Miriam 2* is an ambitious development and flight test program and presently the main project of the Mars Society Germany. Its purpose is the verification of the ARCHIMEDES Mars Balloon concept on Earth with a space vehicle as similar as possible to the actual Mars vehicle. The flight test will be performed under atmospheric conditions similar to the ones encountered at Mars. The main difference between MIRIAM-2 and the ARCHIMEDES Mars vehicle consists in the reduced size of 4 m for the Miriam 2 balloon compared to the planned 10-16 m for Mars.

* Miriam stands for "M ain I nflated R eentry I nto A tmosphere M ission Test"

Main reasons for the reduced size of the Miriam 2 balloon are

• the availability of vacuum test facilities at IABG -the German Space Test Centre in Ottobrunn near Munich- allowing for a test of a balloon with 4 m diameter and its inflation system under vacuum conditions similar to the actual mission
• mass and volume limitations allowing the launch onboard a sounding rocket into appr. 200 km altitude
• the limitation of the required development effort for the balloon and its associated spaceflight system compared with the development of the full ARCHIMEDES system

Miriam 2, like ARCHIMEDES, consists of a "transport system" for the balloon into space in a densely packed condition, and the systems required to deploy, inflate and release the balloon in appr. 200 km altitude for its subsequent free flight into the thin earth atmosphere and down to the ground, while scientific measurements of its behavior and aero-thermodynamic properties are made. The results of these measurements shall demonstrate the validity of the ARCHIMEDES Mars Balloon concept and of the construction principles for the balloon storage, transport, inflation and release.

The Miriam 2 launch is planned for the 3rd quarter of 2021, again from Kiruna and on top of a sounding rocket provided by the German Space Agency DLR.

Miriam 2 succeeds the Miriam 1 mission of November 2008. At this time a first test vehicle -Miriam 1- was launched in Kiruna in northern Sweden, but design and mission sequencing problems prevented an orderly separation of Miriam 1 from the launcher and a full deployment of the balloon, resulting in only a partial mission success with no scientific data for the crucial atmospheric entry phase. Therefore it was decided in 2009 to repeat the flight test with an improved design of Miriam-1, now called Miriam-2, taking into account the lessons learned from the Miriam-mission. This time Miriam-2 will be the only "passenger" of the launcher, contrary to Miriam-1, allowing to integrate Miriam-2 more closely with the launcher as was possible for Miriam-1, and therefore improving significantly the mission success probability.

The following images show the Miriam 2 design and the progress in the development

(click any image to start a full-screen presentation sequence)

Miriam 2 Test Program

Development and Test Program Overview

The scientific and technical validity of the Miriam flight test program is based on scientific research, the development of equipment meeting mission objectives, ground tests, and finally flight tests of the critical balloon storage and deployment systems during parabolic flights under zero gravity

The design solutions for Miriam are based on the research and design results for the ARCHIMEDES Program for the ballute itself and its manufacturing and packing techniques, as well as for the related equipment for storing, deploying and releasing the ballute in space.

The balloon design is based on the results of numerous ground tests tests starting early during the ARCHIMEDES program from 2003 onwards. This included

• balloon drag tests using a 2 m balloon and a car dragging the balloon. Objective: simulating the behavior of a balloon descending through the atmosphere
• balloon inflation tests using a simple 10 m balloon. Objective: observing the behavior of a balloon during inflation
• balloon manufacturing technology tests using different materials, balloon material cutting methods and balloon segment bonding techniques (glueing, welding)
• balloon folding and packing tests. Objective: ensuring that the ballute can be packed into a small container and be deployed afterwards for inflation without being damaged
• development of best suited balloon inflation methodology and related equipment aiming at inflating the balloon as quickly as possible without damaging it. Finally a three-step inflation approach using two different inflation valves was selected
• balloon deployment test in a 1-g environment
• test of the balloon inflation system verifying successfully the function of the balloon inflation system dveloped by the MSD
• balloon inflation test of the Miriam 2 flight balloon in the TV test chamber of IABG

Details of the ARCHIMEDES/Miriam development and test program (in German) can be found here:

Ground Test Program

Scientific Programm

The function of the initial deployment of the balloon from a densely packed condition is particularly critical: the container must be constructed in a way to safely store the balloon but also to push it out of the container allowing the balloon to deploy itself by the residual gas to an extent guaranteeing the subsequent inflation to its full size.

Details can be seen in the picture gallery.

Flight Tests

A first flight test testing the balloon deployment methodology was performed in 2005 with the Rexus-REGINA rocket flight test. This test confirmed the validity of the design of the balloon container as a "blossom".

In 2005 followed a first parabolic flight test on the A-300 Airbus of ESA. The test was performed with a 5-m balloon and a balloon container representing the ARCHIMEDES design, and was successful.

In 2008 followed the first full flight test Miriam 1 with a complete balloon storage, deployment, inflation and release system representative for the ARCHIMEDES Mars mission in a reduced 1:2.5 scale with a 4-m balloon (ARCHIMEDES: 10 m diameter balloon). The missions was only a partial success and resulted in complete redesign of the system, but maintaining the basic design principle of the ballon container in form of a "blossom". This new design was first successfully tested during a ground test of the balloon deployment system in October 2015, followed by a parabolic flight test on an ESA Airbus A-300 in November 2015 using the balloon and balloon storage and deployment system foreseen for the Space flight. This test was only a partial success, since the balloon deployment did not fully function as foreseen, leading to an only partial deployment of the ballon. It was therefore decided to repeat the parabolic flight test in 2017 with an improved balloon storage and deployment system. This parabolic flight took place in November 2017 and was a full success (see image with the perfectly deployed balloon).