New NASA Spacecraft Will Be Propelled By Light

[IDemo]

In 1418, European sailing vessels left their ports to explore the Atlantic Ocean, initiating a great Age of Discovery.

In 2018, a small space probe will unfurl a sail and begin a journey to a distant asteroid. It’s the first NASA spacecraft that will venture beyond Earth’s orbit propelled entirely by sunlight. This technology could enable inexpensive exploration of the solar system and, eventually, interstellar space.

The $16 million probe, called the Near-Earth Asteroid Scout, is one of the 13 science payloads that NASA announced Tuesday. They will hitch a ride on the inaugural flight of the Space Launch System—the megarocket designed to replace the space shuttle and, one day, send the Orion spacecraft to Mars.

It will take 2.5 years for the NEA Scout to reach its destination, a smallish asteroid named 1991 VG. But it won’t be a leisurely cruise. The continuous thrust provided by sunlight hitting the solar sail will accelerate the probe to an impressive 63,975 mph (28.6 km/s) relative to the sun.

http://news.nationalgeographic.com/2016/02/160202-solar-sail-space-nasa-exploration/

[Wounded Bear]

1. Thanks for that!

Pretty cool stuff.

[William Seger]

2. Conservation of momentum?

I started wondering about that when I read that (massless?) photons transferred momentum to the sail, so I did a search, and it turns out there are some differences of opinion about this whole idea:

https://www.newscientist.com/article/dn3895-solar-sailing-breaks-laws-of-physics/

Solar sailing ‘breaks laws of physics’

The next generation of spacecraft propulsion systems could be dead in the water before they are even launched. A physicist is claiming that solar sailing – the idea of using sunlight to blow spacecraft across the solar system – is at odds with the laws of thermal physics.

[muriel_volestrangler]

4. However, as the article says, the Japanese IKAROS has already succeeded

https://en.wikipedia.org/wiki/IKAROS

July 9, 2010 [updated]　
The acceleration by the solar radiation pressure is verified!
By the precise orbit determination after the sail deployment, we verify the photon acceleration by the solar radiation pressure. The thrust force by the solar radiation pressure is 1.12 mN (mN = 0.1 gf), and it is verified that the expected acceleration is achieved.

http://www.jspec.jaxa.jp/ikaros_channel/e/index.html

Sadly, Gold died in 2004 (he was 84) so we don't know how he would have responded to this.

[LastLiberal in PalmSprings]

3. Once again, science fiction writers are ahead of the scientists

More than 50 years ahead.

[hobbit709]

5. Been around a while.

https://davidleesummers.wordpress.com/2014/02/15/solar-sails-in-science-fiction/