3029: Sun Avoidance

2024-12-26T14:02:22Z

172.69.194.219: Christmas Comic detail moved to Trivia. Proper name of the Sun, everywhere but the title text (Randall's error). Removed strange "Icarus's dream" bit that's either wrong or miswritten.

{{comic
| number = 3029
| date = December 25, 2024
| title = Sun Avoidance
| image = sun_avoidance_2x.png
| imagesize = 311x403px
| noexpand = true
| titletext = C'mon, ESA Solar Orbiter team, just give the Parker probe a LITTLE nudge at aphelion. Crash it into the sun. Fulfill the dream of Icarus. It is your destiny.
}}

==Explanation==
{{incomplete|Created by a SANTA BOT FLYING TOO CLOSE TO THE SUN (SKILL ISSUE). Do NOT delete this tag too soon.}}

The comic shows the end of a table of human missions, both terrestrial and space-based, ranked by how far they stayed away from the {{w|Sun}}.

The vast majority of these missions have been on Earth, a few on the Moon, and most of the rest in Earth orbit, so about 157 million km from the Sun. There have also been 8 probes sent to the outer planets; they could be at the top of the list if this were shown, but only if they started by flying directly away from the Sun, at at time when the Earth was farthest from the Sun. Else they would have been closer to the Sun at the start than all missions on Earth when Earth was farthest. It is not how far away the mission ends but how close it comes at closest approach to the Sun.

Most space probes try not to get too close to the Sun, because it's extremely hot{{Citation needed}} and their equipment (especially the electronics) are not designed to work at such temperatures and radiation levels. If they have to venture into the inner Solar System, either because the mission is to an inner planet or other body there or to use {{w|gravity assist}} of Mercury or Venus, mission planners will design the trajectory so it remains tens of millions of kilometers away from the Sun, to minimize the Sun's effect on the spacecraft.

This comic was posted the day after December 24, 2024, when the {{w|Parker Solar Probe}} made its closest approach to the Sun. As a result, it has set a new record for the worst failure in solar avoidance. This mission needs to be really close to the Sun so it can make close-up analysis of its corona and magnetic field. It has been engineered with special solar shields to protect it from the extreme heat and radiation. This can also explain why this comic was released on Christmas Day instead of a Christmas comic, if [[Randall]] found this more interesting than Christmas.

The next closest mission that's still in operation (the {{w|Helios (spacecraft)|Helios}} missions ended in 1985) is the {{w|European Space Agency}}'s {{w|Solar Orbiter}}. The title text jokes that it should nudge Parker so it crashes into the Sun fulfilling the dream of {{w|Icarus}}, a character from Greek mythology who flew too close to the Sun using wings crafted by his father {{w|Daedalus}}, and fell into the sea because the beeswax in the wings melted. Flying too close to the Sun is a saying that relates to Icarus.

If the Solar Orbiter did this it would then retake the lead among missions in operation of being bad at avoiding the Sun. But it would be be difficult to accomplish the feat, since at Parker's aphelion (furthest distance from the Sun in its orbit) it's still only about 7 million km, 35 million km from Solar Orbiter's orbit (and the probes would be much further apart if they're not on the same side of the Sun at the time).

Obviously the joke is to mischaracterize Parker's impressively close approach to the Sun as a failure to avoid it, but it's still perhaps mistaken to title the list as a leaderboard of ''skill''. The Parker mission needed an extremely ''high'' degree of skill to successfully avoid the Sun - and should rank well above all the missions that went nowhere as near the Sun, and therefore showed little to no skill in avoiding it. By analogy, {{w|Shooting_an_apple_off_one%27s_child%27s_head#William_Tell|"William Tell"}} avoided shooting his son with great skill, and would have needed much less if the target had been a beach ball rather than an apple.

==Transcript==
{{incomplete transcript|There should not be a wikitable there, just do it with Transcript-style description. Do NOT delete this tag too soon.}}
:Sun Avoidance Skill Leaderboard
:[A table with an ellipsis indicating a large number of rows being omitted, followed by seven substantive rows. All of the rank numbers except "1." are cut off at the left, with the leftmost digit being a partially cut-off "4", except that on the fourth substantive row, the "4" is shown in full with a cut-off "2" to its left. Hence, these ranks actually represent numbers with at least eight digits.]
:{| class="wikitable"
|-
!Rank
!Mission
!Sun Nearest Miss
|-
| style="text-align:right" | 1.<br>⋮<br>...<br>⋮<br>4303857.
|colspan="2"|[All other expeditions in human history]
|-
| style="text-align:right" | 4303858.
|Mariner-10
|69.0 million km
|-
| style="text-align:right" | 4303859.
|Helios 1
|46.4 million km
|-
| style="text-align:right" | 4303860.
|BepiColombo
|45.8 million km
|-
| style="text-align:right" | 24303861.
|Messenger
|45.3 million km
|-
| style="text-align:right" | 4303862.
|Solar Orbiter
|43.8 million km
|-
| style="text-align:right" | 4303863.
|Helios 2
|43.3 million km
|-
| style="text-align:right" | 4303864.
|Parker
|6.17 million km
|-
|}

:[Caption below the panel:]
:Congratulations to the Parker Solar Probe for setting a new record for "Worst Job Avoiding the Sun."

==Trivia==
This comic was released on Christmas Day of 2024, but makes no reference to Christmas. This year marks the first time in xkcd's 20 year history (of releasing comics around Christmas), that there have been no [[:Category:Christmas|Christmas comics]] released during those days. Also all nine times before this year, when a release day fell on Christmas Day, that comic has always been about Christmas.

{{comic discussion}}

[[Category:Space probes]]

Talk:2982: Water Filtration

2024-09-07T06:39:21Z

172.69.194.219:

On the activated carbon filter, that's a double entendre, referencing both activated charcoal filters often used in filtration systems and the nearby neutron source, which is radioactivity activating the carbon. [[Special:Contributions/172.71.254.23|172.71.254.23]] 04:32, 7 September 2024 (UTC)Corsac

There are a bunch of processes shown that are real, but not actually used in water filtration. For example, electrolysis is used to make hydrogen and oxygen gas, and reverse electrolysis is used in fuel cells to produce electricity, but the electricity cost of doing these steps to purify a useful amount of water would be prohibitive. [[Special:Contributions/162.158.159.14|162.158.159.14]] 06:18, 7 September 2024 (UTC)
:On the other hand, it would be a kind of "extra-intense distillation". We already basically have been "distilling water", as I see it, with the autoclave/condenser pairing that would certainly leave any remaining dissolved minerals or particulates behind. By splitting then recombining the component elements (and some basic gas-chromatography process, not shown) then you'd inarguably get water out that's about as pure as you can hope for in even the most {{w|The Waters of Mars|paranoid fantasies}} about the need for clean water.
:...of course, here it's not even the ''most'' energetic attempt to further 'refine' the components of "watery matter", with the assumed luxury of having energy (and indeed water) to burn... [[Special:Contributions/172.69.194.219|172.69.194.219]] 06:39, 7 September 2024 (UTC)

explain xkcd - User contributions [en]

3029: Sun Avoidance

Talk:2982: Water Filtration