If Breakthrough Starshot succeeds in launching a fleet of tiny probes to Proxima Centauri in 30 or 40 years, their payloads will be highly miniaturized and built to specifications far beyond our capabilities today. But the small ‘Sprites’ launched into low Earth orbit on June 23 give us an idea where the research is heading. Sprites are ‘satellites on a chip,’ growing out of research performed by Mason Peck and his team at Cornell University, which included Breakthrough Starshot’s Zac Manchester, who used a Kickstarter campaign to develop the concept in 2011 (see Sprites: A Chip-Sized Spacecraft Solution for background on the Cornell work).
Breakthrough Starshot executive director Pete Worden refers to Sprites as ‘a very early version of what we would send to interstellar distances,’ a notion that highlights the enormity of the challenge while pointing to the revolutionary changes that may make such payloads possible. The issues multiply the more you think about them — chip-like satellites in space have no radiation shielding and are susceptible to damage along the route of flight. But missions like these will help us analyze these problems and refine the technology.
Consider communications. In an email yesterday, Mason Peck told me that the Cornell team has juiced up the networking capabilities of the tiny spacecraft. “Now we have them talking to each other in a peer-to-peer network, and this demonstration shows how they synchronize like fireflies,” Peck said, a lovely image that points to what is becoming possible. Instead of a single large probe, think of a cluster of them, a fleet of spacecraft on chips, each carried by a sail. Losses along the route are assumed, but they are overcome by sheer numbers.
And as Peck, himself a key player in Breakthrough Starshot, goes on to point out, we’re beginning to learn how such chips can work among themselves:
This [peer-to-peer networking] capability would allow many of them to share science data, for example, or to create a persistent virtual senor out of many discrete sensors-on-chip. Also, in principle, their transmitting simultaneously could amplify the signals, enabling them to be heard from farther away. Or they could each transmit part of a dataset — say part of a large image.
We’ve never launched fully functional space probes as small as these, each 3.5-by-3.5 centimeter probe built upon a single circuit board and weighing in at just four grams. A Sprite can contain solar panels, computers, communications capability and an array of sensors. The tiny spacecraft’s electronics all function off the 100 milliwatts of electricity each generates.
The Sprites went into space aboard an Indian rocket as supplementary payloads. Now in orbit, the Latvian Venta satellite and the Italian Max Valier satellite, operated by OHB System AG, each have a Sprite attached to the outside, while the Max Valier satellite contains four more Sprites that are be deployed into space for subsequent study of their orbital dynamics.
Breakthrough Starshot is saying that communications from the mission show the Sprites are performing as designed, although Lee Billings, in a Scientific American post, has noted that the Sprites aboard the Max Valier satellite are problematic, with mission controllers thus far unable to establish communications with the external Sprite.
That could mean trouble for deploying the Max Valier’s four internal Sprites, but the stable orbits of the satellites give time for attempted fixes. Zac Manchester tells Billings that controllers have picked up signals from one external Sprite but are not sure which one it is. Even so, adds Manchester: “This is the first time we’ve successfully demonstrated Sprites end-to-end by flying them in space, powering them with sunlight and receiving their signals back on Earth.”
You may recall that Sprites have had their day aboard the International Space Station, being mounted for a long-term experiment outside the station before being returned to Earth undamaged from the exposure. Making a point that resonates with yesterday’s post on deorbiting space debris, Billings adds that the 2014 attempt to put 100 Sprites into orbit aboard a crowd-funded KickSat raised concerns over space debris; in any case, the Sprites were not deployed. Sprites will continue to be tested in space, but for now they will need to operate no higher than 400 kilometers above Earth, below which their orbits decay quickly.
How Sprites will evolve as Breakthrough Starshot continues to examine the technology remains to be seen. But remember that along the way, we have numerous potential uses for the tiny spacecraft here in our own system. Mason Peck has even talked about letting Sprites become charged through plasma interactions and then using a huge magnetic field like Jupiter’s as a particle accelerator to push the chips to thousands of kilometers per second.
That’s actually another way to get a payload to Proxima Centauri, though one that would take decades to get up to speed, and would still require several centuries for the journey. Even so, the idea of swarms of Sprites as interstellar probes, each communicating with the others like fireflies, has a surreal kind of beauty. In the meantime, could we use Sprites for interplanetary missions? Peck pointed out in a 2011 IEEE Spectrum article that the chips could use radiation pressure from the Sun to move around the Solar System. Let me quote him:
If a Sprite could be made thin enough, then its entire body could act as a solar sail. We calculate that at a thickness of about 20 micrometers—which is feasible with existing fabrication techniques—a 7.5-mg Sprite would have the right ratio of surface area to volume to accelerate at about 0.06 mm/s2, maybe 10 times as fast as IKAROS [the Japanese solar sail]. That should be enough for some interplanetary missions. If Sprites could be printed on even thinner material, they could accelerate to speeds that might even take them out of the solar system and on toward distant stars.
Image: Artist’s conception of a cloud of Sprite satellites over the Earth. Credit: Space Systems Design Studio/Cornell University.
