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New Horizons: Nasa spacecraft speeds past Pluto

bbc.co.uk

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Re: New Horizons: Nasa spacecraft speeds past Pluto

#261

Post by yellowapple »

mturmon wrote: post #179
buyx wrote: post #143

Plutos "demotion" from being a fully-fledged planet makes me wonder if it would have been politically feasible to start the New Horizons project if the redefinition had happened a few years earlier. Still, I am pleasantly surprised by the excitement this mission is garnering.

It is well-known that the New Horizons PI, Alan Stern, had a strong distaste for the "demotion" of Pluto. (An extreme example, this interview: http://www.space.com/12710-pluto-defender-alan-stern-dwarf-p... , which is rather ... over the top in terms of its arguments.)

I actually think his core argument - that a "planet" should be determined by its physical characteristics rather than where its orbit happens to lie - is pretty reasoned and grounded in logic. I'm on his side about the whole "clearing the neighborhood" criterion; it's totally arbitrary, and has less to do with the object itself than it does with where that object lives.

Re: New Horizons: Nasa spacecraft speeds past Pluto

#262

Post by yellowapple »

chasing wrote: post #45

This is awesome. Congratulations to everyone who pulled this off (and fingers crossed that the data gets back successfully). Everyone has earned the right to chant the name of whatever country they feel like.

Sealand! Sealand! Sealand!

Re: New Horizons: Nasa spacecraft speeds past Pluto

#263

Post by bdamm »

Patrick_Devine wrote: post #169
bdamm wrote: post #156

Earlier quoted context omitted.

What, Kepler is fighting to keep the lights on? The greatest mission that NASA has ever undertaken? I'm saddened to hear that.

It's not helped by being hobbled with two of four broken reaction wheels. It's awesome that we've figured out a way to keep prolonging the mission. You can't argue with the results though; Over a thousand planets discovered with another four thousand candidates. I'm not sure why we don't have multiple Kepler-like missions running simultaneously to map out our entire section of the Milky Way.

How about a Kepler-like mission that uses perturbations instead of transits?

Re: New Horizons: Nasa spacecraft speeds past Pluto

#264

Post by acheron »

xyclos wrote: post #25
lmm wrote: post #15

> Nix is estimated to be about 35km across, and Hydra about 45km in diameter. Kerberos and Hydra are a lot smaller Is one of those Hydras supposed to be something else?

Probably. Styx is the other one.

I'm still disappointed none of them were named "Acheron".

Re: New Horizons: Nasa spacecraft speeds past Pluto

#265

Post by jccooper »

tlb wrote: post #152
el_duderino wrote: post #141

Earlier quoted context omitted.

The reason that the stars do not show up on the image is that the stars are so dim that the camera cannot gather enough of their light in a short exposure.

Since you can see stars near the moon, you should be able to see stars near Pluto, which is less bright. More likely, there are no stars in the (very narrow) angle of the camera.

You can see stars near the moon, but your eye has much better dynamic range than a camera.

See how many stars you see near pictures of the moon: https://www.google.com/search?q=moon&tbm=isch

Most photos from space don't capture stars unless they're trying to, because whatever object they're photographing is sufficiently bright to blow out any stars.

Re: New Horizons: Nasa spacecraft speeds past Pluto

#266

Post by InclinedPlane »

kartikkumar wrote: post #89

Quote from a friend of mine on the team: "After 9.5 years and 6 billion km, we made it to Pluto 72 seconds ahead of schedule." Amazing! The views of Pluto and Charon already reveal how incredibly fascinating this system is. The dichotomy of their surface colours will most definitely lead to further insight into formation processes in the Kuiper Belt. Just such a shame that we can't land this time around. With the vol…

Two things.

In the near future launch prices are going to be much lower, which changes the landscape in exploration and exploitation of space completely. That means that you can get more missions for fewer dollars. It means you can be more adventurous and innovative (since the cost of failure is lower and the time to recover is shorter). Which includes things like making increasing use of advanced propulsion (ion engines, plasma propulsion, etc.) which would enable things like a Neptune orbiter or what-have-you.

As to communications, almost certainly there will be a change to laser based communications over long distances. The technology is maturing and once we have the ability to put more infrastructure off-Earth (orbit, etc.) then you can replace things like the DSN with laser based communication hubs in orbit or at L2 or L4/L5 or wherever. They'd take the form of essentially space telescopes with special instrumentation for sending and receiving laser comms. That would make it possible to send and receive at a much higher rate across the entire solar system.

Re: New Horizons: Nasa spacecraft speeds past Pluto

#267

Post by murbard2 »

grinich wrote: post #166
chasing wrote: post #160

Earlier quoted context omitted.

Any actual engineer will probably find this comment painfully naive, but here we go: If it's infeasible to slow down to get into orbit or land on Pluto, what about the feasibility of designing a probe to impact Pluto at XX km/sec and survive well enough to send back data. Like, fire a (metaphorical) bullet full of scientific instruments directly into the surface of the planet. Is it simply that we have no way to buil…

A bullet travels about 1,700 MPH. New Horizons is going about 36,300 MPH. The probe weighs 480 kilograms, so it's kinetic energy is approximately 63.2 Gigajoules. For reference, this is like 15 tonnes of TNT released on impact. Hard to make something that survives those kind of conditions.

You don't have to crash/land the entire probe, you could land a lightweight sensor that was carried by the probe and which requires little fuel to decelerate.

Re: New Horizons: Nasa spacecraft speeds past Pluto

#268

Post by aunty_helen »

biot wrote: post #191
ringshall wrote: post #101

Interesting note, as of today, the US is the first country to have successful spacecraft missions visit all of the classical planets. There is one big exception, of course: the Soviet Union was the first to have a spacecraft visit Earth, with Spunink. This category is completely arbitrary, especially given that Pluto is now considered a minor planet. Still, it's an achievement of note. Mercury - 1974, Mariner 10 Venu…

The Russians had some amazing firsts with Venus, depending on how you define "visit": https://en.wikipedia.org/wiki/Venera "Among the other results, probes of the series became the first man-made devices to enter the atmosphere of another planet (Venera 4 on October 18, 1967), to make a soft landing on another planet (Venera 7 on December 15, 1970), to return images from the planetary surface (Venera 9 on June 8, 197…

They were also first to test the characteristics of a lens cap on another planet in one of their most infamous science experiments.

Re: New Horizons: Nasa spacecraft speeds past Pluto

#269

Post by TheCoreh »

drjesusphd wrote: post #221
cgriswald wrote: post #193

Earlier quoted context omitted.

It can't actually happen. NASA only has enough Pu-238 for three more RTGs.

Why can't they get more?

I might be mistaken, (and someone please correct me if I'm wrong) but IIRC Plutonium is a side-product of the enrichment of weapons-grade Uranium. I think the non-proliferation of nuclear weapons treaty might impose some barriers on this process, and we're no longer in the Cold War, so it's kinda hard to get Plutonium.

Re: New Horizons: Nasa spacecraft speeds past Pluto

#270

Post by tim333 »

tyho wrote: post #252
chasing wrote: post #160

Earlier quoted context omitted.

Any actual engineer will probably find this comment painfully naive, but here we go: If it's infeasible to slow down to get into orbit or land on Pluto, what about the feasibility of designing a probe to impact Pluto at XX km/sec and survive well enough to send back data. Like, fire a (metaphorical) bullet full of scientific instruments directly into the surface of the planet. Is it simply that we have no way to buil…

I am not an engineer, but it might be easier to launch a spacecraft with an ion engine that over years manages to reduce the speed relative to Pluto to something human scale.

I think that would be the most practical way. Nasa already launched Dawn, an ion drive probe, to visit Vesta and Ceres.
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