IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
Halley's Comet orbiter
Tom Womack
post Feb 2 2015, 04:02 PM
Post #1


Junior Member
**

Group: Members
Posts: 22
Joined: 3-January 07
Member No.: 1551



How hard is it (in delta-V terms) to launch a probe into orbit around Halley's Comet?

The orbit is obviously very eccentric; also inclined and retrograde. From the example of Ulysses, a suitable Jupiter flyby can put you into an orbit which is inclined, retrograde, and with aphelion at Jupiter, but I have no idea how hard it is then to raise aphelion and lower perihelion to match the comet.

It sounds the sort of thing that an orbit-designer would have done as an example at some stage, but I can't immediately find it on the Web.
Go to the top of the page
 
+Quote Post
Explorer1
post Feb 2 2015, 05:05 PM
Post #2


Senior Member
****

Group: Members
Posts: 1449
Joined: 13-February 10
From: Ontario
Member No.: 5221



I checked on this once, but most of the stuff about the 2061 apparition deals with observing details from Earth.
Ray Villard has a bit of layman's speculation to discuss a possible follow-up to the '86 armada: http://news.discovery.com/space/astronomy/...omet-130903.htm
At least there's plenty of time to plan it out....
Go to the top of the page
 
+Quote Post
Paolo
post Feb 2 2015, 06:05 PM
Post #3


Senior Member
****

Group: Members
Posts: 1593
Joined: 3-August 06
From: 43° 35' 53" N 1° 26' 35" E
Member No.: 1004



I remember reading a few papers published in the 60s and early 70s calling for a Halley orbiter using a nuclear electric propulsion stage and Jupiter flyby to enter a retrograde solar orbit and finally rendezvous with the comet in the 80s...
Go to the top of the page
 
+Quote Post
tasp
post Feb 2 2015, 06:19 PM
Post #4


Member
***

Group: Members
Posts: 901
Joined: 30-January 05
Member No.: 162



It didn't progress very far, but there was some interest in a solar sail propelled craft to rendezvous ('orbit' probably being not quite exactly the right term) with Halley in '86.

http://science.nasa.gov/science-news/scien...jul_solarsails/
Go to the top of the page
 
+Quote Post
elakdawalla
post Feb 2 2015, 06:35 PM
Post #5


Administrator
****

Group: Admin
Posts: 5045
Joined: 4-August 05
From: Pasadena, CA, USA, Earth
Member No.: 454



Indeed, and Lou Friedman has been trying to get a solar sail into space ever since!


--------------------
My blog - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
Go to the top of the page
 
+Quote Post
K-P
post Feb 2 2015, 06:41 PM
Post #6


Junior Member
**

Group: Members
Posts: 27
Joined: 27-September 07
From: Tampere, Finland
Member No.: 3919



QUOTE (Tom Womack @ Feb 2 2015, 06:02 PM) *
How hard is it (in delta-V terms) to launch a probe into orbit around Halley's Comet?


Not quite so hard as to find a rationale to launch a probe especially to Halley instead of hundreds of more interesting objects.


--------------------
Spamming the Solar System with greetings since 1997!
(New Horizons, Huygens, Opportunity/Spirit, Deep Impact, Dawn, Phoenix, Selene... to name a few) :)
Go to the top of the page
 
+Quote Post
Explorer1
post Feb 2 2015, 06:47 PM
Post #7


Senior Member
****

Group: Members
Posts: 1449
Joined: 13-February 10
From: Ontario
Member No.: 5221



A famous comet, an opportunity to compare and contrast changes between perihelion from the last visits? Seems like as good reason as any.
We don't know what the science priorities will be in the 2050s, at any rate...
Go to the top of the page
 
+Quote Post
SFJCody
post Feb 2 2015, 07:20 PM
Post #8


Member
***

Group: Members
Posts: 810
Joined: 8-February 04
From: Arabia Terra
Member No.: 12



Rather than Halley, I think it would be a good idea to build a long-period comet flyby spacecraft. It could be prepared with no specific target in mind and launched when an incoming body that can be intercepted is identified. Given the cadence of these things it shouldn't take too long.
Go to the top of the page
 
+Quote Post
ngunn
post Feb 2 2015, 08:52 PM
Post #9


Senior Member
****

Group: Members
Posts: 3434
Joined: 4-November 05
From: North Wales
Member No.: 542



QUOTE (SFJCody @ Feb 2 2015, 07:20 PM) *
I think it would be a good idea to build a long-period comet flyby spacecraft. It could be prepared with no specific target in mind


An excellent idea. All sorts of exciting possibilities come to mind for such a project. For example by picking a sungrazer comet you could hitch a ride really close to the Sun, always keeping the craft in the shade of the nucleus. (A fast and deep perihelion is a good platform from which to launch an interstellar probe, but that's a whole other topic and I don't want to digress too much - anyone interested should look up 'sundiver' missions.)

