A solar storm causes problems by producing shifts in Earth's magnetic field. It's many orders of magnitude away from being anything like a MRI, and wouldn't scramble hard drives directly, it would disrupt power grids and copper communication lines. The only impact on hard drives or other electronic devices on Earth would be from power surges, while satellites would have increased ionizing radiation to deal with.

Aerospike systems are heavier and have more demanding cooling requirements, due to the central plug surrounded on all sides by hot exhaust, with radiative cooling being largely ineffective, and the increase in plumbing to all the injectors. Their advantage is in being less optimized for a particular atmospheric pressure, increased complexity and weight are tradeoffs. This is mainly a large advantage if you're using the same engines for liftoff and for the burn to orbital velocity once outside the atmosphere, which is why aerospikes are common features of SSTO schemes, but it's much less of a benefit if you have a separate booster stage and upper orbital stage or stages. They're not being held up by patents, there simply hasn't been a great deal of interest in developing them for real-world systems (the launch industry as a whole has had little incentive to do anything new for quite a while).

You get the same with a couple geographically separated launch sites. SpaceX launches to equatorial orbits from Florida and polar orbits from California, and they do so far more cheaply than an air-launch system could, without having to make sacrifices in payload, adding risks due to loss of on-pad test fires and abort capabilities, etc.

Sea launch does look much better than air launch, but it still makes the logistics and operations more difficult. SpaceX doesn't even want to land rockets at sea when they can bring them down on land, and is talking about future plans of refueling the first stages for a short flight back rather than shipping them back on the landing platform. Political issues with launch and landing locations might make it simpler to do things at sea, though...

Which is why they can manage to only be 5x the cost per kg of a Falcon 9 launch, right? Perhaps 10x when SpaceX starts reusing first stages...

Aerodynamic drag losses are only important for the tiniest of rockets. For most launchers, it's only in the area of 100 m/s. Additionally, propellant is a fraction of a percent of launch costs, and the cost of rocket hardware is not simply proportional to its size.

The failure rate of Pegasus has dropped a fair bit. The big problem is the extremely high cost (around $30 million for 400 kg to orbit these days) and the inflexibility and lack of scalability of air launch systems in general. The Stratolaunch system is building the largest aircraft by wingspan to ever fly to launch rockets with less payload than a Falcon 9...and they won't be able to attempt anything larger without building an even bigger aircraft, while SpaceX is already building the Falcon Heavy (with about 8.7 times the payload capacity of Stratolaunch) based on Falcon 9 hardware.

There really is little to gain. Air launch doesn't get you meaningfully closer to orbit to start with. You don't operate heavily loaded aircraft in bad weather, especially not aircraft loaded with multimillion dollar payloads and tens to hundreds of metric tons of hazardous rocket propellant. Especially when loss of the aircraft removes your ability to perform launches until a new custom-built/modified replacement is ready. You don't simply operate aircraft carrying such payloads out of whatever airport you like, you need special ground infrastructure and flight plans. The altitude and speed are more simply, cheaply, and effectively achieved with a rocket stage...see Orbital's own Taurus, which is essentially a Pegasus launched on top of a rocket first stage instead of dropped from an aircraft, and has a 1320 kg payload compared to the Pegasus' 400 kg.

Problem: the original poster got their units messed up, and the surface of Mars has pressure equivalent to about 35000 meters, not feet. That's about 115 thousand feet. That's nearly 3 times the "altitude without payload" figure listed there.

1.5% in Neptune and 2.3% in Uranus, not enough to matter for buoyant craft.

Didn't forget them, they're just not very good for ballooning. With their hydrogen-helium atmospheres, the only way to get a reasonable amount of buoyant lift is by heating your lift gas, and the low density of those gases means even that gives little lift at a given pressure. Better than Mars, but worse than Earth.

Lift (along with drag) is proportional to the *square* of airspeed, all else being equal. But the rotor blades on a Mars helicopter would have airspeeds in the transonic to supersonic region, with very different airflow, so simply applying a scaling law like that isn't very accurate.

Titan's atmosphere has about 1.5 times the surface pressure of Earth, and the atmosphere is even denser due to the cryogenic temperatures (about 20 K lower, less than the difference between your freezer and room temperature, and it'd start raining nitrogen). The only place in the solar system better for balloons is Venus, they're barely possible on Mars.

I *was* using the density of CO2...which at 273 K and 600 Pa is about 0.012 kg/m^3. It might reach 0.020 kg/m^3 when it's coldest, but it sounds high for a typical surface density.

A helium balloon on Mars would only carry about 10 g of per cubic meter. A hot air balloon would carry far less. (given 273 K ambient temperature and 373 K balloon temperature...rather difficult to maintain with the available power...around 3 g/m^3)

Less drag for the same blade velocity, but less lift in the same proportion, and what matters is lift to drag ratio, which isn't as good at high speeds (and a Martian helicopter would likely require a supersonic rotor).

And fundamentally, a hovering Mars drone is constantly accelerating by 3.7 m/s^2 by accelerating the nearby atmosphere downward. This is energy intensive, entirely apart from the drag losses. The thinner the surrounding atmosphere, the lower the mass flow rate and higher the velocity you have to accelerate it to, and higher the energy requirements...if a 1 kg drone accelerates 100 g of atmosphere (about 10 m^3) per second to 37 m/s to maintain a hover, it's doing about 70 watts of work, without even looking at losses. For reference, Curiosity gets about 125 W of continuous electrical power from its RTGs.

Weather balloons are quite large and delicate. You need something that can be deployed from a rover without any assistance, and which can survive being tethered to that rover while fully inflated...recall that weather balloons are barely inflated at launch because they expand during ascent, when they actually reach those high altitudes they are far larger than they appear on the ground. We're talking tens of meters across, a hundred cubic meters per kg of payload and balloon, made out of a fragile plastic film...and the goal is to make a rover *more* mobile, so it has to be tethered to something trundling along the surface, or self-propelled effectively enough to stay with it.

There would also be a risk of fouling the rover when the thing inevitably ruptures, something there'd be a particular risk of during inflation. A free-flying balloon probe would be possible, though very difficult and limited, a balloon drone to assist a ground rover is much less practical.

A blimp would suffer the same problem, but even worse. A cubic meter of unpressurized helium will only lift about 10 grams at the surface, and there's nothing you can do about that. The helicopter could at least spin its blades faster, though there's the problem of a power source...