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\begin{document}

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\Large 
\centerline {\bf Project Description}
\normalsize
\vspace{0.25cm}

\section{Results from Prior NSF Support}
Over the past few years, the PI's group at the University of Arizona
has constructed two spectroscopic heterodyne array receivers:
{\it PoleSTAR}, a 4 pixel 810 GHz
receiver that operated at the 1.7~m AST/RO telescope at the South
Pole; and {\it DesertSTAR}, a 7 pixel 345~GHz array receiver for the
10-meter Heinrich Hertz Telescope (HHT) on Mt. Graham,
Arizona.  Both instruments are the very first of their kind.  {\it PoleSTAR}
was completed in 2000 and offers excellent receiver performance on all
4 pixels \citep{rhooph}.  {\it DesertSTAR} went into routine operation on the HHT with an
initial complement of 3 pixels in October 2003 and has been expanded
to the final hexagonal array of 7 pixels  (Figure~\ref{dstar}).   
Both
instruments were funded by NSF programs; work on {\it PoleSTAR} 
was funded by the NSF Office of Polar Programs (A. Stark--PI: OPP-0126090),
and {\it DesertSTAR}
development has been a joint effort between the University of Arizona,
the University of Massachusetts, and the University of Virginia with
partial funding through the NSF ATI program (AST-9622569).  

More recently, a multi-institutional team led by the PI was awarded an 
NSF MRI grant (AST-0421499) to construct {\it SuperCam}, a 64 pixel,
heterodyne array for the Heinrich Hertz Telescope (Groppi et al 2006). {\it Supercam}
represents the cutting edge of heterodyne array technology
in terms of integrated mixers (Puetz et al 2006) and IF
processor/spectrometer technology.   {\it Supercam} will be
completed by the end of 2007 and commissioned at the HHT in
2008. 

In 2006 funding was obtained through NSF/OPP (ANT-0538665) to perform a design study
for HEAT.  This proposal is based upon that design study.

As of June 2007, an NSF-SGER proposal by the PI's team to construct {\tt Pre-HEAT}, a 450~$\mu$m
tipper and spectrometer, for deployment to Dome~A has been recommended for funding. The tipper 
will have a 20~cm aperture and be depolyed in 2007-2008 by the same Chinese and Australian 
collaborators who will take the proposed HEAT observatory to Dome A in 2009.
The experience and heritage gained through these unique efforts will clearly be instrumental 
in making HEAT a reality. 

Finally, in January 2007 this team proposed the instrument portion of {\tt HEAT}
to the NSF under the Major Research Instrumentation (MRI) program.   The
proposal remains under consideration.  If the HEAT MRI is awarded, then the budget in this
proposal will be reduced appropriately and reflect only the cost of the HEAT
science and logistical support. 


\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.5in}{\includegraphics[scale=0.73,angle=0]{../figures/dstar-w3.eps}}}
{\parbox{2.8in}{
\caption{\label{dstar} { Large scale map of CO J=3-2 from the W3
    star forming region taken by
    DesertSTAR, the PI's 345~GHz 7-beam array
    receiver at the Heinrich Hertz Telescope.   The ``cavity'' seen in
    the center of the map represents the location of an OB association
    and its radiative feedback on its parent cloud, indicative of the
    phenomena that HEAT will reveal clearly.
    Furthermore, as shown in the inset,
    every imaged point in a heterodyne map also
    represents a high-resolution ($\lambda/\Delta \lambda \approx
    10^6$) spectrum.}} }}
\end{minipage}
\end{figure}

\vspace{-0.25cm}

\section{Research Activities}

The proposed High Elevation Antarctic Terahertz Telescope (HEAT) will
forge entirely new capabilities for ground based infrared and submillimeter
astronomy, by providing a window on the Universe which otherwise would be
unavailable except via airborne or space-based platforms. The
pioneering surveys to be performed by HEAT will be made
available to the entire astronomical community.  HEAT represents a
true international pioneering effort (US, UK, Australia, China and the Netherlands)
in keeping with the spirit of the International Polar Year ({\tt www.ipy.org}: 2007-2009).  
Here, we outline HEAT's ``key project'', a THz survey of the Galactic Plane observable 
from Dome~A, Antarctica. HEAT is the Dome A component of the multinational 
``AstroPoles'' program which has been offically endorsed by the Joint Committee for 
the upcoming IPY (see attached letter).  This proposal supports the
development of the HEAT observatory through its first year of science
operations.  

\subsection{Introduction}

From the Milky Way to high redshift protogalaxies, the internal
evolution of galaxies is determined to a large extent by the life
cycles of interstellar clouds, as shown in Figure~\ref{cycles}.

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.6in}{\includegraphics[scale=0.37,angle=0]{../figures/LifeCycle-ISM.eps}}}
{\parbox{2.7in}{
\caption{\label{cycles} { HEAT will
    observe the fine structure lines of N$^+$, C$^+$, C, and CO that
    probe the entire life cycle of interstellar clouds.   In
    particular, HEAT will witness the transformation of neutral atomic
clouds into star-forming clouds, the interaction of the interstellar
medium (ISM) with the young stars that are born from it, and the
return of enriched stellar material to the ISM by stellar death. }} }}
\end{minipage}
\end{figure}

These clouds are largely comprised of
atomic \& molecular hydrogen and atomic helium, which are 
notoriously difficult to detect under normal interstellar
conditions.  Atomic hydrogen is detectable via the
21~cm spin-flip transition and provides the observational basis for
current models of a multiphase Galactic ISM.  Its emission
is insensitive to gas density and does not always discriminate between 
cold (T$\sim$70K) atomic clouds and the warm (T$\sim$8000K) neutral medium
that is thought to pervade the Galaxy. 
Furthermore, neither atomic helium nor molecular hydrogen
(H$_2$) have accessible emission line spectra in the prevailing
physical conditions in cold interstellar clouds.   Thus, it is important
to probe the nature of the ISM via rarer trace elements. 
Carbon, for example, is found in ionized form (C$^+$) in neutral clouds,
eventually becoming atomic (C), then molecular as carbon monoxide (CO)
in dark molecular clouds. 

Although we are now beginning to understand star formation, the
formation, evolution and destruction of molecular clouds remains
shrouded in uncertainty. 
The need to understand the evolution of interstellar clouds in the context 
of star formation has become a central theme of contemporary
astrophysics.  Indeed, the National Research Council's
most recent {\it Decadal Survey} has identified the study of star
formation as one of the key recommendations for new initiatives in
this decade. 

\subsection{HEAT Science Goals}
\label{goals}

Via resolved C$^+$, C, CO, and N$^+$ line emission, HEAT uniquely probes
the pivotal formative and disruptive stages in the {\bf life cycles of
interstellar
clouds} and sheds crucial light on the {\bf formation of stars} by
providing new insight into the relationship between
interstellar clouds and the stars that form in them; a central
component of {\bf galactic evolution}.  A detailed study
of the ISM of the Milky Way is used to construct a template
to {\bf interpret global star formation in other spiral galaxies}.

The {\bf minimum science mission} of HEAT is to make significant
contributions to achieving the three major science goals described 
below. Using the proposed instrument and observing methodology,
the minimum mission is expected to be achievable in a single season of survey
operation from Dome~A.   

