Have light gases like hydrogen or helium been explored for ion propulsion? asks what it asks. In the body of the question it's restated as:

Has the "ion sorcery" for light gases like hydrogen and helium been explored experimentally for future ion propulsion technology? What about neon at least?

There was some heavy pushback on the question's premise based on a very narrow view of how electric propulsion is used. The Dawn mission was power-limited rather than mass-limited, so in order to get there quickly they went with a high mass species; xenon. Xenon has an additional advantage that it's easier to ionize so lower mass and lower power consumption components can be used to produce the plasma.

But what I (think that I) see there is a concerted effort to prevent the asking of my question in a way that doesn't presuppose all possible uses of electric propulsion in the future will be Dawn-like in nature.

It takes a while to read through everything there, but of course the answer to my question is "Yes" and since nobody was willing to address the question as asked I've posted a new answer.

Now down voting on that one has begun as well.

Why all the negativity and down voting here? Is someone working on a low-mass species thruster in some startup and doesn't want others to get the idea that there might be some mission-space for a very high Isp thruster or one that could harvest hydrogen/helium and reuse it?

Question: What's going on with all the downvoting on my answers here?


3 Answers 3


Well, answer posts are supposed to actually answer the question.

As you say yourself, it couldn't be clearer what the question is: it's "Have light gases like hydrogen or helium been explored for ion propulsion?" I think that your first answer post is inappropriate because it does not answer that question, and I think that's why that post was downvoted.

On the other hand, your second answer post absolutely does answer the question... but only the second half. The first half of your answer post, on the other hand, barely addresses the question at all. Instead, it's a lengthy criticism of people's behavior with lots of derisive language. Writing such a criticism in an answer post is completely inappropriate. That's probably why that post was downvoted as well.

Granted, it looks to me like Bob's answer post also doesn't actually answer the question that was asked. So what can you do if your question attracts a bad answer? You can:

  • Leave a comment explaining how the answer needs improvement. You've already done this.
  • Downvote the answer. I'm guessing you've already done this.
  • Find the answer yourself and post it. You've already done this.
  • Post a bounty or something in order to attract better answers. This would probably be redundant at this point.
  • In extreme cases, bring the answer to the attention of the moderators or the community by flagging it or making a meta post. I don't think this counts as an extreme case.

And that's about it.

  • $\begingroup$ Thanks for your answer. It seems you've summarized the situation similarly to how I see it, except that you've suggested that I "seem upset" and need to "make peace". Well I'm not and I don't. I think that unapologetic answering of a question as if it's a different question that's more fun to answer is detrimental to Stack Exchange. It undermines the way SE works, and if it goes unchecked it becomes a good way to frustrate and harangue new users who may not be familiar with the way the site works. It's very rare in this site but I've brought it up here to raise awareness. $\endgroup$
    – uhoh
    Apr 20, 2021 at 17:19
  • $\begingroup$ As far as "What's going on with all the downvoting on my answers here?" I think you've probably called it right, I think your explanation is correct. At some point I may edit/adjust the half of the 2nd answer that you mention. I won't do it yet as this question is still active. $\endgroup$
    – uhoh
    Apr 20, 2021 at 17:22
  • 2
    $\begingroup$ @uhoh Well, I'm glad to hear that you're not upset. I'll edit my answer here to remove that bit. That said, there's a point I feel I should make. Often, people on Stack Exchange post questions that, taken literally, are not quite what they actually meant to ask, and in order to give the asker the information they really wanted, it's necessary to look past the question that was literally asked and read between the lines instead. So, sometimes people see a question and wonder: is this a take-it-literally question or a read-between-the-lines question? $\endgroup$ Apr 20, 2021 at 17:30
  • 2
    $\begingroup$ I once took a question literally, and my answer immediately got 3 downvotes, and the asker did not find it useful. I should have read between the lines instead. Anyway, my point is that if an answerer guesses that a question is a you-need-to-read-between-the-lines question, and answers it that way, I think that behavior is totally reasonable, even if the guess was wrong. $\endgroup$ Apr 20, 2021 at 17:33

Looking at that one specifically, it is very obvious you didn't like Bob's answer, despite it being accurate (he wrote Yes, along with info as to why it wasn't used), and wrote a bit of an attack on him in your post without providing anything useful in an answer. You basically said "Yes, but I don't like the way Bob wrote it"

Oh, and then you also wrote two comments linking to "why are my posts downvoted" and as you have been told many times, if someone doesn't leave a comment telling you why they downvoted (and folks are under no pressure to comment) it should just be taken as meaning what the tooltip says:

  • For answers: This answer is not useful
  • For questions: This question does not show any research effort, it is unclear or not useful

In reality, though, there have been quite a few times folks have told you what they think you should improve - that would be a useful starting point.

  • $\begingroup$ Accurate counts in horseshoes but in Stack Exchange it also has to answer the question that's actually asked. That answer would be great on a different question but it's inappropriate on mine. That the answer is great in the abstract explains the up voting, but once they started reading I think most voters didn't go back and check to see if it actually addressed the question as asked. I don't think it was bad faith, it's pretty common for folks to get fired up and pen an insightful answer to what they'd hoped the question was. The question is concise and clear. They simply missed the mark. $\endgroup$
    – uhoh
    Apr 12, 2021 at 10:50
  • $\begingroup$ There are three instances of question marks in my question (apart for quoted related questions) Here they are. Title: "Have light gases like hydrogen or helium been explored for ion propulsion?" Reiteration at the end: (before the background section) Has the "ion sorcery" for light gases like hydrogen and helium been explored experimentally for future ion propulsion technology? What about neon at least?" The answer in question nicely answers "Why didn't Dawn use helium?" But I didn't ask that and didn't constrain to large, heavy, traditional deep-space probes. $\endgroup$
    – uhoh
    Apr 12, 2021 at 12:20

The question couldn't be clearer

The title reads

Have light gases like hydrogen or helium been explored for ion propulsion?

and in the body the question is repeated:

Has the "ion sorcery" for light gases like hydrogen and helium been explored experimentally for future ion propulsion technology? What about neon at least?

These are the only instances of question marks in the actual question.

The question asked is clear and couldn't be clearer. No comments were ever posted asking for clarification under the question, visible there now or moved to chat.

It has now been answered

This answer lists many scholarly works on ion propulsion and uses this to answer "Yes" to the question.

I'm accepting this as the right answer because it's undeniably correct.

If future readers come to the page looking for an to the question as asked they will find that the answer is yes, followed by a list of such works.

The funny business about all the downvoting

What's happened on this answer is that the author a question that was not asked. If someone had asked "Why didn't the Dawn mission use hydrogen?" this would have been a great answer.

It's highly up voted because by itself it reads like a great answer, nobody goes back to see if it actually answers the question after reading it. Had its author been more cooperative we could have quickly generated the 2nd question about Dawn and then the question and answer would match.

All future applications of ion propulsion in spaceflight will not simply be carbon copies of Dawn. All future applications will not be energy limited. Station keeping requires very little thrust, halo orbits may only need a few m/s per year if managed carefully. In these cases the Dawn answer bears no relevance, in addition to not answering the question as asked.

I still wonder if there is in fact some work being done on this and some folks did not like seeing it discussed on the internet.

What happened here is bad

The answer author decided to drive the page to a different place, essentially hijacked the question and pretended it asked a different question.

This is not how Stack Exchange works. I have seen it happen too often in other SE sites but until this question I had never seen it happen here.

I've asked over 3,000 SE questions, over 2,000 in this site. This is the only time I can recall having a question hijacked.

And it's also the only time I've been called dude when trying to point it out.


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