An unmanned NASA spacecraft whizzed by Pluto on Tuesday and survived its close encounter with the distant dwarf planet after a journey of three billion miles (4.8 billion kilometers) and nearly 10 years.
Moving faster than any spacecraft ever built at a speed of about 30,800 miles per hour, the nuclear-powered New Horizons -- about the size of a baby grand piano -- snapped pictures of Pluto as it hurtled by on auto-pilot.
The photos will reveal details of Pluto never seen before in the history of space travel.
Five scientists involved in the NASA's New Horizons team answered questions put up by Reddit users in an AMA. Here is a collection of some interesting questions and answers from the Reddit AMA.
What is the most surprising thing you've discovered about Pluto since the mission began?
Charon's dark pole surprised us quite a bit. We expected Charon's surface to be mostly uniform and featureless.
What is next for New Horizons?
Next is all of the data download. It will take ~16 months to download the amazing data.
What do we hope to learn about Pluto?
We hope to learn about Pluto and its five known moons. The atmosphere, the geology, the composition of the rocks, and much much more.
What other information/pictures/data will New Horizons be sending back?
New Horizons has seven instruments - ALICE, LORRI, PEPSSI, RALPH, REX, SDC, SWAP, so lots of data will be coming down in addition to the images you have seen already.
This view is dominated by the large, bright feature informally named the "heart," which measures approximately 1,000 miles (1,600 kilometers) across. Photo : NASA
What programming languages are used in the software onboard?
We frequently hear that public interest in space programs has steadily declined since the moon landing. How does interest in today’s unmanned missions (such as New Horizons) compare to say something like the moon landing? And does the level of public interest factor into funding of these types of projects?
It's hard to make direct comparisons because the way the public can interact with the missions is so different now. Does live coverage of an event on national TV in the 1960's equate with websites and twitter feeds updating minute by minute? What I really love about our planetary science missions is that the public can ride along with us, and we want you to join us. These missions are YOUR missions.
What's icy, has "wobbly" potato-shaped moons, and is arguably the world's favorite dwarf planet? The answer is Pluto, and NASA's New Horizons is speeding towards the edge of our solar system for a July 14 flyby. Photo: NASA
My first daughter is being born in September, and I'm wondering what you think the first mission will be that will give her the a sense of wonder? What's coming down the pipe in the next 15-20 years or so?
What a great question! I remember holding my newborn son as the first Cassini radar data of Titan was downlinked in the middle of the night. The next big mission that can "grow up" with your daughter is the Europa mission. This mission will investigate if Europa and its huge global ocean is habitable. Take her to the launch in the early 2020's when she is 8 years old, then watch the data come in with her when she is a young teenager.
In the Magic School Bus episode Lost in the Solar System, Arnold removes his helmet on Pluto during an argument and his head is instantly frozen in a block of ice. Although this is obviously not what would happen, does any water ice exist on Pluto? Has the probe discovered more or less water than expected, or any water at all?
Some of us re-watched that episode earlier this month! We haven't seen any water on Pluto yet, but if there is any water, we'll see it when we get our LEISA scans. We've known about the water on Charon since the late 80s.
How close to true colour are the colour images returned so far? This image released today looks incredible, but is it true colour, or has the colour been exaggerated?
Yes it was true color! We tried to get it as close to real color as possible. We combine the wavelengths that we have and translate it into what the human eye would see.
The latest images suggest Pluto’s surface is much newer than Charon’s, even though the dwarf planet and it’s moon are the same age. Are there any theories in the works about the resurfacing process and it’s cause?
There are two likely reasons, but forthcoming New Horizons' data will hopefully let us refine these or figure out a better reason. One is that Pluto is larger than Charon, so it can retain more heat and have active geology longer. Another is that Pluto has a tenuous atmosphere, and during the 248-year orbit around the sun, the atmosphere sublimates from one area in sun and is deposited in another in darkness, and then this reverses half-way through the orbit. This process is very slow, relatively speaking, but so is cratering.
I wanted to ask if there was any chance of turning the New Horizons camera back towards Earth to see if we can pull another "Pale Blue Dot?"
Unfortunately, the LORRI camera is extremely sensitive, and looking back towards Earth would have the sun in the field of view and blow the instrument out. Voyager was able to do this because the instruments were on a platform that could move, and the engineers could orient it such that Voyager's dish acted as a sunshield.
Does New Horizons have the capability to find any undiscovered moons?
New Horizons does have the ability to detect new moons - we have been doing careful searches though all of the images and so far no luck. We will keep looking though, and even as we are departing we will look back at the Pluto system and that will be our best chance to see any faint diffuse material like rings. ~Kelsi
Can you talk about the snow on Pluto? If I were standing on the surface in a spacesuit while it was snowing, what might it look like?