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.9in}{\includegraphics[scale=0.65,angle=0]{../figures/m33.eps}}}
{\parbox{2.4in}{
\caption{\label{m33} { The location of GMCs in the nearby
    spiral galaxy M33 are overlaid upon an integrated intensity map of
    the HI 21~cm line \citep{enga03}.  These observations show that
    GMCs are formed from large structure of atomic gas, foreshadowing
    the detailed study of GMC formation that HEAT will provide in the
    Milky Way.}}}}
\end{minipage} 
\end{figure}

\bigskip
\noindent {\bf Goal 1:  Observing the Life Cycle of Interstellar Clouds}
\medskip

\noindent \fbox{\parbox{6.4in}{
The formation of interstellar clouds is a prerequisite for star
formation, yet the process has not yet been observed! HEAT is designed
with the unique combination of sensitivity and resolution needed to
observe atomic clouds in the process of becoming giant molecular
clouds (GMCs) and their subsequent dissolution into diffuse gas via
stellar feedback.
}}

\smallskip

Theories of cloud formation are guided and constrained by observations
of the atomic and molecular gas components. Based primarily on HI and
CO observations, several mechanisms have been proposed to consolidate gas
into GMC complexes (Figure~\ref{m33}).  HEAT can distinguish these
processes by:  
\vspace{-0.2cm}
\begin{enumerate}
\setlength{\topsep}{-5ex}
\setlength{\partopsep}{-5ex}
\setlength{\itemsep}{-0.4ex}
\setlength{\parsep}{-0.4ex}
\item Accounting for the entire H$_2$ mass (including H$_2$ clouds with
  little CO) when computing global measures of the interstellar medium. 
\item  Making a more complete \& characterized catalog of
  interstellar clouds than CO or HI surveys alone. 
\item Constructing spatial and kinematic comparisons of
sufficient resolution, spatial coverage and dynamic range to probe a
wide range of interstellar phases and environments. 
\end{enumerate}

\vspace{-0.1cm}
\noindent Since the C$^+$ (and C$^0$) line emissivity 
barometrically selects
clouds of atomic gas and H$_2$ clouds with little CO, regions of GMC
formation may therefore be tracked by a large density of clouds per beam, 
or regions with individual
clouds with higher than average columns or pressures. With HEAT's
superlative spectral resolution, these regions can be identified with
superrings or spiral arms or convergent parts of a turbulent
medium.  With guidance from 2MASS extinction mapping and existing CO
and 21~cm HI surveys, 
HEAT will follow cold HI clouds and H$_2$ clouds as they transit
the spiral potential, and will witness the process of cloud formation
directly from the atomic substrate or small H$_2$ clouds. 
These clouds will be identified by C$^+$ and C line emission by HEAT.  Similarly, 
N$^+$ observations of ionized gas survey the location and rate of star
formation in the Galaxy. The rate of star formation is determined by
using the N$^+$ luminosity to determine the ionizing luminosity of OB
stars, a standard metric for the star formation rate.  

{\it HEAT's high spectral resolution enables crucial
kinematic studies of the Galaxy to be made}. HEAT will determine
the kinematics and thermal pressures of most supershells, fossil
superrings, and new molecular clouds condensing via gravitational
instability of old superrings and supershells. HEAT can
determine the role of OB association-driven supershells and superrings
in the production of molecular clouds and the cycling of gas between
the various phases of the ISM. Since N$^+$ measures the flux of
ionizing photons, and C$^+$ measures 
their impact upon neighboring cloud surfaces, HEAT will measure the
resolved photoevaporating atomic or ionized gas driven from clouds
with UV-illuminated surfaces, thereby determining the rate of
mass loss from all cataloged clouds, and their destruction
timescales. HEAT's survey will correlate the star formation rate in a
given OB association with the rate of destruction of any nearby
(within 30 pc) natal GMC.  Such
measurements are crucial for models of star formation feedback and
galactic evolution. 

\bigskip
\noindent {\bf Goal 2: Measuring the Galactic Star Formation Rate}
\medskip

\noindent \fbox{\parbox{6.4in}{
HEAT will probe the relation between the gas surface density on
  kpc scales and the N$^+$-derived star formation rate, so that we might be able to
  better understand the empirical Schmidt Law used to estimate the
  star forming properties of external galaxies.
}}

\smallskip

Star formation within galaxies is commonly described by two empirical
relationships: the variation of the star formation rate per unit area
with the gas surface density \citep{schm59,kenn98} and a
surface density threshold below which star formation is
suppressed \citep{mart01}.  The Schmidt Law has been evaluated from the radial
profiles of HI \& CO emission for tens of galaxies. The mean
value of the Schmidt index, $n$, is $1.4 \pm 0.15$ \citep{kenn98}, 
valid for kpc
scales. This empirical relationship is used in most models of galaxy
evolution with surprising success given its simplicity. Oddly, there
has been little effort to evaluate the Schmidt Law in the Milky Way
owing to the difficulty in deriving the star formation rate as a
function of radius within the plane. 

The HEAT survey of CO, C, C$^+$ and N$^+$
emission provides the optimum set of data to calculate the Schmidt Law
in the Galaxy. The N$^+$ line is an excellent tracer of the star
formation rate as it measures ionizing luminosity with unmatched
sensitivity, angular and spectral resolution, and is unaffected by
extinction.  The C$^0$ and C$^+$ lines, in conjunction with HI~21cm and CO line
emission, provide the first coherent 
map of the neutral interstellar gas surface density and its variation
with radius. HEAT's high spectral resolution allows one to assign a
radial location of any emission feature assuming a rotation curve. The
Schmidt Law is constructed from the radial profiles of the star
formation rate derived from N$^+$ emission and the gas surface
density.  The column density threshold
is inferred from the absence of star formation activity in the outer
radii of galaxies where there is still a significant reservoir of
gas \citep{kenn98}.   Alternately, a threshold-less relation can be constructed by
eliminating the HI gas that is inert to star formation
\citep{blitz06}.  Accounting for the H$_2$ clouds seen only in C$^+$
emission provides a far more detailed test of such a Schmidt Law
formalism than do the CO clouds alone.   
The velocity-resolved star formation rate indicators 
provided by HEAT will be invaluable in interpreting more traditional
indicators, like the far-infrared continuum.
With its resolution and ability to gauge
thermal ISM pressure, HEAT evaluates this critical, regulatory process
in the Milky Way. 

\bigskip
\noindent {\bf Goal 3: Constructing a Milky Way Template}
\medskip

C$^+$ and N$^+$ will be the premier
diagnostic tools for far-infrared studies of external galaxies 
with large redshifts (e.g. with Herschel \& ALMA). In
such spatially unresolved galaxies, however, only global properties
can be measured.  
Detailed interstellar studies of the widely varying
conditions in our own Milky Way Galaxy
serve as a diagnostic template or ``Rosetta
Stone'' that can be used to translate the global properties of more distant
galaxies into reliable estimators of star formation rate and state of
the ISM. The HEAT mission covers a
broad range of density and UV intensity, establishing the relationship
between physical properties, C$^+$, C, CO, N$^+$, HI, FIR
emission, and star formation.   This relationship can be tested by
application to nearby galaxies in the SINGS Spitzer Legacy Survey \citep{sings}, for which a large
amount of ancillary optical, infrared and submm data exist. 

