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#60
by
Comga
on 23 Jun, 2016 00:32
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A cubesat definitely /could/ have high-Isp propulsion. Just because none have so far doesn't mean they couldn't.
Correct
A_M_Swallow reminded us of Busek's program to build high Isp engines for smallsats and cubesats.
Technology Development Project Selections announced on September 4, 2013. These should be available soon and in need of a mission (unless they were cancelled).
http://www.nasa.gov/content/technology-development-project-selections/#.V2YKmDVaHIV
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#61
by
jongoff
on 23 Jun, 2016 04:33
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A cubesat definitely /could/ have high-Isp propulsion. Just because none have so far doesn't mean they couldn't.
Correct
A_M_Swallow reminded us of Busek's program to build high Isp engines for smallsats and cubesats.
Technology Development Project Selections announced on September 4, 2013. These should be available soon and in need of a mission (unless they were cancelled).
http://www.nasa.gov/content/technology-development-project-selections/#.V2YKmDVaHIV
The challenge with high Isp cubesat propulsion is that cubesats tend to be very power limited, which means they probably optimize out to a lower Isp than a bigger satellite would (and they already typically optimize out to far lower Isp than ion engines are capable of).
~Jon
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#62
by
Comga
on 23 Jun, 2016 05:43
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A cubesat definitely /could/ have high-Isp propulsion. Just because none have so far doesn't mean they couldn't.
Correct
A_M_Swallow reminded us of Busek's program to build high Isp engines for smallsats and cubesats.
Technology Development Project Selections announced on September 4, 2013. These should be available soon and in need of a mission (unless they were cancelled).
http://www.nasa.gov/content/technology-development-project-selections/#.V2YKmDVaHIV
The challenge with high Isp cubesat propulsion is that cubesats tend to be very power limited, which means they probably optimize out to a lower Isp than a bigger satellite would (and they already typically optimize out to far lower Isp than ion engines are capable of).
~Jon
Correct. Isp goes up with increasing power. From the Busek presentation going from 60W to 360W raises the Isp by 10%, from 3500 sec to 3850 sec., but several of the former engines may be enough. So the optimum would tend more towards a smallsat than a cubesat, with significant solar panels and redundancy for a year in interplanetary space, but not necessarily something on the scale of Dawn of Deep Space 1.
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#63
by
KelvinZero
on 23 Jun, 2016 08:42
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The challenge with high Isp cubesat propulsion is that cubesats tend to be very power limited, which means they probably optimize out to a lower Isp than a bigger satellite would (and they already typically optimize out to far lower Isp than ion engines are capable of).
By power limited do you mean power/mass? I would have thought there was a scaling problem in the other direction for solar power/mass. (im not claiming any experience, just laymans logic)
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#64
by
A_M_Swallow
on 23 Jun, 2016 16:12
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The challenge with high Isp cubesat propulsion is that cubesats tend to be very power limited, which means they probably optimize out to a lower Isp than a bigger satellite would (and they already typically optimize out to far lower Isp than ion engines are capable of).
By power limited do you mean power/mass? I would have thought there was a scaling problem in the other direction for solar power/mass. (im not claiming any experience, just laymans logic)
He means straight forward power limited. Cubesats have small solar panels so it unlikely to have more than 50-100 watts of power. About the same as the lamp in my lounge used to use.
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#65
by
Danderman
on 24 Jun, 2016 13:51
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Forgetting efforts to design a CubeSAT mission here, what about a more traditional survey, what are the requirements for a Discovery class mission to this object?
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#66
by
KelvinZero
on 25 Jun, 2016 01:09
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He means straight forward power limited. Cubesats have small solar panels so it unlikely to have more than 50-100 watts of power. About the same as the lamp in my lounge used to use.
So is the problem that a thruster of half the power shoots out particles at less speed, rather than just half as many? Is this where the scaling problem is?
Comega said something directly above that could be interpreted that way, (edit, and on re-reading my other interpretations don't make sense).. so the problem is that it is hard making smaller thrusters efficient if you try to keep similar ISP?.. I guess like it is hard building a pistol to shoot bullets as fast as a rifle? There are totally different approaches* but I guess then you are starting from scratch?
*Come to think of it, such as light sails, but there are other electronic ones I have seen mentioned.
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#67
by
Comga
on 25 Jun, 2016 04:29
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I have a message from a gracious gentleman at the Arkansas Sky Observatories who says that the idea that 2016 H03 has low density has been disavowed. My guess is that it was not based on good evidence.
(Perhaps like why Percival Lowell had Clyde Tombaugh search that part of the sky. There were mathematical errors that suggested a large mass there. Instead of a giant, Tombaugh found a dwarf planet by luck. Fortuneately he found Pluto before the errors were corrected!)
Edit: So we have no evidence that 2016 H03 is anything but a natural asteroid trapped in an orbit such that any year we could launch a less-than-one_year round trip to it with practical velocities.
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#68
by
Ludus
on 01 Jul, 2016 22:27
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If 2016 HO3 is in fact a natural 40-100m asteroid (likely) and if it also proves to be type with valuable resources either metallic or carbon (based on an exploration mission), how practical would it be to move it to a more useful location to be exploited? What would be required? Where would you move it?
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#69
by
Solman
on 02 Jul, 2016 01:13
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If 2016 HO3 is in fact a natural 40-100m asteroid (likely) and if it also proves to be type with valuable resources either metallic or carbon (based on an exploration mission), how practical would it be to move it to a more useful location to be exploited? What would be required? Where would you move it?
