Editing 1532: New Horizons

{{comic
| number    = 1532
| date      = June 1, 2015
| title     = New Horizons
| image     = new_horizons.png
| titletext = Last-minute course change: Let's see if we can hit Steve's house.
}}

==Explanation==
''{{w|New Horizons}}'' is a NASA mission launched in 2006 to study the dwarf planet {{w|Pluto}} and its moons. Its closest approach to Pluto was on July 14, 2015 ([http://www.nasa.gov/mission_pages/newhorizons/main/index.html NASA countdown clock]), two weeks after the publication of this comic. In April and May 2015, it captured the first images of Pluto with enough resolution to see some details on Pluto's surface ([http://www.nasa.gov/feature/nasa-s-new-horizons-sees-more-detail-as-it-draws-closer-to-pluto NASA photos from 12 April to 12 May]). These images are similar to the second panel of the comic, with Pluto shown as a gray dot only a few pixels wide.
''{{w|Dawn (spacecraft)|Dawn}}'' is a NASA mission launched in September 2007 to study the asteroid {{w|4 Vesta|Vesta}} and dwarf planet {{w|Ceres (dwarf planet)|Ceres}}. Its closest approach to Vesta began on July 16, 2011 by the {{w|Dawn (spacecraft)#Vesta_approach|Vesta approach}}, and entered orbit around Ceres on 6 March 2015. And in fact the pictures of Ceres are still in a much better resolution like in this comic [[1476: Ceres]], but these images are also still mysterious.

On the day this comic was published, ''New Horizons'' was at 0.34 AU from Pluto and 32.55 AU from the Sun ([http://pluto.jhuapl.edu/Mission/Where-is-New-Horizons/index.php Johns Hopkins University's New Horizons page]). One {{w|Astronomical unit|Astronomical unit (AU)}} is the approximate distance of Earth from the Sun, or about 150 million kilometers.

Distances from the Sun by {{w|semi-major axis}}: Vesta 2.36 AU; Ceres 2.77 AU; Jupiter 5.20 AU; Pluto 39.26 AU.

A {{w|Gravity assist|slingshot maneuver}} is a technique where a spacecraft is maneuvered or accelerated with the help of a gravitational field.  In the comic, presumably someone named Steve made the calculations for the New Horizons spacecraft to accelerate toward Pluto using {{w|Jupiter}}'s gravity.

In the first panel we see [[Cueball]] and [[Ponytail]] standing in front of a computer monitor and observing a series of images sent back from ''New Horizons'' as it approaches the planet. They are about to see the dwarf planet Pluto with the highest resolution ever.

As the spacecraft gets closer, the images return... {{w|Earth}}. Steve had miscalculated the gravity assist and the spacecraft was about to crash into Earth.

Because the spacecraft carries 10.9&nbsp;kg (24&nbsp;lb) of radioactive plutonium-238, a crash on Earth is extremely dangerous.  It was estimated that a worst-case scenario of total dispersal of on-board plutonium during the launch would spread the equivalent radiation of 80% the average annual dosage in North America from background radiation over an area with a radius of 105&nbsp;km (65&nbsp;miles) ([http://pluto.jhuapl.edu/Mission/Spacecraft/docs/NH_DEIS_Full.pdf Draft Environmental Impact Statement for the New Horizons Mission]).  Because of decay during the flight, the situation would be slightly less dire if it crashed years later, but still a major disaster.

Less importantly, this is a huge embarrassment, especially in front of the successful ''Dawn'' team, who were the first to get a probe to visit a dwarf planet. Part of the joke is the utter implausibility of such an error being made, and then not being detected.

The title text suggests the team is considering crashing the probe into Steve's house as punishment for his errors.  However, doing so would expose Steve's neighbors to potentially lethal levels of radiation.  Therefore, the team would most likely have to crash the probe into an unpopulated area or the sea, to minimize human exposure. [[Randall]] described what might happen if ''New Horizons'' crashed into one's car in his ''[[what if? (blog)|what if?]]'' blog [http://what-if.xkcd.com/137/], and assuming the car was parked in the driveway the house would be similarly affected by the blast.

Luckily this was not what happened and when New Horizons reached Pluto 1½ month later Randall made this tribute to the achievement: [[1551: Pluto]] and also on that day he released the first ''[[what if? (blog)|what if?]]'' in over three months, and it was called [http://what-if.xkcd.com/137/ New Horizons].

Randall has used a Steve in a similar context in [[809: Los Alamos]] (set in 1945). If this is the same person, then 'Steve' would be at least 90 years old in 2015. A person named Steve also comes up with an inappropriate suggestion in [[1672: Women on 20s]].

==Transcript==
:[Cueball and Ponytail are standing in front of a large computer console. Cueball's hands are on the keyboard; both are looking at the screen.]
:Cueball: We made it! After all these years, ''New Horizons'' is finally revealing the surface of Pluto!
:Ponytail: Take ''that'', ''Dawn'' team.

:[In the next four frames, we see photos, entirely black except for a circle in the middle. The circle is initially small, indistinct and appears in shades of grey. Successive circles are larger showing more color and shade variation. In the last, we see a blurry but recognizable outline of Africa, the Middle East and part of Western Asia, along with some clouds. The lighting pattern suggests that it is daytime in Africa, sometime in the northern summer.]

:[A close-up of the two at the console.]
:Cueball: OK, who did the calculations for the Jupiter slingshot maneuver?
:Ponytail: (facing away from the computer console) Dammit, Steve...

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Space probes]]