Starship Asterisk*

Orca wrote:New Horizons is the first probe with an ion engine, right?

The spacecraft was retired on December 18, 2001.

Doum wrote:There you have info about Deep space one probe and it's ion engine.

http://nmp.nasa.gov/ds1/

Orca wrote:The JPL site for New Horizons doesn't really discuss the propulsion system, by the way.

orin stepanek wrote:New Horizons passed the half way mark in distance from the Earth.

http://www.planetary.org/blog/article/00002313/ wrote:
Ted Stryk: Report #2 from New Horizons science team meeting

<<This morning, a major topic was the search for Kuiper belt object (KBO) targets. [New Horizons is planned to encounter at least one and as many as three small Kuiper belt objects following its Pluto encounter, but the ones it will encounter might not have been discovered yet. --ESL] There is only one known KBO currently being considered. It has a radius of about 30 kilometers and is magnitude 25.3. The problem in finding targets is that Pluto is passing through the galactic plane, meaning that the background star fields are extremely dense. Searchers are using the Subaru telescope to look for objects against the dark nebulae that block out many of these stars, but it is difficult to track the objects they find once they are no longer in front of the dark nebulae. Right now they are using Subaru's "Suprime" array of 10 CCDs for their search. By the end of the year, a new camera, "Hyper-Suprime," should be available. It has an array of 116 CCDs, each of which covers the same area as the individual CCDs in the original Suprime. This will help to quickly search much more sky (and take images that are a whopping 2 gigabytes each). Unfortunately they did not provide the specific field of view of these instruments.

Meanwhile, another team is looking for KBO targets and is using the dense star fields to its advantage, using the Hubble Space Telescope Fine Guidance Sensors to look for occultations and then trying to recover any occulting objects. They have already had one success, but it is 14 degrees out of the ecliptic.

The team is also using Suprime to look for Neptune Trojans that

New Horizons can observe when it passes through Neptune's L5 point in 2014.

[No Neptune Trojans] are known because no one has looked for them, but they theoretically should exist. Even if they are found, New Horizons will most likely not be able to resolve them as anything more than one pixel. New Horizons might at least provide phase curve data. It would take a huge stroke of luck to get anything better, since actually targeting one of these objects would mean diverting the trajectory away from Pluto. There was also an attempt to recover the potential Himalia ring, but this was not successful.

There was a paper showing New Horizons' results as it flew down the Jovian magnetotail, the first spacecraft to do so.

Dale Cruikshank attempted to look for evidence of methane on Triton in spectra taken in the 1940s by Gerard Kuiper. Unfortunately, an observing assistant – "Brown" (his first name is not recorded) – apparently obscured the portion of the spectrum where methane would appear with a fingerprint, rendering it useless. Cruikshank pointed out that this is likely why we haven't heard of "Brown." However, recent spectra taken with Akari, a Japanese space telescope operating in the red, clearly shows evidence of methane and of HCN. The HCN is thought to be produced in the atmosphere. Spitzer and Voyager's infrared instrument are not sensitive to the band observed. This band shows reflected sunlight, not thermal emissions. Will Grundy showed spectroscopic work indicating that methane, while present globally on Triton, is concentrated in a spot at about 300 degrees longitude and likely in the mid-to-high southern latitudes. This corresponds to a unique pink spot in Voyager data.

Francesca DeMeo showed recent evidence she has obtained showing ethane to be present on Pluto. Several people presented atmospheric results from occultations, showing that the atmosphere has greatly increased in pressure since the first good occultation observation in 1988. There are two good occultations this year, the first on Valentine's Day and visible from Europe, and the second, on July 4th, will be visible from South America and Africa.>>

neufer wrote:Unfortunately, an observing assistant – "Brown" (his first name is not recorded) – apparently obscured the portion of the spectrum where methane would appear with a fingerprint, rendering it useless. Cruikshank pointed out that this is likely why we haven't heard of "Brown."

neufer wrote:

http://www.planetary.org/blog/article/00002313/ wrote:
Ted Stryk: Report #2 from New Horizons science team meeting

• Memorable quotes for Airplane! (1980)
  .........................................................
  Rumack: Can you fly this plane, and land it?
  
  Ted Stryker: Surely you can't be serious.
  
  Rumack: I am serious... and don't call me Shirley

Another milestone passed! Today NASA’s New Horizons spacecraft is 15.96 astronomical units (about 2.39 billion kilometers, or 1.48 billion miles) from the Sun – putting it halfway between Earth’s location on launch day in January 2006, and Pluto’s place during New Horizons’ encounter with the planet in July 2015.

“From here on out, we’re on approach to an encounter with the Pluto system,” says New Horizons Principal Investigator Alan Stern, from the Southwest Research Institute. “The second half of the journey begins.”

This is rare territory; New Horizons is just the fifth probe, after Pioneers 10 - 11 and Voyagers 1 – 2, to traverse interplanetary space so far from the Sun. And it’s the first to travel so far to reach a new planet for exploration.

Humming along at more than 16 kilometers per second – more than 36,600 miles per hour - the spacecraft will next cross a planetary boundary in March 2011, when it passes the orbit of Uranus.

bystander wrote:

http://pluto.jhuapl.edu/news_center/news/20100225.php wrote: New Horizons is just the fifth probe, after Pioneers 10 - 11 and Voyagers 1 – 2, to traverse interplanetary space so far from the Sun. And it’s the first to travel so far to reach a new planet for exploration.

neufer wrote:Make that Dwarf planet.

Chris Peterson wrote:

neufer wrote:Make that Dwarf planet.

It would require a truly bizarre sort of logic to conclude that a "dwarf planet" isn't also a "planet".

In the context of the original passage, "dwarf planet" would be a poor choice, since the comparison was being made between the distance that New Horizons has traveled in its goal to reach a particular planet, and the distance that other probes traveled to reach different planets.

This provides an excellent example of just why "planet" is more useful without a rigorous definition. If planet actually meant only what the IAU has defined it as (which, of course, it doesn't), it would require a cumbersome sentence to say what was said simply- and completely clearly- in the referenced passage.

orin stepanek wrote:I'll always think of Pluto as a planet.
I think of other so called dwarfs as planets as well; Eris, Sedna, and others.