\subsection{Properties of the Proposed Survey}
\label{survey}

HEAT's science drivers represent a definitive
survey that would not only provide the clearest view of interstellar
clouds and their evolution in the Galaxy, but would also serve as the reference
map for contemporary focused studies with Herschel, SOFIA, APEX, and the
ALMA and SMA interferometers.  The following properties define the science
requirements for the HEAT survey.

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.5in}{\includegraphics[scale=0.33,angle=0]{../figures/footprint.eps}}}
{\parbox{2.8in}{
\caption{\label{beams} { The power of HEAT: Each of the 3
    heterodyne beams of HEAT are overlaid upon
    a 2MASS infrared image of NGC~6334.  The beams will measure
    high-resolution spectra in the 0.81, 1.46, and 1.90~THz bands
    respectively.  The (inset) synthetic spectra of 
    NGC~6334 depict a small fraction of the spectral coverage achieved
    with each of HEAT's receiver channels. }}}}
\end{minipage}
\end{figure}

\subsubsection{High Resolution Spectroscopic Imaging}

Techniques commonly used to diagnose the molecular ISM 
include submillimeter continuum mapping of dust
emission \citep{hild83} and dust extinction mapping at optical and
near-infrared wavelengths \citep{lada94}.  Large format detector
arrays in the infrared are now 
commonplace, and with the advent of bolometer arrays like SCUBA at the
JCMT and SHARC at the CSO, both techniques have performed degree-scale
maps of molecular material.  However, these techniques have limited
applicability to the study of the structure of the
Galactic ISM due to the complete lack of kinematic information.   

The confluence of many clouds along most Galactic lines of sight can only 
be disentangled with spectral line techniques.  Fitting to a model of
Galactic rotation is often the
only way to determine each cloud's distance and location within the
Galaxy.  With
resolution finer than 1~\kms, a cloud's kinematic location can
be even distinguished from other phenomena that alter the lineshape, such as 
turbulence, rotation, and local effects such as protostellar
outflows.  These kinematic components play a vital role in the
sculpting of interstellar clouds, and a survey that has the goal of
understanding their evolution {\bf must} be able to measure them.  
{\bf HEAT will easily resolve the
intrinsic profiles of Galactic interstellar lines, 
with a
resolution of $<$0.4~\kms\ up to 370~\kms\ of spectrometer
bandwidth, comparable to the Galactic rotational velocity. }


\subsubsection{A Terahertz Galactic Plane Survey}

Molecular line surveys have been performed over the entire sky in the
light of the 2.6~mm 
J=1-0 line of \co, and have been used to synthesize our
best understanding of the molecular content of the Galaxy.  Still, our
understanding of the evolution of Galactic molecular clouds is
woefully incomplete.  As already described in Section~\ref{goals}, the dominant spectral
lines of the Galaxy are the fine structure far-infrared and
submillimeter lines of C, CO, C$^+$ and N$^+$.  They probe and regulate 
all aspects of the formation and destruction of star forming clouds.
They will provide the first barometric maps of the Galaxy, and illuminate
the properties of clouds and their life cycles in relation to their
location in the Galaxy.   They will highlight the delicate interplay
between (massive) stars and the clouds which form them, a critical
component of galactic evolution.  
A THz survey will dramatically enhance the value
of existing mm-wave CO observations by providing critical excitation
constraints.  


\subsubsection{Angular Resolution and Fully Sampled Maps}

Good angular resolution is a critical aspect of improvement for a new
Galactic survey.  Previous surveys of [N~II] and [C~II] were limited
to very small regions (KAO, ISO) or had low angular resolution (COBE,
BICE) \citep{benn94,naka98}.  HEAT will fully sample both species over
large regions of sky 
to their diffraction limited resolution of 1.7$'$ and 1.3$'$,
respectively.  Arcminute resolution with proper sampling 
is crucial to disentangling
different clouds and cloud components over large distances in the
Galaxy.  For example, the Jeans length for star formation in a GMC is
approximately 0.5~pc.   This length scale is resolved by HEAT to a
distance of 500~pc at CO~J=7$\rightarrow$6 \& [C~I], and 1200~pc at
[C~II].  Warm and cold HI clouds and GMCs can be resolved well past
10~kpc. 

\subsubsection{High Sensitivity}
\label{sensitivity}

HEAT's high sensitivity is owed mostly to
the superlative atmospheric conditions above Dome~A, Antarctica.  The
extreme cold and exceptional dryness allow ground-based observations
into the otherwise forbidden THz windows.  A plot of the expected
atmospheric transmission for excellent winter observing
conditions at Dome~A versus the comparable opacity at the South Pole 
is plotted in Figure~\ref{atmo}.  {\bf The high elevation, cold
  atmosphere and benign wind conditions at Dome~A 
definitively open the Terahertz windows to ground-based observatories and 
cannot be matched anywhere else on Earth.}  The implications for the
sensitivity to each spectral line is discussed below.

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.9in}{\includegraphics[scale=0.39,angle=-90]{../figures/transplot.eps}}}
{\parbox{2.4in}{
\caption{\label{atmo} { Terahertz atmospheric transmission for good 
    ($\sim$25th percentile)
    winter conditions for South Pole (bottom) and Dome~A (top),
    derived from precipitable water vapor (PWV) measurements at Pole, atmospheric models from
    \cite{Law04} and {\bf actual Automatic Weather Station (AWS) data
      collected during 2005 from Dome~A by our Chinese and Australian colleagues}.  The PWV content 
    for each model atmosphere is 220 and 70 microns respectively,
    Arrows indicate the
    wavelengths of the [N~II], [C~II], and CO/[C~I] lines.}}}}
\end{minipage}
\end{figure}

\medskip

\noindent {\it CO J=7-6 {\rm and} [C~I] J=2-1}
\smallskip

We aim to detect all CO and C$^0$ to A$_V$=1-2,
where most hydrogen has formed H$_2$ and CO is just
forming.  This extinction limit corresponds to
N(CO)$\sim 5 \times 10^{15}$~cm$^{-2}$ and $N(C)=1.6\times
10^{16}$~cm$^{-2}$, for integrated intensities of 3~K~\kms\ in CO
J=7-6 and 1.8 K~\kms\ in [C~I].   These sensitivity limits are
achievable (3$\sigma$) within 1.6 and 5 minutes, respectively, of
integration time at 810~GHz in {\it median} winter atmospheric
conditions (T$_{sys}\sim$10,000K) on Dome~A.  Limits on line emission 
in that time would constrain the gas density, based
upon the line brightness of millimeter wave transitions. 

