What is the payload on the IBEX spacecraft?
The payload on IBEX is simple, containing only a single Combined Electronics Unit (CEU), and two sensors, IBEX–Hi and IBEX–Lo. The CEU provides electronic support and control for the sensors. It is represented above by the rectangular box below the cutaway graphics.
The cutaway graphics above represent IBEX–Lo (left) and IBEX–Hi (right). In the configuration represented by these drawings, energetic neutral atoms enter the sensors from the top. Please note that while the drawings suggest that the entry system is only on one side of each detector, the entire detector is actually a circular doughnut shape. The entry system, called the "collimator", blocks unwanted charged particles and stray light while selecting only Energetic Neutral Atoms for analysis. The entrance system also ensures that only particles that enter straight into the detector are analyzed so that an accurate determination of their direction of origin can be ascertained. These neutral particles are then turned into positive ions when they encounter the "ENA to Ion Conversion" material. As they are now ions, the path of each particle can be deflected into the rest of the detector. The "Electrostatic Analyzer" at the bottom of these cutaway graphics, reminiscent of the shape of the bottom of a Bundt cake pan, creates a magnetic field that forces the particles into a curved path. In IBEX–Lo, the particles then pass into the "TOF (Time of Flight) Instrumentation" in the middle of the sensor, where the velocity of the particles can be determined. The velocity of the particles indicates the energy of the particles. IBEX–Hi does not have the exact Time–of–Flight system as IBEX–Lo does, but IBEX–Hi does determine particle velocities using the instrumentation in the middle. The ribs or fins inside IBEX–Lo also deflect and absorb stray visible and ultraviolet light.
IBEX–Lo can detect particles with energies ranging from 10 eV to 2,000 eV (0.01 keV to 2 keV) in 8 energy bands. IBEX–Hi can detect particles with energies ranging from 300 eV to 6,000 eV (.3 keV to 6 keV) in 6 energy bands. There is energy band overlap between the two sensors. The overlap between IBEX–Hi and –Lo maximizes statistics and allows for in–flight cross–calibration, and provides imaging via two completely independent sensors across the most critical energy range for achieving the IBEX science objectives.
For pictures of IBEX–Hi and IBEX–Lo, please go to our Images page.