Author Topic: NASA Selects Two Missions to Explore the Early Solar System  (Read 12618 times)

Offline jgoldader

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It occurs to me that the spacecraft being sent to 13 Psyche would probably need to be seriously hardened. A mass of ferrous metals of that size would probably have a huge induced magnetic field and electrostatic charge from its motion through the field lines of the Sun's magnetosphere. There could even be a synchrotron radiation field close to the surface!

I'd think a few minutes with a radio telescope would tell.  I've never heard of an asteroid being a source of strong radio emission, though.
Recovering astronomer

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https://www.jpl.nasa.gov/news/news.php?feature=6854

NASA Moves Up Launch of Psyche Mission to a Metal Asteroid

Offline joek

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I thought that was the whole reason for certification. If they wanted higher reliability wouldn't they require a Category 3 certification excluding Falcon from the start?

Nope.  You only need an approved certification plan in order to receive award.  You must fulfill that plan (achieve certification) before launch.


p.s. What says this mission requires Cat-3 certification?  IIRC there are some general guidelines for Discovery class missions, but have not seen anything specific to this.
« Last Edit: 05/26/2017 09:03 PM by joek »

Online Blackstar

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Seriously, half the posts on this topic are about what rocket might launch it five years from now. Don't you guys argue that issue enough on just about every other thread on this site?

Offline Khadgars

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Seriously, half the posts on this topic are about what rocket might launch it five years from now. Don't you guys argue that issue enough on just about every other thread on this site?

Was just about to say something similar  :-X  There is plenty of good material to discuss in this thread outside of which launch vehicle is used.

Kudos for NASA finding a quicker path to Psyche and saving money in the process.  That particular mission I find quite exciting, I'd love to hear more details into that mission.
« Last Edit: 05/26/2017 10:13 PM by Khadgars »

Offline Dalhousie

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Seriously, half the posts on this topic are about what rocket might launch it five years from now. Don't you guys argue that issue enough on just about every other thread on this site?

Crazy isn't it?  Personally, I am really excited about Psyche.  I think it as the same poential for the unexpected as Rosetta.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Online gongora

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And that's plenty of posts complaining the the launcher discussion was getting off-topic (which it was, but enough already, on both topics).  Back to Lucy/Psyche discussion until these launches are actually put out for bid.

Offline TrevorMonty

Psyche will be carry laser communications, RF is still primary comms while laser is a test. If it works the orbiter will be able to send huge amounts of data.

Offline vjkane

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Psyche will be carry laser communications, RF is still primary comms while laser is a test. If it works the orbiter will be able to send huge amounts of data.
Psyche' orbit (the asteroid) is well within the asteroid belt.  This will allow testing the laser comm system over a wide range of distances.

Offline Nomadd

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Psyche will be carry laser communications, RF is still primary comms while laser is a test. If it works the orbiter will be able to send huge amounts of data.
Send it to what? Laser without an orbital relay has always had cloud cover making scheduling iffy.
« Last Edit: 05/29/2017 08:47 PM by Nomadd »

Online russianhalo117

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Psyche will be carry laser communications, RF is still primary comms while laser is a test. If it works the orbiter will be able to send huge amounts of data.
Send it to what? Laser without an orbital relay has always had cloud cover making scheduling iffy.
TDRS-4G constellation is in development to fix that.

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They're going to have problems with that system on TDRS. Optical has proven tougher than anybody expected. There were proposals for laser comm in the mid-1960s, believe it or not, and active development in the early 1980s.

I think this is a vital technology for planetary exploration, but it's going to be difficult and expensive.

I'm scratching my brain at the moment, but in the past year or so I saw a semi-detailed history article on the development of optical comm. Maybe somebody else has seen that and can link to it.

Offline LouScheffer

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They're going to have problems with that system on TDRS. Optical has proven tougher than anybody expected. There were proposals for laser comm in the mid-1960s, believe it or not, and active development in the early 1980s.

I think this is a vital technology for planetary exploration, but it's going to be difficult and expensive.

I'm scratching my brain at the moment, but in the past year or so I saw a semi-detailed history article on the development of optical comm. Maybe somebody else has seen that and can link to it.

