Jan 12, 2022 04:24 PM
Can we – should we – send life to the nearest star? (tech ethics)
https://earthsky.org/space/send-life-to-...afercraft/
EXCERPTS: . . . The first voyagers among the stars might not be people. Instead, they might be tiny creatures such as tardigrades (aka water bears). Or they might be nematodes (aka roundworms), such as C. elegans. These little creatures might sail aboard tiny wafer-like ships powered by lasers. That’s the thinking of a team of scientists that published a paper on these topics in the January 2022 issue of the peer-reviewed journal Acta Astronautica.
The scientists want to know … What would it take to send life to the nearest star?
Proxima Centauri is the nearest star to Earth. But in the vastness of the cosmos, near is a relative term. Proxima lies about 4.22 light-years away, with each light-year equaling about 6 trillion miles (9 trillion km). Scientists have already found two planets orbiting Proxima Centauri.
Philip Lubin, of the University of California at Santa Barbara, is one of the new study’s co-authors. [...] Joel Rothman, also of University of California at Santa Barbara, is another co-author of the new paper...
[...] Nematodes, or roundworms, such as C. elegans, are ideal choices for an interstellar flight. C. elegans can go into suspended animation, a useful trick for surviving a long flight. And the creatures are no stranger to space travel. They’ve already taken numerous trips on the space shuttle and to the space station.
[...] They considered the idea that the creatures who would first venture across the space among the stars – to a planet around Proxima Centauri – wouldn’t ever land there and set up camp. Their role would be to take a one-way trip, and thereby determine its feasibility. The creatures would either burn up at entry to the planet’s atmosphere or crash land. And nothing from Proxima Centauri would be making the return trip to Earth, thereby avoiding issues of cross-contamination between a planet in the Proxima system and our own Earth.
Rothman said: "I think if you started talking about directed propagation of life, which is sometimes called panspermia — this idea that life came from elsewhere and ended up on the Earth by comets and other debris, or even intentionally from another civilization — the idea that we would purposefully send out life does bring up big questions."
At this stage, the researchers are still just pondering the questions without answers. Some of the other questions the researchers are considering are: What are the ethics of sending humans to the stars, knowing they may never come home? And what about sending out small microorganisms or human DNA? (MORE - missing details)
Interstellar Reach: The Challenge of Beamed Energy
https://www.centauri-dreams.org/2022/01/...ed-energy/
EXCERPTS: . . . The point is that we have to do a lot better if we’re going to talk about practical missions to the stars. Interstellar flight is feasible today if we accept mission durations measured in thousands of years (well over 70,000 years at Voyager 1 speeds to travel the distance to Proxima Centauri). But taking instrumented probes, much less ships with human crews, to the nearest star demands a completely different approach, one that Lubin and team have been exploring at UC-SB. Beamed or ‘directed energy’ systems may do the trick one day if we can master both the technology and the economics.
[...] Directed energy offers us a way forward but only if we can master the trends in photonics and electronics that can empower this new kind of propulsion in realistic missions. In their new paper, to be published in a special issue of Acta Astronautica, Philip Lubin and Alexander Cohen are exploring how we might leverage the power of growing economies and potentially exponential growth in enough key areas to make directed energy work as an economically viable, incrementally growing capability.
Beaming energy to sails should be familiar territory for Centauri Dreams readers. For the past eighteen years, we’ve been looking at solar sails and sails pushed by microwave or laser, concepts that take us back to the mid-20th Century. The contribution of Robert Forward to the idea of sail propulsion was enormous, particularly in spreading the notion within the space community, but sails have been championed by numerous scientists and science fiction authors for decades. Jim Benford, who along with brother Greg performed the first laboratory work on beamed sails, offers a helpful Photon Beam Propulsion Timeline, available in these pages.
In the Lubin and Cohen paper, the authors make the case that two fundamental types of mission spaces exist for beamed energy.
What they call Direct Drive Mode (DDM) uses a highly reflective sail that receives energy via momentum transfer. This is the fundamental mechanism for achieving relativistic flight. Some of Bob Forward’s mission concepts could make an interstellar crossing within the lifetime of human crews. In fact, he even developed braking methods using segmented sails that could decelerate at destination for exploration at the target star and eventual return.
Lubin and Cohen also see an Indirect Drive Mode (IDM), which relies on beamed energy to power up an onboard ion engine that then provides the thrust. My friend Al Jackson, working with Daniel Whitmire, did an early analysis of such a system (see Rocketry on a Beam of Light), The difference is sharp: A system like this carries fuel onboard, unlike its Direct Drive Mode cousin, and thus has limits that make it best suited to work within the Solar System. While ruling out high mass missions to the stars, this mode offers huge advantages for reaching deep into the system, carrying high mass payloads to the outer planets and beyond...
[...] We shouldn’t play down IDM because it isn’t suited for interstellar missions. Fast missions to Mars are a powerful early incentive, while projecting power to spacecraft and eventual human outposts deeper in the Solar System is a major step forward. Beamed propulsion is not a case of a specific technology for a single deep space mission, but rather a series of developing systems that advance our reach. The fact that such systems can play a role in planetary defense is a not inconsiderable benefit.
If we’re going to analyze how we go from here, where we’re at the level of lab experiments, to there, with functioning directed energy missions, we have to examine these trends in terms of their likely staging points. What I mean is that we’re looking not at a single breakthrough that we immediately turn into a mission, but a series of incremental steps that ride the economic wave that can drive down costs. Each incremental step offers scientific payoff as our technological prowess develops.
