**MTRAP: The Magnetic TRAnsition Region Probe**

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**Mission Objective:**

Measurement of the build up and release of magnetic energy in the solar
atmosphere in order to develop a physics based prediction system for the
release of energetic particles, solar flares and CMEs that pose a hazard
for astronauts involved in the manned exploration of the Moon and Mars.

**Science Objectives:**

Discover, measure, and understand the 3D structure and dynamics of the
magnetic field between the photosphere and the upper chromosphere-corona
transition region.

Connect the structure and events in the magnetic transition region with
their photospheric roots and with the magnetic stress and heating of the
chromosphere and corona.

Resolve and measure the appearance, transport, and destruction of
magnetic field on the fundamental intergranular scales in the
photosphere.

Track the buildup of active-region magnetic energy for flares and CMEs
and pinpoint the triggers of these magnetic eruptions.

**Enabling/Enhancing Technology Development:**

-   Large-aperture, lightweight reflecting optics for visible, near IR,
    and vacuum UV solar space telescopes.

-   Segmented primary mirror, a la James Webb Space Telescope.

-   Multilayer coated surfaces for cold mirror technology (SUMI).

-   Self-deploying lattice truss optical bench (Able Engineering).

-   High stability platform with image motion compensation stabilization
    at the 5 milli-arc sec.

-   Large-format (8k x 8k pixels), low power, large well depth (250
    ke^-^) high-QE, multi-port readout CCDs.

-   500 Mbps downlink with on-board processing and compression.

-   High data volume ground processing.

**Mission Description:**

-   Mission Design: Delta II launch vehicle (3-meter internal diameter
    fairing); Geo-stationary orbit; 3-year duration.

-   Flight System: 3-axis stabilized inertial platform; solar arrays;
    500 Mbps downlink: Payload: 600kg, 400W (peak), spacecraft pointing
    accuracy: 30 arcsec.

**Measurement Strategy:**

-   Maps/images of vector magnetic field, intensity, and velocity in the
    magnetic transition region and simultaneously in the photosphere,
    with:

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-   Large FOV \[5arcmin (300,000km) to cover large active regions\]

-   High resolution \[0.05arcsec (35km)\]

-   Low vector magnetic field detection threshold \[1G longitudinal, 15G
    transverse in photosphere; 3G long., 100G trans. in high
    chromosphere; 15G long., 300G trans. in low transition region\]

-   Integration times \[1-10s in photosphere & low chromosphere, 10-100s
    in high chromosphere & low transition region\]

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-   Coordinated observations with advanced solar missions that observe
    the sub-photospheric field via helioseismology, the high-temperature
    corona and energetic particle emissions.

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***MTRAP***, *a high-resolution magnetrography mission, will enable us
to discover and understand the structure and dynamics of the magnetic
transition region from its origin in the photosphere to its effects on
the corona. The **Magnetic Transition Region** is the relatively
unexplored interface layer between the convectively dominated
photosphere and the magnetically dominated upper chromosphere/inner
corona.*

**The Need for MTRAP:**

MTRAP will measure the fine-scale magnetic structure and dynamics in the
magnetic transition region that are responsible for the Sun's high
temperature, extended outer atmosphere and for the flares and coronal
mass ejections that are the sources of the Sun's energetic particle
emissions. These measurements will allow a clearer understanding of the
dynamic changes of the magnetic field that are the precursors of solar
eruptive events.

MTRAP has the collecting area required, a factor of 100 greater than
Solar-B to measure the magnetic fields in this region.

MTRAP is a crucial element of the system of systems that is needed to
develop an accurate and reliable tool for the prediction of the
energetic particle events that pose a life-threatening hazard for
astronauts working on the lunar surface or on route to Mars.

***The MTRAP Observatory.** The left image shows the observatory in both
its stowed (launch) and deployed configurations. The right hand image
shows the light paths for the telescope. The incoming radiation strikes
one of the primaries and is focused just beyond the aperture ring where
the field stop (not shown) is placed. After striking the secondary the
beam is directed toward the central axis of the telescope.*