NASA’s New Horizons Spacecraft Awakens for Pluto Encounter | Hacker News Reader

NASA’s New Horizons Spacecraft Awakens for Pluto Encounter

nasa.gov

100 points_wp3r27 comments

2015 is shaping up to be a great year. New Horizons visits Pluto and the Dawn probe visits Ceres. Two dwarf planets in one year, when we've never visited a single one before.

Don't forget Rosetta continuing operations around comet 47P while it transitions into being an active comet.

Also don't forget Japan's Akatsuki space probe which will will attempt to insert itself in orbit around Venus in November.

It "missed" in 2010 due to an engine failure and had to wait 5 years for another attempt: http://en.wikipedia.org/wiki/Akatsuki_%28spacecraft%29

There are two sentences in Bill Bryson's "A Short History of Everything" that absolutely amazed me when I read them the first time:

"Even at the speed of light (300,000 kilometres per second) it would take seven hours to get to Pluto. ... On a diagram of the solar system to scale, with the Earth reduced to about the diameter of a pea, Jupiter would be over 300 metres away and Pluto would be two and a half kilometres distant..."

The article says there is "a high-resolution telescopic camera" on board. Does this mean we will get high-resolution pictures of Pluto's surface, like those we have of Mars?

I'd assume so. It has already taken high-resolution photos of some of Jupiter's moons, when it flew past in 2006-2007.

http://en.wikipedia.org/wiki/New_Horizons#Jovian_moons

It really amazes me that we are able to transmit high-res pictures from such distances.

Within our solar system (which is itty-bitty), there is really no theoretical limit to what we can send or receive. Bandwith is pretty high on modern satellites and probes and our only really limiting factor is latency, which doesn't matter so much when the probes can store data locally and slowly send it to you over time. NASA is currently experimenting with the LCRD[1] project for laser-based communications which have a downlink of 622mbps.

[1]: http://en.wikipedia.org/wiki/Laser_Communications_Relay_Demo...

Yes. I read the camera should be able to resolve details "about the size of the pond in Central Park".

If by "like we have of Mars" a complete map of the surface that we can all download in Google Earth, then no. New Horizons is a flyby mission like the Mariner and Pioneer probes.

Yes and no.

New Horizons is a flyby mission. That is, in order to reach Pluto in a reasonable amount of time (it was launched in 2006, time-to-Pluto will have been nine years), it launched with a high speed which was further boosted by gravitational assist from Jupiter. It's not carrying fuel to brake this speed, nor is Pluto massive enough to be used for gravitational assist to slow it (which is how other Gas Giant orbital missions have slowed sufficiently to be captured in orbit).

From Wikipedia: "New Horizons is intended to fly within 10,000 km (6,200 mi) of Pluto. New Horizons will have a relative velocity of 13.78 km/s (49,600 km/h; 30,800 mph) at closest approach, and will come as close as 27,000 km (17,000 mi) to Charon" (Pluto's moon).

http://en.wikipedia.org/wiki/New_Horizons#Pluto_approach

The nearest approaches can still be adjusted depending on mission parameters as the probe approaches Pluto. Some consideration is given to the post-Pluto mission, with other Kuiper belt objects being targeted for study.

In the roughly four hours it takes for radio signals from the flyby to reach Earth, New Horizons will have travelled half the distance between the Earth and Moon. Which is to say, it won't be hanging around Pluto very long.

By contrast in the case of Mars we have multiple probes in orbit around Mars, including the Mars Reconnaissance Orbiter (MRO), which through a combination of thruster fire and aerobraking (dipping into Mars's atmosphere to slow its velocity) has been orbiting Mars at an altitude of 300 km, allowing for both photography and other sensor observations, since 2006. The result is a vast wealth of close-in imagery with a resolution of up to 18 meters.

http://en.wikipedia.org/wiki/Mars_Reconnaissance_Orbiter

So: yes, if all goes well we should get some high-quality imagery of Pluto, from as close as 10,000 km -- 33 times the distance of the MRO from Mars. But it's going to be a once-through pass, at high speed, and with no options for retargeting sensors from Earth to reexamine interesting objects.

I wonder whether Neptune or Uranus could be used to 'aerobreak' in order to get a probe into an orbit around Pluto. I'm guessing with Pluto's eccentric path there should be points in time where it is close to one of these planets, but it is probably a window that only opens up on a timescale of hundreds of years?

That's a possibility, but the bigger problem is simply the size of the solar system.

Uranus is 2.88 billion km from the Sun.

