Astronaut Tracy Caldwell in the International Space Station. (Credit: NASA)

Making The Case For All-Female Exploration Missions To Mars And Beyond

A recent study in Nature Scientific Reports by Jonathan P. R. Scott and colleagues makes the case for sending exclusively all-female crews on long-duration missions. The reasoning here is simple: women have significant less body mass, with in the US the 50th percentile for women being 59.2 kg and 81.8 kg for men. This directly translates into a low total energy expenditure (TEE), along with a lower need for everything from food to water to oxygen. On a long-duration mission, this could conceivably save a lot of resources, thus increasing the likelihood of success.

With this in mind, it does raise the question of why female astronauts aren’t more commonly seen throughout Western space history, with Sally Ride being the first US astronaut to fly in 1983. This happened decades after the first female Soviet cosmonaut, when Valentina Tereshkova made history in 1963 on Vostok 6, followed by Svetlana Savitskaya in 1982 and again in 1984, when she became the first woman to perform a spacewalk.

With women becoming an increasingly more common sight in space, it does bear looking at what blocked Western women for so long, despite efforts to change this. It all starts with the unofficial parallel female astronaut selection program of the 1950s.

Continue reading “Making The Case For All-Female Exploration Missions To Mars And Beyond”

LoRa Goes To The Moon

LoRa is a communications method that allows for long range radio contacts to be made using typically low-powered devices. This shouldn’t be surprising given that LoRa is short for “long range” which typically involves distances on the order of a few kilometers. However, a group of students are taking the “long range” moniker to the extreme by attempting to send and receive a signal with a total path of around 768,000 kilometers by using some specialized equipment to bounce a LoRa signal off of the moon and receive it back on Earth.

Earth-Moon-Earth (EME) communications are typically done by amateur radio operators as a hobby, since the development of communications satellites largely rendered other uses of this communication pathway obsolete. A directional antenna and a signal typically on the order of 1 kW are often used to compensate for the extremely high path losses. Using LoRa, which makes use of chirp spread spectrum modulation, they hope to reduce this power requirement significantly. The signals are being generated and received on a set of HackRF One devices fed into a series of amplifiers, and the team is also employing a set of large dish antennas, one in New Jersey and another in Alaska, to send and receive the messages.

The software used is the open-source SDRAngel which is useful for controlling the HackRF and moving the LoRa signal up to 1296 MHz. Normally LoRa is operated on an unlicensed band, but this method allows for finer control of not only frequency but also bandwidth, which helps reduce the impacts of path loss. Right now they have not yet completed their contacts with the Alaska station (partially due to that antenna being covered in snow) but we hope to hear more news in the future. In the meantime, take a look at some more traditional long-range communications using this protocol with more manageable-sized antennas.

Image courtesy of NASA, Public domain, via Wikimedia Commons

Building A Communications Grid With LoRaType

Almost all of modern society is built around various infrastructure, whether that’s for electricity, water and sewer, transportation, or even communication. These vast networks aren’t immune from failure though, and at least as far as communication goes, plenty will reach for a radio of some sort to communicate when Internet or phone services are lacking. It turns out that certain LoRa devices are excellent for local communication as well, and this system known as LoraType looks to create off-grid text-based communications networks wherever they might be needed.

The project is based around the ESP32 platform with an E22 LoRa module built-in to allow it to operate within its UHF bands. It also includes a USB-based battery charger for its small battery, an e-paper display module to display the text messages without consuming too much power, and a keyboard layout for quickly typing messages. The device firmware lets it be largely automated; it will seek out other devices on the local mesh network automatically and the user can immediately begin communicating with other devices on that network as soon as it connects.

There are a few other upsides of using a device like this. Since it doesn’t require any existing communications infrastructure to function, it can be used wherever there are no other easy options, such as in the wilderness, during civil unrest where the common infrastructure has been shut down, or simply for local groups which do not have access to cell networks or Internet. LoRa is a powerful tool for these use cases, and it’s even possible to network together larger base stations to extend the range of devices like these.

Laptop connected via Ethernet to Raspberry Pi-based secure radio device with antenna

Secure LoRa Mesh Communication Network

The Internet has allowed us to communicate more easily than ever before, and thanks to modern cell-phone networks, we don’t even have to be tied down to a hard line anymore. But what if you want something a little more direct? Maybe you’re in an area with no cell-phone coverage, or you don’t want to use public networks for whatever reason. For those cases, you might be interested in this Secure Communication Network project by [Thomas].

By leveraging the plug-and-play qualities of the Raspberry Pi 4 and the Adafruit LoRa Radio Bonnet, [Thomas] has been able to focus on the software side of this system that really turns these parts into something useful.

Window showing secure text communications
Messages are tagged as “authenticated” when a shared hashing code is included in the message

Rather than a simple point-to-point radio link, a mesh network is built up of any transceivers in range, extending the maximum distance a message can be sent, and building in resilience in case a node goes down. Each node is connected to a PC via Ethernet, and messages are distributed via a “controlled flooding” algorithm that aims to reduce unnecessary network congestion from the blind re-transmission of messages that have already been received.

Security is handled via RSA encryption with 256-byte public/private keys and additional SHA256 hashes for authentication.