\medskip
\noindent {\it N$^+$ and C$^+$}
\smallskip

The fine structure lines of ionized carbon and nitrogen represent the
dominant coolants of the interstellar medium of the Galaxy and
starforming galaxies.  Indeed, the integrated intensity of the
158~\micron\ C$^+$ line alone represents 1\% of the bolometric
luminosity of the Galaxy!  As such, these lines are relatively easy
to detect in the ISM.  
Our most demanding requirements for detection of C$^+$ and N$^+$
lie in the search for the formation of giant molecular clouds
(via C$^+$) and the measurement of the diffuse warm ionized medium in the
Galaxy (via N$^+$).  A flux limit of 2~K~\kms\ will detect N$^+$ in
warm HI as far away as the Molecular Ring, achievable in good winter
weather in 3 minutes with velocity smoothing to
3~\kms, appropriate for hot ionized gas.  
Similarly, the accumulation of GMCs from
many cold neutral clouds of atomic hydrogen occurs at low relative
column densities of $\sim 5\times 10^{20}$~cm$^{-2}$.  Since essentially all
carbon in such clouds is ionized, $N(C^+) \sim
10^{17}$~cm$^{-2}$.  At the $T=70$K common in cold atomic clouds and
$n_{\rm H} = 10^3$~cm$^{-3}$, the expected C$^+$ line emission would
be 2.5~K~\kms, detectable in 10 minutes in excellent winter weather on
Dome~A.  The 3$\sigma$ limit achievable with deep
integrations (2 hours) with HEAT would reach $n_{\rm
 H} = 10^2$~cm$^{-3}$.  This {\it pressure} limit would readily determine whether
interstellar material causing significant
infrared extinction, but without CO,
is gravitationally bound and likely to be a forming
molecular cloud, or is simply a line of sight with numerous
overlapping diffuse HI clouds.  

\subsubsection{Mapping Coverage of the Galactic Plane}

\begin{figure}[!hbt]
\centering
\includegraphics[scale=1,angle=0]{../figures/msxmap.eps}
\caption{\label{MSX} {  Midcourse Space Experiment (MSX)
    8.3~\micron\ map of the Galactic Plane from the Molecular Ring
    through the Scutum-Crux Spiral Arm ($-20^\circ > l > -55^\circ$). 
    The yellow
    rectangle highlights the region to be explored by HEAT in its {\bf
    first season} at Dome~A.    A definitive chemical and kinematic
    survey of star forming clouds in C$^0$~J=2-1, 
    \co\ J=7$\rightarrow$6, and [N~II] of 30
    square degrees ($\sim$10~square degrees in [C~II] emission) 
    can be performed in a single season.  
    No other site on Earth allows routine access to both
    far-infrared lines. }}
\end{figure}

From previous CO surveys it
is known that the scale height of CO emission toward the inner Galaxy 
is less than one degree \citep{dame87,dame01}.  The BICE experiment
demonstrated that the C$^+$ distribution is more extended, but still
is confined to $|b| < 1$. 
Interstellar pressure, abundances, and physical
conditions vary strongly as a function of Galactocentric radius, so it is
necessary to probe the inner Galaxy, the outer Galaxy, and both spiral
arms and interarm regions, to obtain a statistically meaningful survey
that encompasses the broad dynamic range of physical conditions in the
Galaxy.  We propose therefore to 
probe the entire Galactic plane as seen from Dome~A ($0
> l > -120^o$).   A {\it completely unbiased survey} will be
undertaken, ultimately covering up to 240 square degrees ($-1^o < b <
1^o$); however 
90 square degrees in 3 years will be targeted by the Schottky receiver system
proposed here.  Figure~\ref{MSX} demonstrates the sky coverage of HEAT's
survey of the Inner Galaxy, with the first season coverage highlighted
in yellow.  It will probe three crucial components of the Galaxy; the
Molecular Ring, the Crux spiral arm and the inter-arm region.  
The remaining sky coverage will be provided by a future, upgraded
instrument package from SRON, featuring a cryocooled 
4K SIS and HEB system (see SRON support letter).  The ``inner'' Galaxy survey will coincide
with GLIMPSE, a Spitzer Space Telescope (SST) Legacy Program \citep{benj03}. 
Above $l=90^o$, most of the CO emission is located at
higher Galactic latitude, so $l$ and $b$ ``strip mapping'' will locate
the best regions to map, generally following the outskirts of CO J=1$\rightarrow$0
distribution\citep{dame87,dame01} and the best characterized star
forming regions in the Galaxy. The observing program will be designed to maximize
synergies with the ``Cores to Disks'' SST Legacy program
\citep{evans} and other SST GTO programs.  

%As discussed in Section~\ref{instrument}, 
%HEAT exceeds all of these needs and constitutes
%an exceptional Galactic survey instrument.


\subsection{Survey Activities}

\subsubsection{Mapping Strategy}

The most efficient mode of data collection 
which produces the highest fidelity images is 
On-the-Fly (OTF) mapping.  In this mode, the telescope continuously 
scans back and forth across a field while the backends are 
read-out at a sufficient rate to eliminate aliasing and beam smearing.  

The broad coverage of the HEAT survey and the circumpolar
nature of the sky rotation over Antarctica lends itself naturally
to efficient, 24-hr/day mapping. HEAT can reach the requisite sensitivity of
1$\sigma$=0.2~K~\kms\ per beam at 810~GHz (1$\sigma$=0.9~K~\kms\ at
1.4~THz) over a fully sampled square degree in 7 days,
assuming median winter conditions of $\tau_{810}\sim$1. 
30 square degrees from $-20 > l > -60^o$ will be mapped 
in $\approx$210 days.  Mapping of the Inner Galaxy with $-1<b<0$ (30
sq degrees) will
follow in Season~2, and targeted observations (30 sq. degrees) 
in the Outer Galaxy in Season 3 (with the SRON 4K HEB receiver upgrade
if available). 
When the atmospheric opacity at 1.9~THz drops below $\sim$1.5, 
focused surveys including C$^+$ will begin.  Of the best
35 days of winter weather, 3-4 weeks will be devoted to
a medium-sensitivity C$^+$ survey (1$\sigma \sim$1.5~K~\kms), with each square
degree of mapping requiring about 2 days each, for a total of up to 10
square degrees of coverage per season.   10 days will be devoted to deep C$^+$ surveys
of selected regions guided by 2MASS and GLIMPSE for the formation of
molecular clouds -- a total of 0.4~square degrees will be mapped to
1$\sigma \sim 0.4$~K~\kms\ per season.

HEAT's wide IF bandwidth
allows detection of the 158, 205, and 370~$\mu$m dust continuum
emission.  Thus, we will also simultaneously record total power scans
and construct dust continuum maps.  

\begin{table*}[!hbt]
\centering
\small
\begin{tabular}{|l|c|c|l|}
\hline
{\bf Participant} & {\bf Team} & {\bf Affiliation} & {\bf Participation
  Activity} \\
\hline \hline
Christopher Walker & I, S & Univ. Arizona &  Project PI \\
\hline
James Burge & I & Univ. Arizona & Optical systems: opto-mechanics, testing
and metrology \\
\hline
J. R. Gao & I & TU Delft/SRON & Future 4K mixer package upgrade of HEAT \\
%\hline
%Paul Goldsmith & I, S & JPL & THz instrumentation, space flight
%hardware, ISM physics \\
\hline
Jeffrey Hesler & I & Virginia Diodes, Inc. & Schottky mixer
development and LO technology\\
\hline
Jon Lawrence & I & UNSW & Antarctic instrumentation, site testing \& astronomy \\
\hline
Craig Kulesa & I, S &  Univ. Arizona &  Deputy PI, software+electronics integration, ISM physics \\
\hline 
Chris Martin & I, S & Oberlin College & Antarctic Astronomy and
Instrumentation \\
\hline
Mark McCaughrean & I & Exeter & Antarctic astronomy and telescope automation \\
\hline
Michael Schein & I & Univ. Arizona & Optical systems design, pointing \&
tracking, cryocoolers\\
\hline
%Peter Siegel & I & Caltech/JPL & THz Schottky mixer development \\
%\hline
Gordon Stacey & I, S & Cornell & Far-infrared Instrumentation \& spectroscopy\\
\hline
Antony Stark & I, S & SAO/CfA & Telescope Optics \& Systems; Synergy w/ AST/RO \\ 
\hline
John Storey & I, S & UNSW & PLATO Systems, Site testing, Polar Operations \\
\hline
Nick Tothill & I, S & Exeter & Antarctic submillimeter astronomy \\
\hline
Sander Weinreb & I & JPL & IF amplifiers \& processors, backend spectrometers\\
\hline
\end{tabular}
\caption{\label{roles}  Activities of the Science ({\bf S}) and
  Instrumentation ({\bf I}) Teams}
\end{table*}

