Last times catch was incredible, anything groundbreaking being attempted this time?
"An additional objective for this flight will be attempting an in-space burn using a single Raptor engine, further demonstrating the capabilities required to conduct a ship deorbit burn prior to orbital missions."
The feasibility of building big rockets was already demonstrated a long time ago. Given the reliability of the Falcon 9, it looked plausible that a big rocket could work with many engines. And SpaceX had already shown that they can reuse boosters economically. But reusing orbital spacecraft – the entire upper stage with engines, fuel tanks, and whatever – without expensive and time-consuming refits is something nobody has done before.
SpaceX can launch satellites using Falcon9 and do it routinely. Starship needs to be developed and reach milestones, so they can get paid by NASA. Having a payload is a complication (unless it's a fun payload, remember the roadster car :D)
Yeah you might lose the payload, but SpaceX has the cheapest satellites in the business from what I understand.
Why? Remote detonation wouldn't work in that case?
If you did this to a Starship in orbit, you'd likely have large chunks of steel reentering and reaching the ground intact.
As you say, the other part of it--and probably more important--is that if it's turned into orbiting pieces, there's no control over where it lands. Some of it could easily land on the ground rather than the ocean, who knows where. That of course has happened with other satellites and their final stage rockets in the past (notably by the Chinese), but Starship is bigger, and therefore the pieces that hit the ground could be bigger. By launching it sub-orbital for now, and turning off the engines so it lands in the middle of the Indian Ocean, the risks of both orbital debris and unknown ground landing points are avoided.
Unlikely in general, no at LEO and definitely not at the suborbital velocities IFT-6 contemplates.
Obviously not a problem for IFT6 since it's sub-orbital, but the original comment was about why we need a deorbit burn rather than just triggering the flight abort system.
If you have debris in geostationary orbit, it will stay there basically forever whereas in low earth orbit it will burn up within a few years at worst.
No. In LEO orbits degrade in single-digit years at most. There is no known solution for rendering an orbit in LEO inaccessible with a Kessler cascade—the best you can do is blind an area with repeated ASAT fire.
In higher orbits debris last longer. That makes cascades possible, though again it only denies a limited area and requires almost active effort.
> Debris in orbit collides with other objects in orbit, creating debris in orbit. That's a cascade
For the same reason not every nucleus that fractures on neutron bombardment sustains chain reactions not every orbital configuration supports a Kessler cascade. In LEO, it’s virtually impossible: you get a nuisance, not SOL.
Note that Kessler posited his syndrome before we could computationally verify it. We can now. It’s not a real threat in the long term, and is more of an insurance question than existential issue for spaceflight in the medium term. It’s pertinent in the very short term, militarily, which is partly how we know it’s very difficult to trigger across even limited orbits.
A Starship second stage stranded in orbit would be a problem because detonation would cause a bunch of orbital debris, but simply waiting for natural re-entry would result in an unpredictable landing location that could result in large debris reaching populated areas.
Reliable, controlled re-entry to a targeted location is very important for Starship to be an operational launch system.