Talk:New Horizons

Fuel problems

In the Mission Profile section, the article currently says "However, a lack of available plutonium means that the required orbital maneuvers for post-Pluto encounters may not be possible.". Shouldn't that read "a lack of Hydrazine monopropellant"? Or is the plutonium in the radiothermal generator also needed for maneuvering as well as electricity? Ponder 14:45, 2005 Apr 13 (UTC)

lack of plutonium in the radiothermal generators means less operational time, in which they produce enough electicity to keep the spacecraft and its instruments operational. For Pluto flyby there is enough plutonium, but for futher KBO flybys may be not. --Bricktop 15:45, 13 Apr 2005 (UTC)

The comment in the article is at best confusingly phrased, and at worst downright wrong (number of course corrections required won't fix the problem if the problem is lack of power). I've modified the article text to something closer to the meaning of the space.com article cited. --Christopher Thomas 17:31, 29 Apr 2005 (UTC)

Ok, your version is significantly better ;-) --Bricktop 21:55, 29 Apr 2005 (UTC)

It seems that problems with plutonium fuel support were solved, read [1]. Someone should add this to the article (my english is not good enough:-) ). --Bricktop 02:43, 30 Apr 2005 (UTC)

I've updated the paragraph to reflect this development; thanks for the excellent research! --Christopher Thomas 05:11, 30 Apr 2005 (UTC)

Message for Aliens?

Will New Horizons also have a message for aliens on board as the Voyager Golden Record of the Voyagers?

I haven't heard of any, but I haven't read all material about the probe. Check NASA's pages on the craft, linked from the main article. --Christopher Thomas 19:38, 20 Jun 2005 (UTC)

Also haven't heard of any, although I wrote some parts of this article and nearly all of the german New Horizons article and therefor read large amount of NASA material about the probe. But haven't look specifically for such a "message for aliens" --Bricktop 21:45, 20 Jun 2005 (UTC)

You can add your name to a list that is sent with the spacecraft. That's all, I think. [2] Awolf002 18:05, 16 August 2005 (UTC)

The only message that needs being sent anymore is clearly written in the flight path!   freshgavin TALK    04:35, 20 January 2006 (UTC)

Solid Rocket

Are there any concerns that this mission will suffer the same fate as CONTOUR? It has a similar solid rocket booster built into the spacecraft: [3] Awolf002 18:05, 16 August 2005 (UTC)

Not quite - NH has a Star48B upper stage, whereas Contour used the upper stage as well as having a Star30 built in - it was the latter that failed. As far as I know, there is no Star30 on New Horizons. Shimgray 18:11, 16 August 2005 (UTC)

Centaur flyby

I can't confirm the following sentence beyond an offhand comment on a message forum. I'll therefore remove it for the time being. The Singing Badger 19:39, 10 September 2005 (UTC)

During the cruise to Pluto, New Horizons will perform a distant flyby of a Centaur (an escaped Kuiper Belt Object), (83982) 2002 GO9, in 2010.

I did some calculations and tried to verify this, and the flyby will occur around March 8, 2010 at a distance of 412 million kilometers. — Yaohua2000 14:06, 18 January 2006 (UTC)

Magic numbers

Pre–launch

28°30′36″N 80°38′51″W

New Horizons - Pluto
Orbiter UTC	Range (km)	Range-rate (km/s)	Velocity (km/s)
2005-Dec-17 05:58:58	4 790 263 646	0.000	36.325

