The IET Satellite TN recently held a webinar on the above topic. If you missed the webinar you can watch it OnDemand.
Unfortunately, our speaker Rachana Mamidi Reddy was unable to cover all of the questions that were raised during the Q&A session due to the sheer number that were posted during her presentation, however, she has kindly responded to these unanswered questions post event and you can view her responses below:
| Presumably a 'fleet' of small sats could effect SAR? | There are several SAR satellite constellations already in operation and several being planned. Check Capella space, ICEEYE. |
| Arguably large sat manufacturers do standardise on e.g. common bus architectures, standards etc and commonality of design approaches? | Yes, they do, but the standards are internal to the manufacturer. For example, all Airbus small satellites have the same bus configuration but it would be quite different to that of Starlink satellites of a similar weight class. |
| COT (commercially available) components usage - to reduce the cost - comment please | COTs are being used to reduce costs, but they bring down the reliability of the satellite. Makes sense for a 1000 satellite constellation in LEO with frequent replacements, but certainly not for a 20 satellite constellation in MEO or a 6 satellite constellation in GEO. |
| I'm increasingly concerned about 'kessler syndrome', if that's the correct term. | Yes, that's the correct term. Hope the increasing business and strategic interests in space would make us solve the problem together before it is too late. |
| what are the differences between kepler orbits and circular orbits | All orbits are kepler orbits. Google has some pretty great videos :) |
| optical communication needs more pointing requirement. how to solve the beam power loss when light passes through the atmosphere? | Check out the research and white papers published by the optical communiation missions already demonstrated - https://blog.satsearch.co/2020-01-22-optical-communications-for-small-satellites-and-cubesats-product-roundup |
| What you recommend, to follow/study e.g. current or future trends, for someone who is wants to get into the industry? | Keep reading up on the latest developments not just in your area of interest but all areas of space in general and if possible, also in the allied industry verticals. It will help in connecting the dots and creating new opportunities for oneself |
| What happens at the end of life for this myriad of satellites | Most satellites are just left to stay as space debris till their orbits naturally decay - which takes many decades for most of the satellites above 1000 Km altitude |
| Are the large satellite manufacturers (Airbus D&S (not SSTL), Thales-Alenia, Boeing, etc) moving 'back' toward smaller 'birds'? | Airbus already has several satellite platforms in the 300 - 800 Kg range. So, yeah, around 500 Kg seems to be the new sweet spot |
| How do you see the manufacturing of satellites changing to meet the demand | Satellite factories already up and running across the world. Increased use of COTS has been the trend but this presents a conundrum because while this reduces the price/satellite, it has to be replaced often due to lower reliability and lifetime, but this contributes to space debris since the cheap satellite does not have enough fuel to deorbit at end of life. I am personally betting on the world heading towards more reliable satellites equipped with redundant deorbiting strategies, so COTS usage would likely drop and price/satellite would slightly rise. For reference, the cheapest reliable 3U cubesats are currently 100k USD |
| Smallsats are short life satellites - small, cheap and rapid launch. modular satellites make and keep in store and launch when it is required. what is the range of orbital life of smallsats? | Smallsats can also be modular. Orbital life largely depends on the orbit (LEO -> high atmospheric drag -> more fuel to maintain orbit -> smallsats don't have enough so just keep decaying) and satellite components (COTS -> low reliability; higher reliability requires radhard components -> more expensive; redundancy increases operational lifetime -> more mass/power requirements) |
| isn't the graveyard orbit/25 year rule primarily for GEO/MEO | Graveyard orbit was for GEO given the limited GEO slots, even way before the current day mega constellations. The 25 year rule was for the rest of the orbits. But again, these are quite archaic and should be revised. |
| Realistically what's being done about debris now, beyond graveyarding and burning up in lower altitudes deliberately? What's the future 'road plan' to use an Americanism. | Unfortunately, nothing much. Just a few companies/space agencies trying to develop/perfect debris removal technologies, some trying to map space debris better, while what we immediately need to do is make every satellite manufacturer strictly implement reliable end-of-life deorbiting strategies while collectively working towards actively cleaning up the existing debris. |
| 25 years is too long, the technology become obsolete and no buyers or users are not interested to use. | Yes |
| Regarding existing standards used in conventional/large sat industry, I was thinking of e.g. the Alphabus developed by thales-Alenia, Airbus DS. | Alphabus is a GEO platform, tailored for high-power communication payloads |
| What are your thoughts on the idea of a 'laser broom' system to deorbit space debris? It seems like it could be very effective and easier than sending cleaner satellites to space if someone had the funding to build it. | A laser broom (high-power laser beam that could be pointed at any space asset) is often viewed as a space weapon and gets dangesously close to the territory of militarization of space, which is actually more threatening than the current space debris problem. |
| The main contribution for space debris is coming from launch vehicles rather smallsats. Do you agree? | While discarded rocket stages and deployment mechanism parts do contribute to space debris, the largest contributor is unintended explosion and collisions of defunct satellites. The next contributors are deliberate explosions and ASAT tests. Here are more details and nice infographics -> https://directory.eoportal.org/web/eoportal/satellite-missions/o/orbital-debris |
| My concern is more that, if one wants to move away from space engineering to some other field, the opportunities are limited (although defence is a good match, of course). | Largely depends on the area - embedded/electrical/power/RF engineers can find many opportunities. Structures/thermal engineers perhaps in the aviation sector. Aerodynamics experts have ample opportunities too - check out this episode --> Applying aerospace concepts to biomedicine, ship building and particle research ( https://thosespacepeople.transistor.fm/23 ) |
| Obsolescence management is a very well established field in conventional space engineering! | So far, only for the ISS/Hubble. With the upcoming in-orbit satellite servicing, perhaps would find more use cases |
| How do you see the future of star link | Similar to the future of GPS - would achieve global usage, and eventually pave way for major space faring nations to develop their own versions |
| If you take for example a typical University cubesat, how much does it cost to put one in space - roughly? | Considering a 1U cubesat - about 30K USD to buy and another 30K USD to launch. Plus the time, lab space and personnel costs to integrate and test the cubesat. |
| Is the cost of satellite data communications going to converge on the equivalent to terrestrial broadband? It’s currently…expensive. | Terrestrial broadband in densely populated areas will always be cheaper than SatCom for the next 5-10 years. SatCom only beats terrestrial in sparsely populated areas, war zones, islands with a single optical fibre cable links and prone to damages (Tonga undersea cables) |
| Please explain Software defined radio | Google does it best :) |
| seems like the approach most commercial entities operating in LEO are looking to account for deorbit as part of their conops. SpaceX for example installing hall effect EP systems. what are your thoughts on that? | Yes, and that's a big step in the right direction. Active (electric/chemical propulsion) or passive (drag-sails) or assisted deorbiting is absolutely necessary for sustainability. And most of the new mega constellations seem to be incorporating this - Starlink, Oneweb. |
| What is your view on the intersection of 5G/6G%2B and small sats? | Smallsats in LEO would definitely be a part of 5G networks to connect remote areas not serviced by terrestrial cellular. |
| What is your view on space waste, such as abandoned satellites? | High time for some active clean up, but requires a lot of international cooperation. |
If you've watched the webinar and have any questions of your own, please pop them in the comments below!