Neptune is 4.5 billion km from the Sun. Nearly twice as far as Uranus.

Pluto is 5.9 billion km from the Sun on average. It varies a lot, from inside the orbit of Neptune to nearly double the distance - 4.4 to 7.3 billion km. New Horizons will be reaching it at one of its nearer approaches. Pluto is also significantly inclined to the solar plane, unlike the planets.

By contrast Jupiter is less than 1 billion km away: 0.779 billion km.

Saturn is 1.4 billion km -- twice as far as Jupiter.

Note that if you managed to slow yourself down at Neptune on your way out to Pluto, you'd still have the distance from the Sun to Saturn to traverse. Say you cut half your speed -- it would take you nearly six and a half years to reach Pluto, rather than the 3.2 of the current mission trajectory. You're trading speed and time here.

And you'd still have to lose some 20,000 km/h of velocity when you arrived.

Space is big. Really big. You won't believe just how vastly, hugely, mind bogglingly big it is.

Then there's the orbital periods. Neptune's year is nearly 165 Earth years, Uranus is 84 years, Pluto's is nearly 248 years. This means that Pluto, discovered in 1930, won't have completed a full orbit of the Sun until 2177. Neptune, discovered in 1846, completed its first full orbit since only in 2010.

That's what I meant with eccentric path though: As far as I know Pluto is not always that far out, there are points in time where it's closer to the sun than Neptune - which should be a good moment when either Uranus or Neptune could be used to aerobreak.

Edit: but only when they also line up correctly, which is why I think it would take hundreds of years of waiting.

Edit2: After watching the linked video, Uranus would be out, since Pluto is never close to it, but Neptune might work at some point in time when these planets are close.

The Neptune-Pluto alignment is one that might be interesting to explore on a solar system simulator. I suspect you might have to wait a fair fraction of a thousand years for that though, at a minimum.

I actually tried to find a good simulator for that reason, but all the web simulators I've found didn't have a reasonable time slider UI.

There's a KDE astronomy simulator I've used that seems pretty good, though I haven't played with it for a while. Celestia IIRC: http://www.cyberciti.biz/tips/celestia-astronomy-linux-progr...

You might also be interested in the actual trajectory and positions of other planets for this mission:

https://www.youtube.com/watch?v=78U0_XcFP_I

Is there any intention to use New Horizons to test the "Pioneer Anomaly"? Seems like a good candidate, as its moving in the right direction.

Pioneer Anomaly was solved in 2012, once the thermal recoil force is properly accounted for, no anomalous acceleration remains.

Well, confirmation with another probe would be nice, and the New Horizons has an instrument (obviously included before the thermal solution) if NASA so chooses to perform the experiment. Will no doubt depend in part if they can find another object to examine beyond Pluto.

The hibernation mode of New Horizons has the RTG "cylinder" axis perpendicular to the spin axis, so unless there is asymmetry around the axis of the RTG, I would not expect to see any thermal recoil force. I guess that means we would not expect to see any effect, which neither validates nor invalidates the accepted thermal recoil theory for Pioneer, but it would exclude any "New Physics" explanations (which the planets do already).

You can read quite a bit of detail about NH in the data sets archived to-date in the Planetary Data System http://pds.jpl.nasa.gov/ specifically http://pdssbn.astro.umd.edu/holdings/ look for data set directory names starting with nh- and subdirectories of those named catalog/ and document/.

There is also a lot of geometry information available in the SPICE data set under /http://naif.jpl.nasa.gov/pub/naif/pds/data/nh-j_p_ss-spice-6... e.g. start at aareadme.htm

I said that based on a Wikipedia reference to this paper: http://arxiv.org/abs/0710.5135

Which proposed to do testing in late 2007 through 2008, which I gather didn't happen, no doubt because of the reason you point out.

I never heard of the pioneer anomaly before, thanks for mentioning it, it's very interesting.

https://en.wikipedia.org/wiki/Pioneer_anomaly

The anomaly was solved in 2012. The cause was heat being radiated from the power generator in the direction of motion causing the spacecraft to "brake"

It's always a nervy moment for mission operations to re-establish contact with a hibernating spacecraft. Much relief and much to look forward to, as the fastest object in the Solar System speeds towards Pluto. Pluto is a fascinating system and with the discovery of additional moons over the last few years, there's clearly a lot to be discovered.

Wow I just did the math and at this rate it would take New Horizons roughly 20,000 years to travel 1 lightyear. Slingshotting around Jupiter takes longer to play out than a straight shot obviously, but it puts things in perspective.

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