Getting to interstellar flight demands patience. In economic terms, we’re dealing with moving targets, making the assessment at each stage complicated... (MORE - missing details)
https://earthsky.org/space/send-life-to-...afercraft/
EXCERPTS: . . . The first voyagers among the stars might not be people. Instead, they might be tiny creatures such as tardigrades (aka water bears). Or they might be nematodes (aka roundworms), such as C. elegans. These little creatures might sail aboard tiny wafer-like ships powered by lasers. That’s the thinking of a team of scientists that published a paper on these topics in the January 2022 issue of the peer-reviewed journal Acta Astronautica.
The scientists want to know … What would it take to send life to the nearest star?
Proxima Centauri is the nearest star to Earth. But in the vastness of the cosmos, near is a relative term. Proxima lies about 4.22 light-years away, with each light-year equaling about 6 trillion miles (9 trillion km). Scientists have already found two planets orbiting Proxima Centauri.
Philip Lubin, of the University of California at Santa Barbara, is one of the new study’s co-authors. [...] Joel Rothman, also of University of California at Santa Barbara, is another co-author of the new paper...
[...] Nematodes, or roundworms, such as C. elegans, are ideal choices for an interstellar flight. C. elegans can go into suspended animation, a useful trick for surviving a long flight. And the creatures are no stranger to space travel. They’ve already taken numerous trips on the space shuttle and to the space station.
[...] They considered the idea that the creatures who would first venture across the space among the stars – to a planet around Proxima Centauri – wouldn’t ever land there and set up camp. Their role would be to take a one-way trip, and thereby determine its feasibility. The creatures would either burn up at entry to the planet’s atmosphere or crash land. And nothing from Proxima Centauri would be making the return trip to Earth, thereby avoiding issues of cross-contamination between a planet in the Proxima system and our own Earth.
Rothman said: "I think if you started talking about directed propagation of life, which is sometimes called panspermia — this idea that life came from elsewhere and ended up on the Earth by comets and other debris, or even intentionally from another civilization — the idea that we would purposefully send out life does bring up big questions."
At this stage, the researchers are still just pondering the questions without answers. Some of the other questions the researchers are considering are: What are the ethics of sending humans to the stars, knowing they may never come home? And what about sending out small microorganisms or human DNA? (MORE - missing details)
Interstellar Reach: The Challenge of Beamed Energy
https://www.centauri-dreams.org/2022/01/...ed-energy/
EXCERPTS: . . . The point is that we have to do a lot better if we’re going to talk about practical missions to the stars. Interstellar flight is feasible today if we accept mission durations measured in thousands of years (well over 70,000 years at Voyager 1 speeds to travel the distance to Proxima Centauri). But taking instrumented probes, much less ships with human crews, to the nearest star demands a completely different approach, one that Lubin and team have been exploring at UC-SB. Beamed or ‘directed energy’ systems may do the trick one day if we can master both the technology and the economics.
[...] Directed energy offers us a way forward but only if we can master the trends in photonics and electronics that can empower this new kind of propulsion in realistic missions. In their new paper, to be published in a special issue of Acta Astronautica, Philip Lubin and Alexander Cohen are exploring how we might leverage the power of growing economies and potentially exponential growth in enough key areas to make directed energy work as an economically viable, incrementally growing capability.
Beaming energy to sails should be familiar territory for Centauri Dreams readers. For the past eighteen years, we’ve been looking at solar sails and sails pushed by microwave or laser, concepts that take us back to the mid-20th Century. The contribution of Robert Forward to the idea of sail propulsion was enormous, particularly in spreading the notion within the space community, but sails have been championed by numerous scientists and science fiction authors for decades. Jim Benford, who along with brother Greg performed the first laboratory work on beamed sails, offers a helpful Photon Beam Propulsion Timeline, available in these pages.
In the Lubin and Cohen paper, the authors make the case that two fundamental types of mission spaces exist for beamed energy.
What they call Direct Drive Mode (DDM) uses a highly reflective sail that receives energy via momentum transfer. This is the fundamental mechanism for achieving relativistic flight. Some of Bob Forward’s mission concepts could make an interstellar crossing within the lifetime of human crews. In fact, he even developed braking methods using segmented sails that could decelerate at destination for exploration at the target star and eventual return.
Lubin and Cohen also see an Indirect Drive Mode (IDM), which relies on beamed energy to power up an onboard ion engine that then provides the thrust. My friend Al Jackson, working with Daniel Whitmire, did an early analysis of such a system (see Rocketry on a Beam of Light), The difference is sharp: A system like this carries fuel onboard, unlike its Direct Drive Mode cousin, and thus has limits that make it best suited to work within the Solar System. While ruling out high mass missions to the stars, this mode offers huge advantages for reaching deep into the system, carrying high mass payloads to the outer planets and beyond...
[...] We shouldn’t play down IDM because it isn’t suited for interstellar missions. Fast missions to Mars are a powerful early incentive, while projecting power to spacecraft and eventual human outposts deeper in the Solar System is a major step forward. Beamed propulsion is not a case of a specific technology for a single deep space mission, but rather a series of developing systems that advance our reach. The fact that such systems can play a role in planetary defense is a not inconsiderable benefit.
If we’re going to analyze how we go from here, where we’re at the level of lab experiments, to there, with functioning directed energy missions, we have to examine these trends in terms of their likely staging points. What I mean is that we’re looking not at a single breakthrough that we immediately turn into a mission, but a series of incremental steps that ride the economic wave that can drive down costs. Each incremental step offers scientific payoff as our technological prowess develops.
Getting to interstellar flight demands patience. In economic terms, we’re dealing with moving targets, making the assessment at each stage complicated... (MORE - missing details)