Here are two sources.  For a short (few pages) history, see Deep-Space Optical Communications - Visions, Trends, and Prospects.

For a more detailed (81 page) history try Chapter 1 of "Deep Space Optical Communications" by Lesh of JPL.

Offline Nomadd

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They're going to have problems with that system on TDRS. Optical has proven tougher than anybody expected. There were proposals for laser comm in the mid-1960s, believe it or not, and active development in the early 1980s.

I think this is a vital technology for planetary exploration, but it's going to be difficult and expensive.

I'm scratching my brain at the moment, but in the past year or so I saw a semi-detailed history article on the development of optical comm. Maybe somebody else has seen that and can link to it.

Just about all of the difficulties in that study seem to be ground stations having a good line of sight, which are eliminated by the TDRS. No unplanned attenuation, clouds, layers or anything else the atmosphere has to offer. And little risk at the Mars end since simulating the distance is extremely simple without all the uncertain variables you have with ground stations.

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Thanks for those. Neither is the article I was thinking of, which is really recent, but also relatively short. Both those articles deal with deep space optical comm. There were proposals for Earth orbital optical comm as well. The DSP satellites were supposed to have it for crosslinking between satellites in GEO. The DSP-14 satellite even launched with the mount attached, but no lasercomm. There were also proposals for LEO tests in the 1980s. And there were actual LEO tests done (I think) starting in the 1990s. In the early 2000s there was a program called TSAT that was going to have optical comm for the military.

Like I noted earlier, it's been around for a long time.

Offline redliox

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It will be interesting to see how functional a laser com system will be via Psyche.  I don't know how well it would work, but this could be the point: making an attempt and seeing first-hand with actual hardware how far out the system can work in a practical sense.  The LADEE probe seemed to verify it can be done from Luna, but the next step would be either Venus or Mars and the asteroid Psyche is just-about-literally twice the distance as Mars.  I don't expect the system to be reliable at Psyche itself, but we could see at what distance things peter-out and discern what causes that.

If I had to make an off-hand, educated guess about the effectiveness of laser coms, I think a huge factor will be relative stability.  Aiming a telescope and ensuring it tracks the target (the satellite or at least the planet it circles) is a huge pain at times.  However, if the target is predicable and moving relatively slow to Earth, it should be simpler.  Here are some examples:

LEO - pain in rear because the satellite will be moving out of line-of-site fast; if your tracking is slow laser com is worthless for you.
GEO - As easy as you can get, so long as your laser com can handle Van Allen radiation.
Lunar Orbits - Tricky, but probably not as bad as LEO.  It will probably depend on if the orbits get eclipsed by Luna and taken out of site.
La Grange Points (any) - The halo orbits will no doubt require some level of tracking, but this will probably less painful than LEO and slightly less than a lunar orbit.

I'll leave it at that before it gets too off-topic, but including a laser com on Psyche makes for a very interesting technology demonstration; depending on how successful we could see networks placed around Earth or (if somewhat reliable) at least sporadic (but regular) communication between Earth and planets.
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Offline tul

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OICETS established an optical communication link between LEO and a fixed and later a mobile ground station.
https://en.wikipedia.org/wiki/OICETS

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Just about all of the difficulties in that study seem to be ground stations having a good line of sight, which are eliminated by the TDRS. No unplanned attenuation, clouds, layers or anything else the atmosphere has to offer. And little risk at the Mars end since simulating the distance is extremely simple without all the uncertain variables you have with ground stations.

An engineer familiar with this stuff told me many years ago that a key challenge will be converting the optical signals to RF signals for transmission to the ground. He was discussing TSAT, where the bandwidth would have presumably been much much higher than a single spacecraft in deep space. So maybe it's not really an issue for deep space optical comms.

Offline baldusi

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Well, GEO to LEO is being done routinely with the EDRS. So deep space to GEO doesn't seems so much of a stretch.