Zac Manchester makes the same case, adding that Sprites can also be used to form three-dimensional antennas in deep space to monitor the kind of space weather that can damage power grids and orbiting satellites. Flying aboard larger spacecraft, they could be deployed as a rain of small probes to coat distant planetary surfaces with sensors.
“Eventually, every mission that NASA does may carry these sorts of nanocraft to perform various measurements,” says Pete Worden. “If you’re looking for evidence of life on Mars or anywhere else, for instance, you can afford to use hundreds or thousands of these things—it doesn’t matter that a lot of them might not work perfectly. It’s a revolutionary capability that will open up all sorts of opportunities for exploration.”
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Definitely the right approach to interstellar probes.
But there will still be the “overtaking the slower probe, with faster one launched two decades later” problem.
What is the cost to create a 1st
generation Sprite Probe, versus waiting till molecular assembly creates
a viable modular pieces of a probe (one of 60-90) each of which has some redundant functions of the other pieces. If each of these weighs
only 50-100 grams, then launching each to a high fraction of C, means
arrival times of 20-30 years for the closest stars.
The other factor is the ruggedness of such probes, If you are using
microchips ‘s I am sure you can design them to function even when “holed” by many microscopic sized particles/cosmic rays.
If we find a way to build them and launch “cheaply”, then it wont
matter so much if they can only do fly-bys, we send more of them. Shotgun Patterning to explore exo-solar systems.
While the sprite may be 20um in thickness, solar sail material is an order of magnitude thinner. Therefore, why not place the sprite on a larger sail (or as a trailing payload for stability) to aid acceleration? The sail might even be reconfigurable to act as a dish antenna to increase data transmission rates. A 1 m^2 sail would be 99.9% greater in area, dwarfing the sprite’s size and mass, allowing an effective 10x greater acceleration assuming 1/10 the thickness.
However these sprites are propelled, what we need to see if what sort of instruments can be added to such devices. For example, can swarms be used as synthetic large aperture telescopes, and if so, at what wavelengths? Could a small swarm be used as a TOF mass spectrometer?
It should be obvious that the smaller we can make these probes, the more difficult they become to detect. Which implies ETI could be hiding such probes in our solar system. Trying to find them could make the zealous rather desperate – like Harry Caul at the end of the movie, “The Conversation”.
The sprites can’t send a message via radio signal the distance of many light years through interstellar space. One still needs the breakthrough communications with lasers or something since it would take more than a half a million watts of power to send a radio signal from the nearest star in order to be able to be detected by radio telescopes on Earth.
If you send a “stream” of sprites, the information may travel up the stream, where the average distance between two sprites can be within communication range.
The Chinese recently claimed a breakthrough in quantum communication, which is being touted in the press as “teleportation”. I’m not sure what equipment this requires, but my hopes are up.
The Chinese used a satellite to demonstrate quantum encryption.
The pair used will react if the transmission is intercepted by someone.
That is not the same as sending data via the quantum pair. Such is claimed to be impossible.
Yes my main objective to Breakthrough Starshot is that a grams only transmitter never can be powerful enough to send information back.
Many sails working together? How many will that need, at a fraction of a watt per transmitter do we need a million sails?
Then I did read an analysis that stated that the material of the instruments would transmutate into other elements from radiation, so they would not work properly or at all at the destination.
The problem remain no matter how many sails you send as backup.
It would be great if they could create sails that could be used for acceleration then roll up and act as a shield for high speed flight then somehow swing around behind and open up to allow for deceleration and even maybe maneuvering upon arrival. Surely beyond our capabilities now, but maybe not in 35 years.
As much as I want to believe, I can’t give any credibility to this entire endeavor. Sure, some useful tech may come of it but it will likely fall far short of the stars; not even the Ort cloud or the Kuiper belt; perhaps the planets. There are too many orders of magnitude of difficulties in too many areas to be taken seriously.
The money could be better spent on a mission to the sun’s gravitation lens focal point for example.
Whether these StarChips actually go to the stars or not some day, they DO have potential uses as probes in our own Sol system, along with I am sure other useful space utilizations.
Exploring other worlds with multiple probes makes a lot of sense. For one they can literally cover a lot more ground than a single lander or rover. Each tiny probe can be tasked with a single job either as part of a group from the whole or an individual effort. Best of all, if we lose a few such probes, it will be unfortunate but not the end of the entire mission. If school bus-size Cassini had failed, that would have been it for exploring Saturn. There was not even a backup version for that robotic explorer.
As far as interstellar exploration is concerned, I am just happy to see that someone actually built and launched something related to such deep space probes. We have had more than enough speculation and white papers and non-scientific science fiction on the subject. Someone finally did not get off the pot. I hope it is the first of many.
They would have a great many uses, if they worked. They’re unworkable as specced.
Two recent articles come to mind that give some hope the issues of wafer size and survivability and communication can be solved within the timeframe established for launching wafersats to AC.
Here are some past Centauri Dreams articles related to this subject for reference, including those with Mason Peck who is involved with this Sprite project:
Deep Space Propulsion via Magnetic Fields
ChipSat: To the Stars via Magnetic Fields
Putting the Pieces Together in Space
Reconfigurable Structures in Space: Q & A
Gives the frequency for those who would like to listen to the Sprites. Good SETI practice for nearby ETI probes too.
