Increasing efforts to move into space have driven the need for new facilities that are capable of simulating weightlessness and other space gravity conditions on Earth. Simulation of weightlessness/microgravity (approximately 10−6g) is conducted in different earthbound and flight-based facilities, often with poor availability. Other conditions such as lunar or Martian gravity with their partial Earth gravity/hypogravity cannot be performed at a large scale for scientific research on Earth. For multiple Earth gravity/hypergravity, simulation centrifuges are available, but they do not allow the possibility of abrupt acceleration changes. To support this wide range of conditions, a new technique is being developed to combine all of these requirements into a single drop tower facility. Currently under construction, the Einstein-Elevator of the Hannover Institute of Technology at the Leibniz Universität Hannover is an earthbound tool created for simulating micro-, hypo-, and hypergravity research with a high repetition rate. The facility will be capable of performing 100 experiments per day (8-h work shift), each creating 4 s of microgravity. For the first time, statistics can be applied in experiments under space gravity conditions at favorable costs and short mission times. The Einstein-Elevator offers room for large experiments with a diameter up to 1.7 m and a height up to 2 m as well as weights up to 1,000 kg. To perform larger experiments under different gravitational conditions, it was necessary to develop an innovative drive and guide concept. The Einstein-Elevator will be available for general research under different gravity conditions from 2018 onward.
Mankind is setting to colonize space, for which the manufacturing of habitats, tools, spare parts and other infrastructure is required. Commercial manufacturing processes are already well engineered under standard conditions on Earth, which means under Earth’s gravity and atmosphere. Based on the literature review, additive manufacturing under lunar and other space gravitational conditions have only been researched to a very limited extent. Especially, additive manufacturing offers many advantages, as it can produce complex structures while saving resources. The materials used do not have to be taken along on the mission, they can even be mined and processed on-site. The Einstein-Elevator offers a unique test environment for experiments under different gravitational conditions. Laser experiments on selectively melting regolith simulant are successfully conducted under lunar gravity and microgravity. The created samples are characterized in terms of their geometry, mass and porosity. These experiments are the first additive manufacturing tests under lunar gravity worldwide.
In-Situ Resource Utilization (ISRU) technologies pave the way for a sustainable colony on the Moon. Above all, the construction of structures using only the available resources is an important factor in reducing costs and logistical effort. The MOONRISE project aims to melt lunar regolith using lasers on mobile platforms for the additive manufacturing of structures. This process is called Mobile Selective Laser Melting (M-SLM) and has the advantage that only electrical energy and a moving system are required. For a proof-of-principle experiment of M-SLM, which aims for creating 0D, 1D and 2D fused regolith structures on the lunar surface, we designed the MOONRISE payload. The MOONRISE payload can be accommodated on a rover or a robotic arm to ensure mobility for the melting experiments.An Engineering Model (EM) of the payload including a fiber coupled diode laser was developed and environmentally tested. The dimension of the payload is 1.5 U CubeSat. It has a mass of about 2.5 kg with further reduction potential towards flight model (FM) development. Verification tests with the EM were continued by attaching it to a robotic arm to create 2D regolith structures, i.e. flat rectangular specimens. Further tests with the EM were carried out under low gravity conditions in the large-scale research device Einstein-Elevator at the Hannover Institute of Technology (HITec), which allows experiments under zero gravity conditions for about four seconds. The Einstein-Elevator also enables adjustment of the gravity level from 0 to 5 g, a feature that was used to carry out melting experiments with the EM under lunar gravity conditions.
Microgravity platforms enable cold atom research beyond experiments in typical laboratories by removing restrictions due to the gravitational acceleration or compensation techniques. While research in space allows for undisturbed experimentation, technological readiness, availability and accessibility present challenges for experimental operation.

In this work we focus on the main capabilities and unique features of ground-based microgravity facilities for cold atom research. A selection of current and future scientific opportunities and their high demands on the microgravity environment are presented, and some relevant ground-based facilities are discussed and compared. Specifically, we point out the applicable free fall times, repetition rates, stability and payload capabilities, as well as programmatic and operational aspects of these facilities. These are contrasted with the requirements of various cold atom experiments.

Besides being an accelerator for technology development, ground-based microgravity facilities allow fundamental and applied research with the additional benefit of enabling hands-on access to the experiment for modifications and adjustments.
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