Space Forum / Space Flight / August 2006

No, the storage mediums are too allergic to magnetic field disturbances
in the solar radiation field, as well as in the vicinity of Jupiter:

from thread:

[...http://groups.google.com/group/sci.space.policy/browse_frm
/thread/c908cbed581e70/6501c0af54ba70bd?lnk=st&q=&rnum=7#
6501c0af54ba70bd...]

Radio and Plasma wave data were obtained on December 3, 2000 by the
Cassini Radio and Plasma Wave Science (RPWS) investigation from a
distance of just over 27 million kilometers from Jupiter: During this
time period, the RPWS captured radio emissions generated in the
vicinity of Jupiter. These emissions included decametric radio
emissions originating in the auroral regions of Jupiter.
(Decametric refers to approximate wavelength of radio emissions
(10 meters). At somewhat lower frequencies, near 1 megahertz, the
hectometric radiation, around 100 meters, is generated as a part
of the auroral process at Jupiter. Lower in frequency, near 100
kilohertz, are examples of two types of kilometric radiation.
(Kilometric refers to wavelengths around 1 kilometer or 1000
meters.) Even though these two types of emissions are centered at
about the same frequency, they are thought to originate in totally
different locations and by totally different mechanisms. The
broadband kilometric radiation near the center of the display is
again believed to be generated on field lines associated with the
aurora and probably generated by the same or similar mechanism as
the decametric and hectometric radiation. The narrowband kilometric
radiation is generated near the outer edge of the Io torus, which
remains on a different orbital path than Europa. Data on Quasi-
periodic bursts below about 10 kilohertz consist of brief bursts
and sometimes occur at about 15-minute spacing, and sometimes at
about 40-minute spacing. Even though these emissions were discov-
ered by Voyager and studied by Ulysses and Galileo. Very little is
known about where and how they are generated.

(From: http://www2.jpl.nasa.gov/galileo/messenger/oldmess/Ion.html):

On Jupiter's moon, Io, volcanoes constantly erupt, spewing forth
oxygen and sulphur, which then settle on Io's surface. The inter-
action of Io with Jupiter's magnetosphere strips the oxygen and
sulphur from Io's surface at the rate of 900 kg (1 ton) per second,
tearing these particles from Io's gravitational influence and expel-
ling them into Jupiter's magnetosphere. These particles become elec-
trically charged and many diffuse outward to 1.5 to 3.6 million
kilometers (0.9 to 2.2 million miles) from Jupiter, where they are
accelerated by an interaction with the massive Jovian magnetic
field. Ed explains, "About 0.2% of the original particles, now
highly energized, diffuse back toward Jupiter. The ions may have
left Io at one-thousandth the speed of light. By the time they have
returned to within 700,000 kilometers (420,000 miles) of the planet
(near Europa's orbit), these ions have accelerated to one-tenth
the speed of light (about 30,000 kilometers/second (18,000 miles per
hour))!" Some of these ions travel along Jupiter's magnetic field
lines and spiral into the planet's polar region. In fact, these
heavy ions falling into Jupiter's atmosphere may be the single
largest contributor to Jupiter's auroras.

So what do we replace "Hard Drives" with? Try the new optical
storage medium that was invented by the Israelis, whose link
is now defunct, but can also be read at the Wired website:

http://www.wired.com/news/technology/0,1282,61009,00.html

Also try typing in the Google Search engine the words "optical
storage" and "optical processing" and see what Taiwan has been
up to, as well as the rest of the world trying to play "catch up".

PLease clarify what you are saying, cause last time i checked all our
space vehicles had hard drives.

peace
zonker

http://2000ah.blogspot.com

My guess is that Hard Drives are too prone to magnetic turbulence both
in
the Van Allen Belt and Jupiter, therefore not a good storage/processing

medium. There are several methods for holographic storage, one
interesting
one being 3D Atomic Holographic, as seen by one Colossal Storage Corp.:

http://www.i4u.com/article481.html

While there are currently lesser technologies that are exploring
holographic
storage and processing, this technology seems to be at the cutting
edge.
My belief is that these technologies will advance in tandem to some
kind
of FTL propulsion technology, unless, of course, our currently
antiquated
types keep us earthbound.

Reliability. Tape drives and solid state storage have demonstrated
endurances of decades. The moving platters of hard drives do not yet
have the same reputation for reliability.

Mike Miller

Reliability would probably be a problem.

But more interestingly, spinning a drive would change the attitude of
the spacecraft (a la reaction wheels).  I think there may have been at
least one mission which avoided this by having two drives spinning in
opposite directions.  But given the alternatives to hard drives these
days, I'd be quite surprised to see this done now.

Well there you go.  Since you're not likely to collect 400 Gb all at
once, that means you put too much storage on board.  (We tend to not do
a whole lot of flybys anymore, so there isn't one giant burst of data
collection.)  So the basic reasons are:

1.  The data rates from deep space are low, limiting the sustained
collection rates.  You simply don't have any use for storing months
worth of collected data, so you don't really need that much storage.  A
few weeks worth is plenty.

2.  Qualifying (and possibly making design changes to) hard drives to
survive the launch, and in some cases landing environment, not to
mention working in a either a vacuum or a pressure vessel and working
in zero-G, would be an expensive proposition.  I haven't heard of such
a qualification having been done, but it may have.

3.  On the other hand, flash memory is already qualified.  The higher
$/GB of flash memory is not a factor for spacecraft, and the kg/GB is
comparable or better for flash (depending on packaging).

4.  The fewer critical mechanical devices on a spacecraft, the better.
Hard drives crash, flash memory doesn't.

That doesn't mean that some deep space application won't come along
that makes putting a hard drive on it worthwhile somehow.  It's
conceivable, for some application with very high bursts of high rate
data.  Even in that case, I still think the trade between hard drive
and flash will be a close one.  It would basically come down to mass
vs. reliability.  I'd bet on the flash.

mark

Mostly because hard drives have moving parts, and moving parts are a
serious annoyance to engineers who have to design hardware that absolutely
must work for years at a time with absolutely no possibility of repair or
servicing.  

Also, hard drives require air to work - it's guaranteed head crash time if
you try to spin one up in vacuum.  You can seal them inside a pressurized
container, of course, but now you've got a set of seals that absolutely
must not leak, again for years at a time with no maintenance.

Usually, it's easier to go with some sort of no-moving-parts memory;
several technologies to chose from, and they'll hold enough data to keep
the scientists and journalists happy until the next mission.

power requirements, or perhaps the need to "float" the head on a cushion of
air to prevent head crashes.

see the thread on hard drives at 30,000 feet. Also consumer grade hard
drives are just not realiable enough. Its cheap to replace them here on
earth... but up there, on mars? or at Pluto? Solid state looks like the
way to go for deep space applications.

IIRC However i do belive that some LEO satlites may have use them. But
i could be totaly wrong there.

greg

I've no direct knowledge, but would think that the heating/cooling
cycles a deep space probe might encounter would be rather difficult on
a disc drive.  It is a rather delicate component - certainly compared
with say magtape and definitely so compared to core :) I would hazzard
a guess that a disc drive requires environmental conditions not too
far from those desired/required by humans.

rick jones