New Horizons 2, Backup mission Options

[SFJCody]

After the JGA to Uranus opportunity closes, when will the option of a useful JGA to Saturn, Uranus or Neptune next present itself?

[Guest_BruceMoomaw_*]

"After the JGA to Uranus opportunity closes, when will the option of a useful JGA to Saturn, Uranus or Neptune next present itself?"

As a matter of fact, a Jupiter/Neptune opportunity opens up only a year later (Jupiter-assisted flybys to Uranus or Neptune are possible about every 12 years, with a 2 or 3-year window). The next Jupiter/Saturn opportunity starts in, I believe, 2015 -- those come along every 20 years, again with a several-year window. Unfortunately, there seem to be no Saturn/Uranus or Saturn/Neptune opportunities for a long time.

By the way, not only is now possible to get a modest-sized flyby craft to one of the planets beyond Jupiter without a Jupiter flyby in a reasonable period of time -- consider the emergency 2007 backup plan for New Horizons -- but, if you're willing to attach a solar-powered ion drive that shuts down and detaches partway through the Asteroid Belt, you can send quite a large craft to one of those worlds without a Jupiter flyby and then aerocapture it into orbit around that world. Alternatively, you can attach such a drive to a craft that simply flies by its targets without stopping, and then have it utilize its huge solar panels to provide the craft itself with all the electrical power it needs throughout its entire mission, without having to carry along an RTG and its plutonium with all the resulting safety and political problems. JPL designed just such a mission back in the early 1990s that would have flown by Uranus AND Neptune AND several KBOs, and could have dropped off entry probes at the two planets. Unfortunately, that window of target opportunities has since slammed shut -- just as a splendid opportunity to have New Horizons itself make a very close flyby of either Io or Europa was lost due to Goldin's stupidly imposed launch delay on a Pluto probe from late 2003 to early 2006.

[Alan Stern]

Bruce,

I agree about the lost opportunity for deep-penetration Galilean satellite system flybys
had a Pluto mission been launched between 2001 and 2004. Oh well, the good
news is we get a magnetotail exploration possibly out to 1000 Rj which was
not possible for the earlier (sharper turning) arrivals.

That said, I believe you are incorrect about some other things. The JGA-Neptune
window CLOSES in 2007 for about 8-9 years. The JGA-Saturn opportunity opens
about 2010.

...And as to aerocapture-- no one has done it-- ever, and it's not easy--
either thermally or navigationally (during entry/exit). The same applies to solar
arrays beyond 4-5 AU: it's not just the huge size and mass, but the cold
temps the arrays have to run at. We almost ran a tech demo of a few Gallium
cells on NH just to see if they could be made to work far out, as a part of
our EPO, but the Student Dust Counter idea won out instead.

-Alan

[clemmentine]

The PowerPoint Dr. Stern mentioned several posts back is definitely worth reading. It lists several mission scenarios with the Uranus flyby and an example Uranus flyby geometry. Thanks for making it available to us.

Since there is a Jupiter-Neptune opportunity that closes in 2007 (soon after the launch of NH 1), has there been consideration for such a mission? The reason I ask is because there seems to be more interest in Neptune than in Uranus at the present time. Maybe going to Neptune is an easier sell to NASA? Or is there just not enough time to get a Jupiter-Neptune-KBO mission ready for 2007?

Thank you for your time.

- c

[Guest_BruceMoomaw_*]

The answer is the latter -- simply not enough time to get an NH 2 ready by 2007, even if it's funded at all. Two possible contributing factors, however, are:

(1) The 2008 Uranus mission would allow a look at Uranus close to its equinox -- whereas any later Uranus flyby or orbiter will find Uranus in the position with its north pole mostly pointed at the Sun, as its south pole was during the Voyager 2 flyby. An equinoctial flyby would allow us to observe Uranus' weather patterns during such a period (when they seem to be radically different from those in its solstice periods), and would also give us an improved look at the same sides (southern) of its moons seen by Voyager -- whereas a later mission would be able to see only their north sides, with their south sides completely night-shrouded. By contrast, you can get an equally good look at Neptune whenever you choose to visit it.

(2) The 2008 Uranus flyby allows us to set up an NH 2 flyby of an especially large -- and binary -- known KBO (in addition to whatever smaller ones we discover in the meantime, as with NH 1).

I'm not sure that I find these reasons for NH2 adequate to justify spending so much money on it as opposed to other space science missions -- the case is much less clear-cut than with NH 1, where any delay in a Pluto mission managed to simultaneously inflate its cost AND sharply reduce its science output and chances of success. A later Uranus mission equipped with 1 or 2 entry probes -- despite its higher cost than NH 2 (whose cost is lessened by the fact that it's an immediate near-duplicate of NH 1), and the fact that it would miss an equinoctial examination of Uranus and its moons -- might well, on balance, still be more scientifically cost-effective than NH 2. Still, the initially listed points do exist as possible selling points for this mission.