28°34′42″N 80°35′01″W

New Horizons - Pluto
Orbiter UTC	Range (km)	Range-rate (km/s)	Velocity (km/s)
2005-Dec-20 21:12:54	4 790 000 000	-1.354	35.634
2005-Dec-25 01:57:16	4 789 000 000	-3.560	36.056
2005-Dec-27 15:50:57	4 788 000 000	-5.158	35.303
2005-Dec-29 17:22:52	4 787 000 000	-6.041	35.244
2005-Dec-31 11:48:45	4 786 000 000	-7.357	35.526
2006-Jan-02 01:46:24	4 785 000 000	-7.500	35.772
2006-Jan-03 11:54:48	4 784 000 000	-8.784	35.360
2006-Jan-04 19:35:52	4 783 000 000	-8.773	35.087
2006-Jan-06 01:25:05	4 782 000 000	-9.432	35.604
2006-Jan-07 05:22:26	4 781 000 000	-10.353	35.706
2006-Jan-08 07:52:51	4 780 000 000	-11.045	35.524
2006-Jan-09 09:12:42	4 779 000 000	-11.579	35.348
2006-Jan-10 09:30:15	4 778 000 000	-12.061	35.278
2006-Jan-11 08:52:09	4 777 000 000	-12.511	35.305
2006-Jan-12 07:25:10	4 776 000 000	-12.882	35.377
2006-Jan-13 05:14:52	4 775 000 000	-13.116	35.400
2006-Jan-14 02:24:14	4 774 000 000	-13.211	35.248
2006-Jan-14 22:54:37	4 773 000 000	-13.323	34.862
2006-Jan-15 18:49:58	4 772 000 000	-13.743	34.454
2006-Jan-16 14:18:49	4 771 000 000	-14.518	34.459

28°35′00″N 80°34′59″W

New Horizons - Pluto
Orbiter UTC	Range (km)	Range-rate (km/s)	Velocity (km/s)
2006-Jan-17 09:26:33	4 770 000 000	-15.165	34.899
2006-Jan-18 04:07:59	4 769 000 000	-15.204	35.110
2006-Jan-18 22:15:11	4 768 000 000	-15.053	34.604
2006-Jan-19 15:57:37	4 767 000 000	-15.646	34.224

Post–launch

New Horizons - Pluto
Orbiter UTC	Range (km)	Range-rate (km/s)	Velocity (km/s)

Discussion

Ummm... what exactrly are these? Tompw 17:34, 5 January 2006 (UTC)

These are the instantaneous distances between New Horizons and Pluto. — Yaohua2000 19:22, 5 January 2006 (UTC)

OK... but why three tables for different lattitudes and longitudes? And what's the difference between "range rate" and velocity?

The spacecraft to be transported twice during this peroid. The range rate is the rate of range, range is the position difference between New Horizons and Pluto, while velocity is New Horizons' speed with respect to Pluto. They are different. — Yaohua2000 01:44, 6 January 2006 (UTC)

Sorry, I'm still not getting it. Firstly, from what you said, the range is the distance form New Horizons to Pluto, so the "range rate" is the rate at which the range changes... which is exactly the speed relative to Pluto! Secondly, could you explain in a bit more detail abotu the different lat/longs?

Range-rate does not equal to the speed, because the spacecraft does not fly toward its target directly. For the first lat/long, it is Payload Hazardous Servicing Facility at Kennedy Space Center, where the assembly hall at, for the second lat/long, which is Vertical Integration Facility at Launch Complex 41, about 1800 feet south to the launch pad, the third lat/long is the launch pad. — Yaohua2000 20:34, 19 January 2006 (UTC)

Range-rate is the same as pluto-relative velocity (as long as we're treating velocities as scalars now...). "Velocity" on the chart is, I assume, sol-relative? - JustinWick 03:24, 21 January 2006 (UTC)

Fastest ever?

According to [4] (who in turn cite NASA as a source), "About the size of a baby grand piano, New Horizons will be the fastest spacecraft ever to depart Earth, according to NASA. It will pass the moon in nine hours and will reach Jupiter in a little more than a year, the space agency says." I always take such statements in the press with a grain of salt, but that does seem quite fast (didn't Apollo take 3 days to get to the moon?). Can anyone provide any details? I didn't see anything obvious on the public web page for NH, but I didn't spend very much time looking. -Dmh 19:15, 16 January 2006 (UTC)

Yes, it is the fastest ever to depart Earth, but not the fastest to leave our solar system, Voyager 2 has multiple gravitational slingshots and leaves faster. You can imagine that Atlas V rocket 551 is really huge and New Horizons is only 480 kg, so the spacecraft will have an extremely high speed. — Yaohua2000 20:27, 16 January 2006 (UTC)

According to a NASA paper (don't have the link any more) NH will leave Earth at a speed of 12,81 km/s if a Jupiter fly-by is achievable and 12,884 km/s if it flies without Jupiter fly-by. --Bricktop 22:27, 16 January 2006 (UTC)

