January 1, 2025 Quick space links
Courtesy of BtB’s stringer Jay, who surprised me today with these links. I had assumed he’d take the day off!
This post is also an open thread. I welcome my readers to post any comments or additional links relating to any space issues, even if unrelated to the links below.
- Firefly touts a static fire test of its Alpha rocket
The tweet also suggests the company will launch “multiple” times in 2025. We shall see.
- India’s space agency announces it will telecast the docking of its Spadex satellites
The unmanned docking is scheduled to take place at 4 pm (Indian standard time) on January 7, 2025.
- Video of the two Spadex spacecraft in orbit yesterday
Over the next week the chase satellite will approach the target increasingly closer, 5 km, 1.5 km, 500 m, 225 m, 15 m, and 3 m, followed by the January 7th docking.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
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3. A Paypal Donation or subscription:
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You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
Courtesy of BtB’s stringer Jay, who surprised me today with these links. I had assumed he’d take the day off!
This post is also an open thread. I welcome my readers to post any comments or additional links relating to any space issues, even if unrelated to the links below.
- Firefly touts a static fire test of its Alpha rocket
The tweet also suggests the company will launch “multiple” times in 2025. We shall see.
- India’s space agency announces it will telecast the docking of its Spadex satellites
The unmanned docking is scheduled to take place at 4 pm (Indian standard time) on January 7, 2025.
- Video of the two Spadex spacecraft in orbit yesterday
Over the next week the chase satellite will approach the target increasingly closer, 5 km, 1.5 km, 500 m, 225 m, 15 m, and 3 m, followed by the January 7th docking.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
Orbital mechanics confuses me (I think in lines, not ellipses), but very few satellites are VERY location dependent, right?
For example, a geostationary satellite could move itself out of the way of an intercept such as the Spadex without losing functionality. The “cone” created by that much distance is very wide. Moving around enough to avoid intercept while staying within the transmit/receive cone seems as if it should be possible. Whatever maneuver is performed could be reversed to get it back where it wants to be.
Intercepting a constellation satellite seems just plain dumb – unless the debris from crashing into it will spread around enough to disrupt the neighbors – up, down, left, right, forward, and behind – did I miss a direction? What are “left” and “right” anyway? more inclined, less inclined?
Mark Sizer asked: “Orbital mechanics confuses me (I think in lines, not ellipses), but very few satellites are VERY location dependent, right?”
It is OK to be confused by orbital mechanics. It isn’t just ellipses (circular orbits are a special case of the ellipse), it tends to be counterintuitive, too. What kind of stupid system makes you slow down in order to speed up? When you point to your destination and fire your thrusters, you wind up farther away rather than closer to it. What’s up with that? There are other problems with orbital mechanics, too. It is not yet possible to accurately predict a satellite’s position in the future, which is why there are kilometers-big keep-away zones when calculating whether two satellites may collide.
So, with such large error bars on a satellite’s location in its orbit, how can they calculate rendezvous maneuvers? Sure, there are three-dimensional partial differential equations involved in rendezvous calculations, but if you don’t really know the target space station better than a few kilometers, that seems like a lot of work for a nebulous destination.
So, yeah. It is OK to be confused by orbital mechanics. It is part of rocket science, which requires a lot of study to understand, mainly because it is outside of our daily experiences. Driving a car requires focused attention to follow coordinated processes that use our bodies head to toe and are performed obedient to a shelfful of laws. Someone who is just as determined as he is to drive can also understand orbital mechanics or even rocket science. Even if he cannot design a rocket or a rendezvous orbit, at least he can understand it. Despite not being an engineer, Tim Dodd learned to understand, and he explains rockets and orbits with his Everyday Astronaut YouTube channel.
By “location dependent” you probably mean the geostationary locations above the equator, where the satellites remain above a specific point on the Earth. There are probably around a couple hundred geostationary satellites. It is important that they remain in these locations, and with the constant tug of the Moon and the Sun, they occasionally must perform stationkeeping maneuvers (use their thrusters) to keep them from drifting too far away from their proper location in their orbit.