[tedstryk]

I think that there is a clear justification, as it would allow coverage of both the northern and southern hemispheres of Uranus and its moons, and with an instrument like LORRI, this would somewhat makeup for the speed of the flyby in terms of obtaining global coverage. I have placed two links to my recent work that I posted in the Cassini forum, one to my new page on Umbriel and the other to the composite image I created for the page. It was a reminder of just how poor our coverage of the Uranian moons is. Granted, coverage of Ariel and especially Miranda is better, but both could stand to be improved. And some closeup weather coverage during equinox would also be interesting. Unlike Neptune, which is sure to get an orbiter sooner or later, and can better justify one since it has Triton, which, in addition to being interesting, can be used to modify the orbiters path to encounter the smaller moons and change its orbital plane. A Uranian orbiter, it would seem, would need a prohibitive amount of fuel. In other words, this may be our only chance in our lifetimes to get a better view of the Uranian system.

http://pages.preferred.com/%7Etedstryk/umbriel.html
http://i149.exs.cx/img149/5645/umbrielcombo9ci.jpg

[Alan Stern]

My view is that NH2 is an opportunity-- low hanging fruit if you will. We
can seeze it and have a second KB mission by 2020, a revolutionary Uranus dataset
in 2014-2015, and another crack at Jupiter and the satellites about 2010,
or we can wait until Uranus orbiters with probes, Kuiper Belt orbiters,
and the budgetary tooth fairy appear. I'm continually amazed at how many of
my colleagues in the outer planets communty would rather have no
mission than one they do not consider the ultimate mission.

[Redstone]

Alan, what would the deadline for NH2 approval be in order to make the 2008-09 launch windows? If you are just planning on copying NH1, then would you still need to go through the process of PDR, CDR, EIS etc?

Also, I note in the ppt presentation NH2 is described as using an Atlas V 551 or cheaper launch vehicle. Are some of the mission options viable with an Atlas 541 or 531? I know the launch vehicle is one of the biggest costs, so would saving a solid rocket or two may make it significantly easier to win support?

Best wishes for the EIS reviews.

[Alan Stern]

We have the design, the manufacturing specs, all the software, and
the ground and flight procedures, etc.-- inhereted from NH1. The pacing item
is the ELV-- one needs 30 months from contract, which means a fall 2005
start for the spring 2008 window or a year later for the spring 2009 window.
But caution-- 2009 is the last year for JGA-->Uranus at equinox.

As to the ELV, the C3 of the mission is only about 2/3 that of NH1, so
we can fly a smaller Atlas and save beau coup $$$$$.

-Alan

[djellison]

Is the smallest Atlas V much cheaper than the top notch single-core one that NH is using?

Perhaps scope to be a secondary payload on a Atlas V / Delta IV Heavy / Ariane 5 (swop the student dust-counter mass/volume/data budget for an instrument of european origin in exchange for a launch vehicle)
Doug

[Gsnorgathon]

Alan - best of luck (and skill!) to you on both missions. I'm really hoping NH2 gets off the ground in time to fly by Uranus. I'd really like to see the southern hemisphere of all those moons before I die...

The attitude of your colleagues toward "ultimate" missions is frustrating indeed. Suppose they'd pulled the plug on Voyager after Saturn - would we really be any closer to a Uranus/Neptune mission?

[Alan Stern]

From lfrench@iwu.edu Wed May 25 05:01:07 2005
Date: Thu, 19 May 2005 10:34:59 -0500
From: Linda French <lfrench@iwu.edu>
To: Recipient List Suppressed: ;
Subject: DPS #05-12: New Horizons 2

The New Horizons 2 (NH2) Uranus-KB mission effort plans for a new science
team, selected competitively by NASA.

A New Horizons 2 workshop will be held from 7 to 9 pm on Wednesday, June 8th.
This is the evening before the Boulder OPAG (Outer Planets Assessment Group)
meeting.

The goals of the NH2 workshop will be to ask for input to NH2 mission
objectives, the present the results of the NH2 study done this spring by NASA, and solicit desirable science team attributes for NH2.

The workshops will be held at the Southwest Research Institute's Department
of Space Studies, located at 1050 Walnut Street, Suite 400. This is
just 4 blocks from OPAG's Boulderado hotel site; see
http://www.boulder.swri.edu/officeinfo.html for maps.

Food and drinks will be provided. Interested participants should contact Carrie
Chavez at cchavez@mail.arc.nasa.gov to register.

[Bob Shaw]

Alan:

Are there any cost savings on a second spacecraft through the re-use of presently non-spaceflight certified components (such as structural test articles etc) from NH1? I'm thinking of, perhaps, the way Magellan used Voyager components, or even the rebirth of the Mars Observer camera.

Best of luck with the proposals, in any case!

[Alan Stern]

Alan:

Are there any cost savings on a second spacecraft through the re-use of presently non-spaceflight certified components (such as structural test articles etc) from NH1? I'm thinking of, perhaps, the way Magellan used Voyager components, or even the rebirth of the Mars Observer camera.

Best of luck with the proposals, in any case!

Bob- Well, the entire ground system, all of the subsystem and instrument
simulators, the ground and flight software, and the mission and payload
control centers will be reused. Additionally, much the second spacecraft is
available as spares.

Alan

[MiniTES]

Alan:
What is the significance of the workshop mentioned in that e-mail? At the risk of being premature, what do you think the chances currently are that NH2 will get off the ground? How soon does serious work have to start in order for NH2 to be able to lift off in 2007 for the JGA to Uranus? Is it possible that these plutionium issues over at Los Alamos could make it difficult to load the RTGs?