Sorry, these numbers from me were wrong. Spaceflightnow gives the exact speed for yesterday's launch as 10.07 miles per second - 36,256 mph (16,21 km/s) [5]. --Bricktop 06:30, 20 January 2006 (UTC)

In its current format, in the trivia section the page says that after a gravity assist from Jupiter, the probe will be the fastest man made object ever at a speed of 47,000mph. Pioneer 11 attained a speed of 108,000 mph at periapsis on its Jupiter swingby according to this NASA page: [6]. Apologies if I am not conforming to the typical format here, but I'm a newbie and didn't know where else to raise this issue, while doing as little damage as possible.--Andrew

(Don't worry Andrew - you are doing great - Welcome to Wikipedia!). I agree we need to get a little more precision into this. I changed the trivia footnote yesterday because the quote in our article was misleading. It is quite possible I still did not get it right. Our old quote said "The New Horizons spacecraft aboard the Atlas V rocket will only take nine hours to reach the Moon's orbit (compared to the three day trip the Project Apollo spacecraft needed to reach the Moon). This will make it the fastest spacecraft ever launched. The record-holder prior to New Horizons was Voyager 1.", but when I looked at Voyager 1, I saw that the Voyager 1 spacecraft is traveling faster than the claimed current speed for New Horizon. Therefore, I surmised (perhaps incorrectly) that the record would not be broken until after New Horizon's gravity assist. I think the first thing to clear up is what do we mean by "fastest"? Do we mean "fastest speed ever achieved for one instant in time"? "Fastest departure from earth's atmosphere"? "Fastest average travel speed"? "Fastest departure from the solar system"? Or do we mean, at the current instant in time, it is the fastest thing, which would mean that other objects could have been faster in the past if they have slowed down in the meantime. Johntex\^talk 15:04, 20 January 2006 (UTC)

I think it is rather ambiguous. Fastest with respect to what? The earth? The sun? The body it is currently orbiting, or whose sphere of gravitational influence it happens to be in at a particular moment? The earth itself has an instantaneous velocity relative to the sun of more than 60,000 miles an hour. So, relative to the earth, Voyager 1 might be moving on the order of 100,000 miles an hour at the right time of year. So I think in that case they mean relative to the earth's mean position, the sun. After thinking about this, New Horizon's own periapsis speed on its Jupiter swingby might even be similar to Pioneer 11's, I haven't seen any published information about that.

The 47,000mph is probably with respect to the sun, relative to which the planets have a mean velocity of zero, but instantaneous velocities that can easily exceed this. A rigorous standard would account for this, and would probably include something about the spacecraft's mean velocity relative to the center of the solar system over a significant period on a planetary orbital timescale being significantly different from zero. Or some such.--Andrew

The number 36,256 mph given as "fastest ever" seems to be relative to the Earth (center), see [7]. Does this make sense to you, as well? Awolf002

• Like you, I have also wondered about "Fastest with respect to what?" I agree it seems the best comparison would be to the sun, but it is difficult to know if that is what other people are referring to when they give measurements unless they either specify it, or unless someone knows of a definite convention that NASA and others in the field stick to. Johntex\^talk 18:45, 20 January 2006 (UTC)

• Helios 2 Helios 2 Helios 2 Helios 2. Helios 2? Helios 2 Helios 2. Helios 2! --AlexWCovington (talk) 22:14, 20 January 2006 (UTC)

Yup. According to the Guinness World Records, Helios 1 and 2 reached 252 800 km/h and this is the "fastest spacecraft speed". I think they mean "fastest spacecraft speed relative to the Sun". -- Bowlhover 05:36, 21 January 2006 (UTC)

Launch time

Someone changed the launch time to 18:14, but are you sure it will launch at 18:14 UTC? (NASA TV coverage just said 1:02 left, but I doubt if this is correct, because the launch window to be open at 18:24 UTC.) — Yaohua2000 17:16, 17 January 2006 (UTC)

There are builtin "holds" in the countdown. Do not use that number to predict when the launch will happen. It is currently planned for 13:24 EST. Awolf002 17:32, 17 January 2006 (UTC)

