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The Heliospheric Modulation Model

Online Calculator

Version Test

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Fluence Calculator Along a Transfer Orbit.

This site provides access to the HelMod Transfer Orbit Fluence web calculator, which is an application of the latest available HelMod Code:

HelMod data sets and results can be freely downloaded or copied. However, we strongly suggest the user provide an appropriate acknowledgement and/or citation, e.g., see  Citations or Bibliography pages.


How to use this HelMod Calculator

This tool evaluates the modulated integrated fluence and differential fluence along a transfer orbit for theoretical LIS evaluated with GALPROP. The particle transport is described using the Helmod Model. For information about the computation method please refer to Monte Carlo Integration page.

The input parameters and options for the tool are described below. Once the input form has been completed, the "Submit" button will start the calculation and open the "Results" page (allow for a pop-up in your browser settings).

Users must select the cosmic ray species, the transfer orbit and the date interval (up to 2 solar cycles forecasted):

  • Cosmic Ray Species: allow for selecting a single Galactic Cosmic rays species among ions with Z from 1 to 28. Among cosmic rays species, those with Z larger than 28 are not available because their expected overall (from Z=29 up to Z=92) fluence is about a fraction of percent with respect to one of Fe-ion alone.
  • Transfer Orbit: The user can exploit a library of past transfer orbit to Mars, Jupyter, and Saturn as well as provide a custom transfer orbit. These orbits are evaluated as lying on a plane close to the ecliptic.
  • Dates: allow to indicate the initial date of the hypotetical transfer mission that are intended to be evaluated. The selected transfer orbit is then shifted in time to the user requested date: user should be awared that it is not ensured that the past-like transfer orbits could be used by future spacecraft without adjustment. In case of custom orbit also the end of the mission (i.e. the end of the transfer orbit period) should be provided in order to proper inizialize the custom orbit module.

Custom Orbit

In case of custom orbit, User must specify the spacecraft position for all Carrington rotation. The input text area is prefilled with the central date (in the format Y-m-d) within each specific carrington rotation (or a fraction of it) and are processed by calculator with that specific order. The change of the date within the carrington rotation period do not modify the final result. For each carringotn rotation period, user must indicates one spacecraft heliocentric distances from Sun (in AU).


The result page contains the figure of the modulated spectrum and correspondent tabulated data.
The computation time may require up to several minutes depending on the lenght of the trasnfer orbit, do not close the windows. As a reference a calculation of Iron Fluence using Cassini-like transfer orbit (~ 7 years) take 15 minutes, while ~2 minutes are required for computing Mars Express-like transfer orbit (i.e. ~6 months).

It should be remarked that data generated by using the Calculator may be used by HelMod developers for statistical purposes.