EDIT: I think that a long period comet catcher is the sort of imaginative idea that The Planetary Society could consider promoting, maybe by sponsoring a mission design competition? Just a thought.
Go to the top of the page
 
+Quote Post
djellison
post Feb 2 2015, 10:03 PM
Post #10


Administrator
****

Group: Chairman
Posts: 14018
Joined: 8-February 04
Member No.: 1



We already designed, built and launched such a mission - it was called CONTOUR. It, sadly, was lost as it fired a motor to leave Earth orbit - but its extended mission was explicitly to do flybys of newly discovered long period comets.
Go to the top of the page
 
+Quote Post
dmuller
post Feb 3 2015, 02:27 PM
Post #11


Member
***

Group: Members
Posts: 334
Joined: 11-April 08
From: Sydney, Australia
Member No.: 4093



Stumbled over this, although Halley and the 2060s arent quite in there (yet?)
http://trajbrowser.arc.nasa.gov/index.php


--------------------
Go to the top of the page
 
+Quote Post
Gerald
post Feb 3 2015, 02:46 PM
Post #12


Senior Member
****

Group: Members
Posts: 1881
Joined: 7-December 12
Member No.: 6780



QUOTE (ngunn @ Feb 2 2015, 09:52 PM) *
... For example by picking a sungrazer comet you could hitch a ride really close to the Sun, always keeping the craft in the shade of the nucleus. (A fast and deep perihelion is a good platform from which to launch an interstellar probe, but that's a whole other topic and I don't want to digress too much - anyone interested should look up 'sundiver' missions.)

I guess(timate), that's the most challenging version of accompanying a comet in terms of delta-v, and in terms of short-term mission planning, since sungrazers use to come straight from the Oort cloud. But one could rapidly sample the interior of a prestine nucleus as it decomposes near the Sun.
Go to the top of the page
 
+Quote Post
SFJCody
post Feb 3 2015, 05:44 PM
Post #13


Member
***

Group: Members
Posts: 810
Joined: 8-February 04
From: Arabia Terra
Member No.: 12



QUOTE (djellison @ Feb 3 2015, 09:03 AM) *
We already designed, built and launched such a mission - it was called CONTOUR. It, sadly, was lost as it fired a motor to leave Earth orbit - but its extended mission was explicitly to do flybys of newly discovered long period comets.


Arrgh, I'd forgotten the CONTOUR extended mission plans! Such a big loss. Someone needs to propose a similar mission.
Go to the top of the page
 
+Quote Post
Paolo
post Feb 3 2015, 06:06 PM
Post #14


Senior Member
****

Group: Members
Posts: 1593
Joined: 3-August 06
From: 43° 35' 53" N 1° 26' 35" E
Member No.: 1004



two extracts from my series of books on solar system exploratio.
on the Halley orbiter:

QUOTE
Halley’s comet first raised the interest of the astronautics community in 1967, when the Lockheed Missile and Space Company in the United States made the first study of interception and rendezvous missions. A spacecraft could be placed into a similar orbit around the Sun to the comet, to make a slow-speed rendezvous with it. However, since the spacecraft would inherit the direction of Earth’s travel around the Sun, it would have to maneuver into a retrograde orbit. There were a number of options for achieving this: (1) by firing a conventional chemical engine to deliver a brief impulse near aphelion, although the propulsion requirements to perform such a maneuver would be extremely high; (2) by firing a low-thrust engine for a long time to deliver a small but constant thrust to shape and then reverse the orbit; (3) a near-polar flyby of Jupiter or Saturn. Rejecting the first option owing to its deep-space propulsion requirements, NASA then elaborated on the alternatives. A small spacecraft could be launched in 1977 or 1978 by a Saturn V with a Centaur upper stage and a Jovian ‘slingshot’ used to deflect the probe into a retrograde orbit that would intersect the comet’s orbit 5–8 months prior to its perihelion. A small burn would then put the craft into a Halley-centric orbit. Beside requiring the expensive Saturn V launch vehicle, for which production was limited, this plan was rendered unrealistic by the long time of at least 7 years in flight prior to the encounter. The alternative was a probe equipped with ion thrusters powered by either solar panels or a nuclear generator. After being placed into an eccentric solar orbit, this would gradually reduce its speed, and finally, when far from the Sun, make a maneuver to adopt retrograde motion. On heading back towards the inner solar system, it would encounter the comet 2–3 months prior to its perihelion. But such a flight would still take about 7 years, and because solar panels would generate very little power at the heliocentric distance of the reversal maneuver they would need to be inordinately large. A nuclear spacecraft would be able to run its ion engine essentially all of the time, which would cut the flight time to less than 3 years, but it would involve the development of a nuclear generator for use in space.