IT is currently planned for 13:45 EST. --Cyde Weys 2M-VOTE 18:25, 17 January 2006 (UTC)

Resetting clock and recycling

The virtual launch page of NASA says that the clock has been reset to T-4 minutes and holding, but the countdown page says that 'Built-In-Hold' is 40:00. Is the clock at T-4 minutes and holding or is it something else? I guess that the answer to that answers my next question: when the page says 'we will recycle for a 24-hour turnaround' what do they mean by 'recycle'? Do they take out the LO2 and LH2 out of the tanks or is it going to be left there ready for tomorrow's launch attempt? Thanks. DarthVader 23:54, 17 January 2006 (UTC)

During a countdown the clock stops at T-4 minutes and stands for 10 minutes at this point to give the launch team some time to deal with all kind of potentially faults. After that 10 minutes the clock starts again at T-4min and goes on until T-0.

I dont know about kerosine in the main stage, but LOX and LH2 from the main stage and from the Centaur are taken out of the tanks, because of their cryogenic temperatures. --Bricktop 00:37, 18 January 2006 (UTC)

So I am assuming that the LO2 and LH2 are not in the tanks right now. Assuming that this is the case, will the clock start again at say T-120 minutes and counting (or similar) today so that the tanks can be refuelled? Or will the tanks be refuelled at T-4 minutes and holding? DarthVader 07:18, 18 January 2006 (UTC)

Yes LOX and LH2 are now in the ground tanks, not in the rocket. The whole launch procedure of today is the same (or nearly the same) as of yesterday. --Bricktop 12:28, 18 January 2006 (UTC)

Trajectory animation

While I appreciate that a lot of work has gone into making the trajectory animation, I have a few concerns with it:

• The thumbnail version that appears in the article seems to be cropped, as opposed to resized, which results in an image that's very confusing and doesn't really show much.
• Labels on the orbits on the large version would be nice. I can tell what most of them are meant to be, but a new reader might not.
• Per the discussion at Talk:Magnetic resonance imaging regarding the MRI scan animation used there, it might be best to make the basic image static, while having a link in the caption to the full animation for people who want to see the moving version. Perhaps put dots on the orbits in the static version indicating positions at important times, to give some impression of travel time/speed.

Again, thanks for taking the time to produce the animation! --Christopher Thomas 18:58, 3 January 2006 (UTC)

This animation should be longer. It only covers a couple weeks, and thus when it displays in the animation it displays so quickly you can't really make out what's going on. Phaldo 17:41, 17 January 2006 (UTC)

I made this but since no official ephemeris available, I used a gravitation simulator to produce a simulated trajectory, but it is a bit difficult to export the simulated result as GIF animation (I did it manually, but rather take time), the official ephemeris should be available in 2 or 3 hours, so this can be replaced. — Yaohua2000 18:02, 17 January 2006 (UTC)

I also found the animation on the main article page to be annoying and distracting from the reading, without being particularly useful. I like the idea of having the thumbnail be static. Also, how about a link to a "Celestia" presentation? Now that will give a nice orbit plot! — Długosz

The 'Trajectory Aniumation' is not at all clear. It needs more explanation. Can someone supply? Duncan.france 20:38, 18 January 2006 (UTC)

Centaur

What will be the fate of the Centaur stage? Fall back to Earth? Rmhermen 19:38, 19 January 2006 (UTC)

Good question. Acording to the Environmental Impact Statement [8] (pdf), the Aerojet and Atlas stages will separate, break up, and fall into the Atlantic Ocean. The Centaur will accelerate to Earth escape velocity, though, before releasing the spacecraft. It's likely that the Centaur will enter a long solar orbit, though it's not clear to me what velocity it will have when its burn is complete. Potentially it could be leaving the solar system itself, as long as it's going fast enough -- just not going anywhere interesting. --Dhartung | Talk 05:31, 20 January 2006 (UTC)

Mars flyby....

I see an anonymous has added a Mars flyby to the mission timetable.. although I agree that's the date the probe will pass Mars' orbit, does it actually fly past Mars itself? Tompw 19:57, 19 January 2006 (UTC)

No, it will be very far away from Mars. See my animation, the white one is New Horizons, the red one is Mars. — Yaohua2000 20:13, 19 January 2006 (UTC)

I added that and have corrected the entry per this discussion.

