NASA Deep Space 1 makes a new space record

Imran Ghory writes "The NASA spacecraft, Deep Space 1 which is based upon an ion drive has achieved the longest operating time for a propulsion system in space. So far it has travelled 332 million kilometers(206 million miles), daily logs are available here."

Comments

why?

[gammatron]

why is it that all the "interesting" stories aren't linked to from the front page? I thought I might have some categories excluded, but I don't. It isn't just me, as these "hidden" stories have almost no trolls, and hardly any comments...
--

Re:why?

[Kris_J]

I have a very heavily filtered front page, but when I have time I click on the "older stuff" link to see a quick list of what else is going on. Works well, I recommend the technique (hmm, maybe I should patent it...)

Re:why?

[don_carnage]

It's not front page cause it's not about GNOME, KDE, Linux or RIAA. 8^)

Oops -- did I say that outloud? There goes my karma!

--

Re:why?

[QuoteMstr]

Actually, no. I saw this story in the Science slashbox.

Gives new meaning to the term "Gas Mileage"

[human bean]

Let's see, three hundred and seventy-five million miles divided by six and one half gallons (I'm making some assumptions about how NASA would store liquid xenon gas...) is 57692307 miles per gallon.

I want my van to get this...

Re:Gives new meaning to the term "Gas Mileage"

[Kris_J]

I want my van to get this...

And if you pushed it around yourself (a force still millions of times stronger than the ion engine) it would.

Why not for humans?

[gurgi]

Why not make the ion engine more powerful and use this for humans? Even if it was running at 1/100 of a G it would make travel to other planets trival. I belive Heinlein wrote an essay on this once.

Re:Why not for humans?

[calcfreak901]

If I remember correctly, ion engines have exhaust velocities that vary inversely with thrust. That is why this particular ion engine is able to have such a long running time; it sends out ions one at a time at approximately 60000 miles per hour. In order to make the thrust equal to 1/100 of a G, the velocity would be greatly reduced; a variable-velocity engine would likely be well-suited to interplanetary travel.

However, not even this would be adequate for interstellar travel. Provided the speed of light is not exceeded, either by distorting the space-time continuum or by traveling through time (okay, so those are basically one in the same), matter-antimatter reaction rockets are the only theoretically practical form of propulsion. despite the allure of exhaust velocities near the speed of light and large amounts of thrust, that would have problems with creating and storing large amounts of antimatter. A slower but much more viable solution that is still quite fast is nuclear fusion rockets. These fuse heavy isotopes of hydrogen and/or helium-3 to create enormous amounts of thrust with very fast exhaust velocities. It is also possible to fuse ordinary protium, but this is much more difficult than with deuterium, tritium, and helium-3. If protium fusion is efficiently possible, it would enable an almost endless supply of fuel, because hydrogen gas is found in densities of approximately one atom per 10 ccs in space. A magnetic scoop could funnel these into the fusion rocket, thereby enabling very long burn times and vehicle velocities of significant percentages of the speed of light.

Theoretical possibilities for infinite or near-infinite velocities are many many decades into the future, if possible at all. These include manipulating zero-point energy and neutrino jets. The feasability of these according to the laws of physics are largely unknown. While theoretically possible, it will likely take at least another: Bohr, Einstein, Fermi, and Oppenheimer to even begin to test those ideas.

All this came from the mind of a high school junior!

Re:Why not for humans?

[esonik]

Just in case you don't already know these:

• Antimatter and Fusion for rocket propulsion
• NASA Advanced Space Transportation Program
• NASA Breakthrough Propulsion Physics Program

Now manipulating neutrinos is really hard - most of them pass right through earth without noticing it.

You will love studying physics ;-)

Ion Propulsion

[esonik]

Unfortunately xenon is much more expensive than fuel *g* (don't know the numbers though). Note that the energy for propulsion is provided by the solar panels, the xenon gas only serves the purpose of being "thrown away" at high velocity (>110000 km/h). This high exit velocity is the main advantage over chemical propulsion (need less mass for same acceleration).

Re:Ion Propulsion

[esonik]

Now I'm not an expert for ion propulsion, but I can think of some reasons why xenon rather than helium:

1. Helium leaks out very easily (in fact helium is the gas that leaks most easily, it is used to trace vacuum leaks)
2. Helium is lighter than Xenon, i.e. the charge/mass ratio of the ions is probably worse (higher) than for xenon. You want as much mass per charge as possible, in order to reduce space charge effects (i.e. screening of the accelerating field by the ions)
3. Now Xenon isn't *that* expensive, probably just several kilo-bucks for those 80kg.

You may want to check this site: Xenon Ion Propulsion.

Re:DS1 Mission Log archives

[chrissam]

The archives are at http://nmp.jpl.nasa.gov/ds1/archives.html and date back to October 1998.

JPL's main website (www.jpl.nasa.gov) also has lots of links to their other projects.


--

The ion drive is old story

[efuseekay]

I wondered why DS1 tout the ion drive as "new".
It's being used on Geosync Communication satellites as attitude thrusters for years (which due to the high efficiency, extend the life of Geosynchs by a factor of 2).

Gallons or pounds? NASA makes hard word problems!

[GMontag]

From the log on the website:
"That fantastically efficient propulsion system uses only about 100 grams of xenon propellant each day (or about one pound every 4 days)."

Also:
"Today, the ion propulsion system has logged 195 days of operation."

So, 195 days * .25 pounds == 48.75 pounds consumed thusfar.

But, they also have this:
"To reach the correct point in space and time to greet the comet as it streaks around the Sun, DS1 will need to thrust with its advanced ion propulsion system for about 8 months. It has now completed over a month of that thrusting, since resuming powered flight at the end of June."

So, we might assume that it has actually been thrusting for 195 days with the most recent consecutive days being the last 30 days.

8 months == ~ 240 days total

So, 240 * .25 Lbs. == 60 Lbs. of gas (with 48.75 pounds consumed thusfar).

How tightly that gas is packed per gallon is someone else's guess.

Visit DC2600