One possibility might be to use the "mirror bees" or "laser bees" concept. Thrust is generated by.vehicles using lasers or concentrated sunlight to heat regolith while orbiting or in the proximity of the asteroid. Mining vehicles might be designed around a solar concentrator for PV power and use it to act as a "mirror bee" to alter the asteroid,s orbit while waiting for the launch window for Earth return. Alternatively, a solar powered laser might provide power and propulsion for a mining vehicle and the laser used during the wait.
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#70
by
Ludus
on 03 Jul, 2016 16:20
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#71
by
Hop_David
on 03 Aug, 2016 20:29
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If 2016 HO3 is in fact a natural 40-100m asteroid (likely) and if it also proves to be type with valuable resources either metallic or carbon (based on an exploration mission), how practical would it be to move it to a more useful location to be exploited? What would be required? Where would you move it?
For some asteroids that normally pass close to earth moon neighborhood, a small nudge can bring the asteroid close to the moon. A lunar fly by can cut velocity relative to earth. This wouldn't be an option for 2016 HO3, it doesn't come close to the earth.
Moreover, it's inclination is 8 degrees.
There are asteroids such as 2008 HU4 that could be parked in high lunar orbit for just a small amount of delta V. Sadly HO3 isn't one of them.
I talk about catching an asteroid
here.
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#72
by
A_M_Swallow
on 04 Aug, 2016 18:25
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Can we send a reconnaissance satellite to HO3 for less that say $50 million?
A second satellite may be needed to relay the radio signals.
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#73
by
Danderman
on 05 Aug, 2016 18:43
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You would think that some at NASA would be jumping at the chance to send a Pioneer class probe to H03 ASAP, since that would be a great target for the Asteroid mission.
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#74
by
Hop_David
on 05 Aug, 2016 21:14
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You would think that some at NASA would be jumping at the chance to send a Pioneer class probe to H03 ASAP, since that would be a great target for the Asteroid mission.
It's not a great target for the Asteroid redirect mission. See my post above.
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#75
by
knotnic
on 19 Aug, 2016 18:44
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From
http://fluidandreason.com/constantq/, looks like someone crunching real numbers is convinced 2016 HO3 is viable for targeting with a large cubesat with high ISP. (This contest would release it from the spent upper stage of SLS EM-1 mission after TLI.)
The ConstantQ™ thrusters will be used on the CubeQuest competition’s Miles spacecraft. This craft features 12 thrusters with a custom tank design, taking the craft to lunar orbit and to asteroid 2016 HO3.
....
The ConstantQ™ is a hybrid electrostatic thruster, featuring an exceptionally compact and power-efficient design with a self-neutralizing plasma flow. The thruster gives 1.25 mN of thrust (modes up to 2.4mN available), 760 sec Isp (modes over 3,500 sec available), at 5.5 Watts total input power (3W beam power) when tested in Argon. Our “Model H” system includes 4 thruster heads, high voltage electronics, and 1kg of solid Iodine in a 1.5kg total, 0.5U, 22W package, giving a 8kg 6U satellite 995 m/s delta-v. The Model H’s thrusters are canted allowing for both primary propulsion and attitude control without use of moving parts – an important factor in mission assurance.
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#76
by
Zed_Noir
on 20 Aug, 2016 09:55
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You would think that some at NASA would be jumping at the chance to send a Pioneer class probe to H03 ASAP, since that would be a great target for the Asteroid mission.
It's not a great target for the Asteroid redirect mission. See my post above.
Think @Danderman isn't thinking of the Asteroid redirect mission. Seems a small stream of mini spacecrafts with duo cameras & SEP should be enough for flyby look.
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#77
by
bad_astra
on 05 Sep, 2016 20:26
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Why not Dragon asteroid 2017 as a Mars mission precursor!?
because people who become Mars obsessed aren't into rocks
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#78
by
Robotbeat
on 06 Sep, 2016 13:36
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Why not Dragon asteroid 2017 as a Mars mission precursor!?
because people who become Mars obsessed aren't into rocks
Also, since the goal is Mars and the primary difficulty there (the problem which must be solved no matter the other details, and which must be solved to start major even robotic preparations) is EDL, why spend the money on a launch to a rock that isn't testing EDL?
If it's deep space operational experience and high speed reentry you want to test, a loop around the Moon would work, too, and would be faster.
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#79
by
the_other_Doug
on 06 Sep, 2016 18:52
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Why not Dragon asteroid 2017 as a Mars mission precursor!?
because people who become Mars obsessed aren't into rocks
Also, since the goal is Mars and the primary difficulty there (the problem which must be solved no matter the other details, and which must be solved to start major even robotic preparations) is EDL, why spend the money on a launch to a rock that isn't testing EDL?
If it's deep space operational experience and high speed reentry you want to test, a loop around the Moon would work, too, and would be faster.
And heck, if you're also testing landing ability, loop one around the Moon and land another one on it.
It's sort of reminiscent of Charles Lindbergh having Ryan Aircraft in San Diego build him a long-duration airplane capable of flying the Atlantic. Getting it to New York for its departure could have been done one of two ways -- take the wing off, put it all on a couple of train cars, and ship it to New York via rail, or just fly it there.
Just flying non-stop from San Diego to St. Louis set a world's record for non-stop flight, and that was just the warm-up.
Doing a couple of quick shots to the Moon, to test out a few systems, isn't a bad idea. Rather like setting a new world's record just getting your aircraft to the starting line.
But depending on delta-V budgets, I will also say that visiting a NEO as your equivalent of getting the spacecraft to the starting line might be more impressive to potential partners, who might see the Moon as been-there, done-that. I bet the Moon would garner more public interest, though...