Hot answers tagged

59

I think a lot of folks see these gorgeous photos of distant galaxies, with fine detail on dust lanes and spiral arms and assume that since they’re so far away, seeing Pluto would be easy. But while these galaxies are far away, they’re also huge. The (relative) detail that can be seen in any given telescope will be found by the object’s size divided by the ...


42

Velocity relative to what? There's no central universal point to measure velocity at, so your answer is likely going to change based on your frame of reference. New Horizons did indeed have the fasted launch velocity of any spacecraft that has left Earth (relative to Earth): After three years of construction, and several delays at the launch site, New ...


40

Distance. Size of the target. Its poor albedo at such distance to its only source of illumination, the Sun, compared to closer celestial bodies. And movement of the target and the vantage point in their orbits preventing advanced image interpolation techniques combining multiple observations of same side of Pluto at same lighting conditions. Pluto is ...


35

This mission study came up with a 900 kg nuclear-electric-propulsion spacecraft launched on an Ariane V with a C3 of 100 and a Jupiter gravity assist along the way. 1.05 kW electrical power at Pluto from RTGs is required. That would be four "classic" NASA RTGs, or about nine MMRTGs. It has a 20 kg science payload. (New Horizons has ~30 kg of instruments, ...


33

There are a few special things about Pluto, as compared to the other dwarf planets in the Kuiper belt. These include: It is the largest dwarf planet known, by diameter. (Note, this was only determined after the New Horizon's flyby) It orbits relatively close to the Sun, at times it is even closer than Neptune! It has the largest satellite system of any non-...


32

The long distance to the Sun mandates long exposure times. The New Horizons spacecraft needs to be relatively stable and its pointing accurate throughout these long exposure times. New Horizons does not have a scan platform. The cameras and other science instruments are fixed with respect to the vehicle. The satellite has to turn as a whole to keep the its ...


31

Pluto was discovered by a manual search of the sky using a blink comparator. This is an extremely laborious process. For Pluto, it made sense to go to all this trouble, because there were indications that a ninth planet had to be out there: Neptune's orbit was perturbed by the gravity of another planet, it seemed. Later, it turned out that that wasn't the ...


26

Organic Marble is correct in the comment, New Horizons is now busy with Departure Phase (DP2 from Aug 5-Oct 22) science and transmitting plasma and dust data, and no additional images will be transmitted until September 14 when Science Data Playback phase starts. All images from New Horizons Press Conferences Materials: Image sources: (1): Alan Stern, New ...


25

The initial plan was to visit all of the outer planets: The Planetary Grand Tour was to send several pairs of probes to fly by all the outer planets (and Pluto) along various trajectories, including Jupiter-Saturn-Pluto and Jupiter-Uranus-Neptune. Limited funding ended the Grand Tour program, but elements were incorporated into the Voyager Program, which ...


24

New Horizons pans during shots to eliminate motion smear. See this related question. The Voyager mission proved that this was possible: Between Voyager 2’s encounter with Saturn in 1981 and Uranus in 1986, controllers developed a technique called “image motion compensation.” This involved moving the scan platform at slow rates, which was found to be ...


23

It was said in here that the time to reach Pluto was shortened by 3 years. It's also said that after the Jupiter flyby the probe gained ~ 4 km/s accelerating to the speed of 23 km/s relative to the Sun. We can use simple Keplerian estimate (ignoring all complexities of the actual orbital mechanics) to obtain the speed when the probe approaches Pluto, \begin{...


22

Edit as of August 31, 2015: Looks like 2014 MU69 will be the post Pluto target. Paul Gilster has a nice article on Centauri Dreams. Edit as of Jan. 3, 2015: This article says 3 potential candidates were found in December of 2014. This article says the New Horizons team is running out of time to find KBOs to check out after it passes Pluto. No post Pluto ...


22

Modern technology doesn't change the major constraints of rocket propulsion significantly. In the absence of a gravity assist, the most fuel-efficient route from Earth to Pluto is approximately a 45-year journey. Bringing that down to 9 years already represents a large investment in propulsion fuel; New Horizons set the record for the highest launch speed ...


22

For getting really high resolution stuff, you need to get outside of the atmosphere. The best instrument to do this is the Hubble Space Telescope. The resolution of Hubble is about 0.05 arc seconds. Pluto is currently around 3.5 billion miles. That gives a resolution of 850 miles or so. This is limited by the size of the mirror that Hubble has, which is ...


21

This is probably the easiest to answer if we take the same mission profile and just track from the Pluto flyby backwards. I'll make some rather broad assumptions and first order approximations, like that NASA had their NEXT ion thruster developed to the highest technology readiness level (they did exist when New Horizons launched, but not at TRL required to ...


