How to remove vertical space between header and body of text?

Question

I'm writing a Statement of Purpose, in which I've opted to leave out the title altogether, and instead put the details of myself (name, program etc) in the header. While this works fine, I have trouble in reducing the gap between the header and the first line of text on the page. I tried using \vspace, but that doesn't seem to help as I see no difference at all. Also, using vspace is OK for the first page, but since I should have no idea when the next page begin, I wouldn't know where to put the \vspace for Page 2.

Here's a minimal document :

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc} 
\usepackage[margin=1in]{geometry}
\usepackage{fancyheadings}
\pagestyle{fancy}

\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}
\newcommand{\Hrule}{\rule{\linewidth}{0.3mm}}

\fancyhead{}
\fancyfoot{}

\fancyhead[CO, CE]{Name}
\fancyhead[LO, LE]{Statement of Purpose}
\fancyhead[RO, RE]{Computer Science, PhD}


\begin{document}

It is my greatest desire ...

\end{document}

Answer 1

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[margin=1in,headsep=0pt]{geometry}
\usepackage{fancyhdr}
\pagestyle{fancy}

\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}
\newcommand{\Hrule}{\rule{\linewidth}{0.3mm}}

\fancyhf{} % clear all fields

\fancyhead[C]{Name}
\fancyhead[L]{Statement of Purpose}
\fancyhead[R]{Computer Science, PhD}


\begin{document}

It is my greatest desire ...\lipsum

\end{document}

Set headsep to zero; the lipsum package is only used to generate dummy text. Use fancyhdr rather than the obsolete fancyheadings.