MIT's Inflatable Antennae Could Boost Small Satellite Communications

coondoggie writes "Researchers at the Massachusetts's Institute of technology say they have developed an antenna for small satellites (known as cubesats) that can fold into a compact space and inflate when in orbit. The inflatable antenna lets a CubeSat transmit data back to Earth at a distance seven times farther than that of existing CubeSat communications."

Laser

[symbolset]

Can't they get the signal lasers working? Much better for max signal strength, bandwidth, power usage and transmitter size.

Re:Laser

[Jane Q. Public]

"Can't they get the signal lasers working? Much better for max signal strength, bandwidth, power usage and transmitter size."

Signal lasers are WORK and EXPENSE. You have to accurately track your target both for transmission and reception. Far, far more expense than cubesats justify.

Maybe one day it will be cheap and easy. Not today.

Re:

[symbolset]

With an adjustable lens on your transmitter, no you don't. It is not that hard to widen the beam and use feedback to home in on the target and improve the focus until you have a nice strong signal and then ramp the bandwidth. And the parts for this are truly tiny. Compared to an inflatable balloon in space? No contest.

Re:

[Anonymous Coward]

With an adjustable lens on your transmitter, no you don't. It is not that hard to widen the beam and use feedback to home in on the target and improve the focus until you have a nice strong signal and then ramp the bandwidth. And the parts for this are truly tiny. Compared to an inflatable balloon in space? No contest.

So much cluelessness in just 5 sentences. Impressive.

Re:Laser

[Jane Q. Public]

Huh? No, I'm not the one who is wrong here.

The more focused your "lens", the tighter your aim must be. And my whole point was the expense of accurate aiming equipment.

Fine, use a parabolic dish for your RADIO. But a pinpoint laser, today, is about the LEAST cost-effective solution you could come up with for cheap satellites.

Don't take my word for it. Try it.

Re:

[Jane Q. Public]

Just to be clear: I didn't miss your point. I understand that focusable, aimable systems can do the job. Far more so than they could have, say, 10 years ago.

But they STILL can't do it as simply or cheaply as a basic parabolic antenna.

Re:

[symbolset]

So no, they haven't solved this problem yet. Thanks. I see now that they are starting to work on it. It really is not as difficult as you make it out to be so it should not take them long.

Re:

[notKevinJohn]

The problem with that is cubesats get launched piggy-backed on Air Force satellites; and they can't give you particularly accurate orbital dynamics. It's hard enough to get a signal using the 433 Mhz band where you really only have to know the position of the cubesat to within a few degrees. To use a laser for communication, you would have to know the position to within a tiny fraction of an arc-second.

Re:

[ChrisMaple]

Laser beams can be arbitrarily expanded, cheaply and easily. The disadvantages of laser space communication are elsewhere, including blockage by clouds.

Re:

[AHuxley]

Signal lasers for special forces on the ground dragging power with them trying to aim up at something at a set time?

Re:

[bmo]

Can't they get the signal lasers working?

There's this thing called weather. Perhaps you've heard of it.

The problem with lasers is that they do not penetrate clouds at all.

Clouds take lasers and other light beams and spread them out into nothing in only a few feet. That's because they're composed of a bunch of little prisms - water droplets. As a land survey technician, I couldn't get a beam bounce from a retroreflector during a fog even if I could still see it myself 20 feet away.

--
BMO

Re:

[bmo]

Yeah, snow can have an effect when you have to go out and shovel out the C-band dish because the snow is half melted and the water is causing a flat spot in the nice parabola.

This one.

http://i.imgur.com/qg9KGAm.jpg [imgur.com]

--
BMO

Re:

[account_deleted]

Comment removed based on user account deletion

Re:

[Anonymous Coward]

Bad summary, it's the inflation system that's unique.

Re:

[notKevinJohn]

Maybe, but since cubesats are only 10cm x 10cm it needs to be a LOT smaller.

Re:

[AHuxley]

The idea could be to replace a few stealthy or known overloaded platforms with trackable orbits just before action against a real enemy with a hint of having anti-satellite weapons.
Dont bet all on the super expensive stealthy "one" that teams of amateurs blog about.
Flood the short term war zone with cheap new sats and enjoy the high ground for a bit longer.

ENLARGE YOUR ANTENNA

[toygeek]

New research from MIT scientists shows that you can MAKE YOUR ANTENNA BIGGER! Try our fast safe ANTENNA ENLARGEMENT powder!

