Space, Satellites, & Small Kids
Troy Morris, Director of Operations
7 minute read
Credit: Cambridge University
Having co-found a space company startup, there have been many interesting developments, questions, and discoveries along the way. Of the most engaging of opportunities is the chance to engage with our youth, through school programs, family gatherings, or the amazing excitement of small talk with strangers leading to conversations on LEO when taking public transit. In these chances to speak with children, an expert in any field is challenged by the wide-eyed wonder of a curious mind, distracted attention span, and inexperienced insight of, “why?”
These questions engage from the familiar, “how do you get your spacecraft into space,” to the favorites, “why not just throw it in the sun,” to the fantastic, “why don’t the space people just fix their broken stuff?” These answers vary: rideshare rockets, reaching the sun takes WAAAY more energy, and we are working on it; but the key isn’t what the question is asking, but the why. Why does this small creature care about space? Why does my nephew turn any rocket, boat, plane, racecar, or milk carton into a spaceship and fly it around? Why does the steady, shiny orbit of the ISS gleaming overhead cause my brother and I to stare slack jawed with the joy of our inner child? This excitement, glee, and a dozen other synonyms might just be a passing fancy, but it’s the engagement that keeps kids, young and old, coming back for more.
To aim for this audience and engagement, I’ll attempt in this column to tackle a more concrete question rather than the philosophical ones I've pursued a time or two before. As stated by a skeptical preteen as we all were boarding a recent flight, “how do satellites work?” Now due to the depth of necessary knowledge and discussion on these advancing technological wonders, many topics may be summarized, and subtopics skipped, in order to assist both reader and author. In my knows-enough-to-be-dangerous perspective, how a satellite works falls under discussing the following: Payload, Structure, Propulsion, Power, Computing, Communication, Orbit, and Launch.
The payload of most satellites is the reason your mission even exists. Whether measuring the rainfall around the world, providing positioning for navigation, or staring into the farthest reaches of the cosmos, the sensors and systems that allow the satellite to complete its objectives are of primary importance. These factors determine all additional decisions, with the payload either the most publicized or most secret element of the overall mission. To really understand these elements of a satellite, let’s determine our own hypothetical payload. To delight my childhood self, our mission is to make a teddy bear an astronaut, with picture proof and all. This requires a payload that can protect, deploy, and document one small step for stuffed animals everywhere.
In addition to the payload of our satellite is the structure to support it. This structure varies if your mission intends to observe the sun, swoop around Saturn, or settle in for a long life racing around Earth. Our mission, the Teddy Bear Transport, doesn’t require such impressive shielding, longevity, or simplicity as those examples. It does bear (pun intended) responsibilities for having room to host the teddy bear, anything needed during the mission, and the securing of all the additional systems needed to support the satellite. One of the next largest considerations following the payload is the propulsion system.
As discussed by my colleague in The Oomph of Different Engines, there are many options and considerations in selecting what you need to get you to where you’re going. From rocket fuel to solar sails, options exist that range the gambit of reliable, fantastical, and sizeable. These propulsion methods have varying degrees of control, dependability, fuel, and the ever critical delta-V. Far too frequently, fuel limitations determine the end of life for satellites, as there’s not yet fuel stations in space like we find terrestrially. In all, most satellites that even choose to carry propulsion do so in a limited manner, as the law of physics states that “an object in motion stays in motion,” which generally helps maintain an orbital position once reached. Other than small adjustments to stay in position, and dodging debris, the propulsion needs for our Teddy Bear Transport will be minimal, so we can use one of the slow-moving but stable, electric propulsion methods.
To ensure there’s enough electricity to power this propulsion, the power system needs consideration as well. This can be batteries alone, or paired with power producing systems like Solar Panels and Nuclear, all of which makes sure there’s enough ‘juice’ to provide the ‘oomph’ and then some. As our teddy astronaut won’t be recharging a phone during the flight, the power demands are also limited to essential systems already listed, and the few more needed to complete the goals. This power provides for the other necessities on the satellite that aren’t as necessarily tangible as shiny skins and precious payloads.
On many modern satellites, this additional power consumption is often due to the on-board computer. While not as “simple” as a smartphone, most satellites will have more in common with these small solutions than the impressive, yet massive, computers that flew humankind to the moon. The Apollo Guidance Computer weighed 70.1 pounds and each mission included one in the command module and lunar module. Comparatively, our teddy astronaut could have a system using a component as low mass as 7.5 grams, with equally diminished power consumption. Beyond calculating the path for propulsion, ensuring the payload is performing, and both using and supporting the power system, the computer handles the necessary system to share in the discoveries of the satellite: communication.
