How do you disable a textarea using jquery in SharePoint 2010

Question

How do I write a script to disable a comment field called Space Available Comments?
I tried using the following scripts and none of theme work.  I am still able to delete or type in texts in the textarea.
$("textarea[title*='Space']").attr("disabled","disabled");
$("textarea[name*='ctl10']").prop("disabled","disabled");
$('textarea').attr('readonly','true');
$('textarea[id="long id number here']").attr("disabled","false");
Thank you very much.
Here is source:
<tr>
<td nowrap="true" valign="top" width="190px" class="ms-formlabel"><h3 class="ms-standardheader">
<nobr>Space Available Comments</nobr>
</h3></td>
<td valign="top" class="ms-formbody">
<!-- FieldName="Space Available Comments"
FieldInternalName="Space_x0020_Available_x0020_Comm"
FieldType="SPFieldNote"
-->
<span dir="none">
<span dir="ltr">
<textarea name="ctl00$m$g_f9da713c_cff1_48d5_9943_08f4ac2b35b9$ctl00$ctl05$ctl10$ctl00$ctl00$ctl04$ctl00$ctl00$TextField" rows="6" cols="20" id="ctl00_m_g_f9da713c_cff1_48d5_9943_08f4ac2b35b9_ctl00_ctl05_ctl10_ctl00_ctl00_ctl04_ctl00_ctl00_TextField" title="Space Available Comments" class="ms-long" dir="none">&lt;DIV class=ms-rtestate-field&gt;Space Available Comments field value.&lt;/DIV&gt;</textarea>
<input name="ctl00$m$g_f9da713c_cff1_48d5_9943_08f4ac2b35b9$ctl00$ctl05$ctl10$ctl00$ctl00$ctl04$ctl00$ctl00$TextField_spSave" type="HIDDEN" id="ctl00_m_g_f9da713c_cff1_48d5_9943_08f4ac2b35b9_ctl00_ctl05_ctl10_ctl00_ctl00_ctl04_ctl00_ctl00_TextField_spSave" />
</span>
</td>
</tr>

Answer 1

I tried both of your solutions above. It would not disabled.  Your solutions "should" work. But, I don't get it why it does not work. I even tried several other variations of scripts to target the textarea including the solution
below from Robin. See his answers below.
Do you think that it might have help you more to see the problem if I had provided the script below <input name...> between </span> and </td>? 
I don't want to confuse you. But, the ultimate purpose is when a user selected the Space Available? to a "YES" option, the Space Avaiable Comments textarea should be disabled. My script to disable the radio button is working. I just need to find
a solution how to disable the textarea and I running out of ideas. Please help if you can.
Here is the script:
<script type="text/javascript">// <![CDATA[
if (browseris.ie5up && (browseris.win32 || browseris.win64bit) && !IsAccessibilityFeatureEnabled()){RTE_ConvertTextAreaToRichEdit("ctl00_m_g_f9da713c_cff1_48d5_9943_08f4ac2b35b9_ctl00_ctl05_ctl10_ctl00_ctl00_ctl04_ctl00_ctl00_TextField", true, false, "", "1033", null, true, null, null, null,"Compatible", "\u002fpmb_eTracking_Tool",null,null,null,null);}else{document.write("&#160;<br /><span class=\"ms-formdescription\"><a href='javascript:HelpWindowKey(\"nsrichtext\")'>Click for help about adding basic HTML formatting.</a></span>&#160;<br />");};//]]>
</script></span>
Thank you very much for your immediate response.