Offline Star One

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NASA Selects Two Missions to Explore the Early Solar System
« Reply #39 on: 10/02/2017 04:01 PM »
NASA Glenn Tests Thruster Bound for Metal World

Quote
As NASA looks to explore deeper into our solar system, one of the key areas of interest is studying worlds that can help researchers better understand our solar system and the universe around us. One of the next destinations in this knowledge-gathering campaign is a rare world called Psyche, located in the asteroid belt.

Psyche is different from millions of other asteroids because it appears to have an exposed nickel-iron surface. Researchers at Arizona State University, Tempe, in partnership with NASA's Jet Propulsion Laboratory in Pasadena, California, believe the asteroid could actually be the leftover core of an early planet. And, since we can't directly explore any planet's core, including our own, Psyche offers a rare look into the violent history of our solar system.

"Psyche is a unique body because it is, by far, the largest metal asteroid out there; it's about the size of Massachusetts," said David Oh, the mission's lead project systems engineer at JPL. "By exploring Psyche, we'll learn about the formation of the planets, how planetary cores are formed and, just as important, we'll be exploring a new type of world. We've looked at worlds made of rock, ice and of gas, but we've never had an opportunity to look at a metal world, so this is brand new exploration in the classic style of NASA."

But getting to Psyche won't be easy. It requires a cutting-edge propulsion system with exceptional performance, which is also safe, reliable and cost-effective. That's why the mission team has turned to NASA Glenn Research Center in Cleveland, which has been advancing solar electric propulsion (SEP) for decades.

SEP thrusters use inert gases, like xenon, which are then energized by the electric power generated from onboard solar arrays to provide gentle, non-stop thrust.

"For deep space missions, the type and amount of fuel required to propel a spacecraft is an important factor for mission planners," said Carol Tolbert, project manager for Psyche thruster testing at NASA Glenn. "A SEP system, like the one used for this mission, operates more efficiently than a conventional chemical propulsion system, which would be impractical for this type of mission."

The reduced fuel mass allows the mission to enter orbit around Psyche and provides additional space for all of the mission's scientific payload. Psyche's payload includes a multispectral imager, magnetometer, and gamma-ray spectrometer. These instruments will help the science team better understand the asteroid's origin, composition and history.

Additional benefits of SEP are flexibility and robustness in the flight plan, which allow the spacecraft to arrive at Psyche much faster and more efficiently than it could using conventional propulsion.

For this mission, the spacecraft, which will be built jointly by JPL and Space Systems Loral (SSL), will use the SPT-140 Hall effect thruster. Because Psyche is three times farther away from the Sun than Earth, flying there required a unique test of the low-power operation of the thruster in the very low pressures that will be encountered in space.

The mission team called upon NASA Glenn, and its space power and propulsion expertise, to put the mission's thruster through its paces at the center's Electric Propulsion Laboratory.

"This mission will be the first to use a Hall effect thruster system beyond lunar orbit, so the tests here at Glenn, which had never been conducted before, were needed to ensure the thruster could perform and operate as expected in the deep space environment," said Tolbert.

The facility at NASA Glenn has been a premier destination for electric propulsion and power system testing for over 40 years and features a number of space environment chambers, which simulate the vacuum and temperatures of space.

"This was very important to the mission because we want to test-like-we-fly and fly-like-we-test," said Oh. "Glenn has a world-class facility that allowed us to go to very low pressures to simulate the environment the spacecraft will operate in and better understand how our thrusters will perform around Psyche.

"At first glance, the results confirm our predictions regarding how the thruster will perform, and it looks like everything is working as expected. But, we will continue to refine our models by doing more analysis."

As the team works toward an anticipated August 2022 launch, they will use the data collected at NASA Glenn to update their thruster modeling and incorporate it into mission trajectories.

The scientific goals of the Psyche mission are to understand the building blocks of planet formation and explore firsthand a wholly new and unexplored type of world. The mission team seeks to determine whether Psyche is the core of an early planet, how old it is, whether it formed in similar ways to Earth's core, and what its surface is like. For more information about NASA's Psyche mission, visit:

http://www.nasa.gov/psyche

« Last Edit: 10/02/2017 04:02 PM by Star One »

Tags: asteroids Psyche Lucy