Editing 1707: xkcd Phone 4

| titletext = The SpaceX system carefully guides falling phones down to the surface, a process which the phones increasingly often survive without exploding.

This is the fourth entry in the ongoing [[:Category:xkcd Phones|xkcd Phone series]], and once again, the comic plays with many standard tech buzzwords to create a phone that sounds impressive but would actually be very impractical. The previous comic in the series [[1549: xkcd Phone 3]] was released just over a year before this one and the next [[1809: xkcd Phone 5]] was released almost 8 months later.

: Phone battery capacity is measured in {{w|ampere-hour}}s (which, thanks to {{w|dimensional analysis}}, is just an unusual way of denoting electric charge; one ampere-hour is 3600 Coulombs). Usually, the capacity is quoted in milliampere-hours (one-thousandth, or 10^-3, of an ampere hour); however, this one is quoted in ''micro''ampere-hours (one-millionth, or 10^-6, of an ampere-hour), presumably as a marketing ploy to give a more impressive-looking number. Quoted in more standard terms, this phone's battery capacity is 18 mAh. In comparison, an iPhone 6+ has a battery capacity of 2,750 mAh.  This phone's battery is dreadful (under a typical current draw of 0.1A, it would power the phone for about 11 minutes). There is nothing normally called a "nickel-lithium-iron battery" — rather, this seems to be a [[739|malamanteau]] of the experimental {{w|nickel–lithium battery}} and the common {{w|lithium ion battery}} (which does not contain any iron) or the lithium-iron-phosphate battery, often called lithium-iron, but more often called the LiFePO battery. The {{w|nickel–iron battery}} may contain {{w|lithium hydroxide}}, but it's ''terrible'' for most applications. Worse, this battery is non-rechargeable, meaning that it would have to be replaced to use the phone again after it is exhausted (every 11 minutes, at that!). The [[xkcd Phone 3]] was powered by two {{w|AA battery|AA batteries}} (not included), which have an energy capacity roughly 100 times larger.

: A {{w|dog whistle}} is a high-pitched whistle that humans cannot hear, but dogs can. In speaker terminology, a bass speaker is called a {{w|woofer}} because it could reproduce the low pitch of a dog bark. A treble speaker is a {{w|tweeter}}; if this "whistle" is actually a speaker, it might be termed a ''supertweeter''. The scare quotes may be a reference to "{{w|dog-whistle politics}}", in which certain phrases have a particular meaning to a segment of the audience that passes unnoticed by the rest. This allows a candidate to surreptitiously signal agreement with that group, without alienating the rest of the audience, among whom the ideas might be unpopular if plainly stated. The [[xkcd Phone 2]] contained a "dog noticer".

: These {{w|wings}} resemble the ones found on {{w|sanitary towel}}s (usually called "pads", making this a possible iPad pun) which attach the pad to the {{w|gusset}} and keep it in place between the woman's legs during her period ({{w|Menstruation}} cycle). If actually functional as {{w|aerodynamic}} wings, they would likely come into play when the "SpaceX" impact protection feature becomes engaged and would likely make holding the phone awkward if rigid. The [[xkcd Phone 3]] had a similarly positioned wristband.

: The {{w|Julian calendar}} is the predecessor to the modern {{w|Gregorian calendar}} — the difference is that the two calendars calculate leap years differently. The current difference between the calendars is 13 days, which will remain unchanged until February 2100. The Julian calendar is still used occasionally — mainly by Eastern Orthodox Christians — but it's not something so vital that it needs a hardwired switch on the front of the phone. This may be a play on the ability to switch the time display between a 12-hour clock and a 24-hour clock. It could also be playing with the ability to switch between Daylight Savings Time and Standard or change time zones.  

; ''SpaceX'' impact protection<nowiki>:</nowiki> when dropped, phone lands on barge

: The rocket company {{w|SpaceX}}, at the time that this comic was released, had recently trialed a {{w|SpaceX reusable launch system development program|reusable rocket stage}} which, after separating from the launch vehicle, lands on a {{w|Autonomous spaceport drone ship|drone barge}} to be reused. Making a phone land on the nearest barge when dropped would make it very difficult to recover, although the 11-minute battery time there might be a chance to get it even if you can't catch it.

: A {{w|parallel port}} is a type of interface which transfers high-volume simultaneous data. It was often used to connect printers and other devices to computers but was generally considered obsolete by the time smartphones began to appear on the market and would be very bulky and slow compared to the USB ports generally used in phones. It was commonly found together with {{w|serial port}}s, which are used for low-volume sequential data such as [[485: Depth|mouse]] [[1110: Click and Drag|movements]]. Here it is paired with a serial interface for analog data with parallel outputs for several people.

: Headphone jacks are circular ports in a phone that allow audio to be played through headphones connected to the jack. There were [http://www.businessinsider.com.au/apple-headphone-jack-iphone-side-effects-2016-7#/#smaller-headphone-makers-would-be-at-a-disadvantage-4 constant rumors] that Apple's next iPhone would not have any headphone jacks (which eventually proved true for the iPhone 7 announcement two months after this comic). Also, [http://www.google.com Google] was developing a module for the now cancelled [https://atap.google.com/ara/ Project Ara] (archive [https://web.archive.org/web/20160716080118/https://atap.google.com/ara/ here]), a modular smartphone. This module allows the device to have [http://www.overclock3d.net/news/audio/sennheiser_shows_audio_module_concepts_for_project_ara/1 Four headphone jacks], which would allow audio to be shared among 4 people, each occupying one port. The xkcd phone takes this too far when they install a whopping TWELVE of them, which is completely overkill because almost nobody needs to connect to 12 headphones at once. 12 headphones will also drain the battery, like the wireless discharging in the [[XKCD Phone 3]], because playing audio through 24 speakers, two for each pair of headphones, is very power-consuming.

The title text pokes fun at the number of SpaceX rockets that [https://www.youtube.com/watch?v=V3wZRdg-Tmo crashed and exploded] before they got the landing gear right.

:[An image of a smartphone featuring wings is shown. Clockwise from the top left the labels read:]

:''SpaceX'' impact protection: When dropped, phone lands on barge