The Autonomous Systems Lab (ASL) of ETH Zurich has developed the AtlantikSolar and SenseSoar2, two solar-powered, low-altitude long-endurance (LALE) unmanned aerial vehicles (UAVs) that are gathering valuable data on climate change and Agriculture.

Due to their lower cruising height and increased flight endurance, LALE UAVs benefit from improved imaging capabilities, lower complexity, and simplified handling. Unfortunately, they also have to deal with a more challenging meteorological environment in the form of clouds, rain, wind gusts, and thermals.

Designed for multi-day perpetual flight, the AtlantikSolar broke the flight-time world record for its size class in 2015, with an 81-hour, 2338km voyage, while also achieving a 39% minimum state-of-charge. The AtlantikSolar weighs in at 6.9kg and has a wingspan of 5.7m. It now completes multi-day missions using small optical or infrared cameras. Last summer in Greenland, the AtlantikSolar monitored iceberg calving in Greenland – a still poorly understood process which plays an important role in sea-level rise.

With a wingspan of 3m and weighing in at 5.2kg, the SenseSoar2 is a more compact platform. It’s even more robust, though, in dealing with wind gusts and other inclement weather conditions. In fact, this summer, SenseSoar2 completed a 302km, 5.5-hour flight while being battered by high winds.

The SenseSoar2 is currently being used in an ongoing ESA agricultural monitoring mission in the Ukraine. Fitted with a hyperspectral camera that complements existing satellite imagery, it provides farmers, agronomists, and agricultural experts with actionable intelligence.

Rock Seven (now trading as Ground Control) RockBLOCKs are used to send telemetry to the ground station and commands to the UAVs when radio transmission is not feasible. To achieve this, the team integrated a RockBLOCK to the PX4 open-source autopilot via the PX4’s API, giving the ground station fly-by-satellite capability when the AtlantikSolar and SenseSoar2 were downrange of the 868MHz medium-range telemetry link.

Introduced in a paper published in 2010 in the American Meteorological Society, the AirCore has proven itself a robust atmospheric sampling device used with balloons and other airborne assets. Co-developed by the University of Colorado and the NOAA, the heart of the AirCore is 100m of thin, valve-tipped, and coiled stainless-steel tubing that stores gas but prevents its diffusion.

Initially, known amounts of trace gases called fill gas are pumped into the coil. The valves keep the fill gas inside the coil, but as the AirCore ascends through the atmosphere, the exterior pressure drops and the fill gas slowly escapes out.

At around 95,000 feet, the fill gas has almost completely left the coil and, in this current application by the NOAA team, a payload cutdown controller (PCC), which includes the AirCore and all of its auxiliary communications and logging equipment, is separated from a balloon and begins its parachuted descent.

As the PCC falls to the ground, the external pressure slowly builds up, forcing ambient air through a small magnesium perchlorate-filled canister (to dry the air) and into an open valve back into the coil. At ground level, the AirCore will have collected a vertical profile of undiffuse air, almost like a solid core. Back at the lab, the air is then pushed back out of the coil and analysed, ideally in AirCore pairs to make sure that accurate results have been gathered. The small amount of fill gas left in the AirCore indicates the top of the profile.

The PCC uses a Teensy 3.6 board (similar to an Arduino) that controls the cutter. The RockBLOCK itself is programmed to send out location data every five minutes throughout the flight, from power up prior to launch until about 30 minutes after landing. Two-way communication via the RockBLOCK’s SBD Library also gives the team the ability to cut the balloon loose early in flight. Powering the entire PCC for at least four hours are two rechargeable lithium 18650 2200mAh batteries in series.

Usually, a flight will go according to plan but on two occasions the RockBLOCK has gotten more than it bargained for. As Jack Higgs from the NOAA ESRL Global Monitoring Division explains:
 

“On one flight in Oklahoma last week, the balloon string became tangled with the parachute after cutting so the payload was carried up until the balloon burst. The RockBLOCK reached an altitude of 112,913 feet and low pressure of 5 millibar. It still transmitted its location message at that altitude without any problems. The package was also exposed to a low temperature of -75 degrees C during the flight. The electronics are housed in a Styrofoam package but are not heated. They only benefit from heat generated by the components.”

 
In another instance, the team had to borrow a canoe from a nearby homeowner and paddle out into the middle of a lake to retrieve the PCC. Amazingly, all the electronics were still operating, even though they were all wet inside. The RockBlock was transmitting its location every five minutes while saturated with water and floating horizontally in the lake.

The AirCore’s success has been duplicated on this side of the Atlantic, too. Academic institutions such as the University of East Anglia, University of Groningen, and the Finnish Meteorological Institute have used it for similar research.

More information on the AirCore can be found at the NOAA’s Earth System Research Laboratory.

All Octanis software and hardware has been specifically chosen to adhere to the principles of the open source movement, and the RockBLOCK is no exception. The publicly available Rock Seven (now trading as Ground Control) API allows users to deliver messages from RockBLOCKs directly to their own application’s web service or e-mail, and to send messages or commands back to RockBLOCKs in the field.