- Convenient!
- Inexpensive!
- MORE POWERFUL EMISSIONS!
- Bigger girth!
- More Gain!
- Long Lasting!

Guaranteed satisfaction, for you AND for her(tz)!

Re:

[lawnboy5-O]

Can you put your weed in there?

Re:

[beelsebob]

No. Studies that actually score the damage these things do consistently put Canabis very low down the list. Generally far below Alcohol and even Nicotine. The reason it's illegal is purely political.

Re:

[ai4px]

Maybe they just need one of those cell phone antenna booster stickers?

Re:

[notKevinJohn]

First line of the article: "Mylar-based attennae could inflate once launched, withstand micro-meteor threat, MIT says."

Re:

[MobSwatter]

Mylar has gone a long way to being shatter proof, however seeing small object traveling at say around 25 miles per second, I just don't see it resistant to that.

Re:Inflatable?

[khallow]

Article says it can take a number of micrometeor impacts and still stay inflated. I buy that claim. It doesn't take a lot of gas pressure to inflate a piece of mylar and they have a good mechanism for maintaining that modest gas pressure (via sublimation of a particular powdered chemical) even in the presence of a bunch of micrometeor holes (low pressure gas doesn't leak out very quickly).

OTOH, they might have a problem controlling inflation of the antenna in the first place. The sublimation triggers in the presence of vacuum. And they'll have that condition before the cubesat leaves the payload shroud.

Re:

[ChrisMaple]

I find it hard to believe that the system could provide enough gas to keep it inflated for a long time in the presence of even micron-sized holes. I'd be more likely to believe that it would maintain structural integrity if they used a plastic that became stiff when struck by ultraviolet light, or became stiff as a plasticizer outgassed.

Re:

[khallow]

Well, suppose they have a bag of air attached to equipment that feeds pressurized air so as to maintain the bag at standard temperature and pressure (STP which is 20 C and 1 atmosphere) and the bag is suspended in a vacuum. The speed of sound at that temperature for air (which also is the average velocity of molecules in air) is roughly 340 m/s.

For a millimeter sized hole leaking into vacuum (let's say that the hole is a square millimeter in area), that means that in the absence of friction and turbulenc

Best blow up invention since

[maroberts]

the autopilot [/airplane]

My antenna went flat

[Tailhook]

...and I need to change my blinker fluid, lubricate my muffler bearings and put winter air in my tires before it gets cold.

Re:

[toygeek]

Don't forget to check your firewall gasket and the piston return springs!

It takes more than an antenna...

[DerekLyons]

The bird will need an attitude detection and control system to take advantage of this antenna... decreasing the available weight, volume, and power available for other things. TANSTAAFL.

Re:

[ThreeKelvin]

Actually, cubesats need at least a simple attitude control system, i.e., detumbling. Without one they spin up. See e.g. AAUSat II [space.aau.dk]:

We are still working on finding the reason for the fast rotation rate, especially why it accelerated over the course of 40 days. We have a number of ideas, der include the torque caused by the magnetic dipole generated by the solar cells.

That said, being able to actually point in a specific direction with the sat is quite hard, and a lot of work.

Re:

[braindrainbahrain]

Indeed. As they get more gain out of this antenna, it has to be pointed with more precision. Being inflatable, if the antenna has any kind of wobble after movement... well that's just one more aggravating detail.

Re:

[DerekLyons]

Space exploration is nothing if not accounting for one aggravating detail after another...

Illiteracy...

[msauve]

Is MIT an insect with inflatable feelers which somehow assist in satellite communications?

When referring to a radio antenna the plural is "antennas."

Re:

[__aaltlg1547]

It doesn't take reactive chemicals. Just seal a small amount of gas in the balloon when it's on Earth, say, less than 1cc of nitrogen. When it gets to space, it will inflate as soon as you let it out of the enclosure.

Say what?

[__aaltlg1547]

The inflatable antenna lets a CubeSat transmit data back to Earth at a distance seven times farther than that of existing CubeSat communications."

When are they going to be orbiting cubesats 7x higher than they do now? No, what such an antenna can do is allow you to operate at 50x less transmitter power (or 50x the data rate at the same power). Or receive at 50x the data rate. That's all good. but we won't be sending any cubesats past the moon. Spacecraft designed for high orbits must be designed for long missions, and cubesats are designed for short missions because they must compromise something to make things fit in tiny spaces.