Most likely the frosts deposit pretty much directly on the surface, as the atmosphere is very thin - although it is possible that clouds could form, we haven't seen any yet! If there was snow, it would be quite frictiony, like skiing on sand, because it is sooooo cold there. It would not be like the snow on Earth, which is actually quite balmy compared to Pluto.
How old were you when the mission started? How old will yo be when last mission finish?There are many of us on the AMA reddit in a room, so I'll answer for one scientist: I'm 32 and so I was 22 when the probe launched. I was much younger when it was proposed and funded (18 when selected, younger when proposed). The mission is funded for another two years for science analysis (end of downlink (16 months) plus 6 months). An extended mission is being proposed to another Kuiper Belt Object.
A view of Pluto and Charon as they would appear if placed slightly above Earth's surface and viewed from a great distance. Photo : NASA
I heard that New Horizons arrived at its destination 72 seconds early. How hard was it to get this close to the targeted time after 10 years, and will this change anything?
It was hard. We have a great navigation team who worked tirelessly to make this work. We had a wonderful launch, a recent TCM that got us on track, and we are very happy.
Have any problems occured at this point, and how did you tackle them?
We had an issue over the July 4th weekend. Many engineers and scientists worked over the holiday weekend to recover from the fault.
My question is does Pluto have an atmosphere? And if so, what kinds of things can you determine about it?
Pluto does have an atmosphere! It is bit on the thin side, 10 microbars compared to Earth's 1 bar. It is ~98% N2, with trace CH4 and CO. We will be looking at its structure, and its composition - all sorts of good info will come from both the visual images from the LORRI images, and the Alice instrument.
How does data get sent back to Earth from New Horizons? How long does it take for a photo to be received?
The light-travel time is about 4.5 hours at this distance. It takes over an hour for an image to be played back because of the very slow speeds over such a long distance.
Will New Horizons be gathering any more data past the Pluto flyby, or will it just be focusing on transmitting the data it has already gathered?
Many observations are being taken during and around the closest approach to the planet and its moons. This includes observations of the night side as well as what we call "sliver" maps which are the very thin crescent images that the craft will see over the coming weeks. Sliver observations are planned through July 30.
My question would be about hearth shape of Pluto. Do we have at least a theory on how it formed, and what is it made up from?
Thanks! You ask a great question that has one of the very favorite answers that scientists like to give: We don't know! You have no idea how excited scientists get when our answer is "I don't know." It ranks up there with the cogent observation "Well, that's weird..."
So no, we don't have any idea how that formed - yet!
Members of the New Horizons science team react to seeing the spacecraft's last and sharpest image of Pluto before closest approach later in the day, Tuesday, July 14, 2015 at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Photo : NASA
My question is how did you figure out the diameter of Pluto, did you use just trigonometry or something else?
Well, there is some trig, yes. We actually fit profiles to the limb of Pluto. Which is a fancy way of saying that we trace around the edge of Pluto, which provides us something close to a circle, and then measure how many pixels across that circle is. Since we know how many km per pixel, we can figure out the diameter in km by counting those pixels. It sounds straightforward, but the artistry comes in figuring out when you "stop" counting pixels (where the edge is)
At what time did New Horizons make its closest approach to Pluto?
July 14 at 7:49am ET!
How much more expensive would it have been to send the probe into orbit around Pluto instead of a fly-by?
It would not be possible with current technology due to needing so much fuel at launch.
How does the New Horizons probe stay warm? From reading specs, the probe is designed a bit like a thermos bottle to stay insulated and operate at room temperature, but what's the original heat source? Is it the same plutonium radiation that is used to power the probe
We have others heaters that use some of the energy that the plutonium produces.
What type of snacks / drinks do you guys keep on hand for long days working on this mission?
We brought a lot of candied pecans, fudge, and cookies to share with the geology team. We also have been going to Costco every few days and supplying us with jelly beans, M&Ms, jerky, Oreos®, apricots, apples, dried fruit, pretzels, bagels, and chocolate-covered almonds. We get stragglers from other groups coming in to steal our food.
How powerful is the computer inside the spacecraft?
The computer is a whopping 12 MHz. Yes, you read that correctly: 12 megahertz. People are always surprised at how much less powerful our flight computers are compared to their home computers. But we build them rugged. If you bolted your laptop atop a rocket, violently shook it, exposed it to vacuum, and had it endure temperature extremes and radiation, then your vacation pictures might be at risk. But ours will be just fine.
I've heard Pluto is dark and cold, but could you live there when the sun is out?
At -370F, it's a terrible idea.
Hello Nasa, How far the New Horizon is anticipated to travel ?
New Horizons will never stop travelling. The power will last until about 100 AU (around 20+ years).
How long until we lose contact with New Horizon?
The power will degrade over time, so we have about 20-30 years left of enough wattage to use our instruments and antenna.