NASA Begins Planning For An Interstellar Mission In 2069 (nypost.com)

Long-time Slashdot reader cold fjord writes: During the 2017 Geophysical Union Conference, scientists from NASA's Jet Propulsion Laboratory revealed that they are planning an interstellar exploration mission for the year 2069. The goal is to send a probe to Alpha Centauri, some 4.3 light years away. NASA is working on technology to allow a spacecraft to reach 10% of the speed of light, which might allow them to reach Alpha Centauri in as soon as 44 years.

A number of technologies are being explored, although there are many practical hurdles. The New Scientist adds that the 2016 NASA budget directed NASA to study interstellar travel that could reach 10% of the speed of light by 2069.

Comments

Re:That's a PR stunt, not planning

[thinkwaitfast]

Fifty years is a long time. And with an ion engine, we would only need ~10^35000 kg of propellant!

Communications?

[HuskyDog]

Well one wishes them the best of luck, but it seems to me that going fast enough is only a tiny part of their problems and that getting any sort of useful communications back again is a least as big a challenge.

Consider the New Horizons mission to Pluto. The spacecraft is large and has a big high gain antenna. Also, it's power source hasn't been sitting around for 44 years. Never the less, data returns to earth at a few hundred bits per second.

Now consider Alpha Centauri. My quick calculations suggest that it is about 7000 times as far away (can someone confirm that?). Applying the inverse square law gives us a received power level - assuming the same transmit power and antennas - which is 77 dB (49000000 times) lower. Now, I am not saying that it can't be done, and I am sure that NASA have lots of very clever people, but as someone who has spend his career in radio and radar, finding an extra 77 dB is a very challenging requirement!

Re:Communications?

[HuskyDog]

Replying to my own post. A few more minutes though suggests that perhaps optical communications might work. I don't know very much about that technology, but preventing the receiving telescope from being blinded by the light from the star would clearly be a big issue to solve. Perhaps one could choose a wavelength where the star is relatively dark?

Aligning the transmitter sounds tricky, but presumably you could use the same optics to track the sun (which is presumably quite bright when viewed from Alpha Centauri).

Re:Donâ(TM)t. Be. That. Guy.

[K. S. Kyosuke]

It's spelled "you're" and "parties". And you have no idea.

Re:Can you spell "fusion"?

[Baron_Yam]

Fusion drives are actually quite a reasonable technological development to anticipate in the (relatively) near future. It's over-unity fusion we can't manage to crack. I also suspect we never will, and that only gravity can do it on a practical basis, but that's just an ignorant layman guess.

As long as you're not worried about a net energy gain, and you just want what is basically a particle beam created by a poorly confined fusion reaction, a fusion drive appears doable and the math says it'll give you about twice the velocity of a nuclear pulse drive.

After that... it's pipe dreams about micro probes riding massive solar sails and somehow managing to carry useful instrumentation and a strong communication laser.

That would be pretty useless

[Solandri]

The goal is to send a probe to Alpha Centauri, some 4.3 light years away. NASA is working on technology to allow a spacecraft to reach 10% of the speed of light, which might allow them to reach Alpha Centauri in as soon as 44 years.

First, warp drives do not exist (yet). You cannot instantly jump to 10% the speed of light and spend 44 years coasting to Alpha Centauri. To travel 4.3 light years with a constantly accelerating technology would require you to hit 20% the speed of light, not 10%. If you constantly accelerate up to 10% the speed of light by the time you reach the destination, then it'll take you 87 years to traverse 4.367 light years, not 44 years.

Second, you don't want to be accelerating the entire trip. Otherwise once you reach the destination, you're traveling way too fast for the trip to be of any use. Assuming the Alpha Centauri system is about the same size as our solar system, a probe reaching it at 20% the speed of light would pass through the entire system in a little over a day. It's stupid to travel 44 years just to have one day of science gathering. To be useful, you need to accelerate to the halfway point, the decelerate to the destination.

This means the trip of 44 years would require hitting 20% the speed of light by the halfway point - it would need twice the acceleration of a mission which hit 20% at the destination. So combined with the 10% vs 20% speed of light error, you actually need to develop a technology with 4x the acceleration of a mission which would arrive at Alpha Centuari at 10% the speed of light.

