NASA has three smartphones orbiting the earth as mini-satellites

What sort of analysis was used to figure out the power and protection requirements you needed to make these viable?

Are these within reach of an individual to build, if not to launch?

If I build one, how do I launch it?

Why do the signals need to be crowdsourced over Ham?

What are your personal favorite/most cool applications for lots of cheap satellites?

What were the biggest challenges you faced while adapting a smartphone for use in space? At any time, were there any technical hurdles you felt could prohibit the entire project?

This is like being upset that someone referred to a Bentley as a car, which you consider a conspiracy based on people liking Ferraris more.

Alternate theory: the media calls it a smartphone because it's, well, a smartphone.

The problem is unlike iPhone using Android by it's self in a headline is often ambiguous. Saying Android Smartphone is accurate but while iPhone is shorter than Smartphone it takes far more space to say Android Smartphone thus the useage discrepancy. Which is one of the main issues with choosing that trademark.

I think part of it is that for NPR, "smartphone" resonates with a larger audience, while Ars Technica or Slashdot might be more specific with "Android phone" or even "Nexus One".

Also, its a Linux phone as well, standing on the shoulders of all of the years of work poured into making an awesome kernel to build operating systems like Android off of. And the rocket used to launch the satellites. And microsatellite launch programs (like cubesat).

At the end of the day sometimes to get people interested in an article, you just need to find a simple human way to connect to their life--or in this case, their pocket.

Probably steered through thrust vectoring. Liquid fuel rocket engines are often built to gimbal, typically 1...2 degrees to each side. http://en.wikipedia.org/wiki/Rocket_engine#Thrust_vectoring

Another possible method of steering is to build four or more reaction jets around the rocket; could be fed with a monopropellant or exhaust from the main engine or its turbopump.

One of my friends is on the team that built this: thrust vectoring.

I don't know that I'd describe the launch as "neat". I'm searching for the right word to describe it... I guess maybe.... "nominal".

Anyway, almost all modern rockets don't use fins. They steer using thrust vectoring and attitude control thrusters.

This has been being done for a long time. Saturn V's were thrust vectored too. For any large scale rocked, the fins are far to large to move like on smaller missiles.

This works well to cut down on mass and drag and is especially useful for silo/sub launched missiles where fins don't fit well in the launch tube.

I assume the engines are gimbal mounted and can direct their thrust.

You need to play more Kerbal Space Program http://kerbalspaceprogram.com/

When was the last time you saw a rocket with fins?

> Imagine someday where many people own their own personal satellite.

Nice thought, but (unless the satellite is in geostationary orbit, very expensive) it won't work. Imagine having your own personal satellite that is only accessible for perhaps two short periods in 24 hours (for a mid-northern latitude location).

Better to have a subscription to a system with dozens of shared satellites in random orbits, available 24-7.

The reason launching microsats is affordable is because they are piggybacking on someone else's rocket. The delta cost to launch a microsat on a rocket someone already paid full freight for is essentially zero.

There aren't any rockets going to the moon, much less another planet, that they can piggyback on... so, yes, they could send 1000 to orbit the moon, but you would have to pay full freight on the rocket. Ouch.

These are in such low orbit that they're still protected by the Van Allen belts. They'd get obliterated by radiation if they were much higher or around the moon, etc.

It also isn't the first phone in space. The UK sent on up earlier this year.

I think Vernor Vinge has something like that in one of his end-of-civilization post-singularity novels, let's see... Marooned in Realtime, yes. (Great read, too.)

Sounds like a fun place to keep an off-site backup, if there's ever a way to get enough bandwidth without disrupting other systems.

"isnt this small enough to look like space debris, and maybe dangerous?"

The fact that they said this burns up when it runs out of "juice" implies that it is in very low Earth orbit, where the atmosphere still exists and imparts drag. These will reenter the atmosphere on a moderately predictable time scale and burn up. Space junk is only a problem at higher orbits which can be stable for very long periods of time without propellant.

As for 2... they put on up and it worked. What's the point of theorizing about how it might not work, when they've already done it? It might stand up to a good solar blast, but that's hardly a surprise, and if it's disposably cheap, who cares?

> near absolute-zero temps

Although space is cold, due to the vacuum the biggest issue is getting heat away from the devices. That's why the main part of EVA suits is liquid cooling.

> radiation of space without being using radiation hardened silicon

They are only in low earth orbit, so the magnetic field of the earth would provide pretty good protection.

Well, the fact that it's working means that it's working. Your questions may be valid, but either they've been answered by the scientists or they're non-issues.

1. Space debris certainly doesn't have to be small to be dangerous. Objects about 1cm in cross section can be tracked from the ground, and these are in a known orbit, so are probably okay.