\subsubsection{Science Products and Dissemination}

A primary challenge of OTF mapping is data management.
We therefore plan to adopt a scheme akin to that 
developed at FCRAO, whereby
coadded and regridded data is written as FITS \&
CLASS files, and headers for 
each scan are written into a MySQL relational database, which 
facilitates efficient logging and retrieval of the data.
The most demanding storage
requirements for the final 90 square degree maps, regridded to 50$''$ spacing,
with 1024 spectral points per grid position, is 4~GB.  This volume can
be readily handled by embedded computers with disks of nonvolatile
flash memory.  

Access to these data products to the greater scientific community
will be provided through a web browser interface that will
interface with MySQL and the FITS data cubes.   Standard Virtual
Observatory (VO) services will be enabled in this interface.  
Preprocessed data cubes
will be transferred from HEAT over Iridium satellite, while
raw data will be collected from the telescope annually during
maintenance, and hopefully earlier with an occasional downlink from
NASA's TDRSS-1 satellite using a portable field antenna.
Thus, there will be biannual data products -- a
preliminary release midseason, and a final release of the first
season's data in February 2011.  The
final release will be fully calibrated and will include all science
products.  

\smallskip
\noindent \fbox{\parbox{6.4in}{All science tools, packaged reduction software,
    data products and 
    science products will be made available from the HEAT web
    page:    {\tt http://soral.as.arizona.edu/HEAT/}}}

\smallskip

\subsubsection{Synergies with Spitzer, ALMA, SOFIA and Herschel}

{\bf HEAT is timely}.  The Spitzer Space Telescope Legacy program GLIMPSE, 
provides a thermal infrared survey of the
Galactic plane that provides a complete census of star formation, the
stellar structure of the molecular ring, maps the warm
interstellar dust, constrains extinction laws as a function of
galactocentric radius and detects all young embedded hot
stars.   HEAT will provide the best corresponding
interstellar cloud survey that will account for the 
dense cloud material that forms stars,  cloud interaction with
formed stars, and kinematic disruption by mass ejection, outflow, and supernova
remnants.  

HEAT naturally complements the capabilities of heterodyne receivers on
SOFIA and Herschel.  The higher angular resolution
afforded by larger telescopes necessarily reduces their field of
view and mapping speed.  {\bf The HEAT survey would require 
many months of dedicated observing time on either Herschel or SOFIA,
inconsistent with their
use as general purpose observatories.}  In contrast, HEAT is a dedicated mapping
instrument with a focused mission and a lifetime that exceeds the
grasp of long duration balloons.  HEAT will provide
ideal reference maps of THz line emission for more detailed
followup with SOFIA and Herschel.  Indeed, the HEAT data distribution and
databasing system will be aligned as much as possible with that of 
Herschel/HIFI.

Similarly, the small field of view of the ALMA interferometer (8-25$''$)
makes such large scale surveys untenable.  However, HEAT's Southern survey
in atomic carbon and CO emission will be an ideal survey for active
star forming clouds and cores and represents an exceptional reference
map for detailed followup with ALMA when it becomes available.

\subsubsection{Roles of the Collaboration Participants}

Personnel who will initially develop and use HEAT
comprise the Science~(S) and Instrument~(I) Teams tabulated in
Table~\ref{roles}.  They are also represented in an organization
chart, Figure~\ref{orgchart} in Section~\ref{management}.  {\it 
Both graduate and undergraduate students will participate in
the instrument development and science study.}

\section{Research Instrumentation and Needs}
\label{instrument}

\subsection{Overview}

HEAT will be a fully automated, state-of-the-art THz observatory
designed to operate autonomously from Dome A in Antarctica. The
combination of high altitude (4,200~m), low precipitation, and extreme
cold make the far-IR atmospheric transmission exceptionally good
from this site. In Figure~\ref{atmo} we present a plot of the
expected atmospheric transmission above Dome A as a function of
wavelength \citep{Law04}, indicating that winter weather at Dome~A
approaches (to order of magnitude) the quality of that achieved
by SOFIA.  The wavelengths of several important
astrophysical lines are indicated with arrows. HEAT is designed to
take advantage of these unique atmospheric conditions and observe
simultaneously in [C~II](158 $\mu$m), [N~II](205 $\mu$m), and CO 
J=7$\rightarrow$6 \& [C~I] (370 $\mu$m). 

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{4.5in}{\includegraphics[scale=1,angle=0]{../figures/concept.eps}}}
{\parbox{1.8in}{
\caption{\label{concept} { HEAT concept: The telescope has an effective
collecting area of 0.5m. Elevation tracking is accomplished by
rotating the $45^\circ$ flat reflector. The entire telescope structure
is warmed by waste heat 
from the PLATO instrument module below. The Schottky mixers used in
the instrument package are efficiently cooled to $\sim$70~K using
a reliable off-the-shelf closed-cycle cryocooler. }} }}
\end{minipage}
\end{figure}

\smallskip
A conceptual drawing of HEAT is shown in Figure~\ref{concept}. For
robustness and efficiency, the telescope and instrument are integrated
into a common optical support structure (OSS). 
HEAT will be mounted on top of a University of New South Wales Plateau
Observatory (PLATO), a successor to the AASTINO
(Automated Astrophysical Site-Testing InterNational Observatory)
deployed to Dome~C in 2003. PLATO provides power and communications for the HEAT telescope and
instrument. The total power budget for HEAT (including cryogenics, telescope 
drive system, and instrument control system is maximally 600~W, which is
readily provided by efficient, high reliability generators 
within PLATO.  Data
transfer and control of HEAT will be done via satellite and is
described in more detail in Section~\ref{control}. 
UNSW will provide a PLATO for HEAT and participate in the design,
integration, deployment, and operation (see Support Letter from J. Storey).
A 3D rendering of HEAT mounted atop the Dome~C AASTINO is shown in
Figure~\ref{AASTINOHEAT}.  