Re:That would be pretty useless

[Anonymous Coward]

What would make it impossible to speed up to 10 (or 20% for that matter) before being halfway? Why can't it hit 10% speed of light at 1% of the route and run out of energy to accelerate more?

Re:That would be pretty useless

[Zarhan]

Alastair Reynolds has a concept in Chasm City about a spaceship that has your more typical propulsion systems for minor adjustments, but they have two blocks of antimatter stored in a magnetic containment. They burn the first half as they are leaving Solar system, and then use the second half to decelerate at the end.

Now, since we can only generate antimatter a few atoms at a time - tops - the schedule is probably optimistic for such an approach. However, this is just to point our that there are alternatives to constant-thrust approach.

My money would be to use some sort of laser at Sun-earth Lagrange point to accelerate the ship, so they only need to bring propellant for the deceleration part. Another possibility would be a solar sail that would allow you to accelerate at this end and decelerate on approach.

Re:Can you spell "fusion"?

[K. S. Kyosuke]

But where do you get the energy to initiate the fusion in the first place? It's a similar issue as with open- vs. closed-cycle chemical engines. The energy to pump the propellant has to come from somewhere. Likewise, any practical interstellar fusion drive will necessarily have to have significant net electricity output to power itself. Otherwise it's just a slight boost to your initial energy source and you need yet another power source with nuclear-level of energy density, and we don't seem to know about any other. At best, you could make the argument that if, say, your fusion-products-to-electricity conversion is 10% efficient, then it might make still sense to use it as a thrust booster if you're only generating 4x your input, but there doesn't seem to be a significant jump from generating more energy than you put in to generating more electricity than you put in, unless your energy-to-electricity conversion rate for your fusion units is extremely bad, like 1% or so.

and the math says it'll give you about twice the velocity of a nuclear pulse drive.

Doesn't thermonuclear pulse drive already beat it?

Nope.

[gerald.edward.butler]

Quantum entangled particles DO NOT permit sending of information faster than light. You still have to send a "light-like" signal to know the results of the entanglement.

Use Santa's Sleigh and Reindeer.

[pubwvj]

Santa travels at close to the speed of light and uses existing technology. Seems like that is the place to start. It does narrow the launch window as he is busy one day a year.

Microscopic Spacecraft

[Gavagai80]

Accelerating any significant mass to .1c may be practically impossible. Perhaps the least unlikely approach, given our continuing miniaturization progress, is a spacecraft that weighs micrograms. Laser acceleration would seem to be an option, but the problem there is deceleration at the destination, and transmission of data back to Earth. What we really need is something super-light capable of using solar power to both accelerate and decelerate to a sizeable fraction of c, and then the transmission problem can be solved by having it make a return trip using the destination star for power.

The ultimate unrealistic extreme of this approach in sci-fi would be the sophons from Liu Cixin's The Three-Body Problem, which if I recall have the mass of one proton but unfold into useful spacecraft upon arrival.

Re:Actually thats a drug induced haze, not a PR st

[ShanghaiBill]

So it'd have to be a robot mission.

Duh. Both the summary and TFA make it clear that this would be a probe, not a manned mission. It would be a flyby, passing through the Alpha Centauri solar system in minutes, since slowing down and going into orbit would require exponentially more fuel. The proposals are for a probe the size of a pack of cigarettes, or even the size of a postage stamp, driven by a laser boosted sail.

The proposed budget is ~ $100M. A manned mission would cost many many trillions.

Re:Can you spell "fusion"?

[Rick Schumann]

Bussard Ramjet? It's total Science Fantasy, but if we can manage to make a fusion reactor that works, we might be able to design a ramscoop for interstellar hydrogen and a magnetic constriction to force a fusion reaction to use for propulsion.

Re:Can you spell "fusion"?

[K. S. Kyosuke]

Isn't than an entirely different issue? Unless you want to convert the kinetic energy of the particles into electricity. The problem here is how (while in interstellar space) do you provide the energy for ignition which is substantial. For pulsed reaction, you need to provide it for every pulse. In continuous reaction, perhaps you need it once a while, but that's the very definition of high net energy gain anyway and probably not what Baron_Yam had in mind when he spoke of "a poorly confined fusion reaction".