on long-period comet flyby:

QUOTE
It is recognized that long-period comets must be the most pristine material in the solar system, as they rarely, if ever, undergo solar heating at perihelion, but there are many factors that make them some the most difficult targets to explore:

Their apparitions are unpredictable. The comet possessing the longest known period is 153P/Ikeya-Zhang. Its period is 341 years, only two perihelia have been observed, and its return had not been predicted.

They have random inclinations relative to the ecliptic. Encounters designed to occur near their orbital nodes may involving flying a spacecraft far from both the Sun and Earth.

The Earth-comet-spacecraft geometry at the encounter may be unsatisfactory.

Several months of observations are needed before the comet can be verified to be a true long-period one, and its orbit determined with sufficient accuracy to compute an intercept mission.

Because they are usually discovered only a few months prior to perihelion, a mission would have to be launched soon and its flight time would need to be short.

For the same reasons, planners cannot rely on planetary gravity assists.

Despite all of these constraints, studies since the 1980s have shown that even at the rate at which comets were being discovered at the time at least one suitable flight opportunity every year should be expected.1 Given the much higher discovery rate nowadays, many more opportunities can be expected. For example, no fewer than 25 new long-period comets were discovered in 2004, as against just five in 1984. Small probes are probably particularly suited to flyby missions to long-period comets. They could be kept in storage waiting for a target to appear, with storage costs estimated at about $100,000 per year. A small launcher like the US Pegasus or a Russian recycled ballistic missile that was actually designed for long-term storage could be used.
One of the best opportunities for such an intercept mission was presented in 1997 with comet C/1995 O1 Hale–Bopp. With a nucleus estimated at 40 km in diameter, it was one of the intrinsically brightest comets ever observed. It was discovered in July 1995, almost 2 years prior to its perihelion of May 1997, and has an orbital period in excess of 4,000 years. One of the nodes of its orbit was at a heliocentric distance of 1.1 AU, which was conveniently just a little more than the distance of Earth from the Sun. Profiles have been computed for a hypothetical mission that could have set off in early 1996 to intercept the comet at that node. The mission would have used a tiny 150-kg spacecraft carrying only a wide-field camera and a magnetometer in order to collect data on one of the most scientifically interesting bodies ever discovered. It will also be remembered that the failed CONTOUR could easily have been retargeted to encounter a long-period comet if a suitable target had appeared after the spacecraft had achieved its main mission. Had CONTOUR been in space in 1997, it could have encountered Hale–Bopp. Another good candidate for an encounter would have been comet Lulin, which was discovered in July 2007 and had perihelion in early 2009. Its orbit showed little indication of ever having interacted with planets, so it might have been making one of its earliest forays into the inner solar system. It would have been an easy target since its orbit is almost coincident with the ecliptic, but its retrograde direction would have yielded a very high relative speed at encounter.
A mission to a long-period comet would probably answer one of the fundamental questions in the study of the solar system, namely whether the different classes of comets – Jupiter-family objects, Centaurs, objects from the Kuiper Belt or the Oort Cloud – have different chemical, isotopic, and physical characteristics. We now have obtained a significant amount of data for a large number of objects by ground-based and space-based observatories, and a handful of encounters in space, but as yet there is no correlation between the dynamics of a comet and its chemistry.
Missions to long-period comets were mentioned in the first decadal survey, where their necessary synergy with ground-based telescopes was remarked. The report noted that either the discovery capabilities of comets at large distances from the Sun would need to be dramatically improved or a ready-to-go spacecraft would have to be stored on the ground or in solar orbit. A Discovery-class mission was mentioned again in the second decadal survey.


finally, remember that with Siding Spring at Mars we just had a sort of long-period comet flyby
Go to the top of the page
 
+Quote Post

Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 23rd October 2017 - 12:57 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.