New Worlds Mission
The New Worlds Mission is a proposed project comprising a large
Purpose
Currently, the direct detection of
- Exoplanets appearing extremely close to their host stars when observed at astronomical distances. Even the closest of stars are several arcseconds. Angles this small are impossible to resolve from the ground due to astronomical seeing.
- Exoplanets being extremely dim compared to their host stars. Typically, the star will be approximately a billion times brighter than the orbiting planet. This makes it nearly impossible to see planets against the star's glare.
The difficulty of observing such a dim planet so close to a bright star is the obstacle that has prevented astronomers from directly photographing exoplanets. To date, only a handful of exoplanets have been photographed.
To overcome the difficulty of distinguishing more Earth-like planets in the vicinity of a bright star, the New Worlds Mission would block the star's light with an
Methods
Traditional methods of exoplanet detection rely on indirect means of inferring the existence of orbiting bodies. These methods include:
- Astrometry – watching a star move slightly due to the gravitational influence of a nearby planet
- Observing Doppler shifts of the star's spectrum due to the star's movement
- Observing the amount of light from a star change as an extrasolar planet transits the star, preventing a portion of the light from reaching the observer
- Pulsar timing
- Gravitational microlensing
- Observing radiation from circumstellar disks in the infrared
All of these methods provide convincing evidence for the existence of extrasolar planets, but none of them provide actual images of the planets.
The goal of the New Worlds Mission is to block the light coming from nearby stars with an occulter. This would allow the direct observation of orbiting planets. The occulter would be a large sheet disc flown thousands of kilometers along the line of sight. The disc would likely be several tens of meters in diameter and would fit inside existing expendable launch vehicles and be deployed after launch.
One difficulty with this concept is that light incoming from the target star would
This technique would make planetary detection possible for stars within approximately 10
The starshade is a
Objectives
The New Worlds Mission aims to discover and analyze terrestrial extrasolar planets:
- Detection: First, using the space telescope and 'starshade', or occulter, exoplanetary systems will be directly detected.
- System mapping: Following detection, system mapping would involve the direct mapping of planetary systems through the detection of the planetary light separate from the parent star. In a sufficiently high-quality image, planets would appear as individual star-like objects. A series of images of the planetary system would allow measurements of planetary orbits, and the brightness and broadband colors of the planets would provide information about their basic nature.
- Planet studies: At this stage, detailed study of individual planets would take place. With a low noise level and a modest signal, . Photometry will show variation in color and intensity as surface features rotate in and out of the field of view, allowing for the detection of oceans, continents, polar caps and clouds.
- Planet imaging: A large increase in capability is needed to achieve true planet imaging. However, techniques of inclination.
- Planetary assessment: The final step in extrasolar planet studies would be the ability to study these distant worlds in the same way that Earth-observing systems study the Earth's surface. Such a telescope would need to be extremely large, to collect enough light to resolve and analyze small details on the planet's surface. However, these kinds of studies do not lie in the foreseeable future, for it takes square kilometers of collecting area to capture the needed signal.
In addition to finding and analyzing terrestrial planets, it can also discover and analyze
Architecture
There are many possibilities for various New Worlds Missions, three of which are:
- New Worlds Discoverer proposed to use an existing space telescope (like the James Webb telescope), to find exoplanets. The size of the starshade could be optimized for the observing telescope.
- New Worlds Observer would use two spacecraft, one that has a dedicated telescope and one with a starshade to find exoplanets. The possibility of two starshades is also a consideration. One starshade to point towards the desired target while the other moves into position for the next target. This would eliminate some of the time delay in observing different systems and allow for many more targets to be observed in the same timespan.[2]
- New Worlds Imager would use many spacecraft/starshades. This would allow observers to resolve the planet and obtain true planetary imaging.
See also
- Aragoscope
- Coronagraph, a telescopic attachment to block out the light from a star so that nearby objects can be resolved
- Space sunshade
References
- ^ a b CU Proposal To Image Distant Planets Is Funded For Second Round Of Study Archived July 2, 2014, at the Wayback Machine
- ^ a b The New Worlds Observer Archived 2016-11-18 at the Wayback Machine. (PDF) Dr. Webster Cash. University of Colorado, Boulder 2010.
- ^ New Worlds Technology Development for the New Worlds Observer Archived 2016-03-05 at the Wayback Machine, (PDF) Dr. Webster Cash. University of Colorado, Boulder 2011.
- ^ "The Extrasolar Planets Encyclopaedia". 2007-11-27. Archived from the original on 2007-12-04. Retrieved 2008-01-24.
- ^ a b Berger, Brian (December 4, 2006). "Northrop Grumman Concept Uses Shade to Find New Planets". Space. Archived from the original on 2009-05-25. Retrieved 2015-11-17.
- ^ Cash, Webster (January 23, 2015). "New space telescope concept could image objects at far higher resolution than Hubble". Phys Org. Archived from the original on 24 January 2019. Retrieved 26 January 2015.
- ^ "New Worlds Website". Archived from the original on 2019-06-02. Retrieved 2006-09-10.
- ^ "Starshade Specifications". Archived from the original on 2018-07-07. Retrieved 2015-11-17.