2. I heard somewhere that the batteries needed to be replaced but not much else did, don't have a reliable source for that though

regarding 2: The robustness to physical shock isn't particularly relevant once deployed, but during launch the hardware is subjected to huge vibration and g forces. If the hardware is not well assembled, parts will come off. This poses a risk to the cubesat as well as the launch vehicle. Also, radiation hardening is statistically a long-term concern for missions. Most large satellites are designed for a minimum 5 year mission, some for 20-25 year missions (many geostationary birds). On those timescales, radiation is a significant issue. These satellites are in a low earth orbit and will be burned up in the atmosphere within a year - probably less. The chances of a single event upset are really small, and there are 3 phonesats. It takes a long time for radiation to degrade the silicon in a chip, much longer than the lifespan of these particular satellites.

> Not sure if this is off topic, but shouldn't it be simple to make a high altitude balloon out of a material that doesn't explode so easily when it gets to the lower pressures in low earth orbit?

The very early comms sat experiments in the 50s were just aluminised passive balloons that reflected radio signals bounced off them while in orbit. [1]. However they were there because they were put there by a rocket. I'm not sure if your question is implying that you could float your way up to LEO altitude. I suspect you couldn't with anything that could be engineered.

> Or even some kind of contraption that slowly releases gas from the balloon as it detects lower pressure in the atmosphere to help it maintain altitude and prevent the balloon from rupturing?

This is done already in two ways. One passively does what you describe - a zero pressure balloon - by having a hole in the bottom so helium leaks out as it rises. Eventually enough leaks out that the net lift is zero and it just floats.

The other is a super-pressure balloon [2] which does what you described in your first paragraph - it's strong enough to not explode until the pressure (and so density) of the helium inside increases relative to the outside atmosphere until the lift becomes zero. But we're still a long way from an altitude that could sustain orbit. These operate at relatively low altitudes like 45km/150kft. The drag and heating there would be enormous at orbital velocities!

[1] http://en.wikipedia.org/wiki/Project_Echo [2] http://en.wikipedia.org/wiki/Superpressure_balloon

> but shouldn't it be simple to make a high altitude balloon out of a material that doesn't explode so easily when it gets to the lower pressures in low earth orbit?

No, because balloons don't orbit, they follow the wind patterns at a lower altitude than the lowest satellite orbits. And they're relatively short-lived at altitude -- from seconds to days.

> Or even some kind of contraption that slowly releases gas from the balloon as it detects lower pressure in the atmosphere to help it maintain altitude and prevent the balloon from rupturing?

No, not "releases gas" -- that would lose the gas irreversibly. Instead, consider a scheme that used solar power to drive a pump to put some of the gas under pressure as needed, and releases it later as needed to maintain altitude. Sort of how a submarine maintains its buoyancy by filling tanks with either water or gas, depending on the need, and that does this by putting the gas under pressure to change buoyancy (and avoid losing the gas).

But balloons don't have very long lifetimes at the moment. This might change in the future.

Can you actually get something into ORBIT via balloon?

That doesn't sound plausible but I could be wrong.

It's 1000 knots and 60,000 ft, and this is only to meet U.S. ITAR export requirements. There's nothing inherent about the civilian GPS signal itself that prevents you from computing a fix beyond those limits.

For example, you could buy one of these: https://www.sparkfun.com/products/10981

and then design a baseband yourself. I'm currently aware of at least three people that are working on this or have already done it. You'll need to actually take the time to learn how GPS works, and it'll probably take you about a year, but it's definitely possible.

These are satellites in orbit, not suborbital balloon payloads.

Quite unlikely. For paparazzi style imaging, satellites are very unsatisfactory.

1) Clouds. Major bummer.

2) Intermittent time on target - most the time when something interesting is happening, the satellite will be over some other place in the world. Geostationary satellites solve the "hover overhead" problem, but then see #1, #3, #4, #5.

3) Atmospheric distortion. Resolution is inherently limited unless you use adaptive optics.

4) The lens required to get decent resolution isn't going to fit on a microsat. See also #3.

5) Blurry pictures of the tops of celebrities' heads ain't gonna sell well.

I was thinking piratebay.

Cubesats are in general some of the safest / least junky spacecraft in orbit.

There are several factors that influence how much space debris a spacecraft will generate:

1. Surface area vs. density - If a spacecraft is large and has lots of floppy solar panels and things hanging off of it, it's much more likely to be involved in a collision, and if it is involved in a collision, it's more likely that it will generate secondary debris dangerous to other spacecraft.

2. Orbital lifetime - If a spacecraft is in orbit for longer, it's more likely to be involved in a collision.

Cubesats are usually very dense, with few or no deployable components. Cubesats are also typically deployed in a low orbit that has a short lifespan - less than 2 years or so.

There are of course exceptions to both of these rules, but the phonesats are not.