Led by Dr. João Borges de Sousa of the Laboratório de Sistemas e Tecnologia Subaquática (LSTS) of Portugal, a multinational, multidisciplinary team of scientists have designed, built, and deployed seven autonomous underwater vehicles (AUVs) in the North Pacific Subtropical Ocean Front using the Schmidt Ocean Institute’s research vessel Falkor.

Ocean fronts are areas where drastic changes occur in the properties of waters. These changes are of interest to scientists studying Earth’s climate and marine ecosystems. The particular ocean front examined by the teams is situated about 1,000 nautical miles SW of Southern California. It’s here that less dense and cold waters coming from the Arctic meet the otherwise saline waters of the Pacific.

Three scout ASVs (autonomous surface vehicles) were sent to detect the ocean front ahead of the Schmidt Ocean Institute expedition. The area was then mapped for three weeks by a fleet of AUVs, UAVs (unmanned aerial vehicles) and the R/V Falkor.

In order to map the 3D structure of this dynamic front, the AUVs cycled in a ‘saw-tooth’ pattern between the water’s surface at a depth of 100 meters. The AUVs were controlled from either the R/V Falkor or across the world from an ocean space center in Portugal, with commands sent via RockBLOCKs and the Iridium network.

Operating 24/7, the AUVs would also periodically upload preliminary sensor data, like temperature, salinity, chlorophyll, and turbidity profiles (water properties at different measured depths).

When interesting features would appear, UAVs were deployed to measure the same features from the air using thermal and multispectral cameras. This feat wouldn’t have been possible using only traditional marine/aerial vehicles, due to the logistical and financial restrictions involved with these larger assets.

In less than three weeks, the AUVs traversed over 1,000 nautical miles, operating approximately for 500 hours and sending over 12,000 transmissions – or 2.5 megabytes of Iridium data – to researchers via Rock Seven (now trading as Ground Control)’s servers.

The mission’s success proves that lower-cost, autonomous, and connected vehicles can play a key role in collecting abundant data sets from remote locations. This allows research vessels like the R/V Falkor to shift their role from being a primary sampling unit to a command center, reducing operational costs while increasing scientific knowledge.

Iridium connectivity also allowed the replica command center based in Portugal to take over the second shift, giving scientists round the clock control of their research assets.

More information about this research can be found in the Schmidt Ocean Institute’s expedition page.

Thanks to advancements in IT and DIY fabrication, missions reserved for national space agencies just a decade ago are becoming increasingly accessible to hobbyists. Cue the High Altitude Photography Platform (HAPP), created by Christopher Couch and James Mayes.

The two engineers designed and built the HAPP, which is comprised of a jet-stabilized aircraft resembling the iconic three-man Apollo re-entry vehicle: a balloon system designed to take the aircraft to its 30km apogee and all the peripheral equipment and electronics that made that project successful. Though not the first high-altitude photography project, the HAPP is the first to capture stabilized 360-degree video.

Even more amazing was the project’s focus on DIY: over 80% of the 22 months for development were dedicated to creating tools and methods rather than actually producing flight hardware. The result is a project that can be replicated by hobbyists using locally sourced parts.

The HAPP can drift as much as 100km during each mission, so it was important to keep track of the lander and provide flight data to air traffic control. The RockBLOCK 9603 was vital in sending telemetry and system sensor data from the Arduino-based flight control computer at an altitude of up to 22km on the maiden flight, mission HAPP-M1.

While the power supply was in a temperature-controlled enclosure, the U-Blox board and PCBs were exposed to the atmosphere for the duration of the mission, experiencing temperatures ranging from +42°C down to -45°C, and pressures from 1atm down to 0.05atm.

The project’s creators have done a great job in documenting the project build and sharing the valuable knowledge they’ve gained. Their videos, including the glorious 4K mission HAPP-M1, can be found here.

In the spring of 2017, an international team of students from Luleå University of Technology in Sweden gathered together to brainstorm a REXUS/BEXUS program idea. The European program supports scientific and technological experiments on research rockets and balloons, sending two of each into space every year.

After some deliberation by the team, it was a scientific article on the potential of a manned mission to the upper Venusian atmosphere that gave the impetus for the Balloon Ejection Student Prototype INvestigation (BESPIN) Project. Though Venus’s runaway greenhouse effect makes the planet’s surface hot enough to melt lead, at a height of 50km temperature and pressure conditions are very similar to those found on Earth. This makes a balloon-assisted manned mission to Venus highly plausible.

That’s why the BESPIN experiment is made up of two parts – a flotation probe and a descent probe. At apogee (around 80km), both probes are ejected as a single free-falling unit (FFU) from the rocket’s nose-cone. The FFU freefalls until it reaches an altitude of about 5km, when a parachute is deployed on the descent probe.

When the FFU’s velocity has dropped below 7 m/s, a balloon on the flotation probe will inflate. Once it’s fully inflated, the descent and flotation probes will separate. The descent probe will continue parachuting down towards the ground, while the flotation probe uses its fully inflated balloon to attempt a controlled descent.

Following the deployment of the descent probe parachute, the team will be using a RockBLOCK 9603 to communicate housekeeping and positional data to a ground station. Like the rest of the equipment, the RockBLOCK will be undergoing rigorous testing to ascertain its suitability for vibration, shock, and pressure changes associated with the mission.

More on this story from the European Space Agency.