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.5in}{\includegraphics[scale=0.65,angle=0]{../figures/AASTINO.eps}}}
{\parbox{2.8in}{
\caption{\label{AASTINOHEAT} { Rendering of HEAT atop a UNSW
    Plateau Observatory (PLATO).  The combined HEAT \& PLATO facility is functionally equivalent to a
space-based observatory. }}}}
\end{minipage}
\end{figure}

\subsection{Telescope}

The telescope is designed to have maximum efficiency and the minimum
number of optical components. Its design is similar to that of Kraus
(1966) and utilizes an off-axis, Gregorian configuration. Incoming
light is reflected horizontally off a 45$^\circ$, $0.5 
\times 0.7$~m flat reflector to an f/2.2 off-axis parabolic mirror. The
converging beam is intercepted by a hyperbolic tertiary mirror that
directs it to a flat quaternary and into the receiver. The tertiary 
mirror can chop the incoming beam between source and reference
positions ($\Delta {\rm az} \sim 10^\prime$) at a rate of 0 to 4~Hz. The
mirrors are fabricated from aluminum on a numerical milling
machine and have a surface roughness $\le 3\,\mu$m rms.  Elevation
tracking is achieved by rotating the first flat reflector.   
Azimuth motion is achieved by rotating the OSS on a bearing attached to the
roof of PLATO. Mapping will be typically performed in drift-scanning (``on-the-fly'')
mode with the azimuth drive locked and tracking only in elevation.
In fact, some of the Galactic Plane can be mapped purely with sidereal-rate
scanning, using no tracking whatsoever! 
The absolute pointing accuracy will be
15$^{\prime\prime}$, 1/5 of the smallest diffraction-limited beam. The
slew speed will be 1$^\circ$/sec.  The University of Arizona has a
long history of building state-of-the-art telescopes and, with oversight from members 
of the Instrument Team, has the expertise required to optimize the telescope
for operation in a Polar environment. The telescope cost estimate,
which includes detailed design, fabrication, and testing of the
telescope and drive system, is provided in the budget. 

To prevent ice accumulation, the telescope is
enclosed and warmed to -20$^\circ$C by ducted waste heat forced up through the
azimuth bearing from the PLATO module below. A small radome made of a low-loss
dielectric (e.g. Goretex or polyethylene) encircles the first flat
reflector. This optical configuration provides an unobstructed view of
the sky. A near-IR camera (provided by UNSW) is mounted just
outside the radome on an extension of the elevation axis. The camera will
provide pointing and site testing data. 

\subsection{Receiver}

\subsubsection{Design Approach}

Heterodyne receivers are needed to achieve the sensitive, high
spectral resolution ($R=\lambda/\Delta\lambda > 10^6$) observations of
[N~II], [C~II], and CO/[C~I]
required for the proposed Galactic plane survey. The key components of a
submillimeter-wave heterodyne receiver are the mixer and local
oscillator (LO).   There are 3 types of mixers in common
use; the Schottky diode mixer, the SIS mixer, and, more recently, the
Hot Electron Bolometer (HEB) mixer. The Schottky diode mixer is
somewhat less sensitive than either SIS or HEB mixers and requires more
LO power, but is exceptionally stable in operation and
{\bf can operate at ambient temperature}.  In contrast, SIS and HEB receivers require
cooling to LHe temperatures (4K).   HEAT's aggressive development
schedule combined with the critical need for robust technologies that
will work at low power and in a harsh environment leads us to select
Schottky mixer systems for the initial deployment of HEAT.   Virginia
Diodes, Inc. has a long history of delivering submm-wave Schottky
mixer systems and has demonstrated sub-harmonically pumped
Schottky mixers using lower frequency LO sources (see Support Letter from J. Hesler). 
Virginia Diodes will deliver one such mixer at 1.9~THz and another at
1.46~THz.   Two sub-harmonically pumped 810~GHz mixers (one for each
polarization) will be provided to increase sensitivity and
redundancy.  Though the system will function well at ambient
temperatures, we plan to improve HEAT's sensitivity to within a factor
of $\sim$3 of demonstrated THz HEB systems by cooling the 
mixer blocks to $\sim$70K using economical, low power, commercial Stirling-cycle
cryocoolers such as those sold by Qdrive and Sunpower, Inc. In this
manner we will achieve a solid blend of good sensitivity and 
experimental robustness.   A future 4K cryocooled SIS and HEB receiver system 
for HEAT is now in development at the Space Research Organization of the Netherlands
(SRON, see K. F. Wakker (Director) and Wolfgang Wild support letters),
with an initial 600,000 Euros of institutional support. 

\subsubsection{Receiver Optics and Cryostat}

A close-up of the receiver optics is shown in Figure~\ref{optics}. The
incoming beam from the quartenary encounters two bandpass filters,
the first centered on the [N~II] (1.459~THz) line and the second on the
[C~II] (1.9~THz) line.  The three emerging beams are
collimated and directed into the instrument cryostat.    

Sub-harmonic LO pumping of the Schottky mixers eliminates the
quasi-optical injection of the LO signal and simplifies the optical
layout of the cryostat.    Wire grids direct the
horizontal and vertical polarization components of the incoming light
into the two 0.8~THz mixers.

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{4in}{\includegraphics[scale=0.95, angle=0]{../figures/optics.eps}}}
{\parbox{2.3in}{
\caption{\label{optics} { Optical subsystem for
 HEAT's Schottky mixers consists of bandpass filters and wire grids.
 Outside of their nominal passband, the filters are highly reflective.
 Therefore, when the incoming beam encounters the first filter, all
 but a narrow range of frequencies around the [C~II] line 
are reflected to the [N~II] filter. The light reflected off the [N~II]
filter contains the CO J=7$\rightarrow$6 and [C~I] lines.   }}}}
\end{minipage}
\end{figure}

The fabrication and integration of the vacuum vessel (10'' in diameter and 5'' tall) with the
cryocooler will be performed by Universal
Cryogenics of Tucson, Arizona (see attached quote), who has done similar work for the PI's
Supercam instrument, as well as for other Steward Observatory projects.  

\subsubsection{Mixer Performance}

Virginia Diodes will provide subharmonically-pumped, Schottky mixers 
with integrated, synthesizer-driven LO chains for HEAT. These mixers provide 
competitive receiver noise performance
even at ambient temperatures (see attached quote from VDI and Support Letter from J. Hesler).   
With 5 watts of thermal load, the instrument cryocooler (either from Qdrive or Sunpower Inc.) 
will cool the mixers to ~70~K, sufficient to increase
their sensitivity by a factor of ~2 \citep{hesler}.   We
anticipate delivered cooled DSB receiver noise temperatures in the vicinity
of 1500K at 0.8~THz, 3000K at 1.4~THz and 5000K at
1.9~THz. 

%These receiver noise figures were used in defining the scope of the
%science program discussed in Section~\ref{survey}. 

\subsubsection{IF Processors}

The entire IF processing and
spectrometer system will be leveraged from the successful design
being implemented in SuperCam (the PI's 64-pixel, 345~GHz array receiver).
Funds will only be needed to
fabricate additional amplifiers, IF processor modules, and
spectrometer boards for HEAT.    
The 5~GHz-centered IF output of the THz mixers is first amplified by a 
low-noise MMIC amplifier designed by Sander Weinreb's group at
Caltech for the Supercam project.    In order to
simultaneously detect the CO J=7$\rightarrow$6 and [C~I] lines in
separate sidebands, the 0.8~THz mixer will
have an IF center frequency of 1.5~GHz and then be upconverted to 5~GHz 
to match the other channels for subsequent IF processing. Low-noise, cryogenic,
1.5~GHz IF amplifiers are readily available.