The packet-size available through the LoRa device is limited to 256 bytes, of which 80 bytes are reserved for headers. To make matters worse, the remaining 176 bytes must contain encrypted data, which is almost always more lengthy than the raw message it represents. Because of this, longer messages are fragmented by the software, with the fragments sent out individually and re-assembled at the receiving end.

If you’re in need of a decentralized secure radio communications system, then there’s a lot to like about the project that [Thomas] has documented on his Hackaday.io page. He even includes an STL file for a 3D printed case. If you need to send more than text, then this Voice-over-LoRa Mesh Network project may be more your style.

Building A Local Network With LoRaWAN

At its core, the Internet is really just a bunch of computers networked together. There’s no reason that there can’t be other separate networks of computers, or that we all have to tie every computer we have to The One Internet To Rule Them All. In fact, for a lot of embedded systems, it doesn’t make much sense to give them a full network stack and Cat6e Ethernet just to report a few details about themselves. Enter LoRaWAN, a wireless LAN that uses extremely low power for Internet-of-Things devices, and an implementation of one of these networks in an urban environment.

The core of the build is the LoRaWAN gateway which sits at the top of a tall building to maximize the wireless range of all of the other devices. It’s running ChirpStack on the software side and uses a Kerlink Wigrid station to broadcast. The reported range is a little over 9 km with this setup. Other gateways can also be added, and the individual LoRa modules can report to any available gateway. From there, the gateways all communicate back to the central server and the information can be sent out to the wider network, Internet or otherwise.

The project’s creator [mihai.cuciuc] notes that this sort of solution might not be best for everyone. There are other wide area networks available, but using LoRaWAN like this would be likely to scale better as more and more devices are added to the network. For some other ways that LoRa can be used to great effect, take a look at this project which builds an off-grid communications network with it.

e-paper display showing hand-drawn fonts attached to a custom controller PCB

Recycling Junk E-tags Into A LoRaWAN AQI Sensor

E-paper interfacing circuit is just a simple switched-mode power supply
Interfacing to E-paper displays is nothing to be scared of

[Aduecho] had seen those cheap eBay deals of e-paper-based pricing tags, and was wondering if they could be hacked to perform some other tasks. After splitting the case open, the controller chip was discovered to be a SEM9110, with some NFC hardware support but little else. [aduecho] was hoping to build some IoT-connected air quality indicator (AQI) units but the lack of a datasheet for SEM9110 plus no sensors in place meant the only real course of action was to junk the PCB and just keep the E-paper display and the batteries. These units appeared to be ‘new old’ stock, so there was a good chance that both would be fresh and ripe for picking.

The PCB [aduecho] came up with is mechanically the same as the original unit, but now sports a Seeed studio Wio-E5 LoRa module, which uses the STM32WLE5 from ST for the heavy lifting. This has what looks like a Semtech SX126x integrated on-die (we can’t think of a sane way an actual SX126x die could be flip-chip mounted, but you never know). Using this module is a snap, needing only very minimal antenna-matching components and a spot of decoupling to function. On the sensing side of things, a Bosch BME680 gas sensor handling the AQI measurements, and a Bosch BMI270 6-axis IMU, provides a gyro and accelerometer, for all those planned user interaction features. As can be seen from the schematic, interfacing the EPD is pretty straightforward, just a handful of parts are needed to generate the necessary bipolar gate voltages via a simple SMPS circuit. The display controller handles it all internally, programmed via an SPI interface.

One area we’re quite fond of in this project are the neat hand-drawn icons, and variable width font, giving the display a kind of note-like quality when drawn on the low-ish contrast e-paper display.

Air quality measurement projects grace these pages from time to time, like this hacked Ikea Vindriktning, and this very similar Wio-E5-based project we covered last month.

Hackaday Prize 2022: Solar Powered LoRa Weather Station For The Masses

[Debasish Dutta] has designed a few weather stations in the past, and this, the fourth version of the system has had many of the feature requests from past users rolled in. The station is intended to be used with an external weather sensor unit, provided by Sparkfun. This handles wind speed and direction, as well as measuring rainfall. A custom PCB hosts an ESP32-WROOM module and an Ai-Thinker Ra-02 LoRa module for control and connectivity respectively. A PMS5003 sits on the PCB to measure those particulate densities, but most sensors are connected with simple 4-way I2C connectors. Temperature, humidity, and pressure are handled by a BME280 module, UV Index (SI1145), visible light (BH1750) even soil humidity and temperature with a cable-mounted SHT10 module.

All this is powered by a solar panel, which charges a 18650 cell, and keeps the show running during the darker hours. For debugging and deployment, a USB-C power port can also be used to provide charge. A 3D printed Stevenson screen type enclosure allows the air to circulate amongst the PCB-mounted sensor modules, without hopefully too much moisture making it in there to cause mischief.

On the data collection and visualization side, a companion LoRa receiver module is in progress, which is intended to pass along measurements to a variety of services. Think Home Assistant, ESP home, and that kind of thing. Software is still a work in progress, so maybe check back later to see how [Debasish] is getting on with that?

This kind of multi-sensor hosting project is nothing new here, here’s a 2019 Hackaday prize entry along the same lines. Of course, gathering and logging measurement data is only part of the problem, visualization of those measurements is also important. Why not use a mechanical approach, such as a diorama?