21

Per New Horizons science team member John Spencer, via Emily Lakdawalla, the spacecraft is not yet close enough to fully resolve the the shapes of Pluto and Charon. Their apparent shape is dominated by the camera / telescope's point spread function, which is "slightly teardrop shaped, giving that gibbous appearance".


21

A bit of good old Google-fu reveals this blog post by Emily Lakdawalla for when New Horizon's LORRI imagery of Pluto is expected to be of better resolution than that of Hubble Space Telescope's Wide Field Camera 3 (WFC3) (relevant excerpts only, no copyright infringement intended): So New Horizons' vision is is about 25 times less sharp than Hubble's. ...


20

The “Sailboat Island” gets its name from a Poincaré Surface-of-Section (SOS) plot of potentially stable S-type family of orbits in the Pluto-Charon system. From NASA Ames' blog post titled Playing Marbles at Pluto. Looking at the Dynamic Dust Environment. Generators, Sweepers, and Sweet-Spots by Kimberly Ennico: Othon Winter (UNESP Brazil) spoke about “On ...


20

Let's try and do some math with this. Will use Wikipedia for numbers. Gravity at Pluto's surface: 0.61711215789 $m/s^2$ Gravity from Charon- Pluto's near side- 0.0002724276 $m/s^2$ Gravity from Charon- Pluto's far side- 0.00027242753 $m/s^2$ Centripetal Acceleration- Near side- 0.00001749536 $m/s^2$ Centripetal Acceleration- Far side- 0.00006647414 $m/s^2$ ...


19

I am guessing VxWorks but I haven't found any sources to validate this. Close, but no cigar. If New Horizons flight software was built by Jet Propulsion Laboratory (JPL), then I guess Wind River's VxWorks RTOS would have been their first choice (it's also a popular choice for hardware on Mars - Pathfinder, Sojourner, Phoenix lander, Spirit, Opportunity, ...


18

Short answer Yes, what you see in the news are recent images. It takes about 1 hour to the probe to send one image bit by bit, and about 4 hours for the bits to travel from the probe to Earth. If New Horizons could do the scientific work, take images, and send them at the same time, this would be great, but that's not the case. While the probe had more time ...


17

The official trigger for what caused Pluto's demotion as a planet was the discovery of Eris, in October 2005. For a number of years, starting with the discovery of non-Pluto Kuiper Belt Objects (KBOs), and later with the discovery of other large objects in the Kuiper Belt. When Eris was discovered, the IAU decided that it needed to decide what a planet was. ...


16

It's just a coincidence, and officially, the dates aren't that close. The IAU (International Astronomical Union) General Assembly in Prague, Czech Republic where the new definition of a planet was endorsed and with it Pluto losing its planetary status, happened in late August, 2006. Final draft that was voted on states: A planet is a celestial body that ...


15

Why doesn't New Horizons fly by nearer to Pluto so the gravitational pull would slingshot the probe to one of the next dwarf planets in the outer solar system (Eris, Haumea, Makemake,...)? There are two key reasons: It can't. Even if it could, it shouldn't. The reason it can't is because the delta V would be rather small even if New Horizons was to flyby ...


15

How tall are these things? Are they made of ice? Are they the tallest things on Pluto? Are these the tallest ice features in the Solar System? "New close-up images of a region near Pluto’s equator reveal a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body." https://www.nasa....


14

This is the 1978 image of the Pluto system that led to the discovery of Charon. This is a negative, so the big black blob in the middle is Pluto and Charon. Charon? It's the little bump on the upper right of that blob. You can barely make out Charon. Additional satellites? No. This is a 1990 image of Pluto and Charon taken by the Hubble: This was before ...


13

According to this paper, Pluto's atmosphere never collapses. Though it was handy that we thought it did at one time, since that helped to get New Horizons approved as a mission, in order to try to get there before the imminent collapse.


13

Observations will be of two different kinds. Distant, effectively telescopic observations starting months in advance of the flyby and then a torrent of activity during the actual flyby. There will definitely be a chance to observe the known moons of Pluto, which is part of the plan. You can see a timeline of Pluto encounter events on wikipedia. There will be ...


13

From the same blog entry you linked to: The transmission of the High Priority data set will be complete on July 20, and then image transmission will pause. For nearly two months, until September 14, New Horizons will switch to near-real-time downlinking of data from other, so-called "low-speed" instruments while it transmits just housekeeping information ...


13

To add to some already great answers, I'd like to toss in the basic physics of photography that you can experience here on Earth. When you take a picture of something, you're collecting information in the form of light that has been reflected off of it. In a bright, well-lit environment where you're taking pictures up-close or have a huge lens, you can ...


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