Starlink satellites have their own locations in their own orbits. In each orbital plane, the Starlink satellites need to be well spaced in order to ensure that they are available to the ground stations (the subscribers’ antennas), which means that each one has a very specific location within that orbital ellipse. Their spacing can also help assure that they miss each other in the places (locations) where their orbits intersect. So, these thousands of satellites are also location dependent.
“Intercepting a constellation satellite seems just plain dumb – unless the debris from crashing into it will spread around enough to disrupt the neighbors – up, down, left, right, forward, and behind – did I miss a direction? What are “left” and “right” anyway? more inclined, less inclined?”
Nice questions, if I understand them.
One of the major reasons for the U.S. forming the Space Force was to create a new mindset (attitude) within the military. The Air Force (and Navy) were addicted to large, single satellites to perform important functions, but the analysis was that constellations are much harder to destroy, and small satellites are relatively easy to launch a replacement if someone intercepts one or a few of the satellites in a constellation.
Up and down, left and right, and forward and backward are three of the six degrees of freedom. They are the translational degrees. The other three are rotational, the satellite’s attitude (direction it points).
Left and right are relative to the direction of travel. For geostationary satellites, the direction of travel is always eastward (+X). “Down” is toward the Earth (nadir, -Z), and up is away from the Earth (zenith, +Z). That leaves left as toward the north (+Y) and right toward the south. Interestingly, geostationary satellites tend to not point in the direction of travel but point (attitude) down, toward the Earth, with their main engine pointing up, away from the Earth. Yes, that is the engine that circularized the orbit and put the satellite in the geostationary orbit, back when the satellite was pointing in the direction of travel, or at least pointed in the direction of its acceleration. Thus, these satellites generally are traveling sideways during their operational lifetimes. What an unexpected attitude for a satellite to have, right?
So, yes, when a satellite turns to the left or right, it is becoming more inclined with the equator or less inclined.
What have we learned here today? Satellites are inclined to have an attitude.
It isn’t just the mechanics of orbits that can seem confusing. The satellites themselves can be confusing.
Shrapnel from an explosion or the debris from a collision goes in all six directions and in between. Those that go down quickly go deeper into the atmosphere about a quarter of an orbit later, and they will fall out of orbit faster than if the collision had not happened. Those that go up go deeper about three-quarters of an orbit later. Those that go “backward” are only going slower, which seems like a backward direction to anyone who remained in the original orbit, and they go into an elliptical orbit that goes deeper into the atmosphere half an orbit later, on the far side of the Earth. Deeper in the atmosphere means more drag from the air, which means that it goes slower and won’t come back quite as high as the original orbit. Thus orbit after orbit, they slowly get lower and deeper and slow down even faster until they burn up much deeper in the atmosphere. These three directions remain in the same orbital plane.
Debris that goes faster also remains in the same plane, but it is now in an elliptical orbit that goes higher, half an orbit later, so it has less drag during its orbit and remains in space longer than if the collisions had not happened. Debris that goes left or right is in a slightly different plane, a different inclination, but also goes faster and higher on the other side of the Earth, remaining in space longer, too.
The debris that stayed in the plane is only hazardous to the other constellation satellites in the same plane, but only until they degrade to orbital altitudes too low to be hazardous. The debris that went into other orbital planes probably won’t reach any constellation satellites in other planes. The exception is if the collision or explosion happened at the intersection of two planes. Of course, as their orbits degrade, the debris will become hazards to other satellites or other constellations. If you have your own satellites or space stations at lower altitudes than the collision or interception, then your own space assets will eventually be at risk of eventual collision with the debris.
Intercepting any satellite is unwise and dangerous.
Rendezvous and docking with one, as SpaDex is about, can be done safely.