The IF processor board provides each channel with an
initial 48 dB of gain, a variable digital attenuator, a 1~GHz bandpass
filter, a mixer conversion to baseband, a low pass filter, and 
50~dB of baseband gain.  An additional circuit provides total-power
measurements of the IF power for telescope pointing and continuum
measurements.  
%A sample 0.5~GHz bandpass from Supercam's
%rack-mountable 8-channel IF processor module is shown in
%Figure~\ref{IFproc}. 

%\begin{figure}[!hbt]
%\centering
%\begin{minipage}{6.5in}
%{\parbox{3.8in}{
%%\includegraphics[scale=0.75,angle=0]{../figures/IFproc2.eps}
%\includegraphics[scale=0.8,angle=0]{../figures/IFproc1.eps}}}
%{\parbox{2.5in}{
%\caption{\label{IFproc} { Sample 0.5~GHz bandpass from the
%    Supercam 8-channel IF processor.  With the substitution
%    of 1~GHz filters, HEAT will adopt the same IF processing
%    scheme. }}}}
%\end{minipage}
%\end{figure}

\subsubsection{FFT-in-FPGA Spectrometer}

The HEAT Galactic Plane surveys require both fine kinematic resolution  (1~MHz) 
to disentangle cloud components and wide instantaneous bandwidth ($\ge$~1~GHz) to span the
velocity dispersion of the Galaxy.
{\bf  Recent gains in high-speed ADCs and FPGAs have
made such a wide bandwidth, direct-digitization spectrometer economically feasible.  }
The baseband output of the IF processors is fed into two direct
digitization spectrometer boards, each board with 2-IF inputs.
For each IF input the spectrometer board provides 1~GHz of instantaneous bandwidth at
1~MHz resolution.   The resulting velocity coverage (up to 
370~km/s at a resolution $\le 0.4$~km/s) enables all three
lines to be resolved and observed throughout the Milky Way.  
Omnisys Inc. has already
designed and delivered 8 of these boards for the PI's Supercam array project.
The delivered system is
depicted in Figure~\ref{FFTspec} and
performs admirably.  The measured Allan variance (stability) time is 650 seconds
when using a 5~GHz noise source that has been downconverted through the Caltech 
IF processor board.   Funds are requested to purchase three
additional boards for HEAT (2 for deployment, 1 as a spare; see quote
from Omnisys).  

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.8in}{\includegraphics[scale=0.9,angle=0]{../figures/spectrometer.eps}}}
{\parbox{2.5in}{
\caption{\label{FFTspec} { The assembled 8-board, 16~GHz FFT spectrometer from the
PI's Supercam project is no larger than a rack-mounted PC and requires
only 200 watts of input power!  One-fourth of this
spectrometer system will be purchased for HEAT. }}}} 
\end{minipage}
\end{figure}

\subsubsection{Calibration}

HEAT will be able to calibrate observations through several means. 1)
A vane with an ambient temperature absorbing load will be located at
the cryostat entrance window, allowing standard chopper wheel calibration
to be performed. 2) HEAT will routinely perform sky-dips to
compute the atmospheric optical depth in each of its three wavelength
bands. 3) HEAT will regularly observe a standard list of calibration
sources. 4) The PLATO will host {\tt Pre-HEAT}, a 450~$\mu$m tipper 
that will measure 
atmospheric transmission. Its measurements will be
coordinated with HEAT spectral line observations to provide cross
calibration. 

\subsubsection{Control System and Communication}
\label{control}

The HEAT control system consists of several subsystems; 
the telescope drive system, receiver frontend
({\it e.g.} mixers, LOs, and cryostat) computer, and backend
(spectrometer) computer.  The subsystems communicate via Ethernet.  
The subsystems are based on
Technologic Systems TS-ARM embedded computers that draw
less than 2 watts of power, run Linux or NetBSD, and have been
field-tested to survive the cold.   These systems
provide digital I/O, analog-to-digital conversion, serial I/O, and CAN, SPI and I2C bus interfaces for
control of the various electronic subsystems in HEAT.  These
single-board computers are slave to a UNSW-designed ``supervisor'' power control
board that contains a watchdog circuit that will reset the system in
case of a software or hardware malfunction and cycle tasks to the next
available embedded computer.   HEAT will be designed to work 
autonomously for up to a week at a time, performing pre-programmed
observational programs and storing astronomical and housekeeping data
on non-volatile memory.  Preprocessed sample data will be uploaded to
control centers at the Universities of Arizona and New South Wales
via dedicated Iridium satellite channels located on each
``supervisor'' board.  Raw data will be recovered from HEAT each year
during maintenance and processed into the released data products.  We
aim to also integrate a portable field antenna for NASA's TDRSS-1 satellite for
routine downlink of raw data well in advance of annual maintenance. 

\subsection{Integration and Testing}

The use of developed or commercial subsystems in HEAT
allows system integration and testing to be performed in a timely manner. 
A testing schedule is provided in Figure~\ref{gantt}.

\vspace{-0.2cm}
\begin{enumerate}
\setlength{\topsep}{-5ex}
\setlength{\partopsep}{-5ex}
\setlength{\itemsep}{-0.4ex}
\setlength{\parsep}{-0.4ex}

\item {\bf Cold component testing} will be used to determine limiting
temperatures for reliable operation of constituent components in each
subsystem.  These component tests will define a process by which the
telescope can be nominally operated in a range of highest reliability, or
safely resurrected from an idle state in which all components have been
cold-soaked.  

\item  {\bf Subsystem testing} will demonstrate
the proper functionality of large components of the HEAT system, such
as the assembled telescope drive system or the Schottky instrument
package and control electronics, or the spectrometer and data system.

\item {\bf Integrated system testing} involves the interplay of subsystems in the
actual collection of data, such as performing on-the-fly mapping
observations with active receivers, spectrometers, data system, while
monitored over a Iridium satellite connection; i.e. normal
astronomical operation
at Dome~A. 

\item   {\bf Failure Mode testing} involves the intentional
disabling of a component to observe the fault handling and
interplay of the hardware and software systems.   A Failure Mode Effects Criticality
Analysis (FMECA) will be generated to determine system robustness to
component failure.  System reliability will then be
enhanced through application of redundancy, increased reliability rated
components, and improved operational design where indicated.

\end{enumerate}

The combination of Schottky diode receivers, 
interchangable (and in some cases, 
dual string) computer control subsystems, Iridium communication links on robust watchdog circuits, 
diesel power generation with solar
panel backup, and adopting a largely fixed, stable, simple optical system, 
all contribute to a highly {\bf reliable and robust system}.


\begin{figure}[!htb]
\centering
\begin{minipage}{6.5in}
{\parbox{3.6in}{\includegraphics[angle=0,scale=0.4]{../figures/orgchart.eps}}}
{\parbox{2.7in}{
\caption{ \label{orgchart} HEAT Organizational Chart:  The main components of the organization are (1) the PI, who has overall 
responsibility for the project and coordinates the activities of the 
participants, (2) the DP-I (Kulesa) who assists the PI and is responsible 
for instrument control, system integration, and data products, (3) Co-I Burge who is responsible for 
the HEAT telescope design, fabrication, and testing
(4) the Project Manager (PM-McMahon) who oversees the fiscal realities of the project, and (5)
the Science and Instrument Teams who will provide scientific and
technical guidance throughout 
the course of the project.}}}
\end{minipage}
\end{figure}


\section{Project Management}
\label{management}

\subsection{Organization}
HEAT is an exciting, challenging project that requires the coordinated 
participation of scientists and engineers from several academic institutions
and leading-edge companies. We have developed an organizational
structure (described in Figure~\ref{orgchart}) 
to meet this task. Collectively the HEAT
team members represent many years of successful telescope and
instrument development in Antarctica. The organizational structure of
the HEAT project
provides effective control of the project while allowing the delegation 
of authority to be made at the proper level within the organization.
 Table~\ref{roles} provides a listing of the
roles and responsibilities of each member in the
organization.   Endorsement letters from members of the Science and
Instrumentation committees are provided in the Supplementary
Documentation section. 

