Kickstarter is funding 2 space related projects. The first is a solar sail mission sponsored by Bill Nye and the Planetary Society. Yes, this is feasible: in fact the test launch is scheduled two days from now. CubeSats, 10cm cubes that are bundled together, make smaller scale space research possible: launch costs start at $100,000.
The test launch will be in low earth orbit and atmospheric effects will outweigh the energy associated with the lightsail itself. But in April 2016 they plan to release Lightsail-1 into a 500 mile orbit to evaluate whether this method of propulsion is currently viable. The physics of solar sails is described here.
NASA cancelled its solar sail demonstration project Sunjammer in October 2014 because of contractor problems. Better not to throw good money after bad I say. But collapse of the more ambitious project enhances the possible scientific return of the Lightsail-1. Or does it? What specifically are the scientific benefits of this endeavor?
The second project involves a high tech zero g fuel receptacle, the space coffee cup. Astronauts drink coffee too. This represents one of the tens of thousands of less glamorous challenges involved in space colonization. It also advances our understanding of fluid behavior. Projects like this might advance human knowledge more than even small scale solar sail experiments. Or would they?
I post this in IMHO to encourage discussion, scrutiny and due diligence. I am not a physicist.
Fuel (and/or reaction mass) is a major consideration in space maneuvers. Of necessity, it’s bulky, heavy, and has to be lifted up out of Earth’s gravity well. Tiny, lightweight probes that don’t need fuel in order to maneuver have obvious cost advantages if they can be made to work. You could, theoretically, send a cubesat with a lightsail to the asteroid belt as cheaply as you could send one to the moon.
The direct benefits of this project are more engineering than science. It’s a sanity check on the design of the sail and the deployment mechanism, as well as–hopefully–a demonstration that it can be made to work. Once the tech is established, they can start attaching sails to devices that are sent out to engage in more “pure science” endeavors.
Phil Plait aka The Bad Astronomer of this message board, blogs on the Lightsail. Personally, I’m amazed that massless particles can push spaceships to inter-planetary speeds. The Japanese have some bragging rights to this technology: IKAROS flew past Venus back in 2010.
Tomorrow (May 20), the low orbit prototype is launched: the webcast link is here. The ship is burdened by a software bug, but it should still relay images if all goes well. If. Hopefully they will have that sorted out by the April 2016 high orbit launch date.
Are lightsails the space technology of the future? Hard to say. Could lightsails and cubesats put meaningful space exploration in reach of mid-sized countries? I’d like to know.
Space cup. They have a working prototype in the International Space Station. Now they want to make them out of glass for zero g and 1 g encounters.
Q1) Um, why? I know 3-D laser printing is expensive, but c’mon.
My guess: because it’s cool for earthbound folk. Eh, ok.
Q2) That base looks a little narrow for 1 g environments.
The group also says, “With this project supported we’ll also have resources to invest in more like-minded living-and-working in space demonstrations. We’ll let you know what we mean soon…” That I can get behind. I’m pretty excited about working out nuts and bolts stuff. https://www.kickstarter.com/projects/spaceware/space-coffee-cup
NASA has 3 solar sail projects in the works. Each will use 6 CubeSats (Lightsail uses 3). They are budgeted at $15 million a pop which is incredibly cheap. Two will go to the moon; a third will visit an asteroid.
We researched solar sails early on for our cubesat project. We ultimately did something different, given our limited resources, but it was an interesting possibility. We wanted to go to the moon, though reality set in pretty quickly. Comms becomes a bottleneck really quickly; NASA has an advantage here with their big dishes.
I’m impressed that they’ve packed such a large sail into the available volume. Hopefully they can pull it off without tearing, snagging, etc. We never got a design that we were really happy with, though we were working with much less volume (1U vs. 3U), which in practice means more than a factor of 3 difference in usable sail volume.
Over at Kickstarter, Lightsail has surpassed $600,000 and I’m guessing they will top $1.2 million by the end. I’m not too worried about their funding. As for the space coffee cup, it may or may not reach its funding goal of $50,000.
Today’s launch went well. They have established two way communication with the CubeSat: check out its current location here. Once unfurled in another month or so, the orbit will decay in a couple of days and the unit will flame out in the earth’s atmosphere. Next year’s mission will last longer.
Here’s something I don’t understand. Solar sails can be used to tack the satellite towards the sun and indeed Japan’s ICARUS spacecraft visited Venus. But how can that work? Sailboats travel into the wind because their sails turn into air foils, just like aircraft. But photons aren’t fluid. And solar spacecraft don’t have keels.
A solar sail can’t directly accelerate toward the sun on its own. You can get different vectors by adjusting the angle of incidence, but not one pointing “down”. That doesn’t mean a sail-driven craft can’t move sunward; it just makes it more complicated. You could, for example, get gravitational assists from other bodies. I think you could also make the craft’s orbit more eccentric, trading greater distance at aphelion for closer at perihelion.
The Ikaros had a simpler way down, though: it rode piggyback. It was carried by the Akatsuki (Venus Climate Orbiter) craft for the first month of the trip before separating and deploying its sail.
As usual, I recommend playing Kerbal Space Program for insight :).
Pushing on an orbiting craft radially out from a gravitational source (the sun) doesn’t move the spacecraft to a higher orbit. Instead, it makes the orbit more elliptical (if you started in a circular orbit), such that the point 90 degrees ahead of you is raised while the point 90 degrees behind is lowered.
If you want to get closer to the sun, you need to slow down. A solar sail can’t quite achieve this perfectly–it would have to face at right angles to the sun. But if you face 45 degrees to the sun, you’ll still get 71% of the effect. If you keep that angle relative to the sun, the elliptical errors will cancel, and you’ll slowly lower your orbit.
The first of 2 lightsails launched had its issues. The on board computer crashed and there was no way to hit reset. Luckily, the upper atmosphere gets bombarded with cosmic rays from distant supernovas, which can lead to periodic reboots. That happened 8 days later. Later, the breadbox sized satellite went quiet again. NYT article from Saturday: LightSail, a Private Spacecraft, Goes Unexpectedly Quiet - The New York Times
With the sail deployed, the low orbit cubesat will slow down and flame out within the next few days. This effort was considered a test. Next April is the main show: at its higher orbit light pressure will exceed atmospheric drag.
Lightsail unfurls. Mission declared a success. Pic at link.
The next pic might have the Earth in it. That would be nice. Mission control tracks CubeSat’s location: it’s currently over Russia and will be passing over China a little later. Sheesh it travels fast.