Want to listen to the new Breakthrough Sprites? They’re broadcasting at: 437.24 MHz, corresponding to a wavelength of roughly 69 cm
4:59 PM – Jul 26, 2017
a = F/m = k P/(Vd) = k IA/(tAd) = k I/(td)
Thus acceleration is
a) independent of sail area
b) maximised by minimum sail thickness and minimum sail density
Speaking of Breakthrough Nano-Starships…
A new preprint of relevance:
Centimeter-Scale Suspended Photonic Crystal Mirrors
A quote from the preprint:
“Proposals using large light sails like the Starshot Breakthrough, require mirrors with lateral sizes of 4 × 4 m2
, thicknesses of 0.05λ, reflectivities of 90 %, ppmlevel optical absorption and a total mass of only 1 g .
Our PhC are designed with a lattice of holes which remove about 30 % of the mass of the membrane. Additionally,
they are made of LPCVD SiN which has an imaginary refractive index of about 10−6 at 1064 nm and has been shown to withstand high laser powers of around 2.5 · 1011 W/m2  – nearly 2 orders of magnitude more than what is required for the initiative.”
Seems the right material may well be available.
ISRO sows seeds of future interstellar missions:
Breakthrough Starshot Takes to Space:
Scientists demonstrate first quantum communication with microsatellite
by Tomasz Nowakowski
August 6, 2017
A team of researchers from the National Institute of Information and Communications Technology (NICT) in Tokyo, Japan, has recently reported that they succeeded in demonstrating the first quantum communication between a microsatellite and a ground station. The signal was sent by a quantum communication transmitter on board the SOCRATES satellite.
The instrument, known as the Small Optical TrAnsponder, or SOTA, is the world’s smallest and lightest quantum communication transmitter. It has a mass of roughly 13.22 pounds (6 kilograms) and its dimensions are 7 by 4.5 by 10.6 inches (17.8 by 11.4 by 26.8 centimeters). This shoebox-sized tool is capable of transmitting a laser signal to the ground at a rate of 10 million bits per second from an altitude of about 370 miles (600 kilometers) while orbiting at a speed of approximately 15,660 mph (25,200 km/h).
SOTA was launched into space as part of the Space Optical Communications Research Advanced TEchnology Satellite (SOCRATES) microsatellite in May 2014. The mission’s main goal was to test a standard microsatellite bus technology applicable to missions of various purposes. SOTA has successfully completed its objectives by demonstrating its quantum communication capabilities.
“We are proud to say that the SOTA mission fulfilled all the success levels as foreseen and more than doubled its originally designed working life of one year,” Alberto Carrasco-Casado of NICT’s Space Communications Laboratory told Astrowatch.net.
Full article here:
He underlined that space lasercom will play a more and more important role in satellite communications in the future, and all the technologies that SOTA demonstrated are key to these future developments. For example, the SpaceX constellation plans to use over 4,000 satellites, and those satellites will use laser communications to communicate with each other. Moreover, many other constellations and communication networks are being designed at the moment where free-space lasercom plays a key role, with private companies like Google or Facebook investing a great deal of effort in their deployment.
Advances in Microsatellite Propulsion Propel Deep-Space Exploration, Maneuverability
Getting up close and personal with Alpha Centauri? A thruster engine fueled by water? Developments in space technology are charting new courses in otherwise uncharted territory.
Cabe Atwell | Aug 15, 2017
Bold Space Travel
UCSB physics professor’s vision of launching tiny spaceships beyond the solar system lands him in World Book’s ‘Out of this World’ series
By Jim Medina
Thursday, August 24, 2017 – 07:15
Santa Barbara, CA
Lubin’s ambitious vision is showcased in “Laser-Sailing Starships,” one of eight volumes in the new series “Out of this World” published by World Book (of encyclopedia fame). Targeted to middle-school students, the books focus on research fellows involved in the NASA Innovative Advanced Concepts program. NASA aims to foster the next generation of scientific talent.
“A large number of scientists have looked at the technical paper we wrote in 2015 on how to accomplish this,” Lubin said. “Except for saying this is going to be hard to do, no one has found a fatal flaw.”
World’s smallest space probe seen as stepping stone to Alpha Centauri
This is what happens when you live in a society that expects instant gratification:
Last year Milner funded a $100 million “Breakthrough Starshot” project to test the feasibility of the light-sail approach. He brought on Stephen Hawking and Mark Zuckerberg as board members. It’s an unusual cause to take on, even for a Silicon Valley mogul, and the potential payoff would be decades away. “Philanthropy is a very broad space. 99% of it should focus on what people need today,” he said at the event. “At the same time, there should be a relatively small amount — less than 1% — that would explore more outward kinds of things.”
Milner, whose investment firm DST Global once owned 8% of Facebook, thinks his project has slim odds of answering the big question, but the upside is so big that he can’t resist trying. “The chances we’ll find something in the next 10 years are 1%,” he said. “But the significance is such that, if you multiply 1% by the significance, it’s worth it.”