A schedule of key project milestones and tasks is provided in
Figure~\ref{gantt}.   
{\it If the HEAT MRI instrument proposal
prevails, the MRI instrument schedule will take precedence over that
described here.}  Based upon the 2006 design study funded by NSF-OPP,
the project will begin with a 
design review by the instrument and science teams. Procurement of key
components will begin soon after, following the spending profile
outlined in the budget. Integration and test of the 0.8~THz and
1.4~THz receiver system
will take place at the Univ. of Arizona in the PI's lab in Summer
2008.   Pending a readiness review, the 1.4~THz receiver will be
temporarily installed on the Pre-HEAT
tipper at Dome~A in late 2008.  Meanwhile, the 1.9~THz
channel will be constructed and tested in Spring 2009, simultaneous
with acceptance tests of the HEAT telescope.  The receiver
and telescope will then be shipped to the University of New South
Wales, where an extended period of integration and testing with the 
PLATO module will occur; including system evaluation in a -80$^o$C
environmental chamber (see Support Letter from J. Storey).   HEAT will
then ship from Australia in October 2009, with deployment to Dome~A
in January 2010.    

Routine communications between project participants is essential.
There will be quarterly telecons between Science and Instrument team
members to monitor progress, provide insight into solutions to
emerging problems, and redefine priorities as needed. There will
be weekly telecons and quarterly meeting (primarily through
teleconferencing) between the PI, D-PI, Co-I, PM, and Technical Leads
(Storey - PLATO, Burge - Telescope,  Hesler -
Mixers, Weinreb -IF amplifiers and processors, and Kulesa -
spectrometers, control and data systems, software).  


\begin{figure}[!htb]
\centering
\begin{minipage}{6.5in}
{\parbox{4.7in}{\includegraphics[angle=0,scale=0.75]{../figures/gantt.eps}}}
{\parbox{1.7in}{\caption{ \label{gantt} Timeline: two years
of development, 
integration and testing is followed by the first year of survey
work at Dome~A.
Leverage of technologies from commercially available 
mixers and IF technologies from the PI's
SuperCam instrument development makes this timeline achievable. 
}}}
\end{minipage}
\end{figure}

The ability to meet the proposed schedule is made possible by the heavy
leveraging of IF processor and spectrometer technology funded through
NSF-ATI for Supercam, the PI's 64-beam heterodyne array receiver, in
combination with commercially-available mixer and cryogenic
hardware.   The simplicity of the telescope design and operation in
combination with the expertise of the Optical Sciences College at the
University of Arizona in developing optical systems for ground and
space is a solid match.   {\it
Indeed, the HEAT instrument team officially formed over two years ago
and has been optimizing component technologies and system designs
for HEAT since.}   

\subsection{Logistics: Deployment to Dome A}
 
Antarctic science has reached a level of maturity where several options exist
for fielding instruments on remote sites. For Dome~A, these include:

\begin{enumerate}
\setlength{\topsep}{-1ex}
\setlength{\partopsep}{-1ex}
\setlength{\itemsep}{-0.4ex}
\setlength{\parsep}{-0.4ex}

\item {\bf (Chinese) Traverse from Zhongshan to Dome~A}:  UNSW has
  recently signed a Memorandum of Understanding (provided in the
  Supplementary Documentation) with the Polar
  Research Institute of China and the National Astronomical
  Observatories of China for Chinese deployment of a UNSW PLATO to
  Dome~A in 2007-8.   An especially attractive option would be to simply
  install HEAT atop this PLATO module.   It could be installed
  as part of a 2009 Chinese traverse or combined with alternative transport
  options described below.  

\item {\bf Twin Otter Air Support}:  If a
  Chinese traverse brings PLATO (in 2007) and HEAT to Dome~A (in 2009),
  USAP Twin Otter air support would allow personnel to be flown in from South
  Pole or the forthcoming AGAP field camps (such as AGO3) to facilitate the HEAT
  installation. 

\item {\bf CASA 212} (Australian Antarctic Division): J. Storey (see Support
   Letter) will be requesting one CASA 212 cargo flight directly from
   e.g. South Pole to Dome~A for transport of the HEAT experiment,
   with subsequent flights to support fuel and/or personnel for the
   HEAT installation. 

\end{enumerate}

The HEAT team will continue to work closely with the NSF, USAP, Raytheon
Polar Services, and the International Community to implement an optimal plan
for deployment to Dome~A.  

\section{Educational Impact}

The development and establishment of the first astrophysical observatory on 
Dome~A offers many opportunities to tap into the imagination of students of 
all ages. Below we highlight two examples.

\medskip

\noindent {\bf Instrument Development Experience}

\smallskip

The training of students in the development of state-of-the-art
instrumentation is essential to the future of science. This is
particularly true in mm/submm astronomy where technological advances
are happening so rapidly. 
Ironically, there are only a handful of laboratories in the world
where students gain hands-on experience in the design, fabrication,
and fielding of radio astronomy instrumentation. In the PI's lab we
have had a number of students (both graduate and undergraduate)
participate in the development of submm-wave instrumentation
for Antarctica (i.e. AST/RO) and the Heinrich Hertz Telescope
(HHT) on Mt. Graham, Arizona. This work, and the astronomy that has
come from it, has been a major component of 5 Ph.D. dissertations and
numerous undergraduate research projects. HEAT is a natural extension
of these research efforts. In the proposed budget for HEAT, funding for
one full time graduate student is requested. However, as is customary in
the PI's lab, many other students will also participate in making the
program a success. Indeed, one of the most important aspects of
training students in instrument development is experience in working
in teams. Astronomical instrumentation is becoming ever more complex,
and requires the talents of many individuals. Providing students with
both technical training and team-work experience increases their
probability of success.  

\medskip

\noindent {\bf K-12 Outreach: A Student Radio Telescope}
\smallskip

In support of education and public outreach activities the PI and his students 
have constructed a remotely operable, steerable, 3.5~m
Student Radio Telescope 
(SRT) for observing the HI line in the Milky Way. The SRT has been used as 
a instructional tool in undergraduate courses (both major and
non-major).  Students from on and off
campus will soon be able to monitor and control
observations with the SRT. Unlike optical telescopes, the SRT can be
used day and night, making it ideal for classroom instruction.  Like
HEAT, the SRT is a spectroscopic Galactic Plane survey
telescope. During the course of developing and operating HEAT we will
develop instructional modules for various age groups that focus on the
science and technology of HEAT and use the SRT as a ``hands-on''
laboratory with the goal of providing students with an intuitive
understanding of underlying physical concepts.  

\clearpage

\pagestyle{empty}

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\end{document}