While a few steps more complicated than setting up a cell phone, or the ancient landlines of legend, communication to spacecraft shares similarities. The satellite needs a receiver to take inputs and commands with a transmitter to produce outputs and data, with a reciprocal receiver and transmitter (or multiple) to communicate from the ground operators. With various standards, systems, and technologies incorporated in this field, our teddy astronaut has some benefits and drawbacks to the planned orbit in LEO. The communication system doesn’t require the higher power of farther orbits, but at the relatively lower orbit, the satellite will not be in direct line of sight with a station on Earth during each orbit. This requires either multiple stations for constant communication, or gaps in communication while the satellite is out of communication. Choosing the simplicity of a single station, our Teddy Bear Transport will use a simple radio communication, necessary for not only confirming data and power on the satellite for the operators, but confirm that the orbit of the satellite is as intended.
With a payload, propulsion, power, computing, and communication, the satellite structure is only a fancy electromechanical device if it doesn’t actually orbit around a celestial body, in our case the Earth. Reaching this orbit is the final consideration of our mission, and will be discussed next, but a major function of the satellite systems are to maintain its definition and orbit. This station keeping against the micro deviations of actual orbit as opposed to mathematically predicted planned orbits involve fluctuations of solar wind, nodal precession around a equatorial-bulge rotating object like the irregularly shaped ellipsoid of Earth, minor drag of high atmosphere, and non-catastrophic collision with orbital micro debris. To qualify as an “astronaut,” many consider the 100km orbit as the determining factor, known as the Kármán line in addition to a significant amount of training, and our Teddy has not failed a single exercise. Our teddy bear astronaut wants to ensure this accolade, to show that this bear has the Right Stuffing, and will be aiming for an orbit around 300 km. In all, the many systems and calculations assembled on the satellite are intended to deliver the payload into the proper location around Earth and continue in that LEO environment for the length of the mission.
Reaching this location requires the most visible aspect of the space industry: orbital launch. While science and science fiction continue exploring ideas from launch balloons and aircraft assisted launch to rail guns and explosives, most launches occur on familiar rockets. Thankfully to myself and others, I am not a rocket scientist, nor is that necessary to reach orbit in most cases! Many rideshare launch offerings are available for space-bound missions, offering a suite of options our constructed Teddy Bear Transport will need for the trip to LEO.
With all systems selected, installed, and tested, this Teddy Bear Transport would be ready to ride an energetic launch along with other rideshare missions into orbit. Once off the launch pad and successfully separated from the launch vehicle, Teddy Bear Transport 001 (TBT001) would deploy its solar panel system and begin system checks with ground operations. This would test that communications are clear, computing is functioning, and that propulsion is properly responding to reach the necessary orbit. Assuming these aspects of TBT001 are responsive and nominal, the payload can be utilized for its mission.
With TBT001 communicating its orbit, the structure supports the computing and power systems as the propulsion system is carefully deployed to position the payload deployment in the perfect spot. Once reached and confirmed by ground control, the teddy bear “Major Ted” can safely deploy on a tether from the confines of the capsule. Using the installed camera and sufficient surface lighting and positioning of the Sun, the essential mission milestone could be captured in a single image. Interestingly, a weather balloon brought British teddy bears to the upper atmosphere in 2008, and provided a picture of their mission as referenced at the beginning of this column. That mission quickly returned in just over two hours, but our LEO TBT001 would last quite a bit longer, with an expected orbital decay in months at a 300km orbit. As a responsible orbital mission, following the completion of necessary mission goals, TBT001 will begin a planned and controlled re-entry in a short time span. This limits the potential of a collision that would create more debris, and brings home the newly minted astronaut all the sooner.
At the end of it, there’s a lot of planning into producing a successful mission, from payload design to planning end-of-life maneuvers. These details and decisions have been quickly summarized and simplified, but hopefully has engaged a more fulfilling answer of, “how do satellites work.” Satellites work from a lot of hard work, hard work that deserves a chance to continue flying through the completion of their mission. Hard work that deserves a safer, lower-risk, debris-free environment, which is why we keep working on #KeepingSpaceClearForAll.
Recommended column to read next: KMI Restrospective: Keweenaw Rocket Range