up into
space for the rest of his life - but then about a week before he was
going to go up, his body finally responded, but his health has never
fully recovered."

Is that true? If so, which Cosmonaut was it?

wrote:
The article at:

http://www.spacedaily.com/reports/Could_NASA_Get_To_Pluto_Faster_Space_Expert_Says_Y es_By_Thinking_Nuclear.html

includes the following:
...

Is that true? If so, which Cosmonaut was it?
Valery Polyakov http://www.astronautix.com/astros/polyakov.htm holds
the record, at 437.75 days in a single flight (not the 462 claimed).

I don't know about his medical condition after that mission, but, some
other statements in that article ring my BSometer in a big way. For
example
PC: He was up for 462 days. The problem is that even the Moon's gravity isn't
significantly strong enough to elicit a gravity response by the human body. It has to be
at least one-fourth of a G.
There has been no research conducted that could possibly prove this,
given that the longest stay of a human in lunar gravity was measured in
days, and AFAIK no long-term partial gravity studies have even been
done on animals.

Also:
PC: The Russians have said that by 2050 they will have a highly efficient system that
uses an extremely small amount of propellant. It's almost a massless propulsion
system. It interacts with the space energy structure, producing extremely high-velocity
particles that come out of the engine.
That's just straight technobabble as far as I can tell, perhaps with a
vague relation to some crackpot claims. How can he know it will take
till 2050 (or 2060 later in the article) to produce ? If the principles
are understood, why would it take that long ? And if they aren't, how
can he be so sure it is possible at all ?

His implication that the Russians have off-the-shelf nuclear propulsion
is also misleading at best. No doubt they could come up with an RTG
powering an ion or hall thruster, but so could the US, and it wouldn't
provide the kind of high thrust he claims is needed. They do have a bit
more experience flying reactors (from the infamous RORsat program for
example), but even those don't provide anything close to the required
power, and the program was canceled years ago.

I was lucky enough to meet Dr. Polyakov at a party once. He was in
pretty good shape. Good enough shape to dance and flirt with the ladies.

I remember seeing pictures of him out jogging a day or two after landing
after a year or so on Mir.

The article at:

http://www.spacedaily.com/reports/Th...ce_Cadets.html

has more to say on the effects of long-term exposure to zero-G on the
human body, such as:

"No child could grow normally in the low lunar gravity. Even adult
astronauts are carried away on wheelchairs after only 6 months in space
(the last American to return from the ISS actually fainted from the
stress of normal gravity)."

Is long-term exposure to low-G really that bad for the human body? If
so, this might
bode ill for future long-duration manned spaceflights, or colonization
of the Moon or
Mars.

It is true that most Space Station crew cannot walk unassisted
immediately after return, but this is more due to balance problems than
deconditioning. After a few hours most can walk with at most someone
walking beside them to provide stability. Within a couple of days, so
far as I know, all Space Station crewmembers can walk normally. There s
bone and musle loss but the muscle loss and even most of the bone loss
is recoverable, and no one is documented to have ever had an unusual
fracture postflight. Intense exercise in space will reduce this
problem; Ed Lu, who exercised very intensively, was the first to spend
6 months in space and return without any significant bone or muscle
loss.

A child who never experiences gravity will probably not develop the
bone strength needed to walk on Earth, as can be seen in those with
cerebral palsey or paraplegia. Like the amphibans that must return to
the water to breed, we may have to return to the ancestral gravity well
to raise our young - unless they are to live only in space, and never
return to a planetary surface.

Nevertheless, there's reason to believe that adults can tolerate
weightlessness indefinitely, and if not, artificial gravity by
spacecraft rotation is probably practical.

Radiation is more problematic; how do we shield ourselves from cosmic
rays for years without crawling into a cave that would make the space
experience less meaningful? One approach is with an artificial magnetic
field.