Welcome to SpaceRoots

Objectives

This site is devoted to distribute some open-source and free
components concerning mathematics and space dynamics.

It was brought to life by passionated people which are
already involved in space topics and computer science as their
business life. Space systems are extremely difficult to validate
and extremely expensive. A number of decade-old techniques
(fortran language, fixed format flat data files, 4th
order integrators from nineteenth century, historical rules of
thumb ...) have been validated for such systems since the golden
ages of discovery of this new humankind frontier. These two
facts imply that these old techniques are still widely used
today in space dynamics, where budget and available time are
scarce : contrary to popular belief, operational rocket
science does not always deals with bleeding edge
technology, it is quite the opposite. This constrained situation
implied that in their business life, the people behind SpaceRoots
could not always put new ideas and techniques into practice.

SpaceRoots has been set up as a way to explore some ideas without
arbitrary schedule or cost constraints. It is also a proof of concept
experiment to show that object-oriented design and the java
language are well suited for numerical computing and
space dynamics.

What will you find there ?

The main component is Mantissa (Mathematical Algorithms
for Numerical Tasks In Space System Applications). It is a
collection of various mathematical tools developed for
simulation purposes. It contains some linear algebra, estimation
and geometrical features, and a set of state of the art
algorithms for Ordinary Differential Equations solving, all of
them supporting multiple switching functions and dense
output, as well as some other features.

A tool to check the order of
any Runge-Kutta or Runge-Kutta-Fehlberg method using exact
arithmetic if possible is also available.

Some mathematically oriented papers are also published on
this site, mainly as reference material for practical algorithms
implementation

Still there after several years

Spaceroots experiment was started at the beginning of year
2002. What results did it provide ?

The main observation is that the site is still there, up and
running. At the beginning of 2006, there are about 130 different
visits and 1000 hits each day. It is still a small site with a
slowly and steadily increasing popularity. It is easy to find
using the main search engines and a few unrelated sites link to
it.

The main component, Mantissa is downloaded about 150
times each month. It has been reused in different fields ranging
from teaching to studies (universe expansion, ocean currents
simulation, greenhouse gases storage, astronomy calibration,
biological waste process) and other open-source and free
software. Parts of it have also been ported to other languages
in operational space systems related to the International Space
Station. All the feedbacks from users have been very
positive. Very few bugs have been found, and they were all fixed
in a few hours. The part which seems to be the most interesting
for people is the ODE package. All users reports it as an easy
to use but very powerful package. The least squares package, the
3D rotation class and the Mersenne-Twister random generator are
also common entry points. 21 versions of Mantissa have been
published in four years, the publication rate beeing very
irregular (from a few days to a few months between updates).

The two ellipse related documents are also regularly read
online or downloaded, many people seem to find the site from
these documents.

The experiment is therefore quite positive. People are
interested in the components. Java is doing well in numerical
and mathematical fields and several very mathematics oriented
users told me they found Mantissa because they already searched
explicitely for Java libraries, this language being a main criterion
for them. I was surprised to learn this, as from my experience
in the space industry (I do work in this field since about 20
years), Java is very seldom used in the number crunching
community. Rocket science is not what many people think
it is.

The downsides are that feedback is very limited. A few mails
asking for help in using some package, some bug reports
concerning the libraries or the documents. External
contributions or requests for changes are extremelly rare (in
fact, only one change request was ever received, from someone
who did not realized that what he asked for was already
implemented in a more generic way, and who was happy to learn he
could already handle his problem in an elegant way with tips and
examples). One user who already found some bugs proposed to
provide a very interesting and important new feature to Mantissa
I have always wanted to add myself. I hope this will happen soon
as what I have seen is promising.

The site is therefore here to remain. Mantissa will still
evolve and new documents will be added.