A Deep Space Primer

phil reed writes "With the latest Mars missions still in the news, people might be curious about what it takes to actually run a deep space mission: how a spacecraft is designed, how the communications are handled, what kind of project management is in place to make it all work. The Jet Propulsion Laboratory has a primer online that gives broad general coverage of all aspects of putting a satellite into orbit and how to manage it once it's there. Fascinating reading, with lots of links to more detail."

Comments

how the communications are handled

[iminplaya]

veerryy sloowwly. What is it? 20 minutes to mars and back? Light speed won't cut it when we talk about going anywhere farther than the moon. At our current level of comprehension, it's just not practical to go any father than Mars. We need to dream up something entirely different. Something that works like a very long tube filled with ping pong balls for example. Push one into one end and one pops out the other instantly, no matter how long the tube. I'm sure somebody has thought of this and has a name for it, but I sure don't know what it is.

Re:how the communications are handled

[iminplaya]

I posted this thought in another reply...If the "wire" is perfectly rigid, and you push the wire itself, will the whole wire move at the same time?

Re:how the communications are handled

[GigsVT]

Hey, I found exactly this question addressed.

Deep Space?

[glrotate]

Is Mars Deep Space? Shouldn't that term at least be reserved for regions outside the solar system? Or is that "Outer Space"?

Re: communications: Interplantary Internet

[G4from128k]

20 minutes to mars and back? Light speed won't cut it when we talk about going anywhere farther than the moon.

Its more than just the long delay. Interplanetary networking is quite tricky due to the limited bandwidth, line-of-sight interruptions, the need to slew expensive high-gain antennas into precise scheduled pointing directions, as well as the massive levels of latency.

Re:Long-feedback cycles and good design

[steveha]

You are absolutely right -- for the current way we do space.

But I look forward to the day when we can develop space hardware the same incremental way we develop other things. When flying into space is as cheap as flying to Australia, we won't have to have massive, incredibly careful engineering projects. We can just try stuff and go with what works.

P.S. Am I naive to think we can go to space as cheaply as going to Australia? No. We can't do it with the Space Shuttle, which requires many man-years of labor to rebuild after each flight. And we can't do it with expendable boosters, which are completely destroyed when you use them. We will need actually reusable spacecraft. I fear that NASA is no longer, as an organziation, able to build them, but someone else will. Go Xcor! Go Armadillo Aerospace! Go... anyone building these things.

steveha

not quite deep space

[ryanw]

I would see people telneting into satalites from time to time while I worked at Motorola as a unix admin. I was at the plant that built & maintained the hardware and software for the satalites for Iridium. It was interesting to hear engineers talk about the expensive mass of satalites which was at the time (2000) an already outdated network with not enough bandwidth.

The iridium network has only one location on the planet where communications actually uplinks and downlinks to land communications. Of course they have the ability to communicate to any one of the three or four sites if one were to fail, but it would only use one at any given time.

So if you made a call in antartica on a iridium sat phone to someone on a land line it would back haul the traffic using line of sight communications leap frogging each satalite before having the uplink/downlink to the ground. So I think it was a total of like 6 hops or something max unless there were of course other issues with the network, it could reroute through any visible satalites.

So the bandwidth of the entire network is limited to that one uplink/downlink which rotates satalites on an almost hourly basis. So it's not like they could make 1 satalite that could support more bandwidth communication to the ground than the others, they're all built the same. Any iridium sataliate can take the place of any other.

I know it's way off topic, but interesting to me none the less..

The now defunct Breakthrough Propulsion Project

[Pausanias]

Some of us like solar system exploration just fine, but already have our imaginations fixed on what it would take to get to the other stars. Rocks from Mars may be exciting, but getting to Alpha Centauri would be even more exciting, to say the least.

NASA used to have a project devoted to seriously studying what it would take to achieve interstellar travel. Unfortunately, funding for it got cut off in 2002. However, they did manage to publish several papers and still have their results online at the BPP site.

Here is a quote from the abstract of one of their papers:

To travel to our neighboring stars as practically as envisioned by science fiction, breakthroughs in science are required. One of these breakthroughs is to discover a self-contained means of propulsion that requires no propellant. To chart a path toward such a discovery, seven hypothetical space drives are presented to illustrate the specific unsolved challenges and associated research objectives toward this ambition. One research objective is to discover a means to asymmetrically interact with the electromagnetic fluctuations of the vacuum. Another is to develop a physics that describes inertia, gravity, or the properties of spacetime as a function of electromagnetics that leads to using electromagnetic technology for inducing propulsive forces. Another is to determine if negative mass exists or if its properties can be synthesized. An alternative approach that covers the possibility that negative mass might not exist is to develop a formalism of Mach's Principle or reformulate ether concepts to lay a foundation for addressing reaction forces and conservation of momentum with space drives.

Re:No thanks

[photonX]

I remember a Mad Magazine piece when I was a kid (mid-Sixties, I guess) titled something like: "Kids: build your own 707!" It used four of those cylinder-type Electrolux vacuum cleaners for engines, presumably with really long extension cords...If we could only build a *really* big catapult, then the sky's the limit!

Seriously, it's easy to forget that just a century ago we were literally a horse-and-buggy civilization, and how amazing it is that we can make these things work at all. I was talking to a youngster at work the other day, and was suprised to learn that he didn't know what a slide rule was. Now our tools and toys are an order of magnitude better than when we went to the Moon, but we still have a lot of learning to do.

I can never get tired of watching those same rehashed rocket shows on the science channels, so thanks to the originator for the link!