Odd phrasing

In the intro to the article, Pluto's atmosphere is described as "neutral". What does this mean? I've never heard that word used to describe and atmosphere before.

I added an explanation. Hope this helps. Awolf002 22:37, 19 January 2006 (UTC)

Jovian radii

Is Jovian radii the right word? Should it just be Jupiter radii? Unless I am wrong my understanding is Jovian mean Saturn, Jupiter, Uranus and Neptune all together not just Jupiter.

n2271 19 January 2006

Jovian means "of Jupiter". Saturn, Jupiter, Uranus and Neptune are Jovian planets because they're "near" and "like" Jupiter. Zocky | picture popups 03:27, 20 January 2006 (UTC)

'Jovian planets' is not general English usage. J, S, U, N are generally referred to collectively as 'gas giants', though there is a general move to distinguish U and N as, perhaps, 'helium giants' or otherwise because they are rather different from J and S.

'Jovian' is indeed 'of Jupiter' and it only refers to multiples of the planet's radius in this case. Tarquin Binary 03:36, 20 January 2006 (UTC)

Therefore, we should not say "Jovian radii of Jupiter"; this is saying the same thing twice over again, which is immediately obvious to anyone :-) I'm removing the "Jupiter" part and I'll link Jovian to the Jupiter article. Michaël 00:32, 21 January 2006 (UTC)

Oops, that didn't make any sense what I just said. I'm not changing anything. Sorry. Michaël 00:34, 21 January 2006 (UTC)

trajectory animation image

Is there some wrong with that trajectory animation image? In only displays a truncated animation for me, lasting about a full second. -- Pinktulip 05:02, 20 January 2006 (UTC)

doesn't work for me either, I've removed it. optimized gifs don't resize well in my experience. The full size image doesn't work for me either, just a second or so of animation. --Duk 05:42, 20 January 2006 (UTC)

Propulsion

Surprised the probe doesn't have an ion drive. Any reason why still using hydrazine? especially for such a long range mission. Toby Douglass 17:20, 20 January 2006 (UTC)

For an ion drive you need a big amount of electricity, which is usually generated by solar panels. Unless a nuclear reactor for spacecrafts is developed (Project Prometheus, which was cancelled last year), there is no way to use ion drives beyond the asteroid belt between Mars and Jupiter. --Bricktop 19:09, 20 January 2006 (UTC)

Well... an RTG is always a possibility. But they seemed to have trouble getting enough plutonium for just 120 W. --AlexWCovington (talk) 22:16, 20 January 2006 (UTC)

Yes, but you'll need multiple RTGs. You'll need some kW of power to be consumed by an ion drive. --Bricktop 00:26, 21 January 2006 (UTC)

Flyby vs. Orbit

What is remarkable to me is that this mission, alone of all the recent planetary missions, will not achieve orbit around the planet that is its primary target, but instead will only fly by. Clearly, you get less science from this approach, so one must wonder why this choice was made. I'm going to assume that it was because it was not possible to carry enough fuel to decelerate into orbit; in other words, NASA was faced with a choice between "get there fast and stay briefly" versus "get there slowly and settle into orbit." I'd love to know more about this; in particular, how long would it have taken to get a spacecraft of simlar capability to Pluto if the goal had been orbital insertion? What other tradeoffs would be involved? Was the chance to do more KB exploration a significant factor, or was it more a matter of "well, we can't stop, we'll be out there, so we might as well look around"? I haven't seen anything addressing this question; I'd be grateful for anything that anyone here can provide. --orbert Fri Jan 22 22:20:03 UTC 2006

A space probe would need MUCH more fuel to go into orbit around Pluto. And it would have to fly on a much slower hohmann transfer route, on which it would take about 30 years to reach Pluto. --Bricktop 00:34, 21 January 2006 (UTC)

Plasma detectors

¿Does anybody know if the spacecraft carries a plasma detector like those out of work in the Vogager ones, for the time it reaches the termination shock? --Javier Múgica

Cost of this expedition?

Could someone add something about how much this thing cost to this article? I'd be